The views and conclusions contained in this document 

are those of the authors and should not be interpreted as 

necessarily representing the offical policies or recommendations of the Interior Department's Bureau of Mines 

or of the U.S. Government. 

BUREAU OF MINES 

UNITED STATES DEPARTMENT OF THE INTERIOR 
The views and conclusions contained in this document 

are those of the authors and should not be interpreted 

as necessarily representing the official policies or 

recommendations of the Interior Department's Bureau of 

Mines'of of the U.S. Government. 
between February and August of 1982 (6 mos.). Analysis of the data shows that the 

principal benefits are reduction in time required for unscheduled maintenance and 

repair, enhancement of safety, and better coordination of production activities. 

A cost benefit analysis shows a net benefit over cost, although it is also concluded 

that the capacity of the system is greater than can be justified by current activity 

in the mine. 1 

17. DoPaara r - 

radio communication, radio relay systems, data acquisition 

a MMTURUW TM 

mine communication, underground communication 

c -n 17102.1, 14/02 

1% *ruhmrw ~t.bmr* XS=qea8mf~m 

Unclassified 

a-d104 i 

. - -- _- Unclassified P"- 
FOREWORD 

This report was prepared by Atlantic Research Corporation, 

Alexandria, Virginia under USBM contract number J0318074. It was 

administered under the technical direction of the Bureau of Mines 

with James C. Cawley acting as Technical Project Officer. Joseph 

A Gilchrist was the contract admin:istrator for the Bureau of 

Mines. This report is a summary of the work completed under this 

contract during the period September 1981 to December 1982. This 

report was submitted by the authors in December 1982. 
TABLE OF CONTENTS 

Page 

EXECUTIVE SUMMARY 

DESCRIPTION OF THE BLACK RIVER MINE 

TELECOMMUNICATION SYSTEM 

DATA COLLECTION SYSTEM 

3.1 DCS Hardware Description 

3.2 Modat Data 

3.3 Systems Status Channels 

DATA COLLECTION RESULTS 27 

CONCLUSIONS RELATIVE TO SYSTEM UTILIZATION 

5.1 Telecommunications Needs of the Mine 

5.1.1 Unscheduled Maintenance 

and Repair 

5.1.2 Safety 

5.1.3 Supervision and Coordination 

of Production 

5.2 How the System Fulfills the Needs 

5.3 System Alterations 

5.4 How the Mine Utilizes the System 

5.5 How Utilization Could Be Improved 

5.6 Who Uses the Telecommur~ications System 

5.7 Cost Benefit 

5.8 How the System Configuration 

Compares With Other Melzhods 

5.9 Radio Traffic Histographs 

COST BENEFIT 53 

6.1 Mine Revenue 53 

6.2 Loss in Revenue From Production Stoppage 53 

6.3 Savings in Supervision and 

Coordination, Production 53 

6.4 Cost of the Radio System 54 

6.5 Benefits vs Costs 54 

COMPARISON WITH OTHER METHODS OF 

MEETING THE MINE'S NEEDS 

7.1 Leaky Feeder 

7.2 MF Reradiation Systems 
RECOMMENDATIONS 

8.1 Utilization of Truck Dump-Bed Data 

8.2 Dispatching and Operating Procedures 

8.3 Elimination of Channel #3 

8.4 Magazine Entry Records 

REFERENCES 

APPENDIX A HISTOGRAPHS 
EXECUTIVE SUMMARY 

This document is a final report on the evaluation of 

the telecommunications system insta:Lled by the U.S. Bureau of 

Mines at the Black River Mine, Butler, Kentucky. The 

telecomnunications system is one of several sponsored by the 

Bureau of Mines as part of a project to demonstrate improved 

underground communications in metallnon-metal mines. Previous 

demonstrations have included the use of off-the-shelf equipment 

t~ provide leaky feeder communications in a block caving iron 

mine(l), and the demonstration of an EPABX with subscriber 

carrier equipment in a deep-vein silver mine(2). 

The Black River Mine was selected as a typical 

metallnon-metal room and pillar mine. It is nearly 4000 feet in 

diameter, 650 feet deep, and has essentially straight crosscuts 

approximately 30 feet wide and 24 to 40 feet high with pillars 

approximately 35 feet square. Entry is through a 2,200 foot 

slope by means of a single drum, hoist-powered flat car and 

enclosed man carrier. The emergency exit is through a hoistpowered capsule in a 6 foot diameter, 650 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. 

The mine is equipped with a UHF, passive reflector 

distributed antenna, underground radio system installed between 

August 1978 and January 1981. The object sought with chis system 

was to demonstrate in an underground room and pillar limestone 

mine a mine-wide communications and monitoring system that 

fulfills the communications needs of that type of mine. The 

objective of the project covered by this report was to carry out 

an evaluation of the Black River Mine telecommunication system 

and to prepare a report answering the following questions: 

1. What are the telecommunications needs of this mine? 

2. How does this system fulfill those needs? 

3. What system alterations woulci better meet those needs? 

4. How does the mine utilize the current system? 

5. How could system utilization be improved? 

6. Who uses (or doesn't use) the telecommunicatons system? 

7. Of what costlbenefit is the telecommunications system 

to the mine? Discuss specific benefits and costs. 
8. How does this system configuration compare against 

other methods of meeting the mine's needs (leaky 

feeder, for example) in terms of: 

a. Technical feasibility? 

b. Cost? 

c. Reliability? 

9. How does the mine radio traffic look on a histographic 

basis? 

The project covered by this report was begun in 

September, 1981. A computer controlled data collection system 

(DCS) was installed and placed in operation of February 26, 1982. 

Except for occasional outages, some lasting for sevsral days, 

automatic data collection continued uintil August 27, 1982. The 

data collected included date-time information (start and finish) 

on all radio transmissions, transmitter identifications, and some 

limited status information ("PTT-normal", "PTT-emergency", dump 

truck "bed-up" and "bed-down"). Additional data, such as 

maintenance records and information on mine operations, was 

collected manually. 

The quality of the automatically collected data was not 

as good as had been hoped for. The bed-up/bed-down function was 

inoperative during most of the data collection period. Further, 

the tendency of the users to take radios other than the ones 

assigned to them obscured to some extent the attempt to associate 

ID numbers with particular job functions. Another factor 

affecting the analysis was that tlne mine was operating at 

considerably less than full capacity during the evaluation 

period. Radio usage was therefore undoubtedly less than it might 

have been under other circumstances. 

1 a 1 The Data Collection System 

Two types of data were collected and stored by the DCS. 

Hardware data was automatically extracted from the radio system 

hardware through direct interface. Maintenance data was entered 

into the DCS by the on-site maintenance contractor. Management 

and production data required from the mine's management was 

collected and correlated by hand. 

The operation of the DCS was as follows: 

1. The DCS kept a real time clock and a month/day date as 

a background operation. Time resolution was a minimum 

of ten millisecond Intervals. 
2. The SYSTEM and MODAT channels were asynchronously 

monitored for changes in hardware status and incoming 

MODAT data through the use of vectored interrupts. 

3. These data elements were time-tagged and placed onto a 

mass storage device. 

4. By the use of a dial-up comnunications modem, this data 

was down loaded into the data processing facilities at ARC in 

Alexandria, VA for compression and processing. 

5. When appropriate, manual data collection programs were 

run in the background to accept and store maintenance data. 

The DCS controller software was written entirely in 

fast, efficient assembly language. The entire DCS was operated 

from uninterpted power which was available on site and used to 

power the telecommunications system. 
1.2 -- The Data Collected 

Full time data collection began on March 1, 1982, and 

continued through August 27, 1982. Data was collected for each 

day on which activity occured, including Saturdays, Sundays and 

holidays. However, little use of the radio was made on other 

than regular Monday through Friday work days, so that weekend 

traffic was of no great significance. From the data, daily 

records of channel occupancy in seconds were derived for' each 

one-hour time block during the day, transactions for each onehour time block during the day, and daily activity counts for 

each MODAT equipped radio. Valid channel occupancy records were 

obtained for 111 days and daily activity counts for 116 days out 

of a total of 127 work days (i.e., 26 five-day weeks less three 

holidays ) included in the dista collection period. 

Data collection system malfunctions accounted for the loss of 

records from Saturday, April 17 through Wednesday, April 21, and 

from ' Tuesday, May 18 through Monday, May 24. During the week 

preceding the second system outage, a failing clock module 

resulted in unrealisticly high occupancy levels (i.e., 

occupancies greater than 3600 seconds in a one hour period). The 

occupancy data from this entire week was discarded as invalid, 

although the MODAT activity counts were used. - 

The data collectez shows generally that use of the 

radio channels is greater during the day shift and particularly 

from 9 AM to about 3 PM. However, daily variation from the norm 

were noted to be considerable. The highest occupancy was noted 

to be 890 seconds (or 890/3600 = 24.7%) occurring on April 3. In 

one case, (~ugust 5) peak traffic occurred in the 4 to 5 AM time 

block in connection with early morning maintenance activity. On 

one day only (less than 1% of the time) did the peak occupancy on 

channel 1 exceed 24% (24.7% on April 3). It exceeded 12% 

occupancy for less than 10% of the time. The median occupancy 

(exceeded 50% of the time) was 6%. Traffic on channels 2 and 3 

was never more than a fraction of channel 1 traffic. 

Of particular interest were the "bed up" and "bed down" 

indications for the four dump trucks. The original hydraulic 

pressure actuated switches installed to signal these functicns 

did not work. As a result, few indications were recorded during 

the first four months of the survey. In June, these were 

replaced with mechanically operated microswitches with feeler 

arms making direct contact with the dump bed when in the down 

position. Beginning July 12, regular bed up and bed down 

indications were recorded up to the end of the survey. These 

were compared with the logs kept by tlne drivers. For reasons not 

understood, these three sets of figures did not always agree. In 

general, records of bed down came closer to matching logged trips 

than the records of bed up. 

1.3 Recommendations Made 

Recommendations concerning the utilization of truck 

dump bed data, dispatching and operating procedures, elimination 
of channel 3 and magazine entry records were made as a result of 

the evanuation. These recommendations are as follows: 

1. It is recommended that the method of providing a bed-up 

or bed-down indication be examined. Both are not needed if one 

can be trusted. We suggest the use of a pressure sensitive 

switch on the high side of the hydraulic cylinder to be actuated 

each time the dump bed is raised. The system should be 

thoroughly tested for both false indications and failure to 

provide true indications. It should be possible to achieve a 

very high degree of reliability and to provide an accurate record 

of production by this method. 

