NBSIR 74-391

ELECTROMAGNETIC NOISE IN LUCKY FRIDAY MINE

W.W. Scott, NBS

J. W. Adams, NBS

W. D. Bensema, NBS

H. Dobroski, U. S. Bureau of Mines

Electromagnetics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

October 1974

Prepared for

U. S. Bureau of Mines

Pittsburgh Mining and Safety Research Center

4800 Forbes Avenue

Pittsburgh, Pennsylvania 15213

Working Fund Agreement HO 133005

NBSIR 74-391

ELECTROMAGNETIC NOISE IN LUCKY FRIDAY MINE

W. W. Scott, NBS

J. W. Adams, NBS

W. D. Bensema, NBS

H. Dobroski, U. S. Bureau of Mines

Electromagnetics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

The views and conclusions contained in this

document should not be interpreted as necessarily

representing the official policies or recommendations of the Interior Department's

Bureau of Mines of the U. S. Government.

October 1974

Prepared for

U. S. Bureau of Mines

Pittsburgh Mining and Safety Research Center

4800 Forbes Avenue

Pittsburgh, Pennsylvania 15213

Working Fund Agreement HO 133005

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS Richard W Roberts Director

CONTENTS

Page

1. INTRODUCTION 1

1.1 Background 2 1.2 Mine Description 4

2. MEASUREMENT INSTRUMENTATION 6

3. SPECTRUM MEASUREMENT RESULTS 13

3.1 Introduction 13

3.2 Surface Noise Measurements 13

3.2.1 Hoist House 13

3.2.2 Head Frame 14

3.2.3 Noise Near Business District, Center of

Town 15

3.3 Spectra at Levels Within the Mine 16

3.3.1 The 1450 Level- 16

3.3.2 The 3650 Level 17

3.3.3 The 405C Level 17

3.4 Spectra Obtained from Cage Runs, Loop Antenna 21

3.4.1 Mine Not in Operation 21

3.4.2 Mine in Operation 22

4. AMPLITUDE PROBABILITY DISTRIBUTION MEASUREMENTS 74

4.1 Introduction and Uncertainties 74

4.2 Results 75

4.3 RMS and Average Values 76

4.4 Summary Curves ' 77

5. NOISE AND ATTENUATION MEASUREMENTS ALONG THE HOIST

ROPE 114

5.1 Noise Measurements 114

5.2 Attenuation Measurements 115

6. CONCLUSIONS 126

7. RECOMMENDATIONS 126

8. ACKNOWLEDGMENTS 126

9. REFERENCES 127

10. APPENDIX 128

iii
LIST OF FIGURES

Page

Figure 1-1. Isometric projection of Lucky Friday Mine 5

Figure 2-1. Block diagram of portable instrumentation,

first system 8

Figure 2-2. Second field recording system, first

configuration 9

Figure 2-3. Second field recording system, second configuration; used to record data for APD's 10

Figure 2-4. Second field recording system, third configuration; it recorded data for APD's on

3650 level-- 11

Figure 2-5. Second field recording system, fourth configuration; it was used on hoist runs up and

down shaft 12

Figure 3-1. Spectrum of magnetic field strength, hoist

house 24

Figure 3-2. Spectrum of magnetic field strength, hoist

house 25

Figure 3-3. Spectrum of magnetic field strength, headframe 26

Figure 3-4. Spectrum of magnetic field strength, headframe 27

Figure 3-5. Spectrum of magnetic field strength, headframe 28

Figure 3-6. Spectrum of magnetic field strength, headframe 29

Figure 3-7. Spectrum of magnetic field strength, headframe -- 30

Figure 3-8. Spectrum of magnetic field strength, headframe - -- 31

iv
LIST OF FIGURES (Continued)

