3.8 December 1979

A history of the project was prepared and was issued in the December 1979
monthly report to the TPO. This report also included data that was collected
during the signal propagation tests made in November 1977.

The preliminary report on environmental monitoring was revised to con-
form with decisions that were made at conferences during November.

3.9 January 1980

The major items of closed circuit television equipment, which were ordered
during the summer of 1979, and the prefabricated sub-assemblies for the air
quality monitoring room were delivered to the mine.

Installation of Vynal tubing for sampling airborne gases and particulate
matter was behind schedule due to the lack of man power that could be spared
from maintenance work in the mine.

A deficiency in radio communications was discovered in the substation that
is half way down the slope. Signals do not reach a working area that is behind
the power transformers. A passive signal booster consisting of either a reflec-
tor or two high gain Yagi antennas connected together will be installed in an
effort to improve communications.

The Project Engineer submitted a proposal to the TPO to design and con-
struct two way multi-channel signal boosters in conjunction with long trans-
mission lines and distributed antennas to solve the problem of communicating
with miners at the perimeter of the mine. This system could be extended in-
definitely as the perimeter of the mine is enlarged. A preliminary patent dis-
closure was submitted to the TPO since this concept might be patentable.

Mr. Henry Kramer joined Comsul Ltd., and was assigned as Assistant Project
Coordinator for this contract. He will assist Mr. Donald Parrish, Project Co-
ordinator.

61


APPENDIX C

TABLE 2 SIGNAL MARGINS MEASURED AT BASE STATION ABOVE GROUND OF
SIGNALS FROM TWO WATT TRANSCEIVER OPERATED IN A PICKUP TRUCK.

TABLE 3 SIGNAL MARGINS MEASURED AT BASE STATION IN RADIO AND
MONITORING EQUIPMENT ROOM OF SIGNALS FROM TWO WATT TRANSCEIVER
OPERATED ON TRACTOR IN WESTERN HALF OF THE MINE.

TABLE 4 SIGNAL MARGINS MEASURED AT BASE STATION IN RADIO AND
MONITORING EQUIPMENT ROOM OF SIGNALS FROM TWO WATT TRANSCEIVER
OPERATED ON TRACTOR IN EASTERN HALF OF THE MINE.

Page 1 of 6


2.4 Tests to Compare Communications on 812 and 466 MHz.

During November 1977, a series of signal strength measurements were
made in the Black River Mine on 466 and 812 MHz to obtain signal propagation
data in a room and pillar metal/non-metal mine. These measurements included
studies of vertical, horizontal and cross polarization in addition to measure-
ments of passive reflector performance. The data was summarized in the
December 1979 project history report and it was also summarized in a paper
by R.A. Isberg and R.L. Chufo. 2

The signal strength measuring equipment and base stations were located
in a large trailer van near Crusher No. 3. This location was near 115 volt
A.C. power and it also was near the outer perimeter of the mine affording a
large area of long intersecting crosscuts for the signal strength measure-
ments.

Signal strengths of 466 and 812 MHz radio transmissions received by
the base station receivers were simultaneously recorded on two channel strip
chart recorder and four channel instrumentation audio tape recorder. Modi-
fied signal quality modules from a receiver voting system were used for
measuring signal strengths above carrier quieting. Since the modules measured
audible noise, the carriers were not modulated during the measurements. The
receivers and voting modules were calibrated with signal generators and all
readings were in microvolts input to the receiver antenna receptacle.

An array of eight antennas was attached to a roof bolt at the center of
intersecting crosscuts 190S and 111E. Two 10dB gain Yagi antennas and one
unity gain omnidirectional antenna were used for tests on 466 MHz. Each
antenna was connected to a transmission line leading into the van where they
were connected to the base station receivers as required.

(2) Isberg, R.A. and R.L. Chufo, Passive Reflectors as a Means for Extending
UHF Signals Down Intersection Crosscuts in Mines or Large Corridors,
28th Conference Record IEEE Vehicular Technology Society, March 1978.

27


The views and conclusions contained in this docu-
ment are those of the authors and should not be inter-
preted as necessarily representing the official policies
or recommendations of the Interior Department’s
Bureau of Mines or of the U.S. Government.

Reference to specific brands, equipment, or trade-
names in this report is made to facilitate understanding
and does not imply endorsement by the Bureau of Mines.


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CONTROL STATION NEAR BASE OF SLOPE

PAGE 6 OF 8


FIGURE 3.15. CATV LINE AMPLIFIERS FOR THE "BACK BONE" COAXIAL CABLE SYSTEM
ARE ENCLOSED IN GASKETED WATER TIGHT CAST ALUMINUM HOUSINGS AND ARE SUPPORTED
BY STEEL MESSENGER CABLES.

FIGURE 3.16. TV MONITORS AND RADIO CONTROL EQUIPMENT IN THE HOIST HOUSE.

70


Following is a summary of the equipment and features of the radio system:

Three UHF two-frequency simplex channels in the Special Industrial Radio

Service are used as follows:

Channel Frequency Assigned Use
1. (1) 451.950/456.950 mHz Production, mine vehicles and supervisors
(2) 451.950/451.950 mHz Production talk-around simplex
2. (3) 452.175/457.175 mHz Maintenance and general utility and standby
(4) 452.175/452.175 mHz Maintenance talk-around simplex
3. (5) 452.025/457/025 mHz Slope car and loading dock to hoist operator
The numbers in parenthesis indicate channel selector switch positions on

mobile and portable radios.

Seven 12-watt UHF Motorola Micor tone controlled base/mobile repeater sta-

tions are used. All stations are provided with battery emergency power to sus-
tain operation for at least four (4) hours as required by safety regulations.

One

base/mobile repeater station operates on Channel 3 for communicating

in the slope. Six (6) of the stations operate on Channels 1 and 2 and are

equipped
system.
repeater

The
are:

with Spectra-Tac encoders for use with the received signal comparator
The best signal is selected and is relayed over the system. Each
station reverts to "in-cabinet" repeat in the absence of control tones.

Channel 1 and 2 repeaters are located in pairs at three sites, which

The radio room near the mine portal with one antenna covering the
mine property above ground and a Yagi antenna directed into the
slope for emergency communication with personnel in the slone.

The radio and monitoring room near crusher no. 2 where the base/
repeaters feed a distributed antenna system that covers the central
and western side of the mine.

Near crusher no. 3, where the base/repeaters feed distributed an-
tennas which cover the eastern half of the mine.

Each pair of transmitters feeds a hybrid combiner and uses a duplexer

81


for emergency alarms and automatic indentification. This
system would use channel 2 and it also could accommodate
one way tone and voice pagers.

7. Radio equipment for emergency communication might be avail-
able to the mine from the power company which operates the
nearby nuclear power plant. Plans for using such equipment
should insure compatibility with the existing system.

Conclusions

1. A UHF two-way radio communications system has been success-
fully implemented in the Black River room and pillar lime-
stone mine in accordance with Article 1, Scope of Work, of
Bureau of Mines, Contract No. J0377044.

2. The safe operation of UHF mobile radio transmitters in close
proximity to electric blasting caps that were loaded in a
rock face was demonstrated to mine personnel, representatives
of the Mine Safety and Health Administration and the Bureau of
Mines Pittsburgh Research Center. This demonstration alleviated
the apprehensions of miners regarding use of the radio system
in the mine in accordance with the provisions of IME 20,

3. The radio system has enhanced the safety of personnel, expedi-
ted the repair of equipment in the mine, improved efficiency,
and reduced delays and frustrations in communicating with key
personnel.

4. The closed-circuit television surveillance system has greatly
enhanced safety in the loading area at the base of the slope in
the mine. It has improved efficiency and reduced costs by afford-
ing crusher operators views of incipient rock jams at junctions
of the belt conveyor system in time to stop the system, thus
avoiding damage to the equipment and possible ignition of
belts due to friction.

5. The radio and CCTV systems that have been installed in the
Black River Mine are suitable for installing in other metal/
non-metal mines.

7


MINE MEASURED SIGNAL MARGIN
COORDINATES INPUT TO ABOVE 20 dBq
OF TWO-WATT RECEIVER (0.8 uV)

TRANSMITTER uV dB COMMENTS
193/91 30-45 29-33 At Face
193/91 100 40 Excellent
196/94 2-16 12-24 Excel lent
194/99 30-70 29-37 Excellent
200/94 100+ 40 Under Last Antenna
202/94 2-18 12-28 Excellent
205/91 2-10 12-20 Slightly Noisy But Satisfactory
202/93 2-5 12-14 Noisy And Marginal
199/93 2-10 12-20 Slightly Noisy Satisfactory
195/93 3-15 9-23 Satisfactory
199/99 20-80 26-38 Excellent
190/93 3-10 9-20 Satisfactory
190/94 4-15 12-23 Excellent
Near Damaged Reflector
188/93 2-10 6-20 Satisfactory
186/93 1-5 0-14 Noisy Marginal
185/93 1-5 0-14 Noisy Marginal
At Face
187/94 10-28 20-24 Excellent
188/97 10-16 20-24 Excellent
188/99 20-80 26-38 Excellent
188/99 40-100+ 32-40 Excellent
188/100 35 31 Excellent
188/102 40-100 32-40 Excellent
184/102 20-60 26-35 Excel lent
180/102 5-38 14-32 Excellent
180/101 2-10 6-20 Slightly Noisy Satisfactory
180/100 2-10 6-20 Slightly Noisy Satisfactory
180/102 34 31 Excellent
188/103 100+ 40+ Excellent
188/105 100+ 40+ Excellent
186/105 50-80 34-38 Excellent
183/105 15-40 23-32 Excellent
180/105 28 30 Excellent
180/105 Face 20 26 Excellent
180/106 5-10 14-20 Satisfactory
185/106 5-17 14-20 Satisfactory
188/107 12-55 21-35 Excellent
24-70 28-37 Excellent

Page 6 of 6


2V Trucks w/series—parallel switch

Starter

Electric System

24V Trucks
Electric System +
{lt

tk

t Rago

KA

I~

24V Loaders w/switched grounc

1

Electric System + Ie

Radio 4

tH

FIGURE 3.22

POWER CIRCUITS FOR MOBILE RADIOS ON MINE VEHICLES

76


The air shaft also provides an emergency exit to the surface in the event
that the slope cannot be used. The top of the shaft has an access hatch for
lowering a tubular metal escape bucket which is attached to a steel cable from
an electrical motor driven winch located in a hoist house approximately twenty
five feet from the air shaft. The following test results were obtained:

1. As expected, communications in the 450 MHz band is possible through a
straight limestone air shaft which is six feet in diameter and 650 feet
long. The transceivers were aligned near the axis of the air shaft
and polarization was approximately vertical.

2. Communication was ineffective through three foot diameter fan ducts
which join the air shaft at right angles.

3. Communication from the plenum chamber at the bottom of the air shaft
to the interior of the hoist house was surprisingly good. This might
have been due to the UHF induction into the hoist cable.

ESCAPE CAPSULE~_

ire —- HOIST HOUSE FOR AIR SHAFT
ESCAPE HATCH

TWO IMPELLER _ WINCH

FANS IN DUCTS

AIR PLENUM
CHAMBER IN
MINE

FIGURE 2.8 SKETCH OF AIR SHAFT USED AS EMERGENCY EXIT.

34


(18)

4. The results of these tests also are described in a report that
is available from the Mine Electrical Systems Branch of MSHA.
The conclusions from this report are quoted below:

"It is the opinion of the investigators that no hazard exists from
operating this communication system in the Black River Mine, if the
IME guidelines for radio transmissions around blasting caps are fol-
lowed.

"In compliance with IME Publication #20, The Mine Electrical Systems
Branch (MESB) also recommends that the mine establish a procedure to
insure that the radios will not be used any closer than 20 feet from

a blasting circuit". 19

Report No. M092479, "RF Hazards to Electrical Blasting Caps at
Black River Mine", MSHA Mine Electrical Systems Branch, 4800
Forbes Avenue, Pittsburgh, PA 15213.

ME Publication No. 20, Safety Guide for the Prevention of Radio

Frequency Radiation Hazards in the use of Blasting Caps, Institute
of Makers of Explosives, 420 Lexington Ave., New York, N.Y. 10017.

105


_—
CRUSHER NO. 2

CRUSHER NO. 3

oN o
AN
HOIST /

HOUSE
- — RADIO ROOM
y,

IN OFFICE
BUILDING

LEGEND

———o—————_ BACK BONE CABLE NO. 1 INSTALLED THROUGH SLOPE.
wenn nnn enna en o----- BACK BONE CABLE NO. 2 INSTALLED’ IN MINE.
mea or oea--—:--- BACK BONE CABLE ABOVE GROUND TO RADIO ROOM.

The circles in the cable represent multicouplers for
connecting multiplexing FM modulators or demodulators

—-e eee ROCK CONVEYOR BELT.

FIGURE 2.10 ORIGINAL PLAN FOR REDUNDANT BACK BONE COAXIAL CONTROL CABLE.

41


iS) LED

SIGNAL Ay D SIGNAL
SENSOR FILTER, PASS => SENSOR
456.95 &
R.F. TEST
NoD.c, 9 2 T 4574175 MHz 9 < RF. TEST
Pe ° Ss R, NO D.C.
Tx TO 5 c
IL HYBRID Se | Rx TO
wes w rsoLator| °® a Ky—<oase/
aa v. pec. Bl E rec ak Ri) REPEATER
' ga BE baat pc
' F FILTER, PASS a ae + Dae
' 2 451.956 LI] 9
1 <= |
1 n 4526175 MHz I
1 LED 2 F
1 '
1 '
LEGENDS
Aly Ay TRW CA 2820 Linear Hybrid Amplifiers mounted on TRW TFO6
test fixture assemblies.
D Phelps Dodge mobile duplexer Cat. No, 633-6 for 406 - 470 MHz
range.
Filter Band Pass Filters, Phelps Dodge PD-941 PB4
c Capacitor, 1000 mmfd, ceramic 100 volt.
cB Power splitter combiner, 0° phase shift, Mini Circuits
Model ZFSC-2-1.
E NEMA type 4 dust and water proof enclosure.
Fy Fy Type 3AG fuse and fuse holder.
LED Tx, Rx Light emitting diode, orange signal indicator.
P Light emitting diode, green, power "on" indicator.
Ry Type N receptacles for transmission lines to other antennas

or base station,

R2 UHF receptacle for test instruments (isolated from d.c.
voltage on center conductor).

FIGURE 3.12. SCHEMATIC DIAGRAM OF PROTOTYPE TWO-WAY UHF RADIO SIGNAL BOOSTER

The signal sensors will make it possible to visually verify that each
signal booster is operating by keying a portable or mobile transceiver while
observing the LED indicators. A more sophisticated signal sensing circuit
could be used which would report deviations from normal signal levels via a
pilot carrier to the control center. This type of circuit also could digitally
identify the signal booster or boosters having low output. This feature would
be useful in large systems having many signal boosters in series. However, the
mean time between failure for the CATV hybrid amplifiers is estimated to be
twenty years, so the reliability of the system should be adequate.

66


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27

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INADEQUATE SIGNAL
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CTOR OF THE MINE AND

FIGURE 2.9B DISTRIBUTED ANTENNA SYSTEM AS IT WAS ORIGINALLY INSTALLED IN THE EASTERN SE

THE COVERAGE IT AFFORDED.


3.17 October 1980

Six sets of aluminum chassis and brackets for constructing six UHF
two way radio signal boosters were fabricated and one chassis was punched
for the first production unit to verify the hole pattern for the latest
model.

The hole patterns for the NEMA Signal booster enclosures also were
finalized. All receptacles for cables and three LED indicators will be on
the bottom side of the enclosures and the cables connecting to the recep-
tacles will form drip loops to prevent condensed moisture from collecting
around the receptacles. A compliant gasket will be attached inside the
bottom side of the enclosure to seal the areas around the receptacle holes
when the chassis is in place. The chassis will be attached by machine
screws to the factory installed threaded studs in the enclosures.

A key operated security lock will be installed in the cover of each en-
closure and short chains will be attached by rivets to the lower side of
the cover and the enclosure. A transparent envelope will be attached to the
inner side of the cover and it will contain diagrams, maintenance data and
the FCC license.

The enclosures will be mounted on walls in the mine high enough above
the floor that they cannot be reached without using a ladder.

The three LED's under the enclosure will be visible to a person walking
or riding in a vehicle. One LED will glow indicating when 24 volt power is
on, one LED will glow when a signal from the base/repeater is being amplified,
one LED will glow when a strong signal from a portable or mobile is being re-
ceived. An improved signal sensing circuit has been developed and its sensi-
tivity will be adjustable.

Except for small hardware items and some receptacles, sufficient components
are on hand to complete three boosters. The other three signal boosters can-
not be completed until six TRW test fixtures or socket assemblies for the
CA2820 amplifiers have been acquired.

69


FIGURE 5.1

OPERATING PROCEDURES
FOR PORTABLE RADIOS IN THE
BLACK RIVER MINE, BUTLER, KENTUCKY

WEAK SIGNALS WILL BC IMPROVED IF RADIO 15 sex sur ere EAERGENCY ALAR S¥ITEX
MELO SO THAT ANTEAMA TS oT CLOSE O TOUR cLocewtst SPraKE SLIOE Ime SYITOH FORMED THE AXTEWA TO SEWD
ces (WOT CRITICAL) (wor UseD) (MX EMERGENCY CALL. THE RADIO'S IDENTIFICATION
anew aRRice SQUELCH CONTROL AUDIO JACK NUMBER (10) AND AUARM SIGNAL WILL_BE REPEATEDLY

TRANSMITTED UNTIL THE SWITCH 1S RELEASED. YOU
VILL NOT WEAR ANYTHING, BUT THE RADIO. THEN SENOS
TO ID/EMERGENCY MESSAGES. EVERY FIVE. SECONDS
FOR THIRTY SECONDS. TO STOP THE SEQUENCE EARLY,
TURN THE VOLUME CONTROL ON/OFF SWITCH TO THE
OFF POSITION MOMENTARILY AND THEN ON AGAIN: TO
RESUME NORMAL OPERATI

BATTERY STATUS AND TRANSMIT_INDICATOR

GLOWS WHEN PRESS-TO-TALK SWITCH IS. DEPRESSED.
THE LIGHT WILL BE OIM O8 WILL WOT GLOW

THE BATTERY WAS LESS. THAN SH CHARGE REMAINING.
REPLACE THE BATTERY WITHA FULLY CHARGED OME

IF THE LIGHT 15 OK QAVOFF SUITCH ANO VOLUME cOWTROL

TURN CLOCKMISE APPROXIMATELY HALF MAY AND ADJUST
SO VOICES ARE CASY TO UNDERSTAND. TURN OFF BY
ROTATING COUNTER CLOCKWISE TO CLICK STOP.

TOP VIEW OF MOTOROLA MK-300 RADIO.

SADIO CHANNEL SELECTOR SUITOH ASSIONMENTS OPERATING PRocE URES
a ppoUTION cnuwn. MINERS, AO HE 3. WAIN MAINTENANCE CHANKEL 15 USED BY FOREMAN 1. BEFORE TRANSMITTING, LISTEN TO_THE CHANNEL
Te OWAULY WILL Use CHANEL HC TaD RECHANICS AND, IKE CHANNEL 1, TT USES. TO BC SURE OTHERS ARC NOT USING IT,

Uses ve nOST OF THE HAULAGE REPCATERS. PROVIDING COMRNICAT ION THROUG
MNO TRAYEL ROUTES AND WORK AREAS. EHERGENCY THE NINE AND EMERGENCY ALARHS. ARE RECEIVED 2. THE PRESS-TO-TALK SWITCH asromricacy Senos
CALLS MILL BE RECEIVED INTHE SHOP OFFICE I THE SHOP AND ENGINEERING OFFICES. 1A TOME SIGHAL THAT IOENTIFIES YOUR RADIO EACH
[AND INTHE ENGINEERING OFFICE ABOVE. GROUND, TIME THAT TT 15 DEPRESSED SO WAIT ABOUT THO

4. LOCAL MAINTENANCE CHANEL. 15 USED BY FOREHAN SECONDS (TIMF RECUIRED TO COUNT TO YOURSELF
LOCAL PRODUCTION CHANNEL 1S USED BY MINERS BAD RECWINTS WA" KRE NEAR EACH OTHER AND OnE MUMORED OME, ONE HUNDRED THO" BEFORE
Wi) ARE-NCAR EACH OTHER ANO WEN THEIR WHEN THEIR COMMUNICATIONS. DOES: HOT HEED TO SPEAKING:
COMMUNICATIONS DOES NOT NEED TO BE HEARD BY BE HEARD BY OTHERS 1 THE RINE OR ABOVE GROUND. 3. WOLD THE SPEAKER/MICROPHONE APPROXIMATELY THO
DIMERS. INTHE MIME’ OR ABOVE GROUND. THIS. THIS CHANNEL DOES NOT USE THE REPEATERS 50 TWENES FROM LIBS, AND SPEAK. TOWARD THE. GRILL
CHANNEL DOES NOT USE THE REPEATERS 30 BE AE SURE TO SWITCH BACK TO CHANNEL 3. WHEN Hee eatiee WOnCre Mt Isuer MecEseAnt 70
SURE" TD SWITCH BACK. TO” CHANNEL 1. AMEN YOUR YOUR CONVERSATION IS FINISHED IN OROER. THAT SHOUT TEVENCAT NOISY LOCATIONS) AND YOO WILL
‘EORVERSATION TS FINISHED. IN OROER THAT YOU YOU CAN BE CALLED AKO YOUR EHERGENCY CALLS at BETTER UnDERS 1000.
Can BC CALLED AND YOUR. EMERGENCY CALLS ILL MILL BE RECEIVED IN THE SHOP AND ENGINEERING
BE RECEIVED IN THE’ SHOP ANO ENGINEERING OFF ices, 4 AvoIO uewessany coMVERSATION SO OTHERS CAN USE
orice THE RADIO C

3 3

WOLD SPEAKER/MICROPYOME
APPROXIMATELY. 2° FROM LIPS
AND SPEAK TOWARD GRILL IN

NORMAL VOLUME VOICE
ELTHER A MUFF=CO SPEAKER/
MICROPHONE THAT FITS. 1XS1D6
HARD HAT OR A HAND HELO

‘SPEAKER RICROPHONE. PLUGS.
AMTO THIS REPEPTACLE. TF
NEITHER DF THESE ARE’ comMEC-
TED USE THE INTERNAL SPEAKER
MICROPHONE AND SPEAK IN

NORMAL VOLUME VOICE APPROX!