2. It is recommended that a dispatcher position be 

established and that standard operating procedures be developed. 

In an operation the size of Black River Limestone Company, the 

dispatcher could be a person with colateral duties, such as the 

hoist operator. Among the dispatcher's duties would be keeping 

track of which ID numbered portables Elad been issued and to what 

persons. He should keep track of where in the main particular 

persons are working and procedures should be established to keep 

this information updated. The dispatcher should be able to 

disable (knock down) the repeaters and operate the system as a 

group of wire-line controlled base stations. This provides the 

dispatcher with total control of the radio system and eliminates 

chaotic person-to-person transmissions which only serve to 

confuse the emergency situation. It should be the procedure in 

drills and emergencies for each radio equipped person to report 

the locations and status of himself and others for whom he may be 

responsible. 

3. It is recommended that channel #3 be eliminated along 

with the three base/mobile repeaters, modems and voting modules 

associated with channel #3. The surface parts truck (ID #300) 

would shift its traffic over to channel #1. The equipment 

eliminated would go into the spares inventory. This action would 

reduce maintenance costs and eventual replacement costs. Future 

purchases of portable and mobile units need to specify only two 

channels. (~ote: No data was taken on the "talk around" 

channels numbers 2, 4 and 6, but information furnished indicates 

that they were infrequently used.) 

4. It is recommended that the automatic signalling of the 

presence of vehicles or persons at hazardous locations be made 

the subject of a future investigation. 

1.4 Report Orqanization 

A description of the radio system evaluated is 

contained in Section 2.0 of this report. Section 3.0 describes 

the data collection system implemented for the evaluation. The 

results of the data collection and the conclusions drawn relative 

to the utilization of the telecommunications system are presented 

in Sections 4.0 aod 5.0 respectively. A cost benefit analysis is 

given in Section 6.0 and a comparison with other methods of 
meeting the telecommunication needs on the mine is given in 

Section 7.0. Finally, the recommendations resulting from this 

project are given in Section 8.0 
DESCRIPTION OF THE BLACK -- RIVER - MINE 

TELECOMMUNICATIONSYSTEM 

This section provides a summary description of the 

telecommunications system as it was configured at the time of the 

evaluation. A Inore detailed report of its design and 

implementation may be found in reference 3. 

The telecommunicaions system is basically comprised of 

three Ultra-High Frequency (UHF) mobile relay sub-systems, each 

operating independently of the others. Two of the sub-systems 

(channels fl and #3) are intended for use wi.thin the working 

portion of the mine and the third (channel #5) is used 

exclusively for communications in t:he slope entry of the mine. 

Use is made of three UHF frequency pairs in the Special 

Industrial Radio Service. 

~ase/~obile - Mobile Only 

Channel #1 451.950MHz 456.950MHz 

Channel #3 452.175MHz 457.175MHz 

Channel #5 452.025MHz 457.025MHz 

Seven 12-watt UHF Motorola Micor tone controlled 

base/mobile repeater stations are used. One of these operates on 

channel #5 which is used solely for communicating between the 

hoist operator and the brake car (or slope car) in the slope of 

the mine. The station is located in the hoist house and feeds a 

high gain antenna that is directed down the slope. The brake car 

is equipped with a mobile radio which normally is used on Channel 

#5 but can be switched to use channels #1 and #3 if channel #5 

does not function. Alarm switches are provided on the brake car 

which can send digital alarm signals to the hoist operator. 

Channel #1 and #3 systems employ three base/mobile 

repeaters each. These are located in pairs at the following 

locations (see Figure 2-1): 

a. The radio room near the mine portal with one 

antenna covering mine property above ground and a 

Yagi antenna directed into the slope for emergency 

communicaton with personnel in the slope. 

b. ,The radio and monitor building near crusher $2 

where the base/mobile repeaters feed a distributed 

system that covers the central and western side of 

the mine. 

c. Near crusher #3, where the base/repeaters feed 

distributed antennas wlhich cover the eastern half 

of the mine. 

The channel #1 and #3 base/mobile repeater stations are 

each equipped with Spectra-Tac encoders for use with signal 

comparators located in the radio equipment room on the surface. 
LEGEND 

.L - BACK BONE CABLE NO. 1 INSTALLED THROUGH SLOPE. . - 

---------+-------- BACK BONE CABLE NO. 2 INSTALLED IN MINE. 

-*-----*---*-o-*-*-----*- BACK BONE CABLE ABOVE GROUND TO BORE HOLE 

THE CIRCLES IN THE CABLE REPRESENT MULTICOUPLERS FOR 

CONNECTING MULTlPLEXlNG FM MODULATORS OR DEMODULATORS 

BASUMOBILE REPEATER STATION LOCATIONS 

Figure 2-1. Black river mine telecommunications system. 
Each comparator "votes" the best of three receiver outputs to be 

relayed over the system. In the absence of control tones, each 

repeater station reverts to an independent "in-cabinet" repeat 

mode. 

There are three remote control consoles (wire line, 

tone control) in use in the system with each console having 

access to any of the three radio channels. Two are located in 

the mine office building. Of these, one is located in the 

engineering office and operates primarily on channel #1. The 

second is located in the reception area and is apparently 

utilized very little. The third console is located in the hoist 

house and operates primarily on channel #5. 

The system also has three Radio Frequency (RF) control 

stations, each capable of controlling any of the three radio 

channels. One is located on the surface in the company warehouse 

area. The second is located at the base of the entrance slope 

and is used primarily on channel #5 for slope communications. 

The third RF control station is located in the underground shop 

area. 

Two distributed antenna systems are used. The original 

system for the central and western sector of the mine used 

approximately 1,000 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, 5,600 feet of 1/2" lowloss coaxial cable, four two-way UHF signal boosters, and nine 

additional antennas and power dividers were installed. 

The original antenna systern for the eastern sector of 

the mine used approximately 1,600 feet of 7/8" low-loss coaxial 

cable to feed four antennas through power dividers. 

approximately 4,000 feet of 1/2" low--loss coaxial cable and two 

two-way UHF signal boosters have been added to feed seven 

additional antennas through power dividers. 

Most of the antennas are 5dI3 gain mobile whips that are 

attached to one-foot square metal plates wich are bolted to the 

mine roof at the center of the intersecting crosscuts. Several 

9dB base stations antennas, which are 15 feet long, are located 

in high crosscuts which do not have vehicular traffic. Passive 

reflectors are used to enhance signal strengths in crosscuts 

where signal strengths are marginal or unreliable. The locations 

and sizes of the reflectors were determined after the base/mobile 

repeaters stations and the distributed antennas were installed. 

One of the unique features of the telecommunications 

system is the shared use of Community Antenna Television (CATV) 

cable which also carries closed circuit television and 

environmental status and alarm signalLs. This "backbone" cable 

system extends from the radio equipment room down the slope into 

the mine as shown in Figure 2-1. A redundant leg extends from 

the equipment room over the surface to the dust area bore hole 

and into the mine via that entrance. The cable carries 
television video from cameras at the bottom of the slope, the 

crusher #3 conveyor belt transfer point, and at the dust storage 

area to monitors in the hoist house. Environmental monitors in 

the radio and monitor building (Figure 2-1) transmit air flow, 

temperature, fire particulates, carbon monoxide and nitrous oxide 

data over the cable to a display and printer in the engineering 

office on the surface. The cable also carries audio, digital and 

control tones interconnecting base/mobile repeaters, control 

consoles and comparators of the mobile radio system. It is only 

the radio system that is included in the evaluation. 

Altogether, there were 12 Il-watt mobile units and 15 

2-watt portable units in use during the evaluation period. All 

were equipped with MODAT* configured to send a digital 

identification (ID) each time the PTT or emergency alarm switch 

was used. In addition, four mine dump trucks were modified to 

transmit a "bed-up" (truck bed up for dumping) and a "bed-down" 

signal as appropriate. 

There are three MODAT decoders called Basic Logic Units 

(BLU) installed in the system, all of which are physicaly located 

in the engineering office. All three are interfaced to display 

consoles while only the channel #l BLU is interfaced to a printer 

device. 

Mobile and portable unit assignments by ID number in 

effect during the evaluation period are given in Table 2-1. 

--------------- 

*"MODAT" is a registered trademark of Motorola Communications, 

Inc. used in connection with their mobile radio data transmission 

system. Reference to specific brands, equipment or trade names 

in this report is made to facilitate understanding and does not 

imply indorsement by The Bureau of Mines. 
TABLE 2-1. TABLE OF RADIO ASSIGNMENT 

1. Portable Units: 

UNIT # 

2. Mobile Units: 

UNIT # 

PHYSICAL/TASK ASSIGMENT 

Maintenance Foreman 

Lime Plant 

Production Foreman #2 

Engineering 

Underground Electrician 

Radio Maintenance 

Spare (Not used) 

Conveyor Operator 

Mr. Kuehneman 

Spare 

Water Truck 

Production Foreman #1 

Powder Crew 

Half-way (belt transfer point) 

Safety Director 

PHYSICAL/TASK ASSIGMENT 

Slope Car 

Scaler 

Dump Truck #8 

Dump Truck #9 

Dump Truck #10 

Dump Truck #11 

Jumbo Drill #11 

Loader #219 

Loader #220 

Loader (Yale ) 

Loader (Yale) 

Surface Parts Truck 

Loader #920 
3.0 DATA COLLECTION SYSTEM 

A custom Data Collection System (DCS) was engineered 

and built by ARC to perform the task of collection for the large 

amount of data anticipated in the project. Many different 

devices could have been employed with varying degrees of ease of 

implementation. A microcomputer was chosen for speed and 

versatility. 

Two types of data were collected and stored by the DCS. 

Hardware data was automatically extracted from the radio system 

hardware through direct interface. Misintena~ce data was entered 

into the DCS by the on-site rnaintenaince contractor. Management 

and production data required from -the mine's management was 

collected and correlated by hand. 

The operation of the DCS is as follows: 

1. The DCS keeps a real time clock and a month/day 

date as a background operation. Time resolution is 

a minimum of ten millisecond intervals. 

2. The SYSTEM and MODAT channels are asynchronously 

monitored for changes in hardware status and 

incoming MODAT data through the use of vectored 

interrupts. 

3. These data elements are time-tagged and placed onto 

a mass storage device. 

4. By the use of a dial-up communications modem, this 

data is down loaded into the data processing 

facilities at ARC in Alexandria for compression and 

processing. 

5. When appropriate, manuisl data collection programs 

are run in the background to accept and store 

maintenance data. 

The DCS controller software is written entirely in 

fast, efficient assembly language. The entire DCS is operated 

from uninterrupted power which is available on site and also 

powers the telecommunications system. 