Page

Figure 3-9. Spectrum of magnetic field strength, headframe 32

Figure 3-10. Spectrum of magnetic field strength, headframe 33

Figure 3-11. Spectrum of magnetic field strength. Cedar

Street, Wallace, Idaho 34

Figure 3-12. Spectrum of magnetic field strength, Cedar

Street, Wallace, Idaho 35

Figure 3-13. Spectrum of magnetic field strength. Cedar

Street, Wallace, Idaho 36

Figure 3-14. Spectrum of magnetic field strength, 1450

level 37

Figure 3-15. Spectrum of magnetic field strength, 1450

level 38

Figure 3-16. Spectrum of magnetic field strength, 3650

level 39

Figure 3-17. Spectrum of magnetic field strength, 3650

level 40

Figure 3-18. Spectrum of magnetic field strength, 3650

level 41

Figure 3-19. Plan view of portion of 4050 level. Lucky

Friday Mine 42

Figure 3-20. Spectrum of magnetic field strength, 4050

level 43

Figure 3-21. Spectrum of magnetic field strength, 4050

level 44

Figure 3-22. Spectrum of magnetic field strength, 4050

level 45

Figure 3-23. Spectrum of magnetic field strength, 4050

level 46

V
LIST OF FIGURES (Continued)

Page

Figure 3-24. Spectrum of magnetic field strength, 4050

level 47

Figure 3-25. Spectrum of magnetic field strength, 4050

level 48

Figure 3-26. Spectrum of magnetic field strength, 4050

level 49

Figure 3-27. Spectrum of magnetic field strength, 4050

level 50

Figure 3-28. Spectrum of magnetic field strength, 4050

level 51

Figure 3-29. Spectrum of magnetic field strength, 4050

level 52

Figure 3-30. Spectrum of magnetic field strength, 4050

level 53

Figure 3-31. Spectrum of magnetic field strength, 4050

level 54

Figure 3-32. Spectrum of magnetic field strength, 4050

level 55

Figure 3-33. Spectrum of magnetic field strength, 4050

level 56

Figure 3-34. Spectrum of magnetic field strength, 4050

level 57

Figure 3-35. Spectrum of magnetic field strength, 4050

level 58

Figure 3-36. Spectrum of magnetic field strength, zero

level 59

Figure 3-37. Spectrum of magnetic field strength, 4050

level 60

Figure 3-38. Spectrum of magnetic field strength, zero

level 61

vi
LIST OF FIGURES (Continued)

Page

Figure 3-39. Spectrum of magnetic field strength, 150

level 62

Figure 3-40. Spectrum of magnetic field strength, 1450

level 63

Figure 3-41. Spectrum of magnetic field strength, 3400

level 64

Figure 3-42. Spectrum of magnetic field strength, 4250

level 65

Figure 3-43. Spectrum of voltage across a 50 ohm load,

4250 level 66

Figure 3-44. Spectrum of magnetic field strength, 4250

level 67

Figure 3-45 Spectrum of voltage across a 50 ohm load

(comparison of strong unknown source and

typical noise) 68

Figure 3-46. Spectrum of magnetic field strength, 4250

level 69

Figure 3-47. Spectrum of magnetic field strength, 4250

level 70

Figure 3-48. Spectrum of voltage across a 50 ohm load

(unknown narrowband sources) 71

Figure 3-49. Spectrum of voltage across a 50 ohm load

(unknown narrowband sources) 72

Figure 3-50. Spectrum of magnetic field strength, 1800

level 73

Figure 4-1. APD, 30 kHz, headframe 78

Figure 4-2. APD, 7 0 kHz, headframe 79

Figure 4-3. APD, 150 kHz, headframe 80

Figure 4-4. APD, 250 kHz, headframe 81

vii
LIST OF FIGURES (Continued)

Page

Figure 4-5. APD , 30 kHz, headframe 8 2 Figure 4-6. APD, 70 kHz, headframe 83

Figure 4-7. APD, 150 kHz, headframe 84

Figure 4-8. APD, 250 kHz, headframe 85

Figure 4-9. APD, 30 kHz, 1450 level 86

Figure 4-10. APD, 70 kHz, 1450 level 87

Figure 4-11. APD, 150 kHz, 1450 level 88

Figure 4-12. APD, 250 kHz, 1450 level 89

Figure 4-13. APD, 30 kHz, 1450 level 90

Figure 4-14. APD, 70 kHz, 1450 level 91

Figure 4-15. APD, 150 kHz, 1450 level 92

Figure 4-16. APD, 250 kHz, 1450 level 93

Figure 4-17. APD, 30 kHz, 3050 level 94

Figure 4-18. APD, 70 kHz, 3050 level 95

Figure 4-19. APD, 150 kHz, 3050 level 96

Figure 4-20. APD, 30 kHz, 3050 level 97

Figure 4-21. APD, 70 kHz, 3050 level 98

Figure 4-22. APD, 150 kHz, 3050 level 99

Figure 4-23. APD, 35 kHz, 3650 level--- - 100

Figure 4-24. APD, 75 kHz, 3650 level- 101

Figure 4-25. APD, 200 kHz, 3650 level 102

Figure 4-26. APD, 35 kHz, 3650 level- 103

Figure 4-27. APD, 75 kHz, 3650 level 104

viii
LIST OF FIGURES (Continued)