MATELY 2° FROM THE GRILL,

‘ACK FOR

COMNECTING

TO AN EXTERNAL
ANTENNA.

PRESS-TO-TALK

(ry suitor

wry .

munst A —
SEERY BETZ, MOTOROLA PHOIEET LEADER,
Benoa wow TD SPEAK TO A MCaBPVONE
MEWILL BE GLAD TO. ANSWER YOUR QUSTIONS
foot oe A010 STSTER

waren

Ov To REPLACE BATTERY

TURN THE RADIO OFF.

WOLD THE RADIO. IN THE LEFT HAND AND PRESS THE
BATTERY RELEASE BUTTON WITH THE LEFT THM. tt

ROTATE THE BATTERY ABOUT 180 OEGREES, UNTIL THE BAT vERY
CAN LOCK IS CLEAR, AND REMOVE THE BATTERY PELEASE
TO REPLACE THE BATTERY, REVERSE THE
Fonsi EMGAGE THE Cue Lock THEN ROTATE THES
BATTERY CLOCKWISE UNTIL 17 LATCHES IM THE PROPER
POSITION. BE SURE TWE BATTERY ENGAGES THE SLOT
ON THE BOTTOM OF THE RADIO.

BATTERIES CAN BE RECHARGED EITWER MAILE IN THE,
RADIO OR WMEN THEY HAVE BEEN REMOVED. BATTERIES
SHOULD BE RECHARGED AFTER EACH SHIFT

6. WARNING: 00 NOT DISCARD OEFECTIVE BATTERIES 18
rrr

106


MINE MEASURED
COORDINATES INPUT TO SIGNAL MARGIN
OF TWO-WATT RECEIVER ABOVE 20 dBq

TRANSMITTERS uV (0.8 uV) dB COMMENTS
196/117 3-5 9-14 Satisfactory
196/117 3-5 9-14 Satisfactory
195/116 3-6 9-16 Satisfactory
193/116 2-4 6-14 Noisy
193/115 2-4 6-14 Noisy
197/116 3-6 9-16 Satisfactory
197/113 3-6 9-16 Satisfactory
194/111 5-10 14-20 Excellent
193/111 3-5 9-14 excellent
192/111 3-5 9-14 Air Compressor Excellent
192/111 5-10 14-20 Excellent
189/111 3-5 9-14 Excellent
189/111 26-33 28-30 Excellent
189/108 3-5 9-14 Excellent
189/118 4-10 12-20 Crusher Excellent
189/105 4-10 12-20 Excellent
192/105 2-6 6-16 Satisfactory
196/105 2-6 6-16 Satisfactory
199/105 2-5 6-14 Satisfactory
204/106 1-4 0-12 Noisy
204/102 24 27 Base of Slope
206/105 33-100 30-40 Under Antenna Excellent
206/117 3-10 9-20 Excellent
208/117 4-10 12-20 Excellent
211/117 4-6 12-16 Excellent
210/117 4-6 12-16 Excel lent
205/117 10-26 20-28 Excellent
205/120 4-6 12-16 Excellent
205/123 3-5 9-14 Satisfactory

Page 4 of 6


A survey was made of five locations where CCTV cameras are needed to
view transitions of the rock conveyor belts and equipment purchasing was
initiated.

As part of the preliminary work to design and provide an environmental
monitoring system in the mine, Bureau of Mine personnel conducted measure-
ments of the levels of carbon dioxide (CO,), hydrogen sulfide (HS), oxygen
(05) and particulate matter from diesel exhausts and smoke. A pneumtic
sampling system using Vynal tubing to carry the gas samples to the monitor-
ing equipment was proposed. During June 1979, Mr. James C. Cawley became

TPO for this project.

3.3 July-August _1979

During the months of July and August, radio equipment was installed in
all vehicles except the scaler, the repeaters near the slope and crusher
no. 3 and their associated distributed antennas were installed,and one leg
of the back bone cable was installed down the slope and through the mine.
The back bone cable system was completed except for the cable down the air
shaft and operating signal levels of the multiplexers were adjusted. Sig-
nal strength margins were measured in the mine from the channel 1 repeater
which feeds the distributed antenna system that extends into the mine from
the bottom of the slope. A signal strength chart along the principal haul-
age routes and travel roads was prepared on a mine map from these measure-
ments. These measurements proved that the distributed antenna concept is
sound and that coverage along the principal roads in the center of the mine
is approximately as predicted although signal strengths were not adequate
in active mining areas along the perimeter of the mine.

The original reflector at 130W and 205S produced a very noticeable en-
hancement of the signal in the intersecting crosscut 130E and 130W. The
measurements verified some of the measurements that were made in 1977 when
the reflector was first tested.

47


RADIO
EQUIPMENT
ROOM

ASH STO —
AREA

% :
. et cel
ye BORE HOLE _.- HOUSE OFFICE

Mics, BUILDING
= 4+ SE 2

LEGEND

———0—————__ BACK BONE CABLE NO. 1 INSTALLED THROUGH SLOPE.
7-7-7 ->->--O----- BACK BONE CABLE NO. 2 INSTALLED IN MINE.
Timm meme = BACK BONE CABLE ABOVE GROUND TO RADIO ROOM.

The circles in the cable represent multicouplers for
connecting multiplexing FM modulators or demodulators

-—s-TOr OT ROCK CONVEYOR BELT.

FIGURE 3.27 FINAL DESIGN OF BACK BONE CABLE SYSTEM

89


Figure

3.21

3.22

3.23

3.24A

3.24B

3.27

LIST OF ILLUSTRATIONS (Continued)

Schematic Diagram of Interface Unit for Motorola MODAT
Digital Identification and Status Encoder.

Schematic Diagram of Power Circuits on Vehicles to
Furnish 12 Volts D.C. to Radio... 2... ee ee ee

Interior of Radio and Monitoring Equipment Room Showing
Base Stations and Test Equipment Used for Measuring

Signal Margins from a Hand Held Transceiver... ......
Mine Map Showing Signal Margins Above 20dBq Measured at a
Base Station in the Monitoring Building From a Hand Held Two
Watt Transceiver Operated on a Vehicle in the Western Sector
of the Mine. ..... Se ee :
Signal Margin Above 20dBq Measured at a Base Station near
Crusher No. 3 from a Hand Held Two Watt Transceiver Operated
on a Vehicle in the Eastern Sector of the Mine. we
Base Station and Combiner Cabinets Near Crusher No. 3. . .

Combiner Cabinet With Door Removed to Show FM Modulators,
Demodulators, Combiner and Duplexer. ..........

Final Design of "Back Bone" Cable System. . . . .

Composite Block Diagram of Radio and CCTV Systems in
February 1981. ..... . Soe ee

Block Diagram of Radio and CCTV V Systems t that Are Above
Ground (Section 1)... 2. 1 ee ee ee ee

Block Diagram of a Portion of Radio and CCTV Systems
In the Mine (Section 2). .... See ee .

Block Diagram of a Portion of Radio and CCTV V systems
In the Mine (Section 3). ..... :

Simplified Block Diagram for CCTV System. ...... 2...
Pattern of Holes Drilled in Limestone Face. .........
Approximate Locations of Vehicles Near Rock Face. ......
Pictures of Vehicles Near Rock Face. ......- eee eee
Observers of Tests Approximately 120' From Loaded Face.

Operating Procedures for Portable Radios. . .

10

Page

75

76

77

78

79
82

82
89

90

91

92

93
94
98
100
102
102
106


TABLE OF CONTENTS

PAGE
FOREWORD .....- cece cee eeeeeeeeceeee bee e eect ee eeeeee tee eeeeee bene e eens 2
EXECUTIVE SUMMARY... 0... cece cece cece cece eee eee eeeee eee cece ee ccenccencas 11
1.0 INTRODUCTION AND BACKGROUND
1.1 Introduction, Objective and Scope of Project....... cece eee LD
1.2 Selection of the Black River Mine and Comsul Ltd. for
Demonstrating UHF Radio and CCTV Systems............ 000 ee eee 20
2.0 ENGINEERING TESTS PRIOR TO DESIGNING THE RADIO SYSTEM
2.1. Preliminary Qualitative Signal Propagation Tests......... +223
2.2 Evaluation of Test Results and Proposed Solutions of
Problems.......... een eee cence eee eee teen tenet eeeeeeeee 25
2.3. Investigation of Passive Reflectors and Distributed
ANteMNaS. .... cece cece cece tence ence eect nee e eee eeeeeeeenes 25
2.4 Tests to Compare Communications on 812 and 466 MHz.......... 27
2.5 Signal Strengths Measurements to Verify Reflector
PerfOrmanC€ .....c cece cece cece cent ence eee e eee ceeeeseeeee 30
2.6 Measurements of Signal Attenuations Through the Slope
Tune]... cc cece e cece cece cece e cece een ee ee eeeee bee eeeeee 30
2.7. Tests of Portable to Portable UHF Radio Communications
Through the Air Shaft Emergency Exit .......... ccc ee eee 202233
2.8 Design and Procurement of UHF Radio System ................ 235
2.9 Design of Distributed Antenna and Passive Reflector
SyStOMS co.cc cece e eee eee see e cece cece eee e eee eeeees 43
3.0. CHRONOLOGICAL HISTORY OF INSTALLATION AND IMPLEMENTATION OF

THE RADIO SYSTEM

3.1 April - May 1979
- Slope Car Communications.......... cece cece cece eee eeeees 45
3.2 June 1979

- Improvements in Slope Radio System, CCTV Survey and
Preliminary Design of Monitoring Equipment ............... 46

3.3. July - August 1979

- Radio Installations in Vehicles and Development of
Signal Margin Measuring Equipment ............. eee eee eee 47

3.4 August 1979

- Demonstration of Safe Operation of Radios Near
Blasting CapS ...c cece cece eee e cece cence eeeeeeeeeeeeees 53


Since the roof to floor heights in the Black River Mine vary between
twenty-four and thirty-four feet, a four by four foot reflector was a prac-
tical size to permit adequate clearance to vehicles moving below it. For
466 MHz the reflector should be at least one wave length high (25") but it
can be as wide as required to attain the desired area and gain.

The path attenuations Ay and Ay are approximately equal to the free
space attenuation in dB for the first 300' plus a fixed attenuation co-
efficient « in scattering loss due to roughness of walls, roof and floor
and scattering due to tilt of the mean planes of the walls, roof and floor.
Fig. 2.6 (p. 32) shows comparisons of free space attenuation and measured
attenuation on 466 and 812 MHz in the 2200' slope tunnel which is 9.5 x 20'
cross section area.

The path loss between a base station antenna and a transceiver that is
operating in a crosscut which is illuminated by a reflector is equal to:

=A, +A, -G

Atotal ~ 41 * Ap - &

AY is the attenuation from the base station antenna to the

reflector.

Ay is the attenuation from the reflector to the transceiver
antenna.

Gp is the gain of the reflector which is equal to 29 dB for a 16 square
foot reflector at 460 MHz. Gp can be computed using the following formula:

1

Gp 22.2 + 40 logigf + 20 log + 20 10949 cos 0
Gp = Two way gain of reflector in dB
f = Frequency in GHz

A = Area of passive reflector in square feet
Cos @ = % of the included angle between the incident and reflected
paths.

44


MESSAGE STATUS BOARD

4
{
MOTOROLA MODAT !
P/O TLN 4900 4

2 au
(be ord

INTERFACE CIRCUIT ‘
DEVELOPED ON THIS ee
PROJECT FOR MOTOROLA Sniicnes
MODAT ENCODERS TO M
ACCOMMODATE INPUTS - |
FROM EXTERNAL SENSORS a up
DOWN
Fras EaTESTICs| Sy | Hor

FIGURE 3.21 SCHEMATIC DIAGRAM OF INTERFACE UNIT FOR MOTOROLA MODAT DIGITAL
STATUS ENCODER USED ON MINE TRUCKS TO AUTOMATICALLY SEND BED-UP, BED-DOWN,
AND HOT ENGINE STATUS MESSAGES FROM EXTERNAL SENSOR SWITCHES.

on all trucks. The mine will furnish engine temperature and oi] pressure sen-
sors which also will be connected. The interface unit between the sensor switches
and the MODAT encoder operates reliably and its schematic is shown on Figure 3.21.

A major problem is installing radio equipment on mine vehicles is the var-
jous types of dc power systems. Figure 3.22 shows three power circuit diagrams
for radios on various mine vehicles that were developed by the Project Leader.

75


Three control stations also control the base/mobile repeaters. These
stations are all consolettes with 25-watt output power, four-frequency oper-
ation on all three base/mobile repeater frequencies, plus one simplex channel,
and they are equipped with Channel Scan receivers.

° The warehouse control station is used for communicating with the
parts and powder trucks and the hoist house in order to coordinate
transportation of material to the mine. This station uses an omni-
directional antenna on the warehouse roof.

e The control station at the loading dock near the base of the slope
is used mainly for communicating with the hoist operator, persons
on the slope car, and the mine foreman's office. It uses a Yagi
antenna that is directed up the slope.

Radio communications at the base of the slope are necessary to
facilitate moving the slope car, obtaining parts, and contacting
the mine foreman's office. Ambient noise levels are extremely high;
the control station microphone was too sensitive; it picked up the
conveyor belt noise almost to the exclusion of the voice. Three
(3) watts of received audio could hardly be heard over other noise
even when one was standing next to the control station.

To overcome the local noise problems, two changes were required.
A telephone-type handset was used to replace the desk-type micro-
phone, and the received audio power was increased to 15 watts by
adding a power amplifier.

e The mine foreman's office control station can communicate through
both pairs of base/mobile repeaters which are located near crushers
no. 2 and 3. It is used mainly for calling or responding to calls
from mechanics, electricians, mine supervisory personnel, vehicle and
equipment operators. Due to its location, this station cannot access
Channel 3 used in the slope although the radio has Channel 3 crystals.

84


THE IMPLEMENTATION
OF UHF RADIO COMMUNICATIONS
AND CCTV MONITORING SYSTEMS IN A
ROOM AND PILLAR METAL/NON-METAL MINE

FINAL REPORT

Prepared For:

Bureau of Mines
United States Department of the Interior

Contract No.: JO 377044

March 1981

COMSUL LTD.
SAN FRANCISCO, CALIFORNIA


He also commented on the safety value of the radio system and CCTV system
concerning the slope car, the two way speech to the winch operator and the
TV coverage at the foot of the slope. When he is in his office above ground
he monitors all three channels of the radio system on three different speakers,
giving him the jump on any emergencies. One man smashed his hand, used his
emergency call and was helped immediately. Mr. Dick Wehrmeyer, Electrical
Engineer, indicated a time savings in locating the day shift electrician who
could be in any part of the mine area underground or above ground. He can
be reached on the radio system, speak directly to the person reporting the
problem saving trips into and out of the mine.

The hoist house operator, who is the designated monitor of slope acti-
vity, stated that using the radio system for voice communication provides a
whole new gamut of stops for the slope car that were not possible before.
This is because he is able to maintain continuous and immediate communica-
tion with personnel in the slope car and can make unscheduled stops.

The radio system is vital when they are lowering large equipment into
the mine down the slope. They have much more control to stop or start pre-
venting damage to equipment or cables and reducing danger to support people.

The CCTV system provides the hoist operator with TV monitors to monitor
the base of the slope for safety and to prevent lowering the slope car too
far. He also monitors conveyor belt crossovers. The TV system has reduced
belt breakage considerably because of monitoring. Restringing new conveyor
belts has been much quicker using the radio system to coordinate activities

between crews.

When the slope car is being raised or lowered the radio system has saved
time and damage because all action can be stopped by radio when the car jumps
the rails. This prevents damage to the convenyor belt system, danger to per-
sonnel, and alerts the hoist house operator before the slope car gets too far
off the track.

110


FOREWORD

This report was prepared by Comsul Ltd., 417 Montgomery Street, San
Francisco, California 94104 under USBM Contract Number J0377044. The
contract was initiated under the Minerals Health & Safety Research Program.
It was administered under the technical direction of the Pittsburgh
Research Center with Mr. James C. Cawley acting as Technical Project
Officer. Mr. Wm. R. Mundorf was the contract administrator for the Bureau
of Mines. This report is a summary of the work recently completed as
part of this contract during the period of October 1977 to March 1981.
This report was submitted by the authors on March 31, 1981.

We wish to express our appreciation to Mr. Ken Reiser, General Manager;
Mr. Al Cigallio, Construction and Development Manager; Mr. Bob Kuehneman,
Underground Operations Superintendent; Mr. Dick Wehrmeyer, Electrical Engineer;
Mr. Benny Whitmer, Safety Director; Mr. Tim Ellenberger, Mine Engineer; and
Ms. Candy Frey, Secretary/Receptionist, of the Black River Mine.

Our special thanks and commendation to Mr. Jerry L. Bentz of Motorola
Communications and Electronics, Inc., who has been Project Leader and who
has contributed innovative features in the installation and modification of
equipment. We also wish to thank Mr. M. W. Anesetti, Mr. Joseph Rupe, Mr.
Ned Mountain, and Mr. Fred Beard of Motorola Communications and Electronics,
Inc., for their contributions to the project.


5.7 Recommendations to Other Mine Owners

Radio systems and TV systems whether designed for production improvement
or for personal safety of the miners must meet three requirements. The first,
after design and installation have been completed, is management. Someone must
be responsible for the ongoing performance of the entire system on a daily
basis. This person should have a firm belief in the values of the system and
at least rudimentary technical expertise. His role should be that of a.central
hub for all input on the status of the system and associated equipment. He
would.arrange for maintenance, repair and replacement of any part of the system.

Second, and every bit as important as the first, is the end user must be
trained in the proper use, care and maintenance reporting procedures established.
It has been our experience that the user didn't have any. idea to whom he should
report.a problem on his unit. Visual aids such as prominently displayed posters,
paycheck inserts, safety. meetings or new employee introductory meetings could
be used as periodic reminders. When his dependence on the radio system is
channelled toward safety and communications rather than production goals he
can relate to the systems value more readily.

Thirdly, the real weak link in the chain, maintenance. If the system or
segments of the system such as hand held transceivers break down and are not
repaired in relatively short time faith in, or dependence on, the system erodes
and further acceptance is destroyed. A regular maintenance prevention program
should be considered and qualified in-house radio technicians or service com-
panies should be utilized.

5.8 Recommendations for Future U.S.B.M. Research

1. Further development of the signal booster concept is needed before
jt can be extended into hazardous areas such as coal mines or gassey
metal/nonmetal operations.

2. A follow-on independent evaluation will be necessary to compliment
this installation work.

3. Further development of lightweight portable signal margin measuring
equipment should be pursued.

111


30
40

50

80

REFERENCED TO

FREE SPACE ATTENUATION BETWEEN ISOTROPIC ANTENNAS.