3.1 - DCS Hardware Description 

The design of the DCS centers around a dedicated 

microcomputer. A series of specialized interface channels 

communicate with the telecommunicatio~~system equipment while a 

mass storage device accumulates the collected data between weekly 

down-loading intervals. 

A block diagram of the DCS is shown in Figure 3-1. It 

contains a Central Processing Unit (CPU) card based on the 8- 
Figure 3-1. DCS block diagram. 
bit, Zilog Z80B microprocessor chip, The memory complement is 

made up of 48K of.Random Access Memory (RAM) for program storage 

and 16K of RAM for data storage and general working space. A 

clock/calendar card developes real time clock information which 

includes 24-hour clock with 100 micro-second resolution and a 

five digit Julian day calendar. Three of the parallel interface 

cards, referred to as the MODAT channels, monitor the MODAT 

Basic Logic Units (BLU). Another parallel interface card, 

referred to as the SYSTEM channel, monitors strategic logic 

points within the communications systems hardware. A serial 

CONSOLE channel and a serial MODEM channel complete the 

communications channels to and from the DCS controller. The mass 

storage device is a 20 Mbyte, fixed platter, hard disk system. 

The majority of the components were off-the-shelf circuit boards 

and modules. 

Figure 3-2 depicts a portior~ of the telecommunications 

equipment that is of primary interest to the data collection 

process. Also shown are the points of interface to the MODAT 

data streams which were monitored in parallel with the existing 

display and printer equipment. 

Interface to the telecommur~ications system was accomplished by a two level process as shown in Figure 3-3. MODAT 

data had to be recovered from each sub-system in an expedient and 

reliable fashion without drastic interruption of service to the 

mine telecommunication system. Customized parallel interface 

channels were designed and fabricated in order to interface with 

the particular version of BLU currer~tly being employed at the 

mine. 

The DCS was installed in the mine engineering office, 

immediately adjacent to the three BLU's. This was done to the 

reduce noise susceptability of the extensive parallel interfacing 

between the BLU's and the DCS. 

3 2 Modat Data 

The communications hardware was equipped with MODAT 

capability at the start of the data collection process. The 

majority of the radios are equipped to automatically send a 

three-digit identification co2e (ID) each time the push-to-talk 

button is activated. A two digit MODAT data/message code is also 

transmitted with the ID. The system currently employs two 

status codes: normal PTT and emergency PTT; and four message 

codes: bed up, bed down, and several :Location codes. 

These data bursts are automatic to the communications 

and are decoded by the BLU and presented to a console display and 

printer. The DCS monitors the data at this point by monitoring 

the various BLU strobe lines to detect that new data is present 

on the parallel interface. 


3.3 Systems Status Channels 

In addition to the MODAT data, several discrete logic 

points within the telecommunication system's hardware are 

monitored by the SYSTEM channel of the DCS. This channel is an 

eight bit parallel port with two special modifications. 

Electrical isolation and TTL level conversion is performed on all 

incoming status lines. Additionally, a status change circuit 

serves to detect a logic level change in any of the the six 

status bits being monitored. By creating this 'status changed' 

signal and employing it as a processor interrupt device, 

considerable processor overhead is saved because constant polling 

is not necessary. 

These logic points included the 'voted' and! the 

'failed' status indicators available within each receiver voting 

comparator card on channels 1 and 3. Also the 'tone priority' 

status, which indicates system control is via one of the wire 

line remote control consoles, is monitored. The carrier operated 

relay (COR) and push-to-talk (PTT) indicators are used for 

channel #5 as this system is not equipped with voting 

comparators. 

The comparator's 'voted' indicator is true whenever the 

mobile relay transmitters are being keyed on by the voting 

comparator. This applies for both the voted repeat mode of 

operation and remote mode of operation when the system is being 

keyed by a remote control console. 

The comparator's 'tone priority' indicator is true only 

when the mobile relay transmitters are being keyed on and keying 

is initiated by a remote control console. Hence, if only the 

'channel voted' indicator is true then a repeat mode operation is 

in effect. If the 'channel voted' and the 'tone priority' are 

true coincidently, then a remote control console transmit 

operation is in progress. 

The PTT and COR lines of the channel 5 mobile relay 

will perform the same basic function as the 'channel voted' and 

the 'tone priority' indicators respectively. In its basic form, 

this data would yield the needed information regarding the length 

of transmission which is not available from the MODAT equipment. 

Since this system STATUS data is collected in the same 

time domain as the MODAT data, the two sets of data can be 

correlated to determine the length of transmission for a 

particular MODAT identified unit and subsequently a grouping of 

units. As discussed earlier, remote control consoles and control 

stations do not generate MODAT ID data. It can be concluded, 

however, that a true 'tone priority' or 'PTT' indicator with no 

corresponding MODAT ID can be directly attributed to 

transmissions initiated exclusively from remote control consoles 

(wire line control). Correspondingly, true 'channel voted' 

indicators or simultaneous 'COR' and 'PTT' indicators with no 

corresponding MODAT ID point to transmissions initiated 
exclusively from remote control stations (RF control). It must 

be clearly pointed out that although the groups of consoles and 

the group of stations can be distinguished, they cannot be 

individually identified. 

The following is the format:. by which the data gathered 

by the DCS is stored for later retrieval and processing. 

Stored data block format for hardware STATUS information. 

BYTE # -- DATA 

CHANNEL #, 1, 3, or 5, ASCII 

DATE - Julia11 day, hundreds digit, ASCII 

DATE - Julian day, tens digit, ASCII 

DATE - Julia11 day, ones digit, ASCII 

TIME - Hours,, tens digit, ASCII 

TIME - Hours, ones digit, ASCII 

TIME - Minutes, tens digit, ASCII 

TIME - Minutes, ones digit, ASCII 

TIME - Seconds, tens digit, ASCII 

TIME - Seconds, ones digit, ASCII 

TIME - Seconds, tenths digit, ASCII 

TIME - Seconds, hundreths, digit, ASCII 

PLACE HOLDER - '@I, ASCII 

PLACE HOLDER - '@I, ASCII 

PLACE HOLDER - '@I, ASCII 

PLACE HOLDER - '@I, ASCII 

PLACE HOLDER - '@I, ASCII 

STATUS - Old system status, BINARY 

STATUS - New system status, BINARY 

'RS' - Recortl separator, 1E hexadecimal 
Stored data block format for MODAT information. 

BYTE # -- -- DATA 

CHANNEL #, 111 3, or 5, ASCII 

DATE - Julian day, hundreds digit, ASCII 

DATE - Julian day, tens digit, ASCII 

DATE - Julian day, ones digit, ASCII 

TIME - Hours; tens digit, ASCII 

TIME - Hours, ones digit, ASCII 

TIME - Minutes, tens digit, ASCII 

TIME - Minutes, ones digit, ASCII 

TIME - Seconds, tens digit, ASCII 

TIME - Seconds, ones digit, ASCII 

TIME - Seconds, tenths digit, ASCII 

TIME - Seconds, hundreths, digit, ASCII 

MODAT - Data, tens digit, ASCII 

MODAT - Data, ones digit, ASCII 

MODAT - ID #, hundreds digit, ASCII 

MODAT - ID #, tens digit, ASCII 

MODAT - ID #, ones digit, ASCII 

STATUS - Old system status, BINARY 

STATUS - New system status, BINARY 

'RS' - Record separator, 1E hexadecimal 

Three typical exchanges are depicted below with data 

blocks shown as they would be recorded for the particular 

situation. 

Exchange #1 - Portable to Portable 

Operation 

Portable #1 keys Tx 

Carrier received by system 

Comparator keys relay 

Portable #1 sends ID 

BLU receives ID - no errors 

Portable #1 sends voice msg 

Portable #2 receives voice msg 

Portable #1 unkeys 

Portable #2 keys Tx 

Carrier received by system 

Comparator keys relay 

Portable #2 sends ID 

BLU receives ID - no errors 

Portable #2 sends voice msg 

Portable #1 receives voice msg 

... All parties unkey 

Carrier lost by system 

Comparator unkeys relay 

Data Block 

"S" - Voted l1Sll - Busy 

"PI" - DATA + ID #1 

"S" - Not Voted 

"S" - Not Busy 

(see note 1) 

"S" - Voted l1Sll - BUSY 

"Mu - DATA + ID #2 

"S" - Not Voted 

"S" - Not Busy 
Exchange #2 - Portable to Control 

Operation 

Portable #1 keys Tx 

Carrier received by system 

Comparator keys relay 

Portable #1 sends ID 

BLU receives ID - no errors 

Portable #1 sends voice msg 

Portable #1 unkeys 

Control Console receives voice rnsg 

Control Console keys Tx 

Keying tones received by system 

Comparator keys relay 

BLU sends originate msg 

Control console sends voice msg 

Portable #1 receives voice msg 

. . . All parties unkey 

Carrier lost by system 

Comparator unkeys relay 

Console 

Data Block 

"S" - Voted "Sll - BUSY 

"M" - DATA + ID #1 

"S" - Not Voted 

"S" - Not Busy 

(see note 1) 

"S'l - Busy "M" - DATA, NO ID 

"S" - Not Voted In S-" - Not Busy 

Exchange #3 - Mobile Status Report Only 

Operation 

Mobile #1 changes status 

Mobile #1 Tx keys automatically 

Carrier received by system 

Comparator keys relay 

Mobile #1 sends ID 

BLU receives ID - no errors 

Mobile #1 un-keys 

Carrier lost by system 

Data Block 

"S" - Voted 

IIS" - Busy 

"Mu - DATA + ID #1 

"S" - Not Voted 

Comparator unkeys relay "S" - Not Busy 

Note: 1 - System may or may not go 'Not Busy' depending on the 

delay between the loss of carrier (and voted status) and the 

termination of the transmit keying tones sent to the relay 

transmitters by the comparator. 
4.0 DATA COLLECTION RESULTS 

Data collection began on February 27, 1982, and 

continued through August 27, 1982. Data was collected for each 

day on which activity occurred, including Saturdays, Sundays and 

holidays. However, little use of the radio was made on other 

than regular Monday through Friday work days, so that weekend 

traffic was of no great significance. From the data, daily 

records were derived of channel occupancy in seconds for each 

one-hour time block during the day, transactions for each onehour time block during the day, and daily activity counts for 

each MODAT equipped radio. Samples oE these records are shown in 

Tables 4-1 and 4-2 for August 2, 1982 (Julian date 214). Valid 

records of this type were obtained for 111 days (Table 4-1) and 

116 days able 4-2) out of a total of 127 work days (e., 26 

five-day weeks less three holidays) included in the data 

collection period. Data collection slystem malfunctions accounted 

for the loss of records from Saturday, April 17 through 

Wednesday, April 21, and from Tuesday,, May 18 through Monday, May 

24. During the week preceding the second system outage, a 

failing clock module resulted in unrealisticly high occupancy 

levels (i.e., occupancies greater than 3600 seconds in a one hour 

period). The occupancy data from this entire week was discarded - 

as invalid, although the MODAT activity counts were used. 