Page

Figure 4-28. APD, 200 kHz, 3650 level 105

Figure 4-29. Summary curves, headframe, horizontal

(north-south) component 106

Figure 4-30. Summary curves, headframe, vertical component 107

Figure 4-31. Summary curves, 1450 level, vertical component 108

Figure 4-32. Summary curves, 1450 level, horizontal

(north-south) component 109

Figure 4-33. Summary curves, 3050 level, horizontal

(north-south) component 110

Figure 4-34. Summary curves, 3050 level, vertical component 111

Figure 4-35. Summary curves, 3650 level, horizontal

(north-south) component 112

Figure 4-36. Summary curves, 3650 level, vertical component 113

Figure 5-1. EM noise in mine shaft, mine not in operation, 49 kHz 116

Figure 5-2. EM noise in mine shaft, mine not in operation, 49 kHz 117

Figure 5-3. EM noise in mine shaft, mine not in operation, 35 kHz 118

Figure 5-4. EM noise in mine shaft, mine not in operation, 35 kHz 119

Figure 5-5. EM noise in mine shaft, mine in operation,

75 kHz and 100 kHz 120

Figure 5-6. EM noise in mine shaft, mine in operation,

52 kHz and 75 kHz -- 121

ix
LIST OF FIGURES (Continued)

Page

Figure 5-7. EM noise in mine shaft, mine in operation,

52 kHz and 35 kHz 122

Figure 5-8. EM noise in mine shaft, mine in operation,

100 kHz and 75 kHz 123

Figure 5-9. Received signal at cage from 35 kHz source at

headframe 124

Figure 5-10. Received signal at cage from 50 kHz source at

headframe 125

X
ELECTROMAGNETIC NOISE IN LUCKY FRIDAY MINE

Measurements of the absolute value of electromagnetic noise and attenuation along a hoist rope were

made in an operating hard-rock mine. Lucky Friday Mine,

located near Wallace, Idaho. Spectra of electromagnetic

noise generated by various pieces of equipment, spectra

of specific noise signals at various depths, and noise

and attenuation on the 4250 foot (1295 meter) hoist,

were measured. Three techniques were used to make the

measurements. First, noise was measured over the entire electromagnetic spectrum of interest for brief

time periods. Data were recorded using broadband analog

magnetic tape for later transformation to spectral plots

Second, noise amplitudes were recorded at several discrete frequencies for a sufficient amount of time to

provide data for amplitude probability distributions.

A third technique gave attenuation data through the

direct measurement of field strength at various depths.

The specific measured results are given in a number

of spectral plots, amplitude probability distribution

plots and amplitude curves as a function of depth.

Key words: Amplitude probability distribution; digital

data; electromagnetic interference; electromagnetic

noise; emergency communications; Fast Fourier Transform;

Gaussian distribution; impulsive noise; magnetic field

strength; measurement instrumentation; mine noise;

spectral density; time-dependent spectral density.

1. INTRODUCTION

This report gives data concerning electromagnetic noise

in a hard-rock mine. In this section, background information

and a brief mine description are covered. In Section 2,

measurement instrumentation is discussed. In Section 3,

spectral plots of data are presented. In Section 4, amplitude

probability distributions (APD) of magnet ic -field noise are

given. In Section 5, the results of direct measurements of

field strength are given, from which attenuation may be

computed. The last two sections (6 and 7) cover conclusions

and recommendations.
Only representative samples o£ the total data measured

are given in this report, and only a limited set of datapresentation formats have been used. If additional data, or

data presentation in other formats, are required, please

contact any of the authors. With the specific permission

of the Bureau of Mines, we will supply the additional data.

A more complete description of the measurement systems used

is given in the Robena Mine report [1] .