90

PATH ATTENUATION dB.
SE
8 5

o
3

5
$

a
3

60 |

70.

r=
S

(GTH RECEIVED BY FIELD

STRENGTH METER, dBmV into 50 Ohms

SIGNAL STREN

1000
DISTANCE FROM BOTTOM OF SLOPE, FEET

TRANSMITTERS, VERTICAL POLARIZATION

00
SSSR ITUANUGANNGESINNN

466.325 mz, 7 W., 8.5 dBw E.R.P. CIRCULARLY POLARIZED ANTENNA [X NAS SSS SAAN AS SSN SS
812.2375 mHz, 9.3 Wes 9.7 dBW E.R.P. AND FIELD STRENGTH METER J\.\ \SsSQS oS HOIST CABLE

oe ey

~s z
— > - S75 Sy" HOIST CAR

iE CROSS SECTION
J OF SLOPE

ROCK CONVEYOR BELT :

=a

FIGURE 2.6

COMPARISONS OF FREE SPACE AND MEASURED PATH
ATTENUATIONS AT 466 AND 812 MHz IN THE SLOPE TUNNEL

The signal strength measurements that are shown on Figure 2.6 were
recorded on a chart recorder. Measurements were made while the car was
ascending the slope and were repeated while it descended. The two sets
of chart recordings were compared and the average of the two readings
was plotted on the graph.

32


HOIST HOUSE

:
an

Yuden woo : \
i fe Camera |
HALFWAY :

5

WAF EHOUSE

TO THE MINE
THROUGH THE \.
J BORE, HOLE

IME Cc
PLANT [rv y|
leant ge}

CONTINUES
ON
' FIGURE 3.30

©

BACK BONE
| CABLE IN
SLOPE

To

FIGURE 3.29
THIS DRAWING IS AN ENLARGEMENT OF THE LEFT HAND SECTION

91

BLOCK DIAGRAM OF RADIO AND CCTV SYSTEMS THAT ARE ABOVE GROUND.

1 ON FIGURE 3.28.


Following is a list of the vehicles that are equipped with Motorola

Model MCR-100 mobile radios:

Quantity Type of Vehicle

Features

Slope car
4 Mine trucks

Scaler

Loaders
Hydraulic drill
Drill

Delivery truck
Spare

Pe Pe Be

PTT ID, emergency alarm and tone signal
PTT ID, emergency alarm, bed-up and bed-

down status, engine temperature and oil

pressure alarms

PTT ID
PTT ID
PTT ID
PTT ID
PTT ID
PTT ID

and
and
and
and
and
and

emergency
emergency
emergency
emergency
emergency
emergency

alarm
alarm
alarm
alarm
alarm
alarm

The fifteen Motorola type MX~350 portable transceivers equipped with

PTT ID and emergency alarms are assigned to:

Shop

Conveyor
Crusher
Drills
Pinners

PENNE EP ee eee

Blaster

Powder Truck

Halfway station in slope

Underground Operations Superintendent
Production Foreman
Drill Foreman
Maintenance Foreman
Safety Director

Remote speaker/microphones and Muffcoms (noise reduction ear protectors

with bone conduction microphone) are provided for each radio.

86

The choice of


These measurements confirmed the low signal strength margins that were re-
ceived from the base stations in the same haulage ways and further justified
the installation of the signal boosters. A big advantage of the two-way
signal booster concept is that the distributed antenna system can be econo-
mically extended without adding control circuits or complicating the opera-
tion of the system.

Fourteen eleven watt mobile radios equipped with MODAT automatic
identification and emergency alarm encoders have been installed on vehicles
in the mine. The encoders that are used on four mine haulage trucks (LHD'S)
have been modified to automatically send three status signals; truck bed up
(dumping), truck bed down and hot engine. This information is displayed by
number codes along with the truck's identification number on the MODAT dis-
play units in the engineering office above ground and the mine foreman's
office underground. A record of all calls, status, and alarm messages is
automatically printed in the engineering office.

Fifteen two watt transceivers equipped with automatic identification
and emergency alarm encoders also are used by mine department heads, fore-
men and personnel in the mine.

While the radio system was being installed, some miners feared that radio
transmissions might detonate blasting caps and demanded proof that the system
could be safely used. A demonstration was given in the mine, with M.S.H.A.
participation, which demonstrated the safe use of the radio system in the
presence of electric blasting caps when the provisions of IME 20 were followed.

During the system's first year of operation, an emergency alarm that
was sent by a miner who had a crushed hand is credited with bringing him
prompt first aid. The miner probably would have fainted and his injury would
have been more difficult to treat if prompt help via the radio system had not
been available.

The radio system has greatly reduced the time required to request and
deliver materials and services throughout the mine, locating foremen and

supervisors, reducing supply bottlenecks, and increasing the efficiency of

14


é

gmergenty/10

CONNECTOR FOR
CHARGING BATTERIES

No ane
wW—>»

er

——

sit hs

RADIO
TRANSCEIVER

TONE GENERATOR | | MODAT DIGITAL!
FOR BELLING EMERG. ALARM

b 4

HORN EMERGENCY
BUTTON STOP

BUTTON

FIGURE 3.6. SCHEMATIC

MODAT & SINGLE TONE INTERCABLING

Single Tone J, Tor urn on —caI—meying circuit
trevor te calm neying

8
Seirsnea A+

==

MIC RADIO 48 V

PTT PTT BATT.

EMERGENCY ALARM CIRCUIT

When the Emergency Stop Button is
depressed, a digital alarm signal
is transmitted by the MODAT encoder.

FIGURE 3.7.

SCHEMATIC DIAGRAM OF SLOPE CAR

jem Description

A Wreck Braxe—
|B ibartery 48 vor
(eer icireuit Greaner

a2 iGircow Breaner 90Ame overload |
[0 Terarging Pug ssSsS—=~“~*~SY

@_\fas sate Contactor

[cnarging Pig

Th Bx Contactor w/one
2m 18K Contactor w/tw

iomz0] weaengne contacter
| headight

OF SLOPE CAR POWER CIRCUITS

Single Tong

MAGNETIC
BRAKE
SOLENOIDS
BELLING CIRCUIT

When the Horn button is pulsed,
Relay KI fs energized & remains
energized for 1 second after the
Horn button is released. The
delay is determined by Cl, R3 & R4.

SIGNALING AND ALARM CIRCUITS.
56


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7-0, $ ° 3° t fe) $ °
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|
y \
too ° ° ) ° °°
47 46 #6 46 16 ‘7
i
ote |
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a
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b fo} fe} oo
29. 2.2 yo | 8 Pe 815

a

FIGURE 4.1 PATTERN OF HOLES DRILLED IN LIMESTONE FACE FOR BLASTING CAPS USED
FOR DEMONSTRATING SAFE RADIO OPERATION OF MOBILE AND PORTABLE UHF RADIOS IN
THE VICINITY OF ELECTRIC BLASTING CAPS AND ASSOCIATED WIRING.

The hole pattern shown above is normally used in the Black River Mine.
Each of the forty-eight holes was loaded with Atlas Time Master blasting caps
having "time delay" as indicated from 0-9. The caps were connected in series
and the blasting line was run on the ground to the observation point where it
was shunted while persons were near the face.

98


MINE MAP SHOWING
| SIGNAL MARGINS |
MEASURED ON PICKUP |

FOR CALIBRATING

SIGNAL GENERATOR
RECEIVER

FIGURE 3.23 INTERIOR OF RADIO AND MONITORING EQUIPMENT ROOM SHOWING BASE
STATIONS AND TEST EQUIPMENT USED FOR MEASURING SIGNAL MARGINS FROM A HAND
HELD TRANSCEIVER.

3.21 Inspection and Acceptance Tests of Radio and CCTV Systems

The radio and CCTV systems were inspected by the TPO, Project Manager
and Engineer January 28 - 30, 1981. The inventory records were compared
with the equipment that is installed and no discrepancies were found.

Signal strengths from a two-watt hand-held transceiver that was oper-
ated while driving a tractor were measured at the base stations in the mine.
The RF output of the last IF crystal filter in a Motorola Micor receiver was
rectified by an RF probe and the dc voltage output (across meter terminals)
of a Motorola A1063B Multimeter fed an Esterline Mini Servo chart recorder.
This arrangement made it possible to measure signal levels ranging from luv
to 100uv at the antenna terminal of the receiver. These measurements were
later converted to signal levels above 20dB carrier squelch quieting which
are plotted on Figures 3.24A and 3.24B and are listed on Tables 2 and 3 in the
appendix.

Similar measurements and quality evaluations also were made of transceiver
reception above ground and are listed on Table 1 in the Appendix. The measure-
ments generally agreed with those made in November 1979 and confirmed the need
for two way signal boosters.

77


Three pairs of base/mobile relay stations using channels 1 and 2 for
general communications were to be provided, one pair at the hoist house near
the mine portal, one pair near the base of the slope in the mine and one pair
near crusher no.3 in the mine. Each pair of underground base stations was to
feed a distributed antenna system through a combiner.

Two control stations for channels 1, 2 and 3 were to be provided, one
at the warehouse above ground and one near the base of the slope in the mine.
A third control station for all channels was to be located in the underground
shop office.

Two underground antenna systems using a combination of distributed an-
tennas and passive reflectors were to be located at intersections of main
haulage ways as shown on Figure 2.9.

The system design objective was to afford reliable two way communications
between 1.5 watt portable transceivers operating near main haulage ways in the
mine, in the slope, in the air shaft and air shaft hoist house, and above
ground along the roads and in buildings which are near the mine portal. As
is shown on Figure 2.9 complete coverage of the mine was not realized by the
original antenna system which was later modified by extending the transmission
lines, installing additional antennas and providing for future two way signal
booster amplifiers.

All base/mobile relay stations, control stations, alarm annunciators and
control consoles were to be operated by storage batteries and chargers which
will afford uninterrupted operation during power failures.

A redundant "back bone" coaxial cable system was to be provided for multi-
plexed audio and digital signal. and closed circuit television surveillance of
conveyor transfer points and rock crusher operations. Multiplexing signals on
coaxial cable is a new concept for controlling mobile radio communications sys-
tems in mines.

Standard CATV industry hardware and concepts were specified for the "back
bone" cable system using multiplexed FM carriers in the 5 to 300 MHz spectrum.

38


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BASE/MOBILE RELAY STATIONS UNDER GROUND

PAGE 4 OF 8


This power line will bring power from a source on the surface that
is independent of mine power circuits to feed an uninterruptible battery sup-
ported AC power supply (UPS) in the monitoring room to power the pumps, accen-
sors, and other vital equipment required for monitoring environmental condi-
tions, fire alarms, and future indicators which the mine may require.

Two Deltec model 5247 3 KVA non-redundant UPS will be installed, one in
the mine's monitoring room and the other in the sub-station building
above ground. Each system will consist of a phase controlled SCR rectifier/
battery charger with automatic voltage and current controls, a 125 volt 100
ampere hour Lead Calcium storage battery bank, a dc/ac static inverter with a
ferroresonant output transformer, automatic transfer switch from UPS power
line (and vice versa) metering panel for frequency, ac and dc volts and amp-
eres, manual bypass switch, protective circuit breakers and provisions for
external monitoring and alarms. In the event that the AC mains supply fails,
the inverter will be furnished power by the 125 volt batteries which have
enough capacity to furnish 3 KVA for at least four hours.

If a current overload occurs (such as high inrush current to a motor
that is starting), the automatic transfer switch will transfer the load to
the ac bypass power line until the overload condition ends.

Two additional power lines also will be required. One line from the
monitoring room UPS will serve the radio control station at the loading
dock at the base of the slope. The other line from the UPS in the radio room
above ground will serve the radio control console in the hoist house. Power
circuits for the control and alarm equipment in the engineering office above
ground also will be revised and connected to the UPS in the radio room.

Approximately 75% of the passive reflectors specified for the
underground antenna system had been installed and a dramatic improvement in
signal strengths and reliability of radio communications was noted.

Mobile radios for mine vehicles were not initially ordered with crys-
tals for "talk around" short range mobile to mobile communications.

55


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3.22 As Built Radio System Description

The completed radio system is very similar to the system that was designed
in 1978 and which is described in section 2.8 of this report. The principal
changes are:

@ The base/mobile relay stations which were originally installed near the
base of the slope were moved to a prefabricated radio and monitoring
room that is near Crusher No. 2.

e@ The distributed antenna systems have been extended and two-way signal
boosters will be installed to extend reliable radio communications to
the perimeter of the mine.

e@ DC-to-DC converters (48 or 24v to 12v) have proven to be unreliable and
have been removed. Radios have been connected to 12-volt taps on ve-
hicle storage batteries.

e Experience has demonstrated that all radio equipment in a mine should
be installed in NEMA Class 4 or equivalent enclosures and cables should
enter cabinets through gasketed connectors on the bottom side of the
cabinets.

e@ ‘Hard Hat" antennas on vehicles are easily damaged and are less ef-
ficient than whip antennas which are also less expensive to replace.

e@ Interface units for the Modat digital alarm and status encoders were
designed and constructed in order that Modat units on trucks can auto-
matically send bed-up, bed-down, high temperature and low oi] pressure
signals along with the identity of the vehicle. The bed-up signal de-
notes that a load of rock has been dumped into a crusher and the Modat
basic logic unit and printer can tally the number of loads dumped by
each vehicle.

e@ A belling system which sends customary Morse code tone signals over the
slope car's radio has been added. This provides instantaneous nonverbal
communication which is familiar to mine personnel.

80


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90


Following 1s a computation of line of sight path attenuation and sig-
nal margin at a transceiver operating on 466 MHz which is 400' from a reflec-
tor that 800' from a base/repeater antenna radiating 0.4 watts.

Path Ay (800') First 300' free space -66 dB
100' @ 4 dB/100 - 4 GB
Gp Reflector Gain 29 dB
Path Ay (800') First 300' free space -66 dB
500' @ 4dB/100' -20 dB
Antenna derating factor for transceiver -10 dB
Total Attenuation -137 dB
Distributed antenna ERP 0.40 W 26 dBm
Received signal power -111 dBm
Signal power required by receiver for 20 dB
quieting (0.5 uv input to 50 ohms) -113 dBm
Signai margin above 20 dB quieting 2 dBm which is a

noisy but generally usable signal. A 10 to 20 dB signal margin would
provide reliable communication.

3.0 Installation and Implementation of the Radio System

Installation of the radio system began in April 1979 and the progress
was described in monthly technical reports that were issued by Comsul Ltd.
Highlights of the reports are:

3.1 April - May 1979

Essentially all of the material and equipment that had been ordered
for the back bone cable and radio systems were received and inventoried. The
channel 3 radio system was installed and began operating in the slope for
communicating with the slope car, the base of the slope, the hoist house and
engineering office. The base stations for channels 1, 2 and 3 were installed
in an unused shower room in the office building. A trailer (shown on page 20)
was positioned near the portal as the radio system Project Leader's shop and
office.

45


10.

11.

REFERENCES (Continued)
Bosshard, A., Radio Links for Highway Tunnels, Communications
International, May 1979.

Grussi, 0., and Peter Konig, Radio Links for Highway Tunnels,
Bulletin Technique PTT, July 1978.

Wey, E., NATEL, The Swiss Automobile Telephone Network, Technische
Mitteilungen PTT, 1979. (Translation)

Papers in Other Languages

1.

Meyer, H.R., Funkversorgung Services Radio electriques, PTT
December 1980.

Delogne, P. Les Telecommunications par Radio en Milieu Souterrain,
unidentified source.

Block Diagrams and Description (in German) of Radio System In
Gotthard Tunnel in Switzerland.

Verkehrsleitsystem Autophon, Jruzbeschreibung des Anlagenkonzeptes,
Autophon AG, August 28, 1979.

Baumann, A., Breitbandverstarker fur Tunnelfunk TUG 55 F, Autophon
AG, September 10, 1979.

Tunnelverstarker, TUG 55 F bzw. TUV 55 F, Autophon AG, September 12,
1979.

Erganzende Messungen am Strahlenden, Koaxialkabel Typ S 17873 der
Fa. Huber & Suhner AG, PTT Report, July 4, 1978.

Wey, E., NATEL, das Schweizerische Autotelefonnetz, Technische
Mitteilungen PTT, 1979.

Grussi, 0., Statistische Messungen der Feldstarkeverteilung bei
Fahrzeng-Telephononlagen, Technische Mitteilungen, 1970.

115


APPENDIX B

EXPERIMENTAL RESEARCH LICENSE FOR
TESTING SIGNAL BOOSTER AMPLIFIERS IN THE MINE

rec pamaecon «L215 Henry st. Berkeley, Calif. 94709
BEE tee uniten stares oh hursies
FEDERAL COMMUNICATIONS COMMISSION
EXPERIMENTAL
RADIO STATION CONSTRUCTION PERMIT

EXPERIMENTAL (RESEARCH) AND K.K.2.X CA (new)
(ature of terviee) (Call sige)
LICENSE "
CONTRACT DEVELOPMENTAL XC FX 8108-ER-PL-89
(Cinas of station) (File number)
NAME cose R.A. ISBERG, PE.

(Location of station)

(Location of muihorized remote conisel point)
Subject to the provisions of the Communications Act of 1934, subsequent acts, and treaties, and all regulations heretofore ot

hereafter made by this Commission, and further subject to the conditions and requirements set forth in this license, the licensee here-
of is hereby authorized to use and operate the radio transmitting facilities hereinafter described for radio communication.

Authorized Speciol
Frequency Power (Worts) Provisions
451.950 MHz 20F3 0.4 (ERP)
452.175 MHz 20F3 0.4 (ERP)
456.950 MHz 20F3 0.4 (ERP)
457.175 MHz 20F3 0.4 (ERP)

Frequency Tolerance: + 0.00058

Operation: In accordance with Sec. 5.202(c) of the Commission's Rules.

Special Conditions:

(1) This authorization is issued for the express purpose of conducting
experimental operations described in the related application and
required by U.S. Department of Interior, Bureau of Mines Contract
No. 30377044. The use of this radio station in any other manner
or for any other purpose will constitute a violation of the
privileges herein authorized.

(2) Except as subsequently authorized by the Commission, this radio
station shall not be operated after the expiration date of the
contract designated in the related application and enumerated
above.

The above frequencies are assigned on a temporary basis only and are subject to change at any time
without hearing.

Thia authorization is granted subject to the condition that no harmful interference is caused to any
other station or service and may be cancelled at any time without hearing if, in the judgment of the Commission,
‘such action should be necessary. :

‘This license is issued on the licensee's representation that the staterients contained in licensee's
application are true and that the undertakings therein contained, so far as they are consistent herewith, will
be carried out in good faith. The licensee shall, during the term of this license, render such service as will
serve public interest, convenience, or necessity to the full extent of the privileges herein conferred.

Thia license shall not vest in the licensee any right to operate the station nor any right in the use of
the frequencies designated in the license beyond the term hereof, nor in any other manner than authorized
herein. Neither the ficenae nor the right granted hereunder chall be assigned or otherwise transferred in Vio
lation of the Communications Act of 1894" This licenae 1a subject to the right of use or control by the Govern
ment of the United States conferred by Section 606 of the Communications Act of 1934.

‘This authorization effective
will expire 3:00 A.M. EST .

FEDERAL
COMMUNICATIONS
COMMISSION

September...24,...1920 and
August..1,..1982......