Histograms summarizing the occupancy and transaction data 

are shown in Appendix A. Page 63 of Appendix h shows averages of 

both occupancy in seconds and transac1:ions for channel #1 for the 

entire period of the survey. The "hour" column in these and 

TABLE 4-1 all other histograms indicates the beginning of each 

hourly time block. For example, "9" indicates the time block 

beginning at 9 AM and ending at 10 AM. Since a 24 hour clock is 

used, "13" indicates the time block beginning at 1 PM, "14" 

indicates the time block beginning at 2 PM, etc. 

Page 64 shows average occupancy in percentage of the 

hour (3600 seconds) and the average message lengths by hourly 

time block, both for channel #1 for the entire period of the 

survey. Average message lengths were obtained by dividing the 

total occupancy in seconds for the period by the total 

transaction count. "Transactions" include all radio message 

originations regardless of whether or not the originating unit is 

equipped with a MODATS which provides ufiit identification and 

type of transaction. 

Pages 65 through 68 show similar information for 

channels #3 and #5. Histograms for the three channels are 

continued on pages 68 onwards except that each shows data 

averages over all the valid daily records for a single month. 

Each table shows the inclusive dates that apply. 

The information in Appendix A shows generally that use 

of the radio channels is greater during the day shift and 

particularly from 9 AM to about 3 PM. However, daily variation 

from the norm were noted to be considerable. 
Table 4-1. Total system occupancy record for August 2, 1982. 

BLACK RIVER MINE -- DCS SYSTEM OCCUPANCY REPORT FILE: C:08/09.CHl 

Total Sys tern Occupancy for Julian day/ciays : 214 

HOUR SYSTEM USAGE VALID 

OF DAY IN SECONDS TRANSACTIONS 

TOTAL CHANNEL TRANSACT ION COUNT : 629 
Table 4-2. Unit activity report for August 2, 1932. 

BLACK RIVZR MINE -- DCS MODAT ACTIVITY REPORT FILE: C:08/09.CHl 

Unit Activity Report for Julian Diay/Day~: 214 

ID ASS IGNMENT (98) (97) (83) (82) (81) (80) ..................................................................... 

001 Maintenance 

002 Lime Plant 

003 Prod Foreman /I2 

004 Engineering 

005 Undergld Elect 

006 Radio Maint 

007 Spare 

008 Conveyor 

009 Mr. Kuehneman 

010 Spare 

011 Water Truck 

012 Prod Foreman /I1 

013 Powder Crew 

014 Half-Way 

015 Safety Director 

100 Slope Car 

101 Scaler 

106 Truck /I6 

108 Truck t8 

109 Truck U9 

110 Truck /I10 

111 Truck tll 

211 #11 Jumbo Drill 

219 /I219 Loader 

220 #220 Loader 

224 /I224 Loader (Y) 

226 /I226 Loader (Y) 

300 Surf Pts Truck 

920 /I920 Loader 

504 TEST RADIO 

@@@ Non-ID Blocks 

1872 0 0 0 145 113 

Total Data Blocks Read: 2143 

Total Bad ID Numbers: 0 Total Bad Modat Numbers: 3 

MODAT FUNCTIONS: 

(98) = Normal PTT - ALL Units. 

(97) = Emergency PTT - ALL Units. 

MODAT DATA: 

(83) = Clear of all Xagazineti - t300 only. 

(82) = In Blasting Cap Magazfine - t300 only. 

(81) = Bed Down - !I106, 108, 109, 110, 11:. 

In Dynamite Magazine - t300 only. 

(80) = Bed Up - t106, 108, 109, 110, 111. 

In Powder Magazine - $300 only. 
It is the daily peaks or "busy hours" of a 

commrnunication system that determine its required capacity. To 

show this for the Black River Mine system, Table 4-3 was 

prepared. This table shows the maximum one-hour occupancy in 

seconds for each of the three channels for each work day for 

which a valid record was obtained. Also shown is the time block 

during which this peak traffic occurred. Scanning this table 

will show a substantial fluctuation not only in the peaks but in 

the time of day they occur. The highest occupancy is noted to be 

890 seconds (or 890/3600 = 24.7%) occurring on April 3. In one 

case, (~ugust 5) peak traffic occurred in the 4 to 5 AM time 

block in connection with early morning maintenance activity. 

Scanning the table also makes it immediately apparent that 

traffic on channels 3 and 5 is only a fraction of that on channel 

1. 

Figure 4-1 shows the distribution of peak accupancies 

for channel 1 for the entire period of the survey (i.e., for 111 

days for which there are valid data records) . From this it can 

be seen that only on one day (less than 1% of the time) did the 

peak occupancy exceed 24% (24.7% on April 3). It can be said to 

exceed 12% occupancy for less than 10% of the time. The median 

occupancy (exceeded 50% of the time) is 6%. 

The effect of channel occupancy on congestion can be 

determined from Figure 4-2. This shows the percentage of 

messages (X-axis) delayed by more than the amaunt indicated on 

the Y-axis for various values of occupancy. For example, if the 

busy hour occupancy is 2O%, then 20% of messages are likely to be 

delayed more than zero because of channel congestion. Ten 

percent are likely to be delayed more than 0.85 times the average 

message length. Five percent are expected to be delayed more 

than 1.75 message lengths, and so on. Obviously, the average 

message length is itself an important determinant of congestion 

delay, thus short .messages increase channel efficiency. Average 

message lengths for each time are shown in Appendix A. 

A summary of the weekly totals of activity counts of 

ID equipped radios is given in Table 4-4. This is a summary of 

the type of data shown in the first column of Table 4-2. Each 

number indicates how often the push-to-talk (PTT) Sutton was 

pushed during the week on the radio identified. Totals for the 

entire period of the survey and the percentages of the total 

activity that each radio accounts for are given. Activity for 

all three channels is combined in the table. However, with rare 

exception, only the surface parts truck initiated activity on 

channel #3 and only the slope car used channel #5. One spare 

unit (ID #007), truck #6 (ID #106) and the jumbo drill (ID #211) 

were omitted entirely from the table because no activity was ever 

recorded for these units. The five loaders were grouped together 

because the combined activity for these units was very small. 

Some units were down for extended periods because the units 

themselves were down or their ID'S were inoperative. This is 

known to be true for trucks #8, 810 and #11 during March, and for 

the scaler (ID #101) from March until mid June. No activity is 
Table 4-3. Peak (busy hour) occupancies in seconds. 

CHANNEL 1 CHANNEL 3 

PEAK TIME BLOCK PEAK TIME BLOCK 

CHANNEL 5 

DATE PEAK TIME BLOCK 

MARCH 1 

2 

3 

4 

5 

29 

30 

3 1 

APRIL 1 

2 

64 11 

40 13 

6 7 9 

73 TIE 12114 

47 11 
Table 4-3. Peak (busy hour) occupanciee in seconds (continued). 

DATE CHANNEL 1 

TlME BLOCK 

CHANNEL 3 

PEAK TIME BLOCK 

CHANNEL 5 

PEAK PEAK TlME BLOCK 

APRIL 22 

23 

MAY 3 

4 

5 

- 6 

7 

JUNE 1 

2 

3 

4 
fable 4-3. Peak (busy hour) occupancies in seconds (continued). 

CHANNEL 1 CHANNEL 3 CHANNEL 5 

PEAK TIME BLOCK PEAK TIME BLOCK PEAK TIME BLOCK 

194 13 27 11 2 6 15 

151 11 7 4 9 I6 14 

175 13 5 0 9 2 7 9 

347 9 8 8 I 9 7 

328 8 4 6 18 10 15 

DATE 

JUNE 21 

22 

23 

24 

2 5 

JULY 1 

2 
BATE 

AUGUST 2 

3 

4 

5 

6 

Table 4-3. Beak (busy hour) occupancies in seconds (continued). 

CHANNEL 1 CHANNEL 3 CHANNEL 5 

PEAK TIME BLOCK PEAK TIME BLOCK PEAK nME BLOCK 
I I 

25 ;O 75 

PERCENT OF DAYS OCCUPANCY EXCEEDED ORDINATE 

Figure 4-1. Cumuiative distribution of busy hour channei occupancies-channei #l. 
PERCENT MESSAGES DELAYED 

MORE THAN ORDINATE 

Figure 4-2. Affect of channel occupancy of congestion delays. 
C ONQ- tQmC-maNmQOwtrmQmOaOa % - N OOrtOY)V)Y)N NY)N -0- (P 

a .n 

Q ~~Og~o~gaNanNmOQamCaOtmCON 2 C 

tOmNCO re410 Om0 b C- m 

O QttN~atmnOQON~00rrmOOaatOQ c t N -ON'- OOOLn C - - Otm f-lam t 

s C (0 

oOgQa0mg~arCnnrOCntmo~tmOm nr Q - N NNm-O NaLn 000 0 m 00 

0 rtmONO-aCamn~moO~~~mof-oDnOC N a mmaCrt - n -NNC tnm m f- a a 

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C! t FtrNmN 

C 

N -NN m 

C t t 

a t~oanmaOoam~~QOOmNNaOmQNON r - m N Nnnmt- t -WOO NO- UY 

f- m m 

k '"Otnonmm'h NV+NNN- ~~gooNu3-~omamo- C - NNt C 

N N 

ma-~m~t~=om~o~f-o~~amot-m~a 

~t - tm n r NFN m NN t m 

m Q~NC-~CO~~~~~~~~OO~

=n-mz Nmnaa IIN- c f- nmt m m 

- - ooa-nof-mm-m~o~~-mo-~~og~g;;~ 2 -NUY FmN-UY-NNN - is m m 

NONCOC-mmO-OmOnOQ*NOONtCnt a 0 tnnN tOCQ m N N - N m tCmNm m m 

O mQaCmOmNCrtOt~~nO~oCOo~ONn~ x g ton N o a NW - n amm f- m 

C 

X I IIIlllllllllllllll IIIIIII 

- t tOC-rONrro~~m.~COmCOm~mmmf-O - Cn ONN m N-me4 m~m m 

;i m m 

- f- ~nmrCm~~~00nt0m0orr0OnaOmm 

"'N nnrY) an - N - tnm-o m a 

0 0~NmtoNN000N-LoCQOmt0mnntCt 

t CCC nN = f- .- N t-1 C 

to C In o.f-~~~o~tQoot-<aNQO~m~OmmmNa s z Wr r N NCNrr N n 

a mOC~m~~t00~~Ob~t~n~~~OON

r mmm C - N - CU C t tmmf-I- s m m 

~~rOUrQONrcCNOttrnrOOYrNNtm 

u3-a O an rNa-00 --*a UnaON m 0, 
shown for the slope car after July 9. This is probably due to a 

failure of the ID, since occupancy levels on channel #5 (Table 4- 

3) continue about the same. 