1.1 Background

The lack of reliable communication systems in mines is

a long-standing problem. For emergency use, when all power

in a mine is off, the residual electromagnetic noise is no

problem. However, if a communication system were designed only

for emergency use, it would have three serious drawbacks. First,

it would not be ready for immediate use in an emergency; second,

it would not be of any value during normal operations; and

third, even during emergencies, some power must usually be

present. Therefore, the Bureau of Mines decided to design a communication system that could be used for both emergency and

normal operational conditions.

Also, two-way communication to personnel in a moving

hoist is desirable for normal operating conditions, and is

necessary in emergency conditions.

During operation, the machinery used in mines creates a wide range of many types of intense electromagnetic interference (EMI). This EMI is a major limiting factor in the

design of a communication system.

The work reported here gives the results of comprehensive

measurements of this EMI in critical communication locations,

particularly along the hoist path at various depths.

2
Several EMI parameters can be measured: magnetic field

strength, H; electric field strength, E; conducted current, i;

and voltage, v, between two conductors. Two parameters were

emphasized: magnetic field strength measured with loop antennas and noise currents on the hoist cable measured with a clamp-on toroid. (Hoist cables will be referred to a 'ropes'

hereafter .

)

There are several reasons for emphasizing the measurement

of the magnetic field strength. First, at any air-earth interface, only the magnetic field is essentially undisturbed, while

the electric field is severely reduced. Second, any currents

will induce magnetic fields, and hence measurement of the

magnetic field will directly reflect currents. Third, power

line voltages are propagated as transmission line phenomena,

and are directly related to transmission line currents and the

magnetic fields induced. Thus, measuring magnetic field strength

gives a representative composite picture of noise from currents

and voltages from most sources, including arcing equipment.

Voltage from the toroid is measured to determine signal

strength, noise, and hence signal-to-noise ratios for design

information for a specific system, a two-way hoist-phone.

Although magnetic field strength measurements are

emphasized here, even this one parameter is difficult to

measure meaningfully. The IEEE definition [2] of magnetic

field strength, H (magnitude of the magnetic field vector),

is used in this report. Since there are a multitude of different sources that generate all known types of noise, the

resultant magnetic field strength noise vector is a function

of frequency, time, orientation, and location. Small variations in these parameters can cause several orders of magnitude

difference in measured field strength.

3
1 . 2 Mine Description

The results and data presented in this report are based

on measurements made on August 25, 26, and 27, 1973, and on

February 8, 1974, in the Lucky Friday Mine and other locations

near Wallace, Idaho. The mine, shown in figure 1-1, belongs

to Hecla Mining Company and produces ore containing lead,

silver, and zinc. Access is by way of a single, double-drum

hoist, using the No. 2 shaft. There are two hoists on the

No. 2 shaft. Ore is removed from the stopes via raises and

drifts and then is removed from the mine by the same hoist

personnel use. Some equipment is dc powered: the 5-ton, 90

cell, battery-powered locomotives, and the 1250 horsepower

motor used to raise the hoists. Much equipment uses ac power

at 120, 440, and 2400 volts: air-conditioners, ventilation

systems, compressors, lighting, and battery chargers. Other

equipment uses compressed air.

Shifts run to 3:00 p.m., 4:00 p.m., 11:00 p.m., 12 a.m.,

and 7:00 a.m.; blasting is scheduled at 2:20 p.m., 11:20 p.m.,

and 6:20 a.m.

The temperature and humidity are high, although not

excessive in most places.

Of particular interest in this measurement effort is how

signals and noise propagate along the shaft, with and without

hoist ropes. Power cables and compressed-air pipes, as well

as sand- transport pipes, run in this same shaft, so there is

always a composite, single conductor present to serve as one

wire of a two wire transmission line. The presence of either

hoist rope strongly affects transmission characteristics along

the shaft by providing a second wire of a two-wire transmission

1 ine

4
Figure 1-1 Isometric Projection of Lucky Friday Mine.

5
2. MEASUREMENT INSTRUMENTATION

Three measurement techniques were used. The first covers

a large portion of the spectrum as a "snapshot" at one instant

of time. In three-dimensional form, several such "snap-shots"

can show how drastically a signal varies not only with frequency but also with time. The second technique gives variations over a 20-minute time interval as a view over a narrow

frequency window. Usually, noise was measured at a set of

four different frequencies. Both techniques were used to

measure two orthogonal components of magnetic field strength

by either using two systems simultaneously or by varying the

orientation of one system. Both techniques were used in as

many different locations as possible. Whether the noise signal

tends to be Gaussian or impulsive depends on the number of

sources and the distance to each source. With the third technique, values of field strength at various levels under various

conditions were recorded. These measurements gave attenuation

values, complicated mainly by severe standing-wave patterns.