9-24-80

Page 1 of 1


SIGNAL MARGINS MEASURED IN EASTERN
HALF OF THE MINES

MINE MEASURED SIGNAL MARGIN
COORDINATES INPUT TO ABOVE 20 dBq
OF TWO-WATT RECEIVER (0.8 uV)
TRANSMITTER uV dB COMMENTS
189/110 100 40 Excellent
189/113 100 40 Excellent
189/117 100 40 Excellent
189/122 25-60 28-35 Excellent
189/123 10-20 20-26 Excellent
189/125 20-80 26-38 Excellent
189/130 5-10 14-20 Excellent
189/132 5-10 14-20 Excellent
189/136 4-7 12-17 At The Face Scratchy But Satisfactory
187/134 5-10 14-20 Excellent
187/130 5-10 14-20 Excellent
187/128 100 40 Under Last Antenna
187/125 15-55 23-35 Future Amplifier Location
185/125 100 40 Dust Hole Near Antenna
188/125 45- 33 Excellent
187/123 60 35 Excellent
185/123 10 20 Excellent
183/123 5-10 14-20 Excellent
181/123 3-5 9-14 Scratchy But Satisfactory
182/123 1-3 0-9 Transceiver Battery Weak - Scratchy
123/187 10-27 20-28 Excellent
187/117 100+ 40+ Excellent
187/113 100+ 40+ Excellent
Crusher 3 100+ 40+ Excellent
189/105 100+ 40+ Excellent
192/105 100+ 40+ Excellent
192/105 90 39 Excellent
196/105 10-15 20-23 Excellent
199/105 5-10 14-20 Excellent
203/106 3-13 9-22 Transceiver Battery Weak - Scratchy
But Satisfactory
196/105 10-50 20-34 Excellent
196/104 80 38 Excellent
193/104 100+ 40+ Fresh Battery In Transceiver
192/102 100+ 40+ Near Antenna At Shop
189/102 100+ 40+ Excellent
189/99 13-42 22-32 Excellent
190/98 10-45 20-33 Excellent
193/96 100+ 40+ Under Antenna
193/93 100+ 40+ Future Booster Location
193/92 20-80 20-38 Excellent
193/91 5-16 14-24 Excellent

Page 5 of 6


REPORT DOCUMENTATION PAGE

1. Report No. 2. 3, Reciplent's Accession No.
@. Title aod Subtitle — . ‘3, Report Date
THE IMPLEMENTATION OF UHF RADIO COMMUNICATION AND March 1981

CCTV MONITORING SYSTEMS IN A ROOM AND PILLAR METAL/ 6.
NON-METAL MINE

7. Author(s) 8. Performing Organization Report No.

R.A. Isberg, P.E., H. Kramer, D.A. Parrish

9. Performing Organization Name and Address 10. Project/Task/Work Unit No.
Comsul Ltd.
417 Montgomery Street 11, Contract or Grant No, ——
San Francisco, California 94104 J0377044
13, Type of Report
12. Sponsoring Organization Name and Address Final Report

United States Department of the Interior
Bureau of Mines, Pittsburgh Research Center
Cochran's Mill Road, P.O. Box 18070
Pittsburgh, Pennsylvania 15236 v7 4

15. Supplementary Notes

Bureau of Mines Technical Project Officer, James C. Cawley

16. Abstzagt

This report describes the design and implementation of UHF radio and closed-circuit
television systems in the Black River room and pillar limestone mine near Butler,
Pendleton County, Kentucky. Prior to designing the radio system, measurements of signal
attenuation on 812 and 466 mHz were made in the slope tunnel and in the straight and
level crosscuts in the mine. Two distributed antenna systems fed by two sets of base
stations provide approximately 75% coverage of the mine. Passive reflectors are used for
extending signals into intersecting crosscuts and two-way signal boosters will be used to
extend signals to the perimeter and obstructed areas of the mine. Fourteen mine vehicles
were equipped with mobile radios equipped with digital identification, alarm and status
encoders. Fifteen portable transceivers also were used. Six closed-circuit television
cameras provide surveillance of critical transfer points of the belt conveyor system, and
the loading dock at the base of the slope and an ash disposal area in the mine. Two-way
radio communication and closed-circuit telévision have saved considerable man hours,
increased production, reduced maintenance costs and enhanced safety.

Innovative developments were the use of passive reflectors and two-way signal
boosters for extending signals into intersecting crosscuts, development of lightweight
signal margin measuring equipment, modifications of mobile digital encoders to auto-
matically send status information from mine vehicles such as numbers of loads of ore
delivered, hot engine, etc., and the use of CATV technology for multiplexing audio,
digital and video signals onto coaxial cables from the surface to the mine.

17, Originator's Key Words 18. Availability statenent

UHF Radio System, Mine Communications Distributed
Antenna System, Passive Reflectors, Signal Margin
Measurements, Two-Way Signal Booster, Closed Circuit
TV Systems for Mines

Unclassified Unclassified 121

19. U.S. Security Classif, of the Report 20. U. S, Security Classif. of This Page |" No. of Pages i Price

This Form may be reproduced.


5.2 Radio Equipment Costs

All of the radio equipment, cabinets, transmission lines, antennas, etc.,
and the installation of same were funded by the Bureau of Mines. Our calcula-
tions based upon our inventory and purchasing documents indicates the radio
system cost approximately $230,000.

5.3 Radio Licenses

Motorola Communications & Electronics was helpful in obtaining radio
licenses from the FCC. During subsequent periods after the licenses were
issued it became necessary to request certain revisions from the FCC. Addi-
tional locations, for example, were required for the control stations. It
was necessary to license the underground stations as well as the above
ground stations and at one point in time the FCC had switched some frequen-
cies. All these changes and adjustments were covered with the FCC.

One additional radio license was issued to the Project Engineer for
"Experimental Radio Construction Permit & License". This covered research
on the signal booster system.

5.4 CCTV Costs

All of the TV equipment, cabinets, cables, etc., and installation costs
were funded by the Bureau of Mines.

Our calculations based upon our inventory and purchasing documents indi-
cate that the TV system cost approximately $36,200.

5.5 Purchasing, Receiving and Inventory Systems
Procedures for effective control of purchasing, receiving and inventory
were developed and implemented by Comsul Ltd. These procedures greatly faci-

litated ongoing inventory control. The purchasing procedure enabled Comsul

108


x fae sim a se etn
FIGURE 3.13. THE RADIO AND MONITORING EQUIPMENT ROOM IS LOCATED NEAR CRUSHER
NO. 2 APPROXIMATELY AT THE CENTER OF THE MINE.

: 2 % z =a

FIGURE 3.14. CONTROL STATION AND MULTIPLEXING EQUIPMENT IN A GASKETED WEATHER-
PROOF CABINET IN THE LOADING AREA AT THE BASE OF THE SLOPE. AN EXTENSION WAS
ADDED TO A WEATHERPROOF CABINET TO ACCOMODATE THE RACK MOUNTED MULTIPLEXER

UNITS. THE CABINET ON THE WALL CONTAINS STORAGE BATTERIES WHICH PROVIDE UN-
INTERRUPTIBLE POWER FOR THE MULTIPLEXING EQUIPMENT.

68


Although the base station equipment near the base of the slope had been
moved to a higher location, it was still vulnerable to flooding and damage
from vehicles. Also technicians working on the equipment were vulnerable to
electrical shock when the ground is wet. Improvements of the antenna system
in the slope still were needed. The Yagi antennas in the slope were coated
by moist limestone dust and smoke and the hard hat antenna on the slope car
was covered by moist gravel and was inefficient. The brake alarm signal on
the slope car had not been perfected. A portable transceiver was needed by
the person stationed at the power station at the middle of the slope. A
loudspeaker and amplifier was needed for the control station at the bottom
of the slope. The signals from the channel 3 repeater station that was
near crusher No. 3 did not penetrate the metal clad trailer offices in the
new shop area. This was corrected by extending the transmission line from
the distributed antenna system in crosscut 188N and an antenna was installed
in the shop area. A general emergency alarm signal also was needed in the
shop area. Instruction posters were needed for informing mine personnel re-
garding proper radio procedures.

3.6 October 1979

Conferences were held at the Pittsburgh Research Center to review the
status of the project and plans for Phase II monitoring systems with the TPO,
Project Leader, the Principal Administrator and the Environmental Monitor-
ing Engineer.

During these conferences, the concept for adding multiplexed digital
alarm and monitoring signals on the redundant back bone cable system was
approved. This deleted the requirement for multipair shielded cable through
the air shaft. Mine safety regulations require environmental monitoring
equipment to be powered by an uninterruptible power supply (UPS) that will
sustain operations during a four hour power outage.

In order to furnish uninterruptible power to the monitoring equipment,
a pair of number 8 conductors was ordered to be installed from a 480 volt
transformer on the surface to a prefabricated monitoring room in crosscut
111E between crosscuts 205S and 206S.
54


4.4 Computations of the Amount of Radio Energy that is Available Near Mobile
and Portable Radio Antennas.

The radio energy reaching a wired face from nearby portable and mobile
transmitters can be computed as follows:
984 _ 984

fomiz ~ 451 ~ 2-18"

a. Wavelength of radio signal=

b. At one wavelength (2' 2") between two isotropic antennas the avail-
able power would be attenuated 22 dB compared to the radiated power.
Since the portable and mobile antennas have approximately 2 dB gain
compared to an isotropic antenna, the available power at 2' 2" will
be approximately 20 dB (1/100) less than the radiated power.

If a 2 watt portable transmitter is operated 2'- 2" froma blastina
cap, the radio energy reaching the cap would be 2/100 of one watt,

c. Each time the distance from the antenna is doubled the received
power will be divided by four which is an additional 6 dB reduction.
The power reduction versus distance for a mobile transmitting an-
tenna radiating 15 watts on 450 MHz is computed as follows:

Distance From Antenna Power Available, Watts

» Feet

1 2.18' 0.15

2 4.36! 0.0375

4 8.72! 0.0094

8 17.44! 0.0023

16 34.88! 0.0006

32 69.76' 0.0001

103


The mobile radio equipment was mounted on a plywood assembly which was
strapped to the lift platform on a utility tractor as shown on Figures 2.3
and 2.4. This assembly included a lighted map shelf unit, and an audio tape
recorder for recording voice transmissions received and transmitted as well as
the field engineer's and driver's comments. The mobile radios transmitted
simultaneously on 812 and 466 MHz while the tractor was moving and the signal
strengths were recorded at the control
center in the van.

For vertically polarized trans-
missions, one quarter wave length whip
antennas were mounted on ground planes
on top of two poles attached to the
tractor. For horizontally polarized
transmissions, the antennas and ground
planes were reoriented 90° so that they
were perpendicular to the fore and aft
axis of the tractor.

FIGURE 2.3 TRACTOR EQUIPPED FOR
SIGNAL STRENGTH SURVEY

In order to compare the merits of
horizontally and vertically polarized
transmissions, two runs were made by the mobile unit over the same routes
through the mine. There were no significant differences between the range of
propagation on 466 and 812 MHz. Although horizontally polarized signals evident-
ly were more efficiently propagated through intersecting crosscuts and around
pillars, vertical polarization is most practical for mobile and transceiver
antennas except on fixed route or rail vehicles. The tests indicated that the
polarization of the signals received at the van evidently was altered by re-
flections and multipath propagation.

The signal strength survey routes through the mine are shown on charts that
are included in the Project Reports.

(4) History of Project and Progress Report on Implementation of UHF Radio
System in the Black River Mine, Comsul Ltd. Report to BOM TPO, Figures 1-4,
December 1979.

28


FIGURE 2.1 VIEW DOWN CROSSCUT 104E PAST LIGHTED SHOP AREA WHICH
ILLUMINATED FOUR INTERSECTING CROSS CUTS.

parallel crosscuts. However, not all of the crosscuts are level; the
elevation of the mine floor varies + 35 feet in some areas which
eliminates line of sight communication even in straight crosscuts.

3. The range of two way UHF communications between two watt hand held
transceivers was extended through a five watt base/mobile repeater
into areas which were effectively shielded from each other by lime-
stone pillars.

4. Signals received by an antenna that was attached to the ceiling were
stronger than signals received by a hand held transceiver which was
operated by a pedestrian. Deep fades were noticed behind limestone
pillars but signals were usually satisfactory in the intersections
between crosscuts. Multipath distortion in low signal areas was
usually reduced by shifting the transceiver location a few feet.

24


5.0 Project Management

Comsul was awarded the contract to provide engineering and administra-
tive services necessary to design, procure material, test and supervise in-
stallation, maintain and document an emergency/non-emergency communications
system in the Black River Mine which was selected by the Bureau as a likely
location for demonstrating such a system.

Comsul Ltd. selected Don Parrish, Senior Consultant, to represent them
as project manager early into the project in 1977. In this capacity he super-
vised the activities of Mr. R. A. Isberg, P.E., Radio Engineer. Mr. Parrish
maintained the records, began financial reports, provided the Bureau of
Mines with monthly reports, conducted field trips to the Black River Mine and
coordinated Consul Ltd.'s role in all studies.

In February 1980, Mr. Kramer assisted Mr. Parrish in these essential
administrative matters. This additional management support did not increase
costs of Comsul's professional services to the Bureau of Mines. Mr. Kramer
developed an accurate inventory of all communications facilities at the Black
River Mine. He also developed effective procedures for procurement and mater-
jals cost control. The monthly administrative and financial reports have been
produced by him since he assumed the day to day administration of the project.

Mr. Kramer supervised Mr. Isberg's activities and made field trips to
the mine for procedural and inventory purposes. He also administered payment
of invoices including the subcontractor, Motorola.

5.1 Project Leader - Installation and Maintenance
The Bureau of Mines selected Motorola as the source for the radio and
TV equipment. They provided a technician, Mr. Jerry Bentz, to serve as pro-

ject leader. He began serving on the project in March of 1979 and performed
the installation and maintenance functions to date.

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BASE/MOBILE RELAY STATIONS ABOVE GROUND

PAGE 2 OF 8


November 1979

When the underground shop was moved a communications center was estab-
lished in a new foreman's office. The mine requested that emergency alarms
on channel 3 (slope car) also should be annunciated in the shop office. As
installed, slope car alarms are heard only in the hoist house and in the
offices above ground. The mine also requested that emergency alarms received
on all three radio channels should activate an emergency siren, having a dis-
tinctive sound, which should be installed in the shop area. A radio control
unit with a switch for cancelling the emergency alarms was desired outside
the office because the office is locked when it is not occupied.

FIGURE 3.9A FIGURE 3.9B

RADIO CONTROL STATION ON THE MINE FOREMAN'S DESK MODAT ALARM AND MOBILE
UNIT IDENTIFICATION
DECODER IN FOREMAN'S
OFFICE.

60


15,

16,

17.

18.

19.

REFERENCES (Continued)

Fisher, Jack, "A Unique Multichannel Two Way UHF Radio Signal Booster
System for Leaky Transmission Lines in Mines", IEEE 3lst Vehicular
Technology Conference, April 1980.

Isberg, R.A., P.E., "Evaluation of C-COR CATV Distribution Amplifier as
a Signal Booster for VHF Radio Systems", Comsul Ltd. Report to Bureau
of Mines TPO, September 1980.

Isberg, R.A., P.E., "A Study of the Technology of Underground Radio
Communication in Europe", 1980 Rapid Transit Conference, American Public
Transit Assn., June 1980.

Report No. M092479 "RF Hazards to Electrical Blasting Caps at Black River

Pane eat ke Mine Electrical Systems Branch, 4800 Forbes Avenue, Pittsburgh

’

I.M.E. No. 20 Safety Guide for the Prevention of Radio Frequency
Radiation Hazards in the Use of Electrical Blasting Caps, October 1978.

Miscellaneous References Acquired During Research of Technology of
Underground Communication.

Papers in English Language

1. Martin, D.J.R., ARIADNE: A Radio Propagation Highway for Mines,
1980 National Telecommunications Conference, December 1980.

2. Martin, D.J.R., and R.W. Haining, Leaky Feeder Radio Techniques for
Mines and Tunnels, presented at I.E.R.E. Land Mobile Radio Conference,
Lancaster, September 1979.

3. Martin, D.J.R., Radio Communications in Mines, The Mining Engineer
January 1978.

4. Delogne, Paul, Subsurface Radio Communications, I.E.E.E. Spectrum 1980.

5. Delogne, Paul, Mode Converters for HF Tunnels Transmission, Translation
of Unidentified Source.

6. Delogne, Paul, Basic Mechanisms of Tunnel Propagation, Radio Science,
Vol. 11, No. 4, April 1976.

7. Delogne, P., Radio Communication System for Confined Spaces, U.S.
Patent 4,152,648, May 1, 1979.

8. Delogne, P., Radio Communications System for Use in Confined Spaces
and the Like, U.S. Patent 3,829,767, August 13, 1974.

114


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2.5 Signal Strength Measurements to Verify Reflector Performance

A series of signal strength measurements were made on November 17, 1977
to verify the qualitative tests which were previously described in this re-
port on page 26. Three additonal 4' x 4' reflectors were constructed and
were hung in major haulage way intersections.

The tests confirmed that reflectors definitely increased signal strengths
and reduced multipath distortion in the crosscuts extending from the inter-
sections where they were installed. The reflectors are most effective if
they are not more than 500 feet line of sight from a transmitting antenna
and are illuminated by a strong signal. Reflectors are effective with either
horizontal or vertical polarization. However, vertical polarization is most
appropriate for omnidirectional antennas.

2.6. Measurements of Signal Attenuations Through the Slope Tunnel

The attenuations of 466 and 812 MHz signals were measured in the 2200
foot slope of the Black River Mine and the results are plotted on Figure 2.6
along with the two free space attenuation curves. The 466 and 812 MHz ver-
tically polarized signals from the mobile unit, which was parked at the base
of the slope, were measured on the slope car as it was pulled through the
slope tunnel.

The signals received by a wide band circularly polarized log periodic
antenna and field strength meter were recorded on the slope car by an inst-
rumentation tape recorder and a chart recorder. See Figure 2.5.

A mathematical study was made for the Bureau of Mines by Arthur D.
Little, Inc. of the propagation characteristics in the slope of the Black
River Mine using the data shown on Figure 2.6. The sum of the computed
attenuation coeffecients for refraction, roughness and tilt were equal to
the measured values as is shown on Table 1.>

(5) Lagace, Robert L.and Alfred G. Emslie, Propagation of UHF Radio
Waves in Limestone Room and Pillar Mines, Arthur D. Little, Inc.
Bureau of Mines Report for J0387217

30


Television surveillance of the dust storage area is also expected to
improve working conditions in the mine by preventing the air from being con-
taminated with dust if the pipeline is ruptured.

3.24. Research on the State of the Art of Underground Radio Communications

During the course of this project, the Radio Engineer studied the state
of the art in underground radio communications in Europe.

Research was conducted on systems in England and Europe. Reviews were
made of similar studies, symposia and technical conferences to gain insight
on design and technique.

Comsul Ltd. included in the references titles of papers which were::col-
lected and the names of persons who are actively engaged in developing under-

ground communication systems. V7

The systems which appear to be most promising for mine applications are:
The distributed antennas and two way signal boosters that were deve-
loped during this project at the Black River Mine.

The TX/RX two way signal booster and leaky coaxial cable antenna sys-
tem that is being installed in the Sesser room and pillar coal mine
in I]linois by Motorola Communications and Electronics.

The use of CATV amplifiers and multiplexing equipment in the manner
of a system that will be installed in the Washington Metropolitan
Area Transit Authority (WMATA) subway.

The Ariadne daisy chain system with intermediate frequency return
that was developed by Dr. D.J.R. Martin of the National Coal Board
in England is appropriate for mines where only low energy intrin-
sically safe radio systems can be used.

(17) Isberg, R.A., P.E., "A Study of the Technology of Underground Radio
Communication in Europe", 1980 Rapid Transit Conference, American
Public Transit Assn., June 1980.

96


EXECUTIVE SUMMARY

This is the final report for the design and implementation of UHF radio
communications and closed circuit television systems in the Black River Mine
near Butler, Kentucky. This work was accomplished by Comsul Ltd., San Francisco,
California under United States Department of the Interior, Bureau of Mines,
Contract No. J0377044.

The objective of the project was to demonstrate in an underground room
and pillar limestone mine a minewide radio communications system that ful-
fills the communication needs of that type of mine.

The Black River Mine was selected as a typical metal/non metal room
and pillar mine. It is nearly four thousand feet in diameter, six hundred
and fifty feet deep, and has essentially straight crosscuts approximately
thirty feet wide and twenty four to forty feet high with pillars approximately
thirty five feet square. Entry is through a twenty two hundred foot slope by
means of a single drum, hoist-powered flat car and enclosed man carrier. The
emergency exit is through a hoist-powered capsule in a six foot diameter, six
hundred and fifty foot vertical air shaft. Rubber tired, diesel powered mine
vehicles travel along designated haulage and travel roads from the active
faces on the mine's perimeter to two rock crushers, the shop area, and the base
of the slope.

Mine personnel had attempted to use VHF radios for communicating in the
mine but the range was limited to a few hundred feet because the frequencies
that were used were less than the wave guide cutoff frequencies of the cross-
cuts.

Tests of communication between hand-held, two watt UHF transceivers in
the room and pillar limestone mine were satisfactory for approximately two
thousand feet through straight haulage ways but the range of communication at
right angles to haulage ways into intersecting crosscuts was quite limited.
It was evident that the radiation from the transceivers was not being reflected
by the limestone pillars into the intersecting crosscuts. Two passive aluminum

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It was necessary to replace the base station microphone with a
mobile palm-type speaker microphone to overcome a serious hum
problem. The fluorescent lights were inducing a severe noise in-
to the desk microphone and normal grounding was not feasible to
correct the problem.

A Modat basic logic decoding unit is connected to the Consolette
for displaying IDs and emergency signals. However, the consolette
receiver automatically scans both Channel 1 and Channel 2 sequent-
jally, and if an emergency alarm is transmitted on the channel that
was not then being scanned, it might be missed. Several alterna-
tives are being considered, such as adding another receiver and
eliminating the scanning feature. Since the foreman's office is
locked while it is not manned, an audible emergency alarm with a
reset button is needed in the working area of the shop.