Recorded activity also included emergency PTT, bed up 

and bed down indications for the dump trucks, and "clear all 

magazines", "in blasting cap magazine", "in dynamite magazine" 

and "in powder magazine" applicable only to the surface parts 

truck. 

Emergency PTT's were recorded as follows for the six 

month period. 

Line Plant 55 

Engineering 21 

Electrician 22 

Spare (ID 1010) 25 

Water Truck 8 

Powder Crew 4 

Slope Car 23 

Truck $9 

Truck #10 2 

Truck #11 6 

5 Loaders 4 

Surface Parts Truck 7 

However, the mine reports no bona fide emergencies 

during this period except for the slope car. The slope car is 

configured to transmit an emergency signal whenever the automatic 

over-speed brakes are applied. This i.s reported to have happened 

several times. For the others, it. is not known whether the 

emergency indications were due to inappropriate use of the 

emergency switch by the user, or t.o data collection system 

malfunctions. 

The magazine indicators are manually controlled by the 

operator of the surface parts truck. Use of them during the 

survey seems not to have been consistent. There are many weeks 

for which no magazine indications were! recorded at all. At other 

times the "clear all magazines" shows up repeatedly but with no 

indications that the magazines were ever entered. 

Of particular interest are the "bed up" and "bed down" 

indications for the four dump trucks'. The original hydraulic 
pressure actuated switches installed to signal these functions 

did not work. As a result, few indications were recorded during 

the first four months of the survey. In June, these were 

replaced with mechanically operated microswitches with feeler 

arms making direct contact with the dump bed when in the down 

position. Beginning July 12, regular bed up and bed down 

indications were recorded up to the end of the survey. These are 

summarized in Table 4-5 and compared with the logs kept by the 

drivers. Ideally, the three sets of figures should be the same, 

assuming that the driver raises and lowers the bed once for each 

trip between working face and crusher. Why there is disagreement 

is not understood. It can be seen from the totals that records 

of bed down, averaged over a period of time, came closer to 

logged trips than the records of bed up. 
Table 4-5. Comparison of "bed-up" i~nd bed-down records. 

TRUCKS 

REPORTING 

TRUCK TRIPS 

DATE LOGGED 

711 2 

711 3 

711 4 

711 5 

711 6 

711 9 

7120 

7121 

7122 

7123 

7126 

7127 

7128 

7129 

7130 

812 

813 

814 

815 

816 

819 

811 0 

811 1 

811 2 

811 3 

811 6 

811 7 

811 8 

811 9 

8120 

8123 

8124 

8125 

8126 

8127 

BED-UP BED-DOWN 
5.0 CONCLUSIONS RELATIVE TO SYSTEM UTILIZATION 

This section addresses the nine questions, listed in 

Section 1.0, which the project is intended to answer. The 

questions are repeated below. 

1. What are the telecommunicat~~ons needs of this mine? 

2. How does this system fulfill those needs? 

3. What system alterations would better meet those needs? 

4. How does the mine utilize the current system? 

5. How could system utilizatio~n be improved? 

6. Who uses (or doesn't use) the telecommunications system? 

7. Of what cost/benefit is the telecommunications system 

to the mine? Discuss specific benefits and costs. 

8. How does this system configuration compare against 

other methods of meeting the mine's needs (leaky 

feeder, for example) in terrns of: 

a. Technical feasibility? 

b. Cost? 

c. Reliability? 

d. ~ost/benef it? 

9. How does the mine radio traffic look on a histographic 

basis? 

Each question is addressed in order in the paragraphs 

that follow. 

5.1 Telecommunications Needs --- of the Mine 

5.1.1 Unscheduled Maintenance - and Repair 

Mr. Ken Reiser, General Manager, and Mr. Bob Kuehneman, 

Manager of Underground Operations, both concurred that the most 

obvious need satisfied by the radio system is the reduction of 

time required for unscheduled maintenance and repairs. The 

importance of communications in unscheduled maintenance and 

repair is made obvious from the record of production stoppages 

that occurred during the period cove:red by the project. This 

information is shown in Tables 5-1 and 5-2. Both tables show all 

gaps in the production of crushed limestone exceeding 15 minutes 

as recorded on the circular chart recorder actuated by the 
DATE 

411 

412 

415 

416 

417 

418 

OUTAGE 

DURATION 

Table 5-1. Production outages and effect on radio usageMarch 29 through June 11, 1982 

TIME BLOCKS TIME BLOCK AVERAGE 

AFFECTED OCCUPANCY (SECS.) OCCUPANCH (SECS.) 

361 

387 

135 

35 1 

257 

70 

173 

19 

133 

156 

NO DAT A 

NO DATA 

168 

6 0 

7 2 

168 

175 

7 3 

58 

0 

248 

22 

0 

161 

164 

2 2 

139 

INVALID DATA 

INVALID DATA 

NO DATA 

NO DATA 

NO DATA 

NO DATA 

NO DATA 

NO DATA 

NO DATA 

NO DATA 

178 

72 

141 

INVALID DATA 

INVAUD DATA 

INVALID DATA 

IHVALlD DATA 

INVALID DATA 

PERCENT ABOVE 

(BELOW) AVERAGE 
Table 5-2. Production outages and effect on radio usageJune 14 through A,ugust 27, 1982. 

OUTAGE 

DURATION 

TlME BLOCKS 

,AFFECTED 

TIME BLOCK 

OCCUPANCY 

AVERAGE 

OCCUPANCY 

PERCENT ABOVE 

DATE (BELOW) AVERAGE 

6114 

CAUSE 

1 h 52 m SPLICE P-2 

30 m BROKEN HYD, HOSE, #2 CURSHER 

30 m BOULDER #2 CRUSHER 

45 m SKIRT BOARD. '12 WAY 

15 m E STOP TROUBLE 

22m ESTOP 

20 m E STOP 

18 m E STOP 

2 h 30 m CAR OFF TRACKIELECT. TROUBLE 

205 BELT 

2 h 35 m SPLICE 205 BELT 

45 m SKIRT BOARD, '12 WAY 

1 h 8 m ELECT. 205 

2 h 00 m ELECT. TROUBLE OUTSIDE 

27 m PLUGGED CHUTE 

25 m 7 

1 h 30 m PLUGGED CHUTE, 205 BELT 

WON'T START 

25 m BOTTOM SLOPE BELT OFF 

1 h 40 m ELECT. PILOT UGH1 

I 

20 m 2-100 FUSES, '12 WAY 

40 m 2-100 FUSES, '12 WAY 

35m P-5RIP 

35 m P-5 OVERLOAD 

38 m 205 BELT 

10 m BELTS, #2 CRUSHER 
DATE 

813 

Table 5-2. Production outages and /effect on radio usageJune 14 through August 27, 1982 (continued). 

OUTAGE - TIME BLOCKS TIME BLOCK AVERAGE PERCENT ABOVE 

DURATION CAUSE AFFECTED OCCUPANCY OCCUPANCY (BELOW) AVERAGE 

2 h 30 m LOWER SLOPE, PLANNED OUTAGE 13 389 132 195 

14 165 120 3 8 

TAKE UP, '/2 WAY 

BOULDER BREAKER TRIP 

POWER OFF-STORM 

- 

BRAKE CAR BRAKES 

ELECT. OFF 

STOP-UP UNDER CRUSHER 

LOADER-AIR TIRES 

OUT OF ROCK - 

OUT OF ROCK 

CHECK '/2 WAY DRIVE 

BOTH CRUSHERS DOWN 

P-5 OVERLOAD 

ELECT. TROUBLE 2-1 02 

2-102 (205) PULLED IN TWO 

8126 20 m CRUSHER STOP-UP 

8126 1 h 20 m LOWER SLOPE BELT 

BAD SPLICE 
haulage belt span scale at the mine entrance. Table 5-1 covers 

the period from March 18, 1982 to June 11, 1982. No record was 

made during this period of the causes of the gaps in production. 

Beginning June 14, 1982, the circular chart recordings were 

annotated with information accounting for the stoppages. This 

information is noted in Table 5-2 exactly as written on the 

circular charts. The following may 'help in interpreting some of 

the comments. 

"P-l", "205", and "2-102" refer to specific haulage belts. 

"Boulder in crusher" indicates that crusher operation is 

stopped because the chute is blocked by a piece or pieces 

of limestone too big for the crusher to handle. 

"Plugged chute" indicates blockage of a chute at a haulage 

belt transfer point. 

The "skirt board" is a part of the chute that diverts the 

crushed limestone onto the second belt. 

The "E stop" is an emergency belt stoppage, usually 

triggered automatically by a fault in the haulage belt 

system. 

"1/2 way" is the half way point on the slope entrance at 

which a radio equipped safety monitor is stationed. This 

is a transfer point in the slope haulage belt. 

Both tables show the time blocks (i.e., the one-hour periods 

beginning at the time indicated) affected by the stoppage, the 

actual time block occupancy on the date of the stoppage, the 

average occupancy for the time block, and the percentage of tirne 

the actual occupancy exceeds the average. "Average" occupancy is 

based on the traffic recorded over a two-month period beginning 

May 1 and ending July 1, 1982. These figures are the subject of 

a later discussion. 

Of the 127 work days included in the project (~ebruary 

29 to August 27, 1982), stoppages of 15 minutes or longer are 

seen to occur on 68 days. Most (69%) were under one hour. It is 

likely that the duration of these stoppages would run much longer 

without adequate communications. 

5.1.2 Safety 

The enhancement of mine safety is a need perhaps more 

important than all others although more difficult to evaluate in 

terms of economics. One need is for. minewide notification and 

instruction in case of fire or other emergency requiring 

evacuation of the mine. Another need is for accident reporting 

(which could apply to equipment or persons ) . In some cases, 

machinery or moving equipment may be involved, such as the 

haulage belts or the slope car, which is controlled from a point 

remote from the accident. There may be a need in these cases to 
get the equipment stopped before further damage occurs. When 

persons are injured, there is a need to summon first aid and to 

arrange for speedy removal from the mine. 