Noise levels were recorded also, but values taken this way

cannot meaningfully relate the time variations of the noise

parameter. The values given are within the bounds indicated

in the APD's.

All measured noise is reported in absolute quantities

(instead of relative) to allow others to make effective use

of the data. For the magnetic field strength measurements, the

NBS field calibration site is used with each complete measurement

system to assure correct system calibration [3]

The mine environment is generally humid, dusty, hot, and

poorly lighted. This complicated the measurement process.

Most of our portable measuring equipment was battery-operated,

dust-protected, and permissible.

6
Two types o£ noise are recorded in the spectral plots,

and hence two different magnetic field strength parameters are

required, H and H^. Results are given as the rms value of one

component of magnetic field strength, H, versus frequency for

discrete frequencies; it is given as one component of magneticfield-strength spectrum density level [2] , H^, versus frequency

for broadband noise in the spectral plots. In the amplitude

probability distributions, results are given as the rms value

of one component of magnetic field strength versus percent of

time this value is exceeded. The APD gives the distribution

of the actual instantaneous values only as far as the

measurement- system detector bandwidth will allow the detector

to follow the time variations of the actual magnetic field.

(In this context, noise envelope is sometimes used.) Thus,

the results are applicable for a communication receiver whose

bandwidth is similar to the measurement -system detector

bandwidth

.

Two measurement systems were used to make measurements

underground. One system was configured four different ways.

Five block diagrams are shown in figures 2-1 through 2-5.

For a detailed description of these systems, see previous

reports [1,4]. The systems used in Lucky Friday are the ones

used in previous mine measurement but are configured differently

in some cases.

The first system measures data for spectral plots and

is fully permissible and portable. The second system is not

permissible but is transportable; it records data for both

spectral plots and statistical presentations, e.g., amplitude

probability distributions.

7
SIGNAL MONITORS

LOUD

SPEAKER

SYSTEM

#1

LOOP

ANTENNA BROADBAND

AMPLIFIER

OSCILLOSCOPE

IMPEDANCE

TRANSFORMER

10 METERS

OF CABLE

lOO-kHz

LOW PASS

FILTER

SYSTEM

#2

SYSTEM

#3

200H^Hz CRYSTAL

OSCILLATOR

SHORT

JT

MICROPHONE

PORTABLE

TAPE RECORDER

(30 ips, record)

TRACK I (FM)

TRACK 2 (DIR)

TRACK 3 (FM)

TRACK 4 (DIRl

TRACK 5(FM)

TRACK 6 (DIR)

TRACK 7 (FM)

EDGE TRACK

(VOICE)

Figure 2-1 Block diagram of portable instrumentation, first system.

FM tracks are used to record from 100 Hz to 100 kHz;

direct tracks are used from 3 kHz to 3Z0 kHz. Systems

2 and 3 are identical to system 1. When the direct tracks

are used, the 100-kHz low pass filters are eliminated, and

the amplifier bandwidth is increased from 100 kHz to

3 00 kHz. The microphone is used for occasional vocal

comments by the operator.

8
LOOP ANTENNA,

SENSITIVE AXIS VERTICAL

SIMILAR TO 3,

BUT WITH ANTENNA

SENSITIVE AXIS

HORIZONTAL,E-W

25KHi—

Figure 2-2 Second field recording system, first configuration.

9
liJ 8

COo

ILL o

COO fO

tr CD LU Q LJ O

-J Q. <<o < UJ

CO

X

J£

lOm

CDs IT q: ll! H 1- CO UJ od

u.NXo

ro

NXoXo <Zz z

UJ 3

IO -I zz < < < OD

XZ

UJ q:

(T UJ H hCO UJ o

-IUJ

U-NX8 NXOcUJXNXX

1-C3z

LJ Qrr UJ

»-CO UJ o

_IUJ

U.NXo

CM 3o

•H

+J

03

i-> bO

•H

4-1C!Oo

CJOo

0)a

(U 4J

CD

bOQ

C P-i

)-i i-i O O O >+-( OJ +j H t)

OJ •H TJ

)-< Oo

a)

(-1 o

4J

cnI CN3

•H

10
Figure 2-4 Second field recording system, third configuration; it

recorded data for APD's on 3650 level.