Fifteen two-watt transceivers and fourteen eleven-watt mobile radios are
used. All radios send an identification code (ID) each time that the press-
to-talk or emergency call switch is used, and they are equipped with tone coded
squelch.

A printer associated with the Modat decoder in the engineering office
prints the ID and time of day each time that a call is received. Emergency
alarms also are printed and are audibly annunciated in the office building,
hoist house and foreman's office, and a future alarm annunciator is proposed
in the shop area.

The encoders that are used on four mine trucks which haul rock to the
crushers have been modified to automatically send four status signals: truck
bed up (dumping), truck bed down, hot engine and high oil pressure. This in-
formation is displayed by number codes along with the truck's identification
number on the Modat display units in the engineering office above ground and
the mine foreman's office underground. Also, a record of the number of loads
dumped into the crushers is automatically printed in the engineering office.

85


LIST OF TABLES

PAGE
Comparison of Computed and Measured Attenuation Coefficients
in Limestone Slope Tunnel of Black River Mine...............5. 31
APPENDIX C
Signal Margins Measured Above Ground on the Black River
Mine Property... ... cc cece ec cece cece eee eee t tenet tenes 2
Signal Margins Measured in Western Half of Mine............... 3&4
Signal Margins Measured in Eastern Half of Mine..... 5&6
APPENDIX
A. Copies of FCC Radio Licenses Issued to the Black
River Mining Company........ 2. ccc cece cece cece ee eee eee 1-8

B. Copy of Experimental Research License Issued to
R.A. Isberg, P.E. ccc cece cece eee e eee e cece eee ee eens

C. Table 2 Signal Margins Above Ground...............eeeee
Table 3 Signal Margins in Western Section of Mine.
Table 4 Signal Margins in Eastern Section of Mine.



10.

11.

12.

13.

14,

REFERENCES

History of Project and Progress Report on Implementation of UHF Radio
System in the Black River Mine, Comsul Ltd. Report to the Bureau of
Mines TPO, Pages 2 and 3, December 1979.

Isberg, R.A. and R.L. Chufo, "Passive Reflectors as a Means for Extend-
ing UHF Signals Down Intersecting Crosscuts in Mines or Large Corridors",
28th Conference Record IEEE Vehicular Technology Society, March 1978.

History of Project and Progress Report on Implementation of UHF Radio
System in the Black River Mine, Comsul Ltd. Report to the Bureau of
Mines TPO, Pages 4 and 5, December 1979.

History of Project and Progress Report on Implementation of UHF Radio
System in the Black River Mine, Comsul Ltd. Report to the Bureau of
Mines TPO, Figures 1 - 4, December 1979.

Lagace, Robert L. and Alfred G. Emslie, "Propagation of UHF Radio
Waves in Limestone Room and Pillar Mines", Arthur D. Little, Inc.,
Bureau of Mines Report for J0387217.

Proposed Radio System for the Black River Mine, Comsul Report to Bureau
of Mines TPO, March 1978.

Proposal for Black River Mining Company Project, Motorola Communications
and Electronics, Inc., July 6, 1978.

Proposed Radio System for Black River Mining Company, Comsul Ltd. Report
to Bureau of Mines TPO, August 4, 1978.

Bureau of Mines Purchase Order No. P0382795 for Radio Equipment for the
Black River Mine, September 8, 1978.

Report No. M092479 "RF Hazards to Electrical Blasting Caps at Black River
Mine", MSHA Mine Electrical Systems Branch, 4800 Forbes Avenue, Pittsburgh,
PA 15213.

I.M.E. No. 20 Safety Guide for the Prevention of Radio Frequency Radiation
Hazards in the Use of Electrical Blasting Caps, October 1978.

Inventory of Government Furnished Radio and CCTV Equipment in the Black
River Mine, Comsul Ltd. Report to the Bureau of Mines TPO, June 1979.

Proposed Environmental Monitoring and Uninterruptible Power Systems For
the Black River Mine, Comsul Ltd. Preliminary Report to Bureau of Mines
TPO, July 1980.

Suzuki, T., Tetsoro Hanazawa and Shigerv Kozono, "Design of Tunnel
Relay System With a Leaky Coaxial Cable in an 800 MHz Land Mobile
Telephone System", IEEE Transactions on Vehicular Technology, Vol.
VT-29, No. 3, August 1980.

113


and multicoupler to connect the receivers to the antenna system.

Two distributed antenna systems are used. The original system for the
central and western sector of the mine (see Figure 2.9) used approximately
one thousand feet of 7/8" low-loss coaxial cable to feed four antennas
through power dividers. Since coverage was inadequate at the perimeter of
the mine, approximately five thousand, six hundred feet of 1/2" low-loss
coaxial cable and nine additional antennas and power dividers were installed.
Four two-way UHF signal boosters will be added to this system, as shown on
Figure 3.10.

The original antenna system for the eastern sector of the mine used ap-
proximately sixteen hundred feet of 7/8" low-loss coaxial cable to feed four
antennas through power dividers. Approximately four thousand feet of 1/2"
low-loss coaxial cable has been added to feed seven additional antennas
through power dividers and two two-way UHF signal boosters will be added to
this system.

Most of the antennas are 5dB gain mobile whips that are attached to one-
foot square metal plates which are bolted to the mine roof at the center of
intersecting crosscuts. (See Figure 3.20.) Several 9dB base station anten-
nas, which are fifteen feet long, are located in high crosscuts which do not
have vehicular traffic.

The Channel 3 base/mobile repeater is located in the radio room near
the mine portal and it feeds a Yagi antenna that is directed down the slope.

All seven base/mobile repeaters can be controlled by tone signals from
control consoles located in the engineering office in the administration
building and in the hoist house. The control tones and two-way audio be-
tween the consoles and the repeaters are transmitted on 6.2 to 175 mHz FM
carriers over a coaxial "back bone" cable system which extends from the radio
room down the slope and on to the base station sites in the mine.

83


to know who was purchasing what, when and why. The receiving procedure pro-
vided input for our inventory and as a side benefit identified response time
of the various vendor sources.

5.6 Cost and Safety Benefits to the Mine

Since the project was administered and funded by the Department of the
Interior, U. S. Bureau of Mines the vast majority of costs were funded by
them. Expense to the mine in accordance with a standard mutual assistance
agreement was confined to man hours performing installation of certain cables
and the use of some mine vehicles and equipment. Actually, expenses to the
mine have been computed at $30,000.

Interviews were conducted with key mine personnel who use the new radio
and CCTV systems on a regular basis. Mr. William Day, Underground Mainten-
ance Coordinator, declared he saved about two hours per day locating mainten-
ance people by using the radio system. Prior to the implementation of the
radio system, he was required to walk or when possible drive throughout the
mine to locate the person or persons needed. Also, when the telephone system
is busy, the radio system provides them with back up communications.

Another expense savings has been realized when mine equipment breaks
down. The miners can call the maintenance people using the radio system and
describe in some detail what the problem is before the maintenance man is
dispatched. The maintenance man can then take the tools and parts required
instead of making two trips.

Mr. Benny Whitmer, Safety Supervisor, stated that the mine has two fire
drills per year for everyone in the mine. The radio system has reduced the
time for these drills from 30 minutes to 12 minutes. In addition to the ob-
vious improvement in response time the side benefit was a reduction in payroll
costs for the fire drills for 40 men at an average of $7.00 per hour using
12 minutes instead of 30 minutes for the fire drills. He also said the radio
system could cut considerable time in getting an injured man out of the mine
and into a hospital.

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FIGUK: 3.8A PASSENGER COMPARTMENT OF SLOPE CAR SHOWING RADIO BEING USED.

FIGURE 3.8B THE RADIO CONTROL HEAD, HORN SIGNAL AND EMERGENCY STOP BUTTONS
ON THE SLOPE CAR.

58


If tratLer USED AS RADIO
ROJECT OFFICE AND SHOP }
a. ————_

See

SLOPE CAR AND ck
PORTAL OF TUNNEL CONVE’ tes AND WINCH

FIGURE 1.1 VIEW OF RADIO SHOP AND THE MINE PORTAL. THE MINE IS ENTERED
THROUGH THE 2200 FOOT SLOPE TUNNEL WHICH HAS RAILS FOR THE SLOPE CAR AND
A BELT CONVEYOR FOR CRUSHED LIMESTONE.

1.2 Selection of the Black River Mine and Comsul Ltd. for Demonstrating UHF
Radio and CCTV Systems.

The Industrial Hazards and Communications Section of the Bureau of Mines,
Pittsburgh Research Center (PRC), selected the Black River limestone mine near
Butler, Pendleton County, Kentucky as a suitable metal/non-metal room and pil-
lar mine for developing and demonstrating the uses for a radio communication
system.

In December 1975, the TPO visited the mine and verified that it was suit-
able and that the mine management personnel were interested and enthusiastic
about the possibility for using radio communications to enhance the safety and
efficiency of mining operations.

Mine personnel had attempted to use VHF radios for communicating in the

mine, but the range was limited to a few hundred feet because the frequencies
used were less than the wave guide cutoff frequencies of the crosscuts.

20


FIGURE 3.3 SIGNAL MARGIN MEASURING EQUIPMENT BEING USED IN A PICKUP TRUCK.

Signal strength fade margin measurements with respect to 20 dB carrier
squelch quieting (20 dBq) were made on all haulage and travel roads in the mine
in approxmately two hours. The driver of the pick up truck read the coordin-
ates of the East-West and North-South crosscuts and the Project Leader repeat-
ed into the headset microphone of the tape recorder the coordinates and the
attenuator settings which were required to attain a median reading of -20 on
the dB meter. The audio level of the unsquelched portable radio that was being
used to receive the signal was initially adjusted to 0 dB on the meter. During
the tests, the carrier of the base station that was being used was continuously
keyed. Later, the signal margins were marked on the mine map, Figure 3.4, in
less than three hours. This method of signal strength mapping is fast, inex-
pensive and repeated measurements produce similar results.

A more sophisticated signal margin set is being developed which will auto-
matically adjust, in two dB increments, a 0-120 dB attenuator connected in
series with receiver's antenna lead and the amount of attenuation required for
20 dBq will be automatically printed by a small paper tape printer.

49


The proposed signal margin measuring set will read the signal margin a-
bove a preset level every five seconds, which is about every twenty feet while
walking, or forty four feet when traveling 10 miles per hour.

On August 22, 1979, a demonstration was made to representatives of the
Bureau of Mines, the Mine Safety and Health Administration field office, and
employees of the Black River Mine to prove that three UHF mobile and three
portable transceivers can be operated simultaneously near a face that is load-
ed with electrical blasting caps. These tests are described in Section 4.0 of
this report and also in an MSHA report. 10,11

The Bureau of Mines ordered a prefabricated room which was installed near
the air shaft for housing monitoring and the radio equipment that was removed
from the base of the slope where it had been vulnerable to flooding.

3.5 September 1979

The Project Coordinator and the TPO visited the mine, reviewed the status
of Phase I radio system implementation and conducted an inventory of items fur-
nished by the Bureau of Mines.

Approximately 80% of the radio installation work had been completed.
Radios had been installed in ten vehicles but the MODAT status and alarm
modules had not been installed. Four radios had not been installed in ve-
hicles which were scheduled to be equipped. Interface units for the MODAT
digital encoders which will automatically transmit hot engine, bed up and bed
down status messages had to be designed and constructed. Radio channel 1 was
operating throughout the mine and channel 3 was operating in the slope. Channel
2 was not operating at the time of the inspection because some of the multi-
plexing interface equipment had not arrived.

(10) Report No. M092479 "RF Hazards to Electrical Blasting Caps at Black
River Mine", MSHA, Mine Electrical Systems Branch, 4800 Forbes Avenue,
Pittsburgh, PA 15213.

(11) IME Publication No. 20, Safety Guide for the Prevention of Radio Fre-
quency Radiation Hazards in the Use of Blasting Caps, Institute of
Makers of Explosives, 420 Lexington Ave., New York, N.Y. 10017.

53


FIGURE 3.25. BASE STATIONS AND COMBINER NEAR CRUSHER NO. 3. THE CABINETS
ARE WEATHERPROOF AND THE ENCLOSURE ON THE WALL CONTAINS STORAGE BATTERIES
FOR UNINTERRUPTIBLE POWER.

FIGURE 3.26. COMBINER CABINET WITH GASKETED DOOR REMOVED TO SHOW CATEL FM
MODULATORS AND DEMODULATORS (TOP PANELS) AND THE TRANSMITTER COMBINER AND
DUPLEXER.

82


the hoist operation; however, its greatest advantage is that it is has
enhanced the safety of personnel.

The closed circuit television monitoring system also is credited with
enhancing safety, particularly at the hoist car loading area at the base of
the slope. Two cameras are used at the base of the slope; one for viewing
the slope car loading area and the junction of the two conveyor belts; the
other camera provides a close up view of the crushed rock being transferred
from one belt to the other. The third camera views the crushed rocks moving
across the transition between two conveyor belts half way up the slope, and
a fourth camera views the rock movement across the transition of conveyor
belts near the mine's portal above ground. A fifth camera views the dust
collection area in the mine where ash from the lime kilns is dumped.

The video signals from the CCTV cameras modulate FM carriers in mod-
ulators which feed the back bone cable system. All multiplexed TV camera
signals are available from appropriate demodulators connected to any tap
on the back bone cable system. TV monitors are provided in the hoist house
for viewing the loading area and conveyor belt transition at the base of the
slope and the transitions half way in the slope and above the portal. A TV
monitor in the lime plant affords a view of the ash collection underground
which must be contained behind dust curtains. TV monitors also are provided
for the two crusher operators for viewing rock movement across transition
zones of the conveyor system.

The CCTV system has become an indespensible item for the hoist operator
who can see that all personnel at the base of the slope are safe and material
is properly loaded before the hoist is engaged to pull the hoist car up the
slope. Incipient problems that could cause rocks to pile up in hoppers at
conveyor belt transitions or fine ash particles to be dispersed throughout the
mine can be averted thereby reducing down time, expensive repairs, and dis-
comfort of the personnel.

15


This feature was desired on both channels 1 and 2. Therefore, two
sets of crystals for each of the thirteen mobile radios were purchased
and installed.

The radio installation on the slope car was extensively revised by the
Project Leader after the following problems occurred:

1.. A 48/12v dc converter which supplied power for the radio was sub-
ject to damage by high voltage transients when the magnetic brakes
were operated.

2. A power failure occurred in the mine, and shortly thereafter, power
on the surface also failed. The slope car was underway in the slope
when the power failed on the surface which caused the car's battery
operated magnetic brakes to be automatically energized. After fif-
teen minutes, the batteries on the car were discharged and would no
longer supply power to the radio.

Both problems were corrected, as shown on Figure 3.6,by eliminating the
48/12 volt converter and tapping the slope car battery at 12V to power the
radio through a series diode. A Gel/Cel battery was provided, having enough
capacity to power the radio for several hours should the car's battery be-
come discharged.

The radio equipment including the tone encoder for horn signaling and
MODAT emergency alarm unit were remounted in a NEMA Class IV enclosure to
protect them from moisture and falling rock damage.

The horn signaling circuit includes a time delay relay which energizes
the horn for a minimum of one second each time that the signal button is
pressed. The schematic diagrams of the horn circuit and the MODAT brake
alarm signal are shown on Figure 3.7 and the radio control head, horn signal
and emergency stop and alarm buttons in the hoist car are shown on Figure 3.8.

57


+10

ll

12

13

14

15

TABLE OF CONTENTS (Continued)

September 1979
- Inventory of Equipment and Improvements in Base

Station Installations......... cc. c cece cece c cece eee eee eee

October 1979
- Preliminary Design of Multiplexed Digital Alarms

And Monitoring System....... 0. ccc cece cece eee eee eee e eee

- Preliminary Design of Uninterruptible Power System
- Improvements in Sope Car Radio Installation...............

- Preliminary Design of Interface Units for MODAT Encoders...

November 1979
- Radio Control and Alarm Center in the Mine Foreman's

OFFICE. eee ceecceccececeet eee tenet n nen eee eneees
December 1979
- A Project History was Issued to the BOM.................05
- First CCTV Installation. ........ cee cece cece eee eee eee
- Invention of Two Way UHF Signal Booster................06-
February 1980
- Patent Disclosure for Signal Booster.........eeeeeeeee eee
March 1980

- Plans for Extending Antenna Systems with Signal Boosters...

- Task Schedule for Installing Air Monitoring Tubing and
for Completing Radio and CCTV Systems............00000000-

April 1980

- New Project Manager was Appointed................e eee eens
- Inventory of All Items Purchased.............eeeeeeeeeeeee
- New Receiving Reports and Purchase Order Forms............
May - June 1980

- Technical Acceptance Criteria Were Proposed.............65
- Prototype of Signal Booster was Constructed and Tested....

- Monitoring and Radio Room was Installed Near
Crusher NO. 2.... cece cece cee eee eee eee e eee eee ee te eenee

duly 1980

- Conferences Held at Mine Regarding Progress...............
August 1980

- First MODAT Interface Unit Was Tested on a Mine Truck.....
- Need for Water Tight Enclosures Recognized.............06-
- CCTV Cameras were Installed at Base of Siope.............-

4

PAGE

53

54
55
57
59

60

61
61
61

63

63

63

63
63
63

65
65

65

65

65

65
67


FIGURE 3.19. VIEW OF YAGI ANTENNA INSIDE THE PORTAL SHOWING SEVERAL MONTHS'
ENCRUSTATION OF LIMESTONE DUST AND SMOKE PARTICLES ON THE ANTENNA RODS. THE
ANTENNA VSWR WAS NOT READABLE WITH 2.5 WATTS FORWARD POWER AND PERFORMANCE
EVIDENTLY WAS NOT DEGRADED.

FIGURE 3.20. TYPICAL MOBILE ANTENNA USED FOR DISTRIBUTED ANTENNA SYSTEM

MOUNTED ON TWO FOOT SQUARE METAL PLATE THAT IS ATTACHED TO ROOF NEAR THE
CENTER OF INTERSECTION OF TWO CROSSCUTS.

74


ANTENNA POLES
\ AY

THROUGH LINE
RF WATTMETERS MOBILE RADIO
CONTROL HEADS
CLIPBOARD 2
AUDIO TAPE - d /—— SPECIAL AUDIO

RECORDER INTERFACE
MAP DESK HEADSET

15 WATT MICROPHONE
466 MHz
MOBILE RADIO
15 WATT
812 MHz

MOBILE RADIO

FIGURE 2.4 MOBILE RADIO ASSEMBLY THAT WAS MOUNTED ON LIFT PLATFORM ON
TRACTOR FOR MOBILE SIGNAL STRENGTH MEASUREMENTS .

The special audio control unit shown on Figure 2.4 was constructed by
Bureau of Mines' technicians for controlling the modulation of both trans-
mitters and for interfacing the audio tape recorder and two headset micro-
Phones which were worn by the tractor driver and mobile radio operator. The
audio tape recordings made on the mobile unit were very helpful for identify-
jing the regions where the mobile unit was not heard at the control center.

At each intersection, the tractor driver would announce the mobile unit's
location. The signal strength measurements were made while the mobile unit
was in motion and the median values were tabulated from the chart recording.
Audio tape recordings were also made of all communications received in the
control center which were later compared and correlated with the signal chart
readings and positions of the mobile unit. By comparing the two audio tape
recordings, the routes followed by the mobile unit were marked later on mine
maps showing locations of all transmissions that were attempted as well as
those which were received.

29


FIGURE 3.17. TV CAMERA VIEWING ROCK MOVEMENT AT THE TRANSITION OF CONVEYOR
BELTS ABOVE THE MINE PORTAL.

FIGURE 3.18. TYPICAL RADIO INSTALLATION IN A MINE VEHICLE SHOWING THE MODAT
EMERGENCY ALARM, IDENTIFICATION AND STATUS ENCODER UNDER THE ROOF AND THE
RADIO CONTROL HEAD MOUNTED ON THE COLUMN.

72


3.13 May - June 1980

Technical Acceptance Criteria for the radio system was prepared by the
Project Engineer and was submitted to the TPO for comments.

The prototype signal booster design and testing continued, new preselec-
tors were installed and the performance was satisfactory. Signal sensing and
DC isolation circuits were needed to complete the booster unit. See Figures
3.11 and 3.12.

The monitoring room was erected near crusher No. 2 in the mine and a
temporary power line was installed to power air quality monitoring and radio
equipment. One of the greatest problems was unsatisfactory automatic answer-
ing of the data telephone line. See Figure 3.13.

3.14 July 1980

Conferences were held at the mine to determine how much progress was
made since the task list was prepared in March, and to coordinate the plans
for installing the UPS system and to complete the preliminary report. !3

3.15 August 1980

A pilot installation of the MODAT interface circuit boards was tested
on a mine truck. The circuit board functioned satisfactorily, but the pro-
per sensors for bed up, bed down, engine temperature and oi] pressure were
not on hand.