5.1.3 Supervision and Coordination of Production 

Excluding the needs of safety and equipment 

maintenance, there remains a need for cornrnunications in the 

routine supervision and coordination (or production. This is true 

because production activities (1) require a high degree of 

coordination, and (2) are spread 0u.t over too large an area to 

permit coordination without some form of radio or telephone 

communications. Most communication,^ by the production foreman, 

the equipment operators, truck drivers, powder crew, driller, 

etc., are considered to be associated with routine production 

activities. 

5.2 How the System Fulfills the Needs 

The radio system provides complete coverage throughout 

the active part of the mine as well as above ground all the way 

to the line plant and parts warehouse. When equipment break 

downs occur, time is saved by radio reporting and by the use of 

radio in replacement parts retrieval. 

Safety is improved by the ability to contact all 

personnel almost instantaneously in case of fire or other 

emergency requiring evacuation of the mine. Specific 

instructions can be issued, for example, on whether to evacuate 

via the entrance slope or the air shaft. Safety is also improved 

by the provision of direct communications between the slope car 

and hoist operator. The hoist operator can be directed to stop 

or start the car at anytime from the car itself. Radio 

communications is also used to report accidents and speed up 

evacuation of injured person(s) . I:t does this by summoning 

transportation for the injured party and arranging to have him 

met by the slope car when he arrives at the bottom of the slope. 

In routine production, the radio system permits 

supervisory and coordinating communiczltions among the individuals 

involved. It is particularly useful in communicating with moving 

vehicles, such as the trucks, for which telephones are not 

convenient. 

5.3 System Alterations 

The subject of system alterations that would better 

meet the needs of the mine is covered in Section 8.0, 

Recommendations. 

5.4 --- How the Mine Utilizes - the System 

The communications needs of the mine are fulfilled by 

two systems: the radio system and the Femco telephone system. 

Telephones are located at the hoist house, the half-way station, 
bottom of the slope, the air shaft, the crushers, and the shop 

area. 

The use of communicatiorns in a typical unscheduled 

maintenance situation, such as a haulage belt break, is 

illustrated in Figure 5-1. The trouble is likely to be first 

observed by the crusher operator, t.he conveyor or the half-way 

observer. The crusher operator would normally report the problem 

via the Femco telephone at his work station. The conveyor, 

because he roams, would find it more convenient to report by 

radio. The half-way observer could use either, but typically 

uses radio. 

The radio is also used to save time in maintenance 

activities other than those resulting from major production 

stoppages. For example, quoting from Reference 3: 

Interviews were conducted with key mine 

personnel who use the new radio and CCTV 

systems on a regular basis. Mr. William Day, 

Underground Maintenance Coordinator, declared 

he saved about two hours per day locating 

maintenance 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 needled. Also when the 

telephone system is busy, the radio system 

provides them with back up communications. 

Another expensive savings has been realized 

when mine equipment breaks down. The miners 

can call the maintenance people using the radio 

system and describe in sorne 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. 

Also, quoting from Reference 3: 

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. 

Quotations from Reference 3 also indicate how radio 

communications has been used to improve mine safety. 

Mr. Benny Whitmer, Safety Supervisor, stated 

that the mine has two fire drills per year for 

everyone in the mine. The radio system has 
MAJOR PRODUCTION STOPPAGE 

BELT BREAK 

TROUBLE REPORTED TO EITHER PRODUCTION 

OR MAINTENANCE FOREMEN BY: 

1. CRUSHER OPR - VIA FEMCO 

2. CONVEYOR OR HALFWAY - VIA RADIO 

MAINTENANCE FOREMAN DISPATCHES 

MECHANIC CREW (NORMALLY WORKING IN 

SHOP AREA) TO TROUBLE SPOT. IF MAJOR, 

FOREMAN GOES TOO. 

TROUBLE IN SLOPE 

RADIO ALWAYS TAKEN 

(BECAUSE NO FEMCO.) 

TROUBLE UNDERGROUND 

FEMCO USED PRIMARILY 

I 

PART RETRlEVAli 

TRACTOR TOIFROM SHOP 

RADIO TO WAREHOUSE IF NECESSARY 

Figure 5-1. Procedure used for major production stoppage. 

48 
reduced the time for these drills from 30 

minutes .to 12 minutes. In addition to the 

obvious 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. 

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. 

The usefulness of the radio in the slope is further 

emphasized by the hoist house (winch) operator as follows: 

The hoist house operator, wlno is the designated 

monitor of slope activity, 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 rnaintain continuous 

and immediate communication 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 preventing damage to equipment or cables 

and reducing danger to support people. 

One fire drill was held during the period of the 

survey. The drill was initiated at 9:33:18.9 AM on March 2, 1982 

and ended 20 minutes and 21.7 seconds later. During this period 

the Maintenance Foreman came on the air 14 times for a total of 

49.7 seconds. The Safety Director used his radio 4 times for a 

total of 9.9 seconds. The only other voice activity was the 

half-way monitor who talked twice for a total of 6.3 seconds. 

Total occupancy for the one hour titme block was 334 seconds, 

indicating that activity during the remaining part of the hour 

was much greater than during the fire drill. 

There are fewer specifics oln the use of radio for the 

supervision and coordination of routine production. This is 

partly because the advantage of radio over the Femco telephone 

system is not as great in situations that are predictable and 
routine. Telephones are provided at all regular work stations 

and locating a person away from his work. station usually is less 

urgent. However, the radio is used in production related 

activities as is discussed in Section 5.6. 

5.5 How Utilization Could Be Improved 

This subject is covered in Section 8.0, 

"Recommendations. " 

5.6 Who Uses the --- Telecommunications System - 

Reference back to Table 4-,4 reveals which ID equipped 

radios were used to initiate messages, or more specifically, the 

number of times the normal push-to-t.slk button was pressed. An 

assumption is made that the person using the radio is the one 

listed. This is believed to be accurate with respect to mobile 

units permanently attached to the ve'hicle with which it is used. 

Persons assigned portable radios are understood to have used the 

radios assigned for the most part. However, no accurate records 

were kept as to when a spare unit may have been temporarily 

substituted for one regularly assigned, or if and when, radios 

may have been "swapped" for any reason. 

Table 4-4 shows that the person making the most use of 

radio is the Maintenance Foreman (~r. Johnny Jones, using ID 

#001). The table shows that his radio accounts for 22.6% of the 

total activity for the six month period, even though it was 

barely used during four weeks in July and August. During the 

same four weeks, the use of the spare radio (ID #010) jumps to a 

level of use comparable to ID #001 preceeding and after the four 

week period. If it can be assumed that the spare radio was in 

fact used for the maintenance function, the percentage of use 

assigned to this function would be 25.3%. 

After maintenance, radio users are ranked as follows: 

Hal f-way 

Electrician 

Spare 

Conveyor 

Surface parts truck 

Powder crew 

Foreman #2 

Mr. Kuehneman 

Foreman #1 

Truck #10 

Safety Director 

Water truck 

Lime plant 

Engineering 

Truck #9 

Truck #11 

Slope car 

Radio maintenance 

9.48 

7 . 2% 

6.4% 

6.2% 

5.6% 

5.0% 

4.9% (used mostly as a spare) 

4.2% 

4.0% 

3.9% 

3.5% 

3.18 

2.6% 

2.5% 

2.5% 

2.3% 

2.2% 

0.8% 
Truck #8 

Scaler 

5 Loaders 

No usage was recorded for the Jumbo Drill. No usage was recorded 

for the slope car for the final eight weeks of the survey, 

although traffic was recorded on channel #5 which is used 

exclusively by the slope car. This could be due to a failure of 

the MODATS ID on the slope car radio. 

It is of interest to break down radio usage by the 

three functions previously discussed: maintenance, safety and 

production. It is not likely that any one individual is 

exclusively concerned with any one of these functions. However, 

it is estimated that the following are primarily concerned with 

maintaining mine equipment, detecting malfunctions (i.e., 

monitoring belts, etc.), and making repairs as expeditiously as 

possible when breakdowns occur. 

Maintenance Foreman 

Lime Plant 

Engineering (40%) 

Radio Maintenance 

Conveyor 

Mr. Kuehneman (40%) 

Half-way (50%) 

Slope car (50%) 

Surface parts truck (50%) 

These, at the percentages indicated, *would account for 50% of all 

the activity. 

All mining personnel are, or should be concerned with 

safety. The only ones identified whose primary responsibility is 

safety, however, are the Safety Director and the half-way 

monitor. The latter also monitors the slope haulage belt, so 

that his radio activity is assumed to deal 50% with maintenance 

and 50% with slope safety. Safety routinely accounts for about 

8% of the radio activity. In an emergency, it would obviously 

account for much more. The value of radio for safety purposes is 

that it is there when needed. T:he remainder of the radio 

activity, about 42% would be that used to support routine 

production activities. This would include both supervisory 

activities and communications between persons engaged in 

production. 

5.7 Cost Benefit 

The costs versus benefits of the radio system is the 

subject of Section 6.0, following. 
5.8 -- How the System Confiquratiokn 

Compares With Other ~ethodsThe comparison of the radi.0 system configuration with 

other methods of meeting the mine's needs is the subject of 

Section 7.0, following. 

5.9 Radio Traffic Histographs 

Histographs of radio traffic for all three channels 

shown in hourly time blocks are con.tained in Appendix A. The 

daily peaks and the time blocks in wh.ich they occur are extracted 

in Table 4-3. 
6.0 COST BENEFIT 

Mine management plans to continue the radio system 

after the financial support of the! U.S. Bureau of Mines is 

terminated. Management believes tha-t the system is justified by 

the reduction of down time for unsclheduled (or unanticipated) 

maintenance and repairs. 

6.1 Mine Revenue 

The mine was, during t,he period of the survey, 

operating at less than its full capacity. Even so, its average 

output of crushed limestone was about 683 tons per hour during 

the 8:30 AM to 3:30 PM* period of active production. The value 

of a ton of crushed limestone at the mine portal is about $2.65. 

Any interruption in this production, such as a break in a haulage 

belt, cost the mine $1,810 per hour because of the loss of 

product with no compensating sa;ing in operating cost. 

6.2 -- Loss in Revenue From Production Stoppaqe 

Tables 5-1 and 5-2, previously referred to, show 68 

production stoppages for periods of 15 minutes or more during the 

period of the survey. The total time lost during the six month 

period was approximately 63 hours. This, of course, is the 

production loss with radio. If the radio were not in use, it 

would take longer to locate and dispatch maintenance personnel. 