11
TO RIGID LOOP ANTENNA

ON TOP OF HOIST CAGE

1

BALUN TO COLLAPSIBLE LOOP ANTENNA

ON TOP OF HOIST CAGE

FIELD STRENGTH

METER

25 kHz

OSC

TO TOROID

AROUND HOIST ROPE

BALUN

FIELD STRENGTH

METER

BROADBAND

AMPLIFIER

20 kHz

LP FILTER

ANALOG TAPE

RECORDER

CHANNEL

3

'4(DIR)

.5(DIR)

•7(FM)

Figure 2-5 Second field recording system, fourth configuration; it

was used on hoist runs up and down shaft.

12
3. SPECTRUM MEASUREMENT RESULTS

3 . 1 Introduction

In this section of the report, spectrum plots are presented and discussed. Most of these plots present magnetic

field strength to either 100 kHz or 200 kHz. The curves to

100 kHz or less have an uncertainty of ± 1 dB. The curves

to 200 kHz have an uncertainty of ± 2 dB from 3 kHz to 200 kHz.

Measurements were made at many different locations and results

can be used to characterize electromagnetic noise levels

generated by most fixed and mobile equipment used in this

mine

3 . 2 Surface Noise Measurements

3.2.1 Hoist House

The hoist house contains a 1250 hp, direct current,

double- drum hoist with dc current supplied by a motorgenerator. Figures 3-1 and 3-2 show the noise measured in

the hoist house. The antenna sensitive axis was vertical

and about two meters from the electrical cables supplying

the dc current to the hoist motor. The cables were below

the concrete floor. For figure 3-1 the hoist was lifting a

load (8.2 metric tons) of waste rock at 1300 feet/minute

(396 m/min.), and for figure 3-2 at 1700 feet/minute (518 m/min.).

This noise is one of the higher levels measured at Lucky

Friday. Figures 3-1 and 3-2 are typical of several spectra

taken in the hoist house, on Monday, August 27, 1973, a typical working day at the mine. This group of spectra (including

figures 3-1 and 3-2) differs from other spectra taken around

other machinery in that (1) noise in figure 3-2 is not dominated by powerline harmonics, (2) there are no obvious

13
commutator -produced spectral lines, which might normally be

expected to occur around dc commutated machinery, (3) the

spectral lines at 300 Hz and 925 Hz are the only lines that

appear regularly; also, they are not harmonically related,

and (4) other lines at non-harmonically related frequencies

appear irregularly. The line at 1090 Hz is typical; it appears

only in the spectrum shown in figure 3-2 and in none of the

other spectra taken in the hoist house. Note that on figure

3-1, the spectrum has a minor increase centered around 19 kHz.

Later in this report, other spectra taken elsewhere will show

a similar increase. The inference will be drawn that the

hoist house noise is propagating down the 11/2 inch (3.8 cm)

steel hoist cable (rope) to some extent.

3.2.2 Head Frame

The head frame was 75 m away and uphill 40 m from the hoist

house. The steel head frame stood about 20 meters high and

supported two large sheaves, which in turn supported wire ropes,

one each for the north and south shafts. Figures 3-3 and 3-4

show the noise measured on the surface 0.7 m from the open

north shaft, with the antenna sensitive axis horizontal EW

(pointed toward the wire rope) . These measurements were made

on August 27, 19 73, a typical working day. The minor increase

at 19 kHz seen in the hoist house does not show up here; however, it may have been masked by a sferic impulse. The same

type of noise as heard on the audio monitor in the hoist

house could also be heard at the head frame. However, at

the head frame, there was a regular periodicity to the noise

that probably can be correlated to the rotation of the main

hoist drum. Finally, figure 3-3 shows the 18.6 kHz signal from

the Navy Jim Creek transmitter, NLK Washington.

14
I

Spectra of three components of magnetic field noise at

the head frame are shown in figures 3-5, 3-6, and 3-7. The

noise levels are much lower than might be expected near operating

machinery. Either distant sferics or arcs from the hoist house

(where dc motors were operating) raise the noise levels slightly

and in unpredictable ways. This is shown in figures 3-8, 3-9,

and 3-10. The two hoist ropes leading from the hoist house

to the head- frame serve as two-wire transmission lines, but

the increase or decrease in impulsive noise does not seem to

be related to rope movement. Compare figures 3-9 and 3-8.