The need for properly gasketed enclosures (NEMA class 4) for electronic
equipment in mines was emphasized by the failure of a CATEL amplifier that had
been installed in an ungasketed enclosure. Moisture condensed on the cables,
entered the enclosure and collected on its bottom surface. CATEL and Motorola
were advised regarding this problem and the Project Leader has modified some
gasketed enclosures which are on hand to protect the CATEL equipment, Figure
3.14.

(13) "Proposed Environmental Monitoring and Uninterruptable Power Systems

for the Black River Mine", Comsul Ltd., Preliminary Report to BOM TPO,
July 1980.

65


LEGEND

Bl, 82, 83 BASE/REPEATER STATIONS
C1, C2, €3 CONTROL STATIONS
W TELEVISION CAMERAS

TS WOON O1OWe

(WAREHOUSE CT |

—

<a

(CONVEYOR BELT 10 LIME PLANT

[$391 430

FIGURE 1.3 MAP OF BLACK RIVER MINE SHOWING LOCATIONS OF BUILDINGS, SLOPE
TUNNEL CONVEYOR SYSTEM, ROCK CRUSHERS, AND RADIO STATIONS.

The mine is entered through a twenty two hundred foot slope tunnel that is
approximately twenty feet wide and nine and one half feet high by means of a
single drum hoist powered flat car and enclosed man carrier. The emergency exit
is through a hoist powered capsule in a Six hundred and fifty foot vertical six

foot diameter air shaft.

Rubber tired diesel powered mine vehicles travel along

haulage and travel roads through designated crosscuts from the active mining
faces on the perimeter of the mine to two rock crushers, the shop area and the

base of the slope.

22


The 5 to 30 MHz spectrum was to be used for communication from above
ground into the mine, 50-300 MHz for mine to the surface and the 30-50 MHz
spectrum was to be used for crossover filtering. The FM modulators and
demodulators were to be powered through the back bone cable by 60 volts AC
and batteries were to be provided to insure uninterrupted operation during
power outages.

Two "back bone" cables were to be installed through the mine in adjacent
crosscuts, one of the cables was to extend up to the slope to the radio room
on the surface and the other cable was to extend through a bore hole to the
surface.

In the event that the back bone cable extending up the slope is damaged
the other cable would be used for controlling the base/repeater stations in
the mine.

Radio control consoles were to be provided in the hoist house and in
the engineering office for controlling all base/mobile relay stations. A
radio receiver voting system was to be used for selecting the best signal
received from transceivers and mobiles. The system was to operate under
either the control of an attendant or as a base/mobile repeater relaying
communications between transceivers and mobile units.

The equipment for the radio system included:

e Three twelve watt base/mobile relay (BMR) stations on the surface
near the hoist house for above ground and slope communications.

e Two twelve watt BMR stations near the base of the slope in the
mine with an associated combiner to feed four antennas at prin-
cipal intersecting haulage roads in the center of the mine as
shown on Figure 2.9.

e Two twelve watt BMR stations near crusher no. 3 with a combiner to

feed four antennas at major haulage road intersections in the east-
ern sector of the mine.

39


The slope car radio was initially equipped with a tone encoder for send-
ing an audible signal which is heard in the hoist house. By providing a tone
decoder for the channel 3 receiver in the mine and a relay which will close
the signal horn contacts, persons on the slope car would be able to activate
through radio communication the customary horn signal from the car. The sig-
nals would be heard at the base of the slope, mid-slope and in the hoist house.
The Project Leader ordered the decoder and other items that were required.

During October Motorola MODAT alarm and status reporting units were in-
stalled in nine underground mine vehicles. Two other vehicles plus three
new vehicles also are scheduled to be equipped.

As originally installed, alarm signals and status messages could be ini-
tiated by push buttons on the MODAT control panels in the vehicles causing
audible alarm signals to be heard and alarm and status records to be printed
in the mine's engineering office above ground. Tests of this manually opera-
ted system have included printing records of the number of loads of limestone
rock that are dumped into the crusher. The truck drivers were cooperative and
the system functioned satisfactorily. However, in order to avoid human errors
and to insure a count each time that a load is dumped, it was decided to in-
stall mercury switches on the hand operated levers that causes the truck dump
beds to be raised and lowered. The Project Leader and Motorola Engineers under-
took the task of designing an interfacing circuit to operate the MODAT for send-
jing status messages including the vehicle number, bed up, bed down and hot
engine. Several push button status messages also will be available for assign-
ment.

Mine personnel had developed confidence in the radio system and evidently
feel comfortable with the Institute of Makers of Explosives (IME) Safety Guide
No. 20 recommendations to not use a UHF radio transmitter with up to 50 watts
output power if it is within twenty feet from an exposed blasting cap.

59


2.2 Evaluation of Test Results and Proposed Solutions of Problems

Tests 1 through 4 in the Black River Mine demonstrated that 450 MHz
communication was satisfactory with two watt transceivers for approximately
1700' down a limestone crosscut that is essentially straight and level. How-
ever, the range of communication down right angle intersecting crosscuts was
limited to a few hundred feet and was subject to multipath interference.

This appeared to be due to the high degree of attenuation of the 450 MHz sig-
nals through the limestone pillars and the lack of efficient reflecting sur-
faces on their sides. The following solutions to the problem were considered:

1. The use of metal reflecting surfaces as passive repeaters.

2. The installation of a distributed antenna system using line powered
transmitters to feed long transmission lines with power dividers
feeding antennas located in the intersections of the crosscuts.

3. The use of leaky coaxial cable fed by base/repeater stations or
daisy chain amplifiers.

4. A combination of distributed antennas and passive reflectors.

2.3 Investigation of Passive Reflectors and Distributed Antennas for
Extending the Range of 450 MHz Communication into Intersecting Crosscuts.

A review of the design specifications for passive microwave reflectors
revealed that a flat metal reflector having sixteen square feet of area would
provide 29 dB of gain to a 450 MHz signal and that it should be possible to
use such reflectors to extend communications into intersecting crosscuts.

In order to qualitatively verify that passive reflectors can be used for
extending the range of 450 MHz communications in the mine, two 4' x 4' flat
aluminum sheet passive reflectors were constructed and tested in the Black
River Mine on October 26, 1977. Two reflectors were mounted on a wood frame
so that the included angle between the reflecting surfaces was 90°

25


TO

CRUSHER
UP BORE HOLE NO 3
LIME
PLANT
CONTINUES ON
FIGURE 3.26. 1
; BRANCH OF
} ‘vee fap ay! BACK BONE
z5 ! atte | CABLE
ot 1 7 ie" oo
‘ Or] aiese oan
/, | UNDERGROUND * “ SHOP a j
~“ iv
BACK BONE CABLE
Oo eye TO CRUSHER NO. 2
1
ey

CONTINUES ON
! FIGURE 3.31.

BACK BONE CABLE

BACK BONE CABLE

FIGURE 3.30.

MINE.

92

BLOCK DIAGRAM OF A PORTION OF RADIO AND CCTV SYSTEMS IN THE
THIS IS AN ENLARGEMENT OF SECTION (Q) SHOWN ON FIGURE 3.28.


An order for additional items to complete the system was issued to
Motorola Communications & Electronics, Inc. The channel 3 signal strength
fade margins were measured on the slope car as it descended in the slope and
were found to be greater than required for 20 dB squelched carrier quieting
except at the end of the track in the slope.

3.2 June 1979

All back ordered equipment for the Phase I purchase order was received
and purchase orders were issued for three additional radios. Minor improve-
ments were made in the slope radio system as a result of operating experience.
Two radio installations were made in mine vehicles, a loader, and a dump
truck. The first back bone cable was installed in the slope. Two base sta-
tions and multiplexing equipment were installed in three gasketed weather-
proof enclosures (shown on Figure 3.1) near the loading area at the base of
the slope. This area was flooded after a rainstorm so the equipment was
moved to a higher location. The high water marks can be seen near the bottom
of the cabinets, however no water entered the cabinets, and the equipment was
not damaged.

FIGURE 3.1. INITIAL INSTALLATION OF MULTIPLEXING EQUIPMENT AND BASE AND
CONTROL STATIONS AT THE BASE OF THE SLOPE.

46


speaker/microphone or Muffcom is up to the individual user; the Muffcoms are
used in noisy areas.

The radios were initially equipped with Heliflex antennas. Coverage
using these short antennas was not adequate, so they were replaced with
flexible one-quarter wave (6") whips which increased their range.

A combination of single and multiple-unit battery chargers are provided
to keep all radio batteries fully charged. All batteries can be rapidly
charged in one hour. A full complement of fifteen (15) spare one-hour rapid
charge batteries is provided for emergency backup.

The two Motorola type T-1617 control consoles, located in the engineer-
ing office and the hoist house have the following basic features:

a. Tone control of base/repeater stations

b. Tone busy light to indicate when any channel is being used at the
other console

c. Call light for indicating incoming call

d. Mute switch for attenuating unselected channel

e. Individual line level control for each channel

f. Digital 12/24-hour clock

g. "Private line" tone-coded squelch

h. Intercom

i. Alert tone

The console in the engineering office is a standard model, equipped
with a desk microphone.

The console in the hoist house is mounted on a shelf in front of the
hoist operator. A boom microphone and a foot-operated PTT switch are used
because of the high noise level and the need for hands-free operation. (See

Figure 3.16.)

Also due to the high noise level in the hoist house, the selected and

87


FIGURE 3.11.A PROTOTYPE TWO WAY UHF SIGNAL BOOSTER IN NEMA CLASS 4 ENCLOSURE

AMPLIFIER

FIGURE 3.11.B CHASSIS FOR PROTOTYPE TWO WAY SIGNAL BOOSTER

64


unselected loudspeakers had to be relocated immediately behind and on either
side of the hoist operator's head. Two standard mobile radio speakers were
installed and have been very satisfactory.

Horn (or belling) signals sent from the slope car must be answered by
the hoist operator before moving the car. The horn signalling button that
is normally used by the hoist operator also is connected to send the alert
tone signal from the consoie by radio on Channel 3. Thus, the customary
horn signals which are heard in the hoist house, top of the slope, midway
and at the base of the slope also are heard on the moving slope car as long-
short alert tones emanating from the radio loudspeaker.

A unique feature of the radio and CCTV systems is the use of CATV tech-
nology and equipment for transmitting control, audio, digital and television
signals over a coaxial cable network. Figure 3.27 shows the "back bone" co-
axial cable layout on a mine map.

The completed system will use a pair of coaxial cables to provide re-
dundancy; one cable which is completely installed and equipped extends from
the radio equipment room in the office building down the slope and branches
to serve the radio CCTV and monitoring equipment in the mine. The second
cable has been installed in a bore hole near the lime plant, and it extends
in the mine using different routes to the same equipment that the first cable
serves.

The second cable will be extended above ground via pole attachments
from the lime plant to the radio equipment room. Both cables will be simul-
taneously fed, and in the event of the failure of one cable, the other cable
can be used.

Twenty-seven CATEL FM modulators and demodulators are used to multiplex
the control, audio, digital and video signals on carrier frequencies ranging
from 6.2 to 175.1 mHz, as is shown on Figures 3.28 through 3.31 four addi-
tional modulators and demodulators have been proposed for a future digital
environmental monitoring system.

88


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PAGE 8 OF 8


TABLE 2
SIGNAL MARGINS MEASURED ABOVE GROUND ON THE BLACK RIVER MINE PROPERTY

These measurements of signals from a two way transceiver were made at a
base station receiver on January 28, 1981, during final acceptance tests of the
radio system. .

MEASURED SIGNAL MARGIN

INPUT TO ABOVE 20 dBq

RECEIVER (0.8 uV)

TEST LOCATION uV dB COMMENTS

Highway 8 and road to
the air shaft 100+ 40+ Excellent signal
Powder magazine 6 - 10 16 - 20 " "
Walking around air shaft
hoist house 5-9 14 - 19 " "
Walking near fans 3-6 9 - 16 " "
Air shaft sub station 5-9 14 - 19 " "
Riding past dump 3-7 9-17 " "
Near cooling towers 9 - 30 19 - 29 " "
Walking around lime kilns 6 - 50 16 - 34 " "
Mobile enroute to
warehouse 20 - 100 26 - 40 " "
In lime kiln buildings 20 - 100 26 - 40 " "
On back side of kiln
building 5 - 12 14 - 22 " "
Near back door of kiln
building 6 - 14 16 - 23 " "
On second level of kiln
building 10 - 100 20 - 40 " "

Page 2 of 6


BASE STATION
YAGI ANTENNA
43 WATTS E.R.P.
H. POLARIZATION

ra VAS aw
SLOPE CAR PY SS AAS

7 WATTS E.R.P.KSS SVN SAAN AN RASRONONG

\ Lv. POLARIZATION] \\\ SS Wes A

HOIST

<coeee
NAAN

Roa 1 CABLE 5
SSCS SRSRACEEE ES SLOPE TUNNEL Se eOee Se
v ¥ _ VAN Vv Aye
———— Ty DS VATS ve\
STN EE ANE VYANS VSS ASAING
TIA SO , ve \\ AYN
ony NAS ANY VV NAY \ IOAN \\yae SSA AS

SIGNAL MARGINS IN dB ABOVE 20 dB SQUELCH QUIETING ON 454.025 MHz '
i} 0 5 0 0 10 30 40 45 55 70 80 From Base Station
— — — — ++ _
0 0 0 5 10 5 10 20 40 45 80 70 80 From Hoist Car
a _ a _ .
2000" 1800" 1600" 1400' 1200° 1000" 800' 600° 400' 200° 0’

DISTANCE, FEET FROM TOP OF SLOPE TUNNEL

FIGURE 2.7. SIGNAL STRENGTH MARGINS ABOVE 20 dB CARRIER SQUELCH QUIETING IN
THE SLOPE TUNNEL.

On May 11, 1979, signal strength or fade margins above 20 dB carrier
squelch quieting were measured on the slope car as it descended into the mine
while the base station above ground was continuously keyed. The measurements
were repeated at the base station while the radio on the slope car was contin-
uous ly keyed.

During the tests, a vertically polarized "hard hat" antenna was used on
the slope car. It has been replaced by a horizontally polarized whip antenna
which has noticeably improved the fade margins but they have not been re-

measured.

2.7 Tests of Portable to Portable UHF Radio Communications Through the Air
Shaft Emergency Exit.

On December 8, 1977, qualitative tests were made to determine the effect-
iveness of 450 MHz radio communication between the bottom of the air shaft and
various points in and around the escape hatch on the surface.

The air shaft is six feet in diameter and extends vertically six hundred
and thirty feet to a plenum chamber on the floor of the mine. The top of the
air shaft is covered by a metal housing that is attached to two horizontal air
inlet ducts containing large impeller type fans. (See Figure 2.8).

33


Figure

3.11A
3.11B
3.12

3.16
3.17

3.18

LIST OF ILLUSTRATIONS (Continued)

Signal Margin Measurements Made in the Mine
November 1979 Western Section. ...........

Signal Margin Measurements Made in the Mine
November 1979 Eastern Section. ... .

Schematic Diagram of Signal Margin Measuring Equipment. ...

Schematic Diagram of Slope Car Power Circuits. .....
Schematic Diagram of Slope Car Signaling and Alarm Circuits.

Passenger Compartment of Slope Car Showing Radio Being
Used. 2... ee ee Se eee

The Radio Control Head, Horn Signal and d Emergency Stop
Buttons on the Slope Car Se ee

Radio Communications Control Station is the Foreman's
Office... . . ee ee ee Bo ee

MODAT Alarm and Mobile Unit Identification Decoder in
Foreman's Office... 6 ee eee ee ee es

Map of Black River Mine Showing Extended Antenna System
and Future Locations of Two Way Signal Boosters.

Prototype of Two Way UHF Signal Booster in NEMA Enclosure.
Chassis for Prototype Two Way Signal Booster. . .
Schematic of Signal Booster. .......

Prefabricated Radio Base Station and Monitoring Room Near
Crusher No. 2. 2... 2 2 ee ee ee ee eee

Control Station and Multiplexing Equipment in Weatherproof
Cabinet at the Base of the Slope. ...... Soe eee

CATV Line Amplifier for the "Back Bone" Cable System. . . .
TV Monitors and Radio Control Equipment in Hoist House. . .

TV Camera Viewing Rock Movement Across the Transition of

Conveyor Belts Above the Mine Portal. ..... we ee

Typical Radio Installation in a Mine Vehicle... ......

View of Yagi Antenna Encrusted With Limestone Dust and Smoke

Particulates... .......4. So ee

Typical Mobile Antenna Used for Distributed Antenna System.
9

Page

50

51
52
56
56

58

58

60

60

62
64
64
66

68

- 68
- 70
- 70

72
72

74

~ 74


FIGURE 3.2B
BACK VIEW OF SHOULDER HARNESS
SHOWING ATTACHMENT TO BELT STRAP
WHICH RELIEVES PRESSURE ON NECK.

FIGURE 3.2A
PORTABLE SIGNAL MARGIN MEASURING EQUIPMENT

The equipment used for measuring the signal strength or fade margins weighs
less than twelve pounds and it can be supported by a shoulder harness. This
equipment substanially reduced the time required for taking signal strength
measurements and for tabulating the data. This development probably will be
remembered as a major improvement of the technology of signal strength measure-
ments.

The signal margin measuring set was constructed in two 10" x 14" x 3" alum-
inum chassis which are bolted back-to-back forming a shielded compartment for a
portable receiver and two attenuators. (0-70 dB and 0-10 dB) which are in series
with the antenna lead. The unsquelched audio is adjusted to OdB on a VU meter
and is mixed into the head set and tape recorder. The head set microphone audio
also is mixed into the tape recorder input so voice recordings of location, data,
etc., can be made. See Figure 3.5.

48


Figure
1.
1.

1.
2

«9A

-9B

-10

U
-12

.2A
2B

LIST OF ILLUSTRATIONS

View of Radio Shop and Mine Portal. .
View of Entrance to the Black River Mine Property. ... ..

Mine Map Showing Locations of Buildings, Slope Tunnel
Conveyor Belt System, Rock Crushers, Radio Control and

Base Stations. .......... So ee ee

View Down Crosscut 104E Showing I]luminated Intersecting
Crosscuts. .... se eee Se ee

Portion of Mine Map and First Reflector. ....
Tractor Equipped for Signal Strength Survey. .....

Mobile Radio Equipment Assembly That Was Mounted on Lift
Platform on the Tractor for Signal Strength Survey.

Circularly Polarized Antenna Mounted on Slope Car for
Measuring Signal Attenuations in the Slope Tunnel. . .

Comparison of Free Space and Measured Path Attenuation
At 466 and 812 MHz in the Slope Tunnel. .........

UHF Signal Strength Margins Measured in the Slope Tunnel. . .

Sketch of Air Shaft Used for Emergency Escape.

Distributed Antenna System as it Was Originally Installed
in Western Sector of Mines... 2... 2.2... -2- :

Distributed Antenna System as it Was s Original ly Installed
in Eastern Sector of Mine. :

Original Plan for Redundant "Back Bone" Coaxial Control

Cable... 2... eee ee eee ee

Block Diagram of Radio System for the Black River Mine.

Typical Sheet Aluminum Reflector. .........-..08.

Base Stations in Weatherproof Cabinets as Originally
Installed at the Base of the Slope. ...... wee

Portable Signal Margin Measuring Equipment. . . .
Back View of Shoulder Harness Attachment to Belt.

Signal Margin Measuring Equipment Being Used in a
Pick Up Truck. ........ So

Page

22

24
26
28

29

31

32
33

34

36

37

41
42
43

46
48
48

49


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CONTROL STATION IN MINE SHOP

PAGE 7 OF 8


CONVEYOR BELTS
TO LIME PLANT

ROCK CONVEYOR BELT FROM HOIST
HOUSE PASSES OVER HIGHWAY 8

UHF RADIO
ANTENNA

FIGURE 1.2 VIEW OF ENTRANCE TO THE BLACK RIVER MINE PROPERTY. IT IS ON
KENTUCKY HIGHWAY 8, APPROXIMATELY 40 MILES SOUTH OF COVINGTON AND ONE HOUR
DRIVING TIME FROM THE CINCINNATI AIRPORT.

The mine was using a VHF radio system for communicating with key per-
sonnel above ground and Citizens Band equipment for communicating with per-
sonnel at the lime plant and for coordinating the loading of barges on the
Ohio river.

A cooperative agreement was negotiated between the Bureau and the Black
River Mining Company and, in February 1977, the Bureau of Mines solicited pro-
posals from communications engineering firms to design and develop an improved
underground radio communications system for the mine. Comsul Ltd. was select-
ed as the prime contractor and was awarded a contract in October 1977.