Often, without two-way communications allowing questions and 

answers, it would be necessary for the maintenance man to make 

two trips, once to inspect the problem area and a return trip to 

bring the right tools and parts. More time would be lost if a 

part were required from the parts warehouse on the surface. 

Assuming that radio communications saves an average of 30 minutes 

in getting the system back in operation after each unscheduled 

stoppage, mine revenue would be increased by 

2 X 68 stoppages per 6 mo. period X 0.5 hr X $1810 

= $123,080 per year. 

6.3 Savings - in Supervision -. and Coordination, Production 

Production operations, although highly interdependent, 

are spread out over a considerable area. Close coordination is 

required between working face and crushers, and between crushers 

and the haulage belt system which extends out of the mine all the 

way to the lime plant. Radio puts the production foreman in 

immediate contact with all key personnel at all locations. He is 

relieved of having to personally be at all locations where his 

supervision extends. Without radio, it is estimated that one 

additional lead person would be required to assist in maintaining 

-------------- 

*Based on production records for July and August, 1982. 
supervisory control over activities at widely separated location. 

The cost to the mine of such a person (with employee benefits and 

overhead expenses) is estimated as $30,000 per year. 

6.4 --- Cost of the Radio System 

The initial cost of the radio system was, by Reference 

3, $600,000. It is usual to amortize such equipment over a 

period of 10 years. Allowing 12% as the cost of money, the 

annualized cost is $106,190. This does not include maintenance. 

During the survey, the equipment was maintained by a full-time 

Motorola representative under a contract with the US Bureau of 

Mines. When the Bureau of Mines contract expires, mine 

management plans to continue service but under a "time and 

materials" arrangement with the Motorola Cincinnati office. It 

is assumed that at least two days, or 16 hours a week will be 

required at a rate of $25 per hour. This multiplies out to 

$20,800 per year. In addition, two round trips a week out of the 

Cincinnati office will, at $0.25 a mile, add another $40 per week 

of cost. The estimated annual cost of maintenance is therefore: 

Maintenance labor $20,800 

Travel (52 X $40) 

Adding this to the annual equipment and installation 

costs : 

Annual equipment cost $106,190 

Maintenance cost 22,880 

Annual cost of radio system $129,070 

6.5 Benefits - vs Costs 

The two benefits identified are the reduction of 

production losses to unscheduled stoppages and a saving in labor 

cost by more efficient supervision and coordination. Estimated 

savings from these two are: 

Reduction of production losses $123,080 

Savings in supervision & coordination 30,000 

$153,080 

There are other benefits more difficult to quantify. These 

include added safety and the reduction of time needed to remove 

injured personnel. The reduction in time needed to evacuate the 

mine during a fire drill, for examplee, will save a small amount 

of production time each year, but in a real emergency could 

result in the saving of lives. 

The benefits can be compared with the estimated cost of 

$129,070 per year. To the extent that benefits are greater than 

the cost, the radio system is economically justified . If a 

second, production shift were added, the benefit would increase 

proportionately with small increase im cost. 
It should be borne in mind that the radio system is one 

of two communications systems used in the mine and that the 

functions of the two overlap to a large degree. Without either 

system, it is unlikely that the mine would operate at all. The 

benefits of having at least one system of communications are 

therefore very great. There is a lesser benefit in adding a 

second system, although this benefit is greater for radio than 

for telephones. As previously noted, radio allows communication 

with moving vehicles and allows a radio equipped individual to 

communicate from any point. 

Benefits of the radio system would be greater if the 

MODATS reporting system were made to work better. There is no 

basic reason why the bed-up and down indications could not be 

made to work more reliably and used as a measure of production. 

The erratic surface parts truck indications with respect to its 

presence in the magazines could possibly be improved by making 

them automatic - not requiring any action by the driver. These 

matters are more fully covered in Section 8.0. 
7.0 COMPARISON WITH OTHER METHODIS OF MEETING THE MINE'S NEEDS 

The present communications needs of the mine are being 

satisfied by both the radio system and a Femco telephone system. 

They are often used interchangeably and one serves as a backup to 

the other. The radio has an advantage in communications with 

moving vehicles and roving personnel when not near a telephone 

station. A requirement of the radio system is that it provide 

complete coverage of at least the active areas of the mine and of 

the surface in the vicinity of the outside haulage belt system, 

the lime plant and the parts warehouse. The system in use was 

carefully engineered to perform these functions. 

7.1 Leaky Feeder 

The only other similar (UHF) system that might do as 

well is one using "leaky feeder" cable. Reliability and 

technical feasibility should be the same. However, this was 

originally considered for Black River and ruled out in favor of a 

system using "distributed antennas" and strategically placed 

passive reflectors, as described in Section 2.0. The distributed 

antenna design made use of 2600 feet of 7/8 inch diameter coaxial 

cable and 9600 feet of 1/2 inch coaxial cable. Had leaky feeder 

been used, an equivalent length (12,200 feet) of leaky feeder 

cable would be required to cover the same area covered by the low 

loss cable network of the distri'buted antenna system. In 

addition, about 1800 feet of additional leaky feeder cable would 

be required for each antenna and passive reflector to fill in the 

crosscut tunnels (900 feet in each direction). There are 24 

antennas and 27 reflectors. If eac'h is replaced with 1800 feet 

of leaky feeder cable, 91,800 feet additional cable would be 

required. The 12,200 feet of trunk cable should be 7/8 inch 

diameter to keep losses to a minimum. The 91,000 feet of 

branching cable could be 1/2 inch in diameter. A comparison of 

material cost is as follows: 

Present System 

2600 ft. of 7/8" coax @ 4.05/ft $10,530 

9600 ft. of 1/2" coax @ 1.55/ft 14,880 

24 antennas @ 30 720 

27 reflectors @ 20 540 

TOTAL $26,670 

Leaky Feeder 

12,200 ft. of 7/8" Radiax @ 5.50 $ 67,100 

91,800 ft. of 1/2" Radiax @ 2.76 253,368 

TOTAL $320,468 

It is obvious that the use of distributed antenna 

systems combined with passive reflectors results in a 

considerable saving over an equivalent leaky feeder system for 

wide-area coverage of a room and pillar mine. Leaky feeder would 

find greater justification in covering long tunnels as opposed to 
large two-dimensional areas. 

7.2 MF - Reradiation Systems 

A traditional "trolley-wi.re" system would not have 

accomplished the objective of complete coverage. The 

transceivers would normally be able to operate only in close 

proximity to the specially installed conductor using a 24 inch 

elongated loop antenna. However, the Bureau of Mines has 

recently announced a "whole-mine medium frequency radio 

communication system" which if it performs as claimed, does 

provide mine-wide communications t.o both vehicles and roving 

personnel. The system operates in t.he range of 0.3 to 3 PlHz and 

utilizes parasitic coupling onto an2 re-radiation from existing 

mine wiring to achieve the desired coverage. The personnel 

transceivers consist of radio modules distributed in the pockets 

of a special vest. A loop antenna is sewn into the back of the 

vest. Repeaters located at strategic points in the mine enhance 

signal strength very much as VHP and UHF rspeaters do. 

Insufficient information is currently available on the 

cost of the MF communication system to make a comparison. 

However, it is a system that merits further consideration for 

mine use. 
8.0 RECOMMENDATIONS 

8.1 Utilization of Truck Dump-Bed Data 

Despite the inconsi~tenci~es shown in Table 4-5, in 

which "bed-up" and "bed-down" data are compared with logs kept by 

the drivers, there is no fundamental. reason why such data cannot 

be used to provide a reliable record of production. Table 8-1 

shows production figures that would have resulted if the data 

accumulated during the July 16 to August 27 period (the only 

period during which consistent bedL-up and bed-down data was 

recorded) had been used for this purpose. Based on figures for 

July and August of 1982, the average load carried by a truck is 

30.1 tons. Each bed-up or bed-down indication can therefore Se 

assumed to represent 30.1 tons of limestone dumped into a 

crusher. This being the case, th.e bed-up figures would have 

fallen 19.5% short of the tonnage manually logged over the six 

week period. The bed-down figures would have fallen short by 

only 4.3%. 

It is recommended that the method of providing a bed-up 

or bed-down indication be examined. Both are not needed if one 

can be trusted. We suggest the use of a pressure sensitive 

switch on the high side of the hydraulic cylinder to 5e actuated 

each time the dump bed is raised. The system should be 

thoroughly tested for both false indications and failure to 

provide true indications. It should be possible to achieve a 

very high degree of reliability and to provide an accurate record 

of production by this method. 

Table 8-1. Production records from bed-up and beddown indications. 

TONNAGE DETERMINED FROM 

WEEK 

ENDING BED-UP % ERROR IBED-DO W N % ERROR 

TONNAGE 

LOGGED 
8.2 Dispatching - and Operating - Procedures 

Essential to effective operation and control is a 

dispatcher responsible for maintaining circuit discipline, 

keeping track of all radio equipped vehicles and personnel, and 

exercising control during drills and emergencies. There is 

currently no person fulfilling this role. 

It is recommended that a dispatcher position be 

established and that standard operating procedures be developed. 

In an operation the size of Black River Limestone Company, the 

dispatcher could be a person with colateral duties, such as the 

hoist operator. Among the dispatcher's duties would be keeping 

track of which ID numbered portables 'had been issued and to what 

persons. He should know where each person is working and 

procedures should be established to keep this information 

updated. The dispatcher should be able in emergencies to disable 

(knock down) the repeaters and operate the system as a group of 

wire-line controlled base stations. This provides the dispatcher 

with total control of the radio system and eliminates chaotic 

person-to-person transmissions whiclh only serve to confuse the 

emergency situation. It should be the procedure in drills and 

emergencies for each radio equipped person to report the 

locations and status of himself and others for whom he may be 

responsible. 

8.3 Elimination of Channel #3 

The total traffic on the radio system does not justify 

three channels. From the viewpoi~nt of safety, it may be 

desirable to continue the use of channel #5 as a dedicated slope 

channel. However, channel #3 traffic could easily be combined 

with that on channel #1 with only a minor effect on the peak 

loadings recorded for channel #1. For one thing, the average 

peaks on channel #3 were only 21% of the average for channel #1. 

For another, the time blocks during which the peaks of the two 

channels occurred coincided only 21 times out of the 111 days for 

which valid data was available, i.e., the peaks add directly less 

than one time in five. 