3.2.3 Noise Near Business District, Center of Town

Three components of surface noise were measured on the

sidewalk along a row of buildings with neon signs. This is

representative of surface noise over a mine that is under a town or city. The noise was predominantly at 60 Hz or its

odd harmonics, and was quite strong, approaching 90 dB above

a microampere per meter at 300 Hz, and 80 dB above a microampere per meter at 180 Hz. At frequencies above 2.5 kHz,

all harmonics were of nearly equal amplitude. Valleys between

the power line harmonics are about 40 dB above one yA/m up to

2.5 kHz, but are down to 10 dB above one yA/m from 5 to 10 kHz.

The vertical and horizontal (N-S) components of magnetic

field strength were both strong, while the horizontal (E-W)

component was about 20 to 30 dB lower. The component which

is strongest or weakest will be different in each location

depending principally on the directionCs) of the strongest

source (s). The magnetic field noise spectra are shown in figures

3-11, 3-12, and 3-13.

15
3 . 3 Spectra at Levels Within the Mine

3.3.1 The 1450 Level

The levels within the mine are named by the depth, and

correspond to the depth below the zero level in feet. The

zero level is 40 meters below the headframe located on the

surface. The depth in meters is obtained by multiplying the

depth in feet by 0.3048 and adding 40 meters; the 1450 level

is therefore 482 meters deep.

The 1450 level contained a 300 hp water pump. The

motor used 67 amperes at 2300 V, three phase. Figures 3-14

and 3-15 show the noise measured at this level with the pump

not operating. There is no longer any mining activity at

this level. The measurement was made on Saturday, August 25,

1973, a non-working day in the mine. The antenna was one

meter from the shaft with the sensitive axis horizontal N-S,

tangent to the opening to the shaft. Figure 3-14 shows the

same minor increase in the spectrum around 19 kHz that was

noted in the hoist house. The noise, as heard on the audio

monitor, had the characteristic sound of "grease-frying,"

but was too regular for atmospherics. The noise from the

hoist house is similar to noise at the 1450 level. With the

300 hp pump turned on, the only change was a 20 dB increase

in the 60 Hz noise.

While the teams from NBS were in the mine making noise

measurements, another team from a communications firm was

making rope transmission and impedance tests by injecting

a single frequency signal into the north rope. The signal

was coupled into the wire rope using a ferrite ring, and was

nominally at a frequency of 50 kHz. Figure 3-14 shows a cw

signal as it was received at the 1450 level. The frequency

of this signal was 44.6 kHz, but this was not one of the

16
frequencies used in their tests. The transmitter might

have been detuned at the time of our measurement, or there

may have been some other source present. For example, see

noise signals as shown in figure 3-49.

3.3.2 The 365Q Level

Noise measurements were made at a working level on

February 8, 1974. Activity was very low at the time, so

the noise levels measured may be somewhat lower than occur

normally. A spectrum of the vertical component is shown in

figure 3-16; a horizontal (N-S) component is shown in figure

3-17. Each covers time intervals during a transient of noise.

Antenna location was about two meters east of the hoist doors.

Figure 3-18 shows the spectrum of typical machine noise.

3.3.3 The 4050 Level

The 4050 level (1274 meters below the surface) was the

deepest level at which normal mining was being carried on in

August, 1973. The mine extended about a hundred meters lower

to some mine development workings. The 4050 level contained

a complex array of wires and switchboxes controlling pumps,

fans, battery chargers, lights, etc. Figure 3-19 shows a plan view of the area near the shafts

.

Figures 3-20 and 3-21 show the noise measured at location

A (shown on figure 3-19) on Saturday, August 25, 1973, a nonworking day in the mine. The antenna was 0.6 meters in front

of the open shaft door, with sensitive axis horizontal N-S.

Figure 3-20 shows the low noise level present at the 4050 level

with most of the mine shut down. Figure 3-20 also shows what

we believe is a strong test signal; the frequency was 48.6 kHz.

It is significant that this test signal (if such it is) has

penetrated the mine from the surface along metallic paths.