Black River Mine has a single level that is approximately six hundred fif-
ty feet deep and it is nearly four thousand feet in diameter. It has essent-
jially straight crosscuts approximately thirty feet wide and twenty four to
forty feet high with pillars approximately thirty five feet square.

21


Innovative developments which should be useful in the mining industry

include:

The use of passive reflectors for extending UHF signals into
intersecting crosscuts or tunnels.

The development of two-way multichannel signal booster and
distributed antenna systems to serve distant regions in a
mine. A patent disclosure was submitted to the Bureau since
some features of the signal boosters may be new and useful.
The development of a lightweight radio signal margin measur-
ing unit that can be easily carried and operated by persons
walking or riding through a mine.

The application of CATV technology and equipment for multi-
plexing audio, video, and digital signals for controlling
mobile radio base repeater stations.

Development of interface units for digital mobile radio en-
coders in order to automatically transmit vehicle status (bed
up, bed down, hot engine) to a control center.

Recommended improvements in the Black River Mine:

Complete the installation of improved alarm annunciators in
the hoist house.

Install uninterruptible power systems (UPS) for radio consoles
and future monitoring equipment that is located above ground.
Install UPS system for control stations and future monitoring
equipment in the mine.

Evaluate and measure the two way signal strengths through the
air shaft. Also, verify escape procedures by conducting a
safety drill at the air shaft using the radio system for all
surface to mine communications.

Complete six radio signal boosters, install them in the mine,
and evaluate their effectiveness for extending communications
to the perimeter of the mine.

Replace the VHF equipment used above ground with UHF trans-
ceivers and mobile equipment that is equipped with encoders

16


TABLE OF CONTENTS (Continued)

September 1980

- Completed Design of Multiplexing and UPS Systems
For Air Quality Monitoring.......... cc eee cece eee eee

- Redundant Coaxial Cable Installed In Bore Hole

- DC to DC Converters were Removed from Vehicles Due
to Unreliability

- Research Continued on Signal Boosters and CATV
Technology

October 1980

- Fabrication of Six Signal Booster Began...............e0ee

- Transmission Lines for Extending the Antenna System
were Completed... ....... cece cece cece e ee eee eee eens

- TV Cameras were Repositioned at Base of Slope.............
November 1980

- Results of Testing MODAT Interface Unit
- Improvements in Above Ground Radio Communications.........
December 1980

- Need for TV Monitoring of the Ash Disposal Area in the
MING. cee cece eee eee eee eee e eet e eee e ete enenee

- Radio Failure Due to Battery Problem on the Slope Car.....
January - February 1981

- Emergency Alram Annunciators for Office Building,
Hoist House and Mine Shop Area..........sse cece eeere eens

- Improvements in Sensors for Truck Bed Positions

- Adapting Radio Circuits to Mine Vehicle Power Systems.....
Inspection and Acceptance Tests of Radio and CCTV Systems...
- Signal Margin Measurements........ ccc cece cece cee eee eens
As Built Radio System Description...........c cece eee e eee
- Radio Channel and Frequency Assignments...

- Description of Distributed Antenna Systems................
- Description of Control Stations........... cece eee e eee e eee
- Description of Mobile and Portable Radios.................

- Description of MODAT Identification, Alarm and Status
SYSTEM. occ eee ec cece cece ee eee eee eee eee eee eee eeeeee

- List of Vehicles and Personnel Equipped with Radios

PAGE

69

71
71

71
71

73
73

73
73
75
77
77
80
81
83
84
85

85
86


The Tx/Rx signal booster system that is being installed by Motorola

in a room and pillar coal mine in southern I1linois promises to afford
many advantages over systems using conventional base/mobile relay
stations and distributed or leaky antennas.

The Ariadne daisy chain system with IF return that has been developed
in England should be tested in a mine where intrinsically safe require-
ments apply.

5.9 Pending Tasks

Several items not covered elsewhere in this report that need to be further
addressed are:

Maintenance - A contract with a reputable service company or in-
house employee has not yet been resolved.

MODAT reporting system - All the units involved in this service have
not as yet been installed, tested and brought into use by the Black
River Mine.

Records of performance - Accurate records of performance of the entire
system and individual components should be kept on a regular basis.
Signal Booster System - This part of the project has not yet been
completed as far as assembly is concerned and therefore the concept
has not had a field test to observe its practicality.

112


Nearly all of the ten thousand feet of coaxial cable for extending the
antenna system in the mine has been installed and several antennas also have
been installed. The redundant back bone coaxial cable has been installed
from where it enters the mine to the radio base stations located near crusher
No. 3.

The CCTV camera that views the slope car loading area at the bottom of
the slope was moved in an effort to provide a better view for the hoist oper-
ator. After trying it at the new location, it was decided to move it back to
the original position and mount it on an adjustable pan tilt head. The pan
tilt head that was originally installed under the camera that views the con-
veyor belt transfer point at the top of the slope has not been needed so it
was available for installation underground.

All radio equipment at the Black River Mine is now more than one year
old and is out of warranty and it will be necessary to purchase replacement
parts when they are needed. The CCTV camera equipment is less than one year
old and is still covered by the warranty.

3.18 November 1980

The first MODAT interface unit on a mine truck is functioning satisfac-
torily and the bed up - bed down switch has been replaced by a switch that
is actuated by the bed instead of the hand lever. Erroneous indications
could be transmitted when the switch was actuated by the hand lever, indi-
cations from the switch that is actuated by the position of the bed are accu-
rate and reliable. It will now be practical to equip all mine trucks with
the MODAT interface units and proper sensors and switches. See Figure 3.21.

Unexplained problems with radio communications in the slope have been
traced to a loose connector in the antenna system of a repeater which eli-
minated suspected losses due to moist dirt on the antennas.

The antenna above ground was moved to a tower which supports the
belt conveyor system (see page 21). This vastly improved communica-
tions between persons using transceivers near the air shaft, substation,
lime plant and administration building.

71


CECE
900:
oc
00 2 oem
eo:
egoc
ecg!
aha
mae &
Toc

take PASSIVE REFLECTOR SUSPENDED FROM WIRES
Set ra) Q ceo TO THE MINE ROOF.
oon POE Bs
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a - Saas ;
atalaie ca fawccesstane] Pe afernecron 5 ri
es dx: Lown 2e2 re
ao oy ~! — bey FEI any teaunag FE
gonodonno@onoons cago
Goto SOMA at

QUALITATIVE SIGNAL EVALUATION

Excellent signal, full quieting, no multipath.

Good signal, some impairment.

Satisfactory signal, some impairment.

Wurm Mt Marginal, critical squelch or multipath objectionable.

Unsatisfactory, occasionally breaking squelch.

AULLDALMLULOLOLWUOMLLOLEE

FIGURE 2.2 PORTION OF
REFLECTOR SHOWN IN THE

MINE MAP SHOWING RESULTS OF FIRST TESTS OF THE PASSIVE
INSERT.

The apex of the reflector was aligned along the axis of crosscut 205S fac-

ing the base station site at Crusher No. 2 as shown above. The reflecting sur-
faces were at 45° angles with respect to the axis of crosscuts 130 (E and W).
A two watt 450 MHz transceiver was operated as a fixed station in crosscut 205S
near crusher No. 2. It communicated with similar transceivers which were car-
ried by persons walking through intersecting and parallel cross cuts to quali-
tatively evaluate the range and quality of communications. The passive reflec-
tor definitely enhanced two way signal strengths in crosscut 130 compared to

the signal evaluations in parallel crosscuts 128, 129 and 131. 3

(3)

History of Project and Progress Report on Implementation of UHF Radio
System in the Black River Mine, pages 4 and 5, December 1979.

26


reflectors, each four feet square, were installed near the ceiling and
positioned 45° with the respect to the axis at an intersection of a main
haulage way and a crosscut. The range of communication down the intersecting
crosscuts was significantly extended. Propagation measurements on 466 and 812
MHz in the same mine demonstrated that passive reflectors are a practical and
inexpensive means for extending communications into intersecting crosscuts.
The same formulae and nomograms used for microwave passive reflectors can be
used for UHF reflector design.

Since portable transceivers using 812 MHz were not commercially available
in 1978, the radio system was designed to operate on three 451/457 MHz channels
in the Special Industrial radio service. One channel is assigned to communi-
cating with the hoist car in the slope, the second channel is for mine opera-
tions, and the third channel is for general communication on the surface and
in the mine.

A leaky coaxial cable antenna system along the principal haulage and
travel roads was considered but was rejected because the range of communication
at right angles to the leaky cable into intersecting crosscuts would have been
much less than the range of communication from antennas at the centers of
major road intersections. The leaky cable system is appropriate for long
tunnels but not for intersecting roads in room and pillar mines; also, a
leaky cable would be more expensive than a distributed antenna system consist-
ing of low loss transmission lines feeding numerous antennas through power
dividers.

Two distributed antenna systems were designed and installed and are per-
haps the first application of this technology in the mining industry.

One system with all three channels serves the slope, the center and wes-
tern side of the mine. The other system, with two channels, serves the east-
ern side of the mine. The twelve watt base repeater stations are controlled
by control stations located in the mine foreman's office and at the hoist car
loading dock near the base of the slope. A third system, with all three chan-
nels, is located on the surface and feeds conventional antennas. This system
is controlled by consoles in the hoist house and engineering office and by a
control station in the warehouse.

12


TABLE 1

COMPARISON OF COMPUTED AND MEASURED ATTENUATION COEFFICIENTS
IN LIMESTONE SLOPE TUNNEL OF BLACK RIVER MINE

COMPUTED ATTENUATION COEFFICIENT &
Measured %
f Refraction Roughness Tilt Total
mHz dB/100' dB/100' dB/100' dB/100' dB/100'
466 3.60 0.551 0.377 4.03 4.02
812 1.43 0.029 0.589 2.05 2.03

Measurements of ein the larger cross-section area crosscuts in the Black
River Mine have not been made, but signal margin measurements have indicated
that 4 dB/100' beyond the first 300' from an antenna is a conservative value
unless line of sight conditions are impaired by variations in floor elevation
or alignment of pillars. Satisfactory two-way signal strengths are obtained
within a 500-foot radius from a base/repeater antenna that is radiating ap-
proximately one-tenth watt effective radiated power and a hand-held trans-
ceiver that is radiating two watts. Beyond 500 feet from the base/repeater
antenna, signal strengths diminish rapidly in crosscuts which are parallel
to the crosscuts that are illuminated by the base repeater antenna.

FIGURE 2.5. CIRCULARLY POLARIZED ANTENNA
USED FOR SIGNAL STRENGTH MEASUREMENTS IN
THE SLOPE TUNNEL.

31


LIMESTONE ROCK FACE DRILLED AND LOADED WITH
48 ATLAS TIME MASTER BLASTING CAPS.

PICKUP TRUCK
11 W. RADIATED.

THREE PORTABLE 2 WATT
TRANSMITTERS WERE
TURNED ON AND LEFT ON
A REAR SEAT OF THE
PICKUP DURING THE TESTS.

TRUCK #8
11 W. RADIATED

BLASTING LINE WITH
SHUNT WHICH WAS
CONNECTED WHILE
PEOPLE WERE NEAR
THE FACE AND
DISCONNECTED DURING
TEST.

OBSERVATION POSITION APPROXIMATELY
120' FROM FACE. THREE TOGGLE SWITCHES
WERE USED FOR KEYING THE MOBILE RADIOS
"ON" FOR APPROXIMATELY ONE MINUTE.

FIGURE 4.2 APPROXIMATE LOCATIONS OF VEHICLES EQUIPPED WITH MOBILE UHF RADIOS
WHICH WERE PARKED ADJACENT TO THE DRILLED FACE LOADED WITH 48 BLASTING CAPS
IN THE BLACK RIVER MINE, AUGUST 22, 1979.

100


CRUSHER 3

' 1
TO | ' Avdio Demoo '
DIRECTIONAL an i, .
COUPLER = 7 L4
FOR BACK BONE + 7 ae
CABLE UP ; A pate
BORE HOLE —firsce | -

Video Demoo

BACK BONE CABLE 9 ===
TO UNDERGROUND oo,

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3

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vigeo Oe =

TO SPLITTER |
AND BACK
BONE CABLE

1 MONITOR BUILDING)

| directional

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AT P2 BELT I
TRANSFER 2

ORO)

An :

i ‘Counter, 7 - :
TO BACK BONE / \
CABLE UP KA

THE SLOPE | Ce 2a

FIGURE 3.31. BLOCK DIAGRAM OF A PORTION OF RADIO AND CCTV SYSTEMS IN THE
MINE. THIS IS AN ENLARGEMENT OF SECTION @ OF FIGURE 3.28.

93


All three systems can be simultaneously keyed to afford radio communi-
cations between persons in principal areas in the mine and persons above
ground.

The control consoles and the base/repeater stations are interconnected
through a redundant coaxial "back bone" cable system using FM modulators and
demodulators on multiplexed frequencies ranging between 6.1 and 175 MHz. This
is a new and unique application of CATV technology and equipment to mobile
radio communication.

The "back bone" cables are installed along separate routes in order to
provide redundant communication capability if one cable is damaged. One
cable reaches the surface and the control equipment through the slope and the
other cable is routed through a bore hole which reaches the surface near the
lime plant. It is attached to poles until it reaches the control equipment
jin the mine office building.

Signal margin measurements of the base/repeater station signals along
haulage and travel roads were made after both distributed antenna systems
had been completed which demonstrated that approximately 75% of the mine area
received satisfactory signals but active mining areas along the perimeter of
the mine were not adequately served. Obviously, the distributed antenna sys-
tem would have to be extended to serve additional antennas near the mine faces.
However, the cable attenuation would so drastically reduce the power radiated
from the antennas and the signals received from the mobiles and portables that
very little improvement would be realized. Additional base/repeater stations
were considered; however, the added complexity and cost of multiplexing equip-
ment and for extending the back bone cable control system stimulated the
development of a two-way multichannel signal booster system. A prototype
signal booster was constructed and tested in the laboratory. A patent dis-
closure was filed since it was believed that it was a new idea. A six amp-
lifier signal booster system was designed, ten thousand feet of cable, and
sixteen additional antennas were installed in the mine in anticipation of the
completion of the booster amplifiers.

Measurements also were made of signal strengths received by base sta-
tion receivers from a two watt transceiver that was operated in the haulage ways.

13


A pair of detonator leads were connected to the network of blasting

caps and was extended to the observation position approximately 120' from the
loaded face. Removable shunts were connected across the detonator leads at
the face and also at the observation point. These shunts were required by
the MSHA representatives to insure the safety of personnel while they were
near the loaded face. The shunts at the face were disconnected after the
shunt was connected at the observation point. Three operating portable two
watt transmitters were then carried by a technician to the face and placed
on the back seat of the pick up truck which was parked nearby. After the
technician returned, the shunt at the observation point was disconnected
leaving the detonator line open circuited except for the resistance in the
network of blasting caps. See Figure 4.2.

The relative positions of the three vehicles, the wired face and the ob-
servation point are shown on Figure 4.2. The transmitter keying leads of the
mobile radios on the three vehicles were extended by a multiconductor cable
approximately 110' to the observation point where they were connected to three
single pole single throw switches.

Bird Thru-Line Watt meters were connected in series with the antenna
lead from each of the mobile transmitters and placed where they could be
read from the ground level.

4.3 Test Results

Test 1 - Three mobile transmitters and three portable transmitters were
simultaneously operated on 451.95 MHz for approximately one minute.

Vehicle Transmitter Output to Antenna
Loader 224 14 Watts
Truck #8 11 Watts
Pick up Trunk 11 Watts
Portable 1 2.2 Watts
Portable 2 2.1 Watts
Portable 3 2.1 Watts

99


Following is an estimate of the amount of radio power reaching the
loaded face from the three mobile and three portable transmitters
during the tests on August 22, 1979.

Radiated Approximate Approximate
Power Distance Power Received
Vehicle Watts From Face, Feet At Face, Watts
Loader #224 14 18' -0023
Truck #8 11 35! -0004
Pick up Truck 11 gt +0004
Portable 1 2.2 g' -0014
Portable 2 2.1 g' -0014
Portable 3 2.1 9! +0014
0.0072

4.5 Conclusions

This demonstration proved that three eleven watt mobile transmitters
and three 2 watt portable transmitters can be safely operated simul-
taneously in the 451-457 MHz spectrum when they are all located with-
in ten to forty feet from a rock face drilled in a hole pattern that
' and 31' long and loaded with forty-eight Atlas Time Master
electrical blasting caps which were connected as shown on Figure 4.1.

was 22-4

The total amount of radio energy that reached the wired face during
the tests with three mobile and three portable transmitters opera-
ting nearby was seven milliwatts.

The miners in the Black River Mine were satisfied with the results

of the demonstration and have not objected to using the radios near
blasting areas.

104


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CONTROL STATION IN WAREHOUSE ABOVE GROUND

PAGE 5 OF 8


The CCTV cameras have been very effective for viewing the hoist car at
the bottom of the slope and the flow of material at transfer points along the
belt conveyor system.

3.16 September 1980

The multiplexing system for the air monitoring system was designed and
the CATEL modulators and demodulators were ordered by the Environmental Moni-
toring group at PRC.

An experimental Research license, KK2-XCA was received which authorizes
the operation of the signal booster systems in the Black River Mine.

Research on CATV and other signal booster amplifiers continued, and one
of the Japanese engineers who prepared a paper describing a signal booster
system for highway tunnels in Tokyo was interviewed.!4 The Nippon Telegraph
and Telephone Public Corporation has tested a two way 800 MHz signal booster
system that is similar in concept to the ones that have been designed for the
Black River and Sesser Mines. !® A C-COR CATV distribution amplifier was
tested, it exceeded its published specifications and is suitable for use in
mines and tunnels.!6

The redundant back bone coaxial cable was installed in a bore hole that
is near the lime plant.

The coaxial cable for extending the signal booster system to the eastern
perimeter of the mine was partially installed and a schedule was prepared for
completing the installation of cables and antennas.

The DC to DC inverters on the vehicles that have 24V or higher battery
voltages have been quite unreliable and will be removed from service. Since
the radios require a small amount of current, they will be connected to
twelve volt taps on the batteries.

(14) Suzuki, Hanazawa & Kozono, "Design of Tunnel Relay System with a Leaky
Coaxial Cable in an 800 MHz Land Mobile Telephone System."

(15) Fisher,Jack, "A Unique Multichannel Two Way UHF Radio Signal Booster
System for Leaky Transmission Lines in Mines", IEEE 31st Vehicular
Technology Conference, April 1981.

(16) Isberg, R.A., "Evaluation of C-COR CATV Distribution Amplifier as a
Signal Booster for VHF Radio Systems", Comsul Ltd., Report to BOM TPO,
September 1980.

67


3.19 December 1980

The mine constructed a brattice cloth curtain enclosed area in the east-
ern sector of the mine for storing ash that is collected from the lime kilns.

The dust is dropped down the “dust hole" into a hopper where it is mixed
with high pressure air and blown through a large pipe to the curtained storage
area. While no one was in the mine a coupling in the pipe line separated
and the dust was blown into the mine. The operator at the lime plant had no
indication of the problem which persisted until the first shift reported that
the air was so full of dust that they couldn't work.

Since a TV camera can detect large quantities of dust in the air, one of
the cameras will be moved to the dust collection area to feed a monitor lo~
cated in the lime plant control area. The operator will be able to visually
monitor the performance of the underground dust storage system and to turn off
the machinery when trouble is detected.

A failure of the radio on the slope car was traced to lack of water in
the slope car's storage batteries. When water was added the batteries recov-
ered and the radio functioned normally. The mine has ordered vapor condensing
battery caps to prevent this type of problem.

3.20 January - February 1981

Materials for constructing new alarm annunciator panels for the under-
ground shop, the hoist house and the administration building were obtained.
Emergency alarms that are sent from any radio in the system will be annunci-
ated at all three locations. Each of the three annunciator panels can be in-
dependly reset.

Over the past several months various types and locations for the truck
bed position sensors and actuators have been tried. The most successful
arrangement is a normally open switch that is actuated by a stiff piece of
rubber that is attached to the truck bed. This arrangement will be installed

73


Recommendations for Additional U.S.B.M. Studies,
Development and Research

1. Further development of the signal booster concept is needed
before it can be extended into hazardous areas such as coal
mines or gassy metal non/metal mines.

2. A follow-on independent evaluation will be necessary to
compliment this installation work.

3. The Tx/Rx signal booster system that is being installed by
Motorola in a room and pillar coal mine in southern I]linois
promises to afford many advantages over sytems using conven-
tional base/mobile relay stations and distributed or leaky
antennas.