It is recommended that channel 43 be eliminated along 

with the three base/mobile repeaters, modems and voting modules 

associated with channel #3. The surface parts truck (ID A300) 

would shift its traffic over to channel 41. The equipment 

eliminated would go into the spares inventory. This action would 

reduce maintenance costs and eventual replacement costs. Future 

purchases of portable and mobile units need to specify only two 

channels. (~ote: No data was taken on the "talk around" 

channels numbers 2, 4 and 6, but information furnished indicates 

that they were infrequently used.) 
8.4 Maqazine Entry Records 

If information on the location of the surface parts 

truck with respect to the powder, dynamite and blasting cap 

magazines is important to safety, then the record of entry and 

exit from the magazines needs to ble automated. The present 

system is unreliable. Each vehicle that enters a magazine could, 

for example, be equipped to detect the presence of a low power 

responder inside the magazine and immediately signal the 

dispatcher that the vehicle is at that location. 

It is recommended that the automatic signalling of the 

presence of vehicles or persons at hazardous locations be made 

the subject of a future investigation. 
REFERENCES 

1. Chufo, R.L. & Vancura, P.D., "The Installation, Operation 

and Maintenance of an Underground Minewide Radio System" 

JEEE-IAS Conference Proceedings, Chicago, IL, Oct. 1976. 

2. Cory, T.S., "Telephone Communication System for a Deep-Vein 

Metal Mine," Final Rpt. prepared for the US Bureau of Mines 

under Contract NO. 50100093, March 1982. 

3. Isberg, RoA., Kramer, H. & Parrish, D.A., " The 

Implementation of UHF Radio Communication and CCTV 

Monitoring Systems in a Room and Pillar ~etalj~on-metal 

Mine," Final Rpto prepared for thu US Bureau of Mines under 

Contract NO. 50377044, March, 1981. 
APPENDIX A 

HISTOGRAPHS 

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+---------A---------A---------*-A---------A---------A---------A 

30.0 60.0 90.0 120.0 150.0 180.0 210.0 

Channel 5 

Total File Days Used 108 

Average SecondslTransactton for 60 (311182) to 239 (8127182) 

(Each I*' represents 3 seconds.) 

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10 

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+---------A---------A-----------A---------A---------A---------A 

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Channel 1 

Total File Days Used 23 

Average Percent of System Occupancy for 60 (3ili82) to 90 (3/31/82) 

(Each I*' represent,^ 0.07 percent.) 

Hour I 

0: 

1 :**************** 

80.0 160.0 240.0 320. 0 400.0 480.0 560.0 

Channel 1 

Total File Days Used 23 

Average SecondsiTransaction for 60 (3/1/82) to 90 (3/31/82) 

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6 

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+---------A---------A-----------A---------A---------A---------A 

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Channel 3 

Total File Days Used 23 

Total Seconds of Use for 60 (311182) to 90 (3131182) 

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+---------A---------A---------*-A---------A---------A---------A 

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Channe 1 3 

Total File Days Used 23 

Total Transactions for 60 (3/1182) to 90 (3131182) 

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Hour 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

2 0 

2 1 

2 2 

2 3 

Hour 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

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2 0 

2 1 

2 2 

2 3 

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I 

I 

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1 

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0.2 0.3 0.5 0.6 0.8 0.9 11 

Channel 3 

Total File Days Used 18 

Average Percent of System Occupancy for 91 (411182) to 120 (4130182) 

(Each I*' represents 0.015 percent.) 

+---------A---------A---------*-A---------A---------A---------A 

120.0 240.0 360.0 4.60. 0 600.0 720 .0 840.0 

Channel 3 

Total File Days Used 18 

Average SecondslTransaction for 91 (411182) to 120 (4130182) 

(Each I*' represents 12 seconds.) 

Hour : 

0: 

1: 

2 ; 

3 ; 

4 : 

5: 

6 : 

7 ;******************* 

6 ;************************* 

9 ;*********** 

10 I***************** 

11 ;******* 

12 :* 

13 :********** 

14 :  

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16 : m** ********n******************a***********e***************** 

17 ;***************** 

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19 :******** 

20 ;*********r  

21 :** ******************* 

22 : 

23 :*** 

+---------A---------A---------a-A---------A---------A---------A 

0.1 0.2 0 2 0 3 0.4 0 5 0 6 

Channel 5 

Total File Days Used 18 

Average Peroent of System Occupancy for 91 (411182) to 120 (4130102) 

(Each '*' represents BE-03 percent.) 

Hour 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

1 5 

16 

17 

18 

19 

2 0 

2 1 

2 2 

2 3 

+---------A---------A---------A---------.A---------A---------A---------A 

250.0 500.0 750.0 % 1000 % 1250 % 1500 % 1750 

Channel 5, 

Total File Days Used 18 

Average Seconds/Transaction for 91 (411182) to 120 (4130182) 

(Each '*I represents 25 seconds.) 
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0: 

1: 

21 

3: 

4 : 

5: 

6 : 

7 ;********** 

+---------A---------A-------------A---------A---------A---------A 

10 2 0 3 0 4 0 5 0 6 0 7 0 

Channel S 

Total File Days Used 8 

Total Seconds of Use for 123 (513t82) to 148 (5/28/82) 

(Each I*' represents 1 seconds of use.) 

Hour 

0 

f 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

1 s 

16 

17 

18 

19 

2 0 

2 1 

2 2 

2 3 I 

+---------A---------A-----~---A--------.-A---------A---------A---------A 

3 6 9 12 15 18 2 1 

Channel 5 

Total File Days Used 8 

Total Transactions for 123 (513182) to 148 (5128182) 

(Each '*' represents 0.3 transactions.) 
< m el 

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Hour I 

0 : 

1 : 

2: 

3: 

4: 

S I 

6: 

7 1 

8 ................................. 

+---------A---------A-----------A---------A---------.4---------/'\ 

100 2 0 0 300 4 0 0 500 600 700 

Channel 3 

Total File Days Used 20 

Total Seconds of Use for 152 (611182) to 180 (6129182) 

(Each I*' represents 10 seconds of use.) 

Hour 

0 

1 

2 

3 

4 

C 

6 

7 

8 

9 

4 0 8 0 120 160 200 240 280 

Channel 3 

Total File Days Used 20 

Total Transactions f-or 152 (611182) to 180 (6127182) 

(Each '*' represents 4 transactions.) 
Hour 

0 

+,--------A---------A---------A---------.A---------A---------A---------A 

0.2 0,3 0.5 0. 6 0.8 03 11 

Channel 3 

Total File Days Used 20 

Average Percent of Bystern Occupancy for 152 (611182) to 180 (61291823 

(Each '*' represents 0.015 percent.) 

Hour : 

0 :********* 

300.0 600.0 900.0 H 1200 W 1500 K 1800 % 2100 

Channel 3 

Total File Days Used 20 

Average Seconds/Transaction for 152 (611182) to 180 (6129182) 

(Each '*' represents 30 seconds. 

,-. 

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Hour 

0 

b 

2 

3 

4 

S 

4 

7 

8 

9 

+---------A---------A---------*-A---------A---------A---------A 

0 7 14 2.1 2.8 3.5 4.2 4 9 

Channel 1 

Total File Days Used 21 

Average Percent of System Occupancy for 182 (711182) to 211 (7130182) 

(Each '*I represents 0.07 percent.) 

Hour I 

0 : 

1; 

2: 

3: 

q :*** 

60 .O 120.0 180.0 240.0 300.0 360.0 4 2 0 

Channel 1 

Total File Days Used 21 

Average Seconds/Transaction for 182 (711182) to 211 (7130182i 

(Each '*I represents 6 seconds.) 
Hour : 

0 : 

1; 

2 I 

3: 

4 I 

5: 

6 i 

7: 

8 ..................................... 9 ................................................... 10 ............................. 11 .................... 12 :******** 

13 ;******************** 

$4 I********************************************** 

1s : ********* 

16 :   

17 ; ** **** 

18 :*** 

19 : 

20 : 

21 : 

22 : 

23 : 

+---------A---------A---------*-A---------A---------A---------A 

100 200 300 400 500 600 700 

Channel 3 

Total File Days Used 21 

Total Seconds of Use for 182 (711182) to 211 (7130182) 

(Each '*' represents 10 seconds of use.) 

Hour : 

0: 

1: 

2: 

3: 

4: 

5: 

6 1 

7 :** 

8 :*********************************a** 

9 ...................................................... 10 ........................... 11 I********************* 

12 ;********* 

13 ; ****************** 

14 .................................................... 15 :********* 

16 :*** 

17 :  

18 :**  

19 I 

20 : 

21 : 

22 I 

23 : 

+---------A---------A---------A-------.--A---------A---------A---------A 

5 0 100 1 SO :2 0 0 250 300 350 

Channel 3 

Total File Days Used 21 

Total Transactions for 182 (711182) to 211 (7150182) 

(Each I*' represents 5 transactions.) 
A 

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Channel 5 

Total Pile Days Used 21 

Total Seconds of Use for 182 (711182) to 211 (7130!82) 

(Each I*' represents 15 seconds of use.) 

Hour 

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Channel 5 

Total Pile Days Used 21 

Total Transactions tot 182 (711182) to 211 (7130182) 

(Each '*' represents 3 transactions.) 
Hour 

0 

a 

2 

3 

4 

5 

6 

7 

8 

9 

18 

11 

12 

13 

14 

15 

16 

17 

18 

19 

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23 

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1 

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3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

2 0 

2 1 

2 2 

2 3 

+,--------A---------A---------A-------.--A---------,A---------A---------.A 

0.2 0 4 0.6 0 . 8 1.0 1.2 14 

Channel 5 

Total File Days Used 21 

Average Percent of System Occupancy for I82 (711182) to 211 (71301823 

(Each '*' represents 0.02 percent.) 

+---------A---------A-----h-------A---------A---------A---------A 

150.0 300.0 450.0 600.0 750.0 900. 0 % 1050 

Channel 5 

Total File Days Used 21 

Average SecondslTransaction for 182 (711182) to 211 (7130182) 

(Each '*' represents 15 seconds ) 



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Channel 5 

Total File Days Used 19 

Total Seconds of Use for 214 (812182) to 239 (8127/82) 

(Each I*' represents 8 seconds of use.) 

Hour 

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4 

5 

6 

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10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

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+---------A---------A-----------A---------A---------A---------A 

2 0 4 0 6 0 I3 0 100 120 140 

Channel J 

Total File Days Used 19 

Total Transactions for 214 (8/2/82) to 239 (8127182) 

(Each '*I represents 2 transactions.) 
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