17
Figures 3-22 and 3-23 show the noise in the same location

with the antenna sensitive axis vertical. At that time both

the test signal and a 30 hp, 70 ampere, 440 volt water pump

below the 4050 level were off. The next figures show spectral

features that appear whenever this particular pump was operating.

Figures 3-24 and 3-25 show the noise measured in the same

location when the pump was operating. In figure 3-24 arrows

indicate three spectral features that appear whenever the

pump is operating. These features are the fundamental, second

and third harmonic of 2.86 kHz. Because of their association

with this pump, these features can be attributed to, and

called, the signature of this water pump. Other spectra, not

included in this report, occasionally show higher order harmonics. Figure 3-25 shows spectral lines (marked by arrows)

above 2050 Hz, also from this water pump, that are separated by

approximately 117.5 Hz instead of 120 Hz (the second harmonic

of 60 Hz). Possibly the 117.5 Hz lines arise from the pump

induction motor squirrel cage rotor "slipping." Induction

motor rotors increasingly "slip" (i.e., run slower than the

synchronous electrical rotation of the field) as the mechanical

load is increased. These and other spectra in this report show

harmonic structure that could probably be traced to other

rotating machinery.

With the antenna in the above position (sensitive axis

vertical, 0.6 m in front of the open south shaft door), during

lunch, the 48.6 kHz (nominally 50 kHz) signal was transmitting

into the north rope, with the north cage at the zero level

(40 m below the surface) . Measurement results at the 4050

level showed a 48.6 kHz signal strength of -12 dB relative to

1 yA/m for the south cage at the bottom of the shaft (about

50 meters below the 4050 level), 0 dB re 1 yA/m for the cage

18
at the 4050 level, -16 dB re 1 yA/m for the cage 6 meters

above the 4050 level, and -15 dB for the cage 40 meters above

the 4050 level. A possible explanation for these results is

that the cage acts as a moving transmission line termination.

When the cage is at the 4050 level, the antenna picks up the

current in the termination.

Figures 3-26 and 3-27 show the noise measured at location

B in figure 3-19. The antenna was then 10 meters away from

the north shaft with the sensitive axis vertical. A large

number of harmonically related spectral lines can be seen

from 1 kHz to 15 kHz on figure 3-26. These lines are generally

present on most spectra taken while at this level . The lines

arising from the water pump previously pointed out in figure

3-24 appear here also and are marked by arrows. The noise

at 4.2, 8.4, 11.2 and 14.2 kHz also appears on the spectra

taken with the antenna axis horizontal N-S. For the horizontal orientation, the noise is about the same at the upper

three frequencies mentioned, and is as much as 12 dB lower

at other frequencies.

Three large fans, one 20 hp, and two 40 hp, 440 volt

three phase, were turned on and spectra were taken. The

spectra are not shown, as very little difference in the magnetic noise was noted. The noise at 8.6 kHz on figure 3-26

was 6 dB higher. These fans were acoustically very noisy.

A fourth 20 hp fan remained operating at all times at a level below 4050 (possibly accounting for some of the 8.6 kHz

noise in figure 3-26).

Measurements made at 4050 with the cage ascending or

descending showed a series of weak impulses, probably

originating in the hoist house. At the 4050 level they were

not a serious problem.

19
Figures 3-28 and 3-29 were taken with two rotary battery chargers operating, 4 meters distant from antenna location B. One of the battery chargers was relatively quiet, while

the other contributed almost all the noise observed in the

two spectra. This battery charger was the noisiest piece of

equipment encountered at the 4050 level. Figure 3-29 shows

a fine structure to the noise spectrum, with lines separated

by about 2 8 Hz.

The mine used 5-ton, 90 cell, battery-operated electric

locomotives. The battery chargers mentioned above were used

for recharging these locomotive batteries. Spectra taken with

the antenna at location B while the locomotive was running

back and forth across the ore dump produced no measurable

spectral lines. An impulse was received every time the locomotive motor contactor engaged or disengaged. In an attempt

to determine the effective noise field near a cap-mounted

receiver worn by the locomotive operator, spectra were taken

with the antenna around the operator, sensitive axis vertical,

while the locomotive was operating. Figures 3-30 and 3-31

show the resultant spectra. Figure 3-30 looks like noise

received from the hoist house. Listening to the audio monitor

during this recording reveals a low frequency, low amplitude

commutator brush-noise whenever the battery was connected to

the motor and the locomotive was