4. In many mines, CATV amplifiers and technology could be used
very effectively in the same manner that it will be used in
the Washington Metropolitan Area Transit Authority (WMATA)
subway.

5. The Ariadne daisy chain system with IF return that has been
developed in England should be tested in a mine where intrin-
sically safe requirements apply.

6. Further development of light weight automated signal strength
measuring equipment also should be pursued.

18


Test No. 1 (Continued)

A. The mobile radios transmitted continuously for approximately one
minute until they were turned off by time-out timers which created
three tone signals that were heard by all present at the observation
point.

B. The portable transmitters were operated for approximately two minutes
because they were turned on and off manually and were left on the
seat of the pick-up which was parked near the loaded face. See Fig-
ure 4.3.

C. The caps were not detonated.

Test 2 - This test was identical to Test 1 except the transmitter fre-
quency was changed to 457.175 MHz. The output power was the same as
tabulated for Test 1 and the caps were not detonated.

Test 3 - Identical to Test 1 except the transmitter frequency was
changed to 452.175 MHz. The output power was essentially the same as
for Test 1 and the caps were not detonated.

Test 4 - Only three portable transmitters were operated on 457.025 MHz.
The output power was approximately 1.9 watts for each portable and the
caps were not detonated.

Test 5 - Test of the blasting caps with a detonator.

A DuPont capacitor discharge detonator was connected to the firing line

and all caps were detonated proving that the caps were all live and that the
electrical wiring of the caps' leads was correct and satisfactory.

101


2.0 ENGINEERING TESTS PRIOR TO DESIGNING THE RADIO SYSTEM
2.1 Preliminary Qualitative Signal Propagation Tests.

Prior to beginning the radio system design Comsul's project engineer
visited PRC to confer with the TPO and they also inspected the Black River
Mine. The mine's general radio communications requirements were reviewed with
Management personnel and preliminary project goals were established. In order
to obtain needed technical information regarding UHF propagation in the mine
four preliminary tests were conducted in the mine to qualitatively evaluate
signal strengths and propagation conditions which could affect the design of
the system.

Following is a brief summary of the test results:

1. Communications between two watt 460 MHz hand held transceivers car-
ried by pedestrians was satisfactory in straight and essentially
level crosscuts for distances up to approximately 1750 feet. The
range of communications on oblique paths through a maze of pillars
was approximately 800 feet. The crosscuts were approximately thirty
five feet wide and twenty five feet high and the limestone pillars
were approximately thirty five feet square on seventy five foot cen-
ters. Figure 2.1 is a view down a typical cross cut that is essent-
jally straight and level. Four intersecting cross cuts are illuminated
by light from the shop area. Crosscuts in old sections of the mine
are not straight and the floor level is not uniform which increases
the attenuation of radio signals compared to attenuations in straight
and level cross cuts.

2. Signals from a two watt hand held transceiver, operated by a person
riding on a tractor, to a signal strength measuring receiver at a
fixed location demonstrated that satisfactory communications with a
moving vehicle had a range of 1600 to 1800 feet through essentially
level and straight crosscuts and approximately 800 feet in adjacent

(1) History of Project and Progress Report on Implementation of UHF Radio
System in the Black River Mine, pages 2 and 3 - December 1979.

23


RECEIVING ANTENNA
TIGHTLY FITTING ALUMINUM COVER ON
ALUMINUM 10" x 14" x 3" CHASSIS

0 - 70 dB
~ PAN
0 - 10 dB PORTABLE RADIO
RECEIVER AUDIO
ANTENNA (UNSQUELCHED)
TERMINAL
~ luf >=

HEADSET
MICROPHONE ~ | 100 k cLuf
EARPHONE —— $ |

3k

MICROPHONE RECORD

VU
METER

~
RADIO RECORD
RADIO MONITOR
a
AL
~
ADJUST VU INOICATION

TAPE RADIO na
MON. MON.
CONTROL
PANEL
MON. MIC. LIGHT
AUDIO TAPE FOUR
RECORDER RECHARGEABLE
D CELLS

FIGURE 3.5. SCHEMATIC DIAGRAM OF SIGNAL MARGIN
MEASURING EQUIPMENT

52


4.0 DEMONSTRATION OF SAFE OPERATION OF 450 MHz MOBILE AND PORTABLE RADIO
TRANSMITTERS ADJACENT TO A DRILLED ROCK FACE LOADED WITH BLASTING CAPS.

4.1 Background and Purpose of Demonstration

While the radio propagation tests and installations were being made in
the mine several of the mine's employees requested assurance that operation
of the mobile and portable radio transmitters in the vicinity of electrical
blasting caps would be safe. Accordingly, the Black River Mine Com-
pany requested the Bureau of Mines, Pittsburgh Research Center (PRC) to de-
monstrate to the employees in the mine that a typical mobile radio trans-
mitter of the type to be used in the mine would not cause blasting caps
loaded in a rock face to detonate. A successful demonstration was made by
representatives of the PRC and Motorola Communications and Electronics, Inc.,
in December 1978.

However, several of the mine's employees were not satisfied with the
results of the tests because only one transmitter was used and several radio
equipped mine vehicles plus several hand carried portables might be operated
simultaneously near a loaded face thereby radiating more energy which might
be received by the wires leading to the caps and detonate them. The miners'
union representatives requested another demonstration using three radio
equipped mine vehicles and several portable radios operating simultaneously
near a drilled rock face loaded with electrical blasting caps.

The mine forwarded this request to the PRC and the Mine Safety and
Health Administration (MSHA) at Lexington, KY. Comsul Ltd. was then asked
by the PRC to plan and coordinate another demonstration of safe radio opera-
tion near a wired face on August 22, 1979.

4.2 Procedures for Conducting the Demonstration

A rock face in crosscut 97 was drilled in the normal pattern of holes
and each hole was loaded with an electrical blasting cap, as shown on Figure
4.1.

97


2.8 Design and Procurement of UHF Radio System

Following the analysis of the data which was obtained from the propa-
gation tests, a 450 MHz radio system was designed which would use a combin-
ation of distributed antennas and passive reflectors to afford two way comm-
unications along principal haulage and travel roads in the mine. During de-
sign conferences in May and June 1978, the scope of the project was expanded
to include a redundant multiplexed "back bone" coaxial cable system for radio
and CCTV systems control. The radio system was designated Phase I and the
CCTV monitoring system was designated Phase II of the project. A design re-
port was prepared and submitted to the TPO for review and comments. 6

The system plan required three UHF radio two frequency simplex channels
licensed in the 451/456 MHz Special Industrial Radio Service for digitally
calling and identifying mobiles and transceivers, digital alarms and data,
and voice communications.

Channels 1 and 2 were to be used principally for communications between
mobile radios and transceivers in conjunction with both mining and above
ground operations. They also were to be used for back up of channel 3 in
the slope in the event of equipment failure.

Channel 3 was to be used solely for communicating between the hoist
operator and the hoist car in the slope of the mine. One base/mobile relay
(BMR) station using channel 3 near the hoist house was to feed a high gain
Yagi antenna that is directed down the slope. The hoist car in the slope
was to be equipped with a mobile radio which normally would be used on
channel 3 but it could be switched to use channels 1 and 2 if channel 3 did
not function. Alarm switches were to be provided on the hoist car for send-
ing digital alarm signals to the hoist operator. However, this system was
modified to conform with the mine's horn signal system.

(6) Proposed Radio System for the Black River Mine, Comsul's report to
Bureau of Mines, TPO, March 1978.

35


1.0 INTRODUCTION AND BACKGROUND

1.1. Introduction, Objective and Scope of Project.

This final report summarizes the results of a design and demonstration
project conducted by Comsul Ltd. San Francisco, California under a contract
to the United States Department of the Interior, Bureau of Mines. The
objective of the project was "To demonstrate in an underground room and
pillar limestone mine a minewide communications and monitoring system that
fulfills the communication needs of that type of mine".

The scope of the work included furnishing engineering and administrative
services necessary to design, procure material, test, prepare installation
instructions, supervise installations, operate, maintain and document the
radio communications and monitoring systems.

In addition to the specified work for the UHF radio system, additional
services were furnished to design a closed circuit television system and a
redundant "back bone" coaxial cable system with multiplexing equipment for
radio system control and television monitoring which provides communication
between the engineering office and hoist house above ground and systems in
the mine and which can accommodate future communication services.

The project was initiated in October 1977 and was completed in March

1981. Monthly progress reports were issued and are listed in the reference
index.

19


3.10 February 1980

A complete patent disclosure for the signal booster concept was prepared
and submitted to the TPO.

3.11 March 1980

In order to expedite and coordinate the installation of the air sampling
tube bundles, the redundant back bone coaxial cable, the CCTV system, added
antennas and signal booster system and other items, a two day conference was
held at the mine. Representatives from the Mine, the TPO, the Project Leader
and the Project Coordinators and Engineer from Comsul Ltd., participated in
the conference. A GANTT chart listing fifteen tasks was prepared which shows
tasks to be completed, their priorities, schedule for completion and list of
those who are responsible for completing them.

As an aid for training mine personnel regarding radio operating procedures,
a poster was prepared by Comsul Ltd. The mine management approved it and auth-
orized it to be displayed on bulletin boards in locker and lunch rooms.

Preliminary plans were prepared for two distributed antenna systems with
two way signal boosters. One system will extend UHF radio communication along
the Southeastern and Northeastern areas of the mine and the other will cover
the Southern, Western and Northwestern areas as shown on Figure 3.10.

Electronic parts for constructing a prototype of a two way signal booster
also were ordered.

3.12 April 1980

Henry Kramer of Comsul Ltd. was appointed Project Manager and he conducted
a complete inventory of all Government furnished equipment and materials for
the radio, CCTV and monitoring projects at the Black River Mine. He also de-
veloped new receiving report and purchase order forms for simplifying and im-
proving financial records.

63


PAGE

APPENDIX A

FCC RADIO LICENSES FOR BLACK RIVER MINING COMPANY

CALL SIGN
WYK-240
WYK-240

WYK-242

WYK-241
WYK-241
WYK-241
WYK-241

WFJ-985
WFJ-985
WFJ-985

WFJ-984
WFJ-984

WFE-459
WFE-459

KA-40145

KA-40145
KA-40145

1

1

CHANNEL

Above Ground

Slope

Under Ground

Under Ground

" "

Under Ground

Above & Under
Ground

FREQUENCY
451.950
452.175

452.025

451.950
452.175
451.950
452.950

457.025
457.175
456.950

456.950
457.175

456.950
457.175

456.950

457.175
457.025

PAGE 1 OF 8

TRANSMITTER LOCATION

Radio Room in Office Bldg.

Monitor Room in Mine

Near Crusher No. 3

" " "oon

Warehouse Control Station

Bottom of Slope Control

Foreman's Shop Control

Mobiles and Portables


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BASE/MOBILE RELAY STATION FOR SLOPE COMMUNICATION
PAGE 3 OF 8



TABLE OF CONTENTS (Continued)

PAGE
3.22 (Continued)
- Description of Control Consoles and Solutions to
Operating in Noisy LocationS...........ee cece cece eee eens 87
- Belling by Radio Arrangement in Slope Car.. : 88
- Back Bone Control Cable System.......... ec cece eee eee eee eee 83 & 88
3.23 As Built CCTV System Description.......... cece cece eee eee eee 95
- List of Camera and Monitor Locations..................0085 95
- Advantages of CCTV to Enhance Safety and for Monitoring
Conveyor Belt Operation... cece cece ee eee cece eee eee 95
3.24 Research on the State of the Art of Underground
Radio Communication..... cc cece s cece cece eee ence eee eens 96
- Application of Two Way Signal Boosters, CATV Amplifiers
and Intrinsically Safe Radio Systems..............-. eee 96
4.0 DEMONSTRATION OF SAFE OPERATION OF 450 MHz MOBILE AND PORTABLE
RADIO TRANSMITTER ADJACENT TO A DRILLED ROCK FACE LOADED WITH
BLASTING CAPS
4.1 Background and Purpose of Demonstration..............04- 97
4.2 Procedures for Conducting the Demonstration.. . 97
4.3 Test RESUItS... 6. cece cece cece eee e renee e teen neces 99
4.4 Computations of the Amount of Radio Energy That is
Available Near Mobile and Portable Radio Antennas....... 103
4.5 COMCTUSIONS..... cee eee cece eee e eee nett n eee eens 104
5.0 PROJECT MANAGEMENT
5.1 Project Leader - Installation and Maintenance 107
5.2 Radio Equipment CostS...... cece cece cece cece eee eee eee eee 108
5.3 Radio LICENSES... .. eee eee eee eee eee ett enee 108
5.4 CCTV COSTS... cece ee ccc ccc cece eee ence teen eee enee 108
5.5 Purchasing, Receiving and Inventory Systems.... 108
5.6 Costs and Safety Benefits to the Mine............-..--5. 108
5.7 Recommendations to Other Mine Owners...........-+esseeee 111
5.8 Recommendations for Future U.S.B.M. Research............ 111
5.9 Pending. ....... ccc cee ccc cece eee eee teen eens 112
REFERENCES... 1. cee ccc eee cece eee ee eee eee eee teen ene eee e nn enees 113


3.23 As-Built CCTV System Description

Six Motorola V-10003C CCTV cameras, seven Motorola 51252 nine-inch TV
monitors and accessory equipment are used for observing critical areas at the
mine. Each of the cameras feeds its composite video signal to a CATEL modu-
lator and a CATEL demodulator feeds each TV monitor as shown by Figures 3.28
through 3.32. Following is a summary of the equipment and how it is used:

Back Bone Cable
Modem Frequency,

Location Viewed MHz. TV Monitor Location
Conveyor belt transfer Direct video on Hoist house

above hoist house coaxial cable

Conveyor belt transfer 76.0 Hoist house

midway in slope

Conveyor belt transfer 48.0 Hoist house

at base of slope

Loading dock at base 62.0 Hoist house

of slope

Conveyor belt transfer 34.0 Crusher No. 2

No. 2 in mine 34.0 Crusher No. 3

Dust storage area camera 90.0 Lime plant control con-
(is also equipped with a sole. A camera control
pan tilt head and camera encoder for the pan tilt
control decoder). head also is provided.

The CCTV surveillance system has greatly enhanced safety and improved
the efficiency of loading and unloading the slope car at the base of the
slope. The hoist operator can see that all personnel are in the clear and
materials are properly loaded before the winch is started to pull the slope
car to the surface.

The down time of the belt conveyor system has been reduced because
the crusher operators and hoist operator can see rock jams building up at
the critical transfer points. Without television surveillance, rock jams
have stopped the belts, and friction at drive pulleys has caused belts to
burn or to be otherwise damaged. Drive motors also have failed due to ex-

cessive loads.
95


e Two control consoles including voting signal comparitors; one for
the engineering office and the other for the hoist house.

e@ Three twenty watt control stations located in the warehouse, the load-
ing area at the base of the slope and the mine foreman's office in the
underground shop.

e@ Ten six watt mobile radios with MODAT automatic identification alarm
and status encoders for mine vehicles.

e Fifteen two watt portable transceivers with automatic identification
and alarm encoders.

@ Two coaxial back bone cable systems including 15,000 feet of 7/8"
aluminum jacketed cable, and six CATEL FM modulators and six CATEL
FM demodulators, four two way CATV line amplifiers and associated
items. See Figures 2.10 and 2.11.

@ Test equipment for the radio and "back bone" cable systems.

Comsul's preliminary radio system design report was revised August 2,
1978 and a purchase order for the test equipment, radio and "back bone" cable
system was issued by the Bureau of Mines on August 16, 1978. In September
1978 Comsul began negotiations with Motorola Communications & Electronics, Inc.
to furnish the services of a full-time Project Leader to install and maintain
the radio and CCTV systems, to instruct mine personnel regarding its operation,
keep records of the systems installed and furnish monthly progress reports.
This position was filled by Mr. Jerry Bentz a radio technician for Motorola

Communications & Electronics, Inc. Cincinnati, ohio.”? 8,9

(7) Proposal for Black River Mining Company Project, Motorola Communications &
Electronics, Inc., July 6, 1978.

(8) Proposed Radio System for Black River Mining Company, Comsul Ltd., Report
to Bureau of Mines TPO, August 4, 1978.

(9) Bureau of Mines Purchase Order No. P0382795 for Radio Equipment for the
Black River Mine, September 8, 1978.

40


Table 3

SIGNAL MARGINS MEASURED IN WESTERN
HALF OF THE MINE
These measurements of signals from a two-watt transceiver operated by a per-
son riding on a tractor were made at a base station in the radio room on
January 30, 1981 during final acceptance tests of the radio systems. The
test locations are shown on Figure 3.24A page 76.
MINE MEASURED

COORDINATES INPUT TO SIGNAL MARGIN
OF TWO-WATT RECEIVER ABOVE 20 dBq

TRANSMITTERS uV (0.8 uV) dB COMMENTS

206/108 10-20 20-6 Excellent

207/108 2-5 6-14 Satisfactory

209/108 1-3 0-9 Noisy

210/108 2-4 6-12 Satisfactory

211/108 2-4 6-12 Slight Picketing

214/108 3-5 9-14 Satis factory

217/108 2-3 6-9 Noisy

218/117 2-5 6-14 Satisfactory

218/117 1 0 Moved 10', Transceiver unreadable
210/109 2-5 6-14 Satisfactory

212/109 3-6 9-16 Satisfactory

212/108 3-6 9-16 Satisfactory

206/105 2-5 6-14 Good

199/105 1-3 0-9 Noisy

198/105 2-5 6-14 Good Received from Crusher 2 Receiver
199/109 1-3 0-9 Noisy

199/111 5-10 14-20 Excellent Signal

199/117 40-50 32-34 Excellent Signal

199/114 5-12 14-22 Excellent Signal

199/117 5-7 14-17 Excellent Signal

200/118 5-26 14-28 Excellent Signal

200/121 5-7 14-17 Excellent Signal

200/123 5-7 14-17 Excellent Signal

200/123 5-7 14-17 Excellent Signal

200/127 4-6 12-16 Good Signal

200/130 4-6 12-16 Good Signal

200/134 3-5 9-14 Noisy

200/135 2-4 6-12: (future

booster location) Noisy

200/137 2-4 6-12 Noisy

200/140 2-4 6-12 Good

200/142 3-6 9-12 Good

200/143 - - Noisy Not Readable Blank Area
200/145 - - Noisy Not Readable Blank Area
197-124 1-3 0-9 Noisy

197-118 20-29 26-29 Excellent

197-117 20-30 26-29 Excellent

Page 3 of 6


QUIPPED VEHICLES WERE PARKED ADJACENT TO THE DRILLED
LOADED WITH ELECTRICAL BLASTING CAPS.

FIGURE 4 THE RADIO E
CK Fi;

3. 10
ACE THAT HAD BEEN

FIGURE 4.4. THE OBSERVERS OF THE TESTS WERE APPROXIMATELY 120' FROM THE FACE
THAT WAS LOADED WITH BLASTING CAPS. THE LEADS FOR KEYING THE THREE MOBILE
TRANSMITTERS AND FOR SHUNTING THE FIRING LINE CAN BE SEEN ON THE FLOOR.

102


2.9 Design of Distributed Antenna and Passive Reflector Systems

The principal haulage and travel roads through the mine were identified
on a map of the mine. Two distributed antenna systems were designed, as
shown by solid lines on Figure 2.9 to provide either an antenna or reflector
at the intersection of principal haulage and travel roads. Each antenna sys-
tem consisted of approximately 1,200 feet of 7/8" low loss foam dielectric
transmission line which fed, through 2 to 1 power dividers, four 5 dB gain
mobile whip antennas that were suspended above the centers of principal inter-
sections. Two thirteen watt base stations were connected through hybrid com-
biners and a power divider to feed approximately 7.1 dBw (5.1 watts) into
each branch of the tee section transmission line.

The effective radiated power from the various antennas ranged from 17
watts for the antenna nearest to a base station to 0.05 watts for the antenna
farthest from a base station. The signals from transceivers received at the
most distant antennas were attenuated 21 dB by losses in the transmission line
and power dividers.

Twenty-seven passive reflectors, also shown in Figure 2.9 were installed
at principal intersections to enhance signal strengths. The reflectors which
received line of sight signals over paths that were less than 1,000 feet long
were very effective but reflectors which were not within line of sight of a
ceiling mounted antenna did not appreciably extend the range of communication.

The reflectors were formed
from sheets of 4' x 8' #16 gauge
soft aluminum sheet that are sus-
pended by wires attached to roof
plates and rock bolt anchors at
the centers of intersecting tra-
vel and haulage roads. The apex
is pointed toward the nearest
base station antenna.

FIGURE 2.12 TYPICAL REFLECTOR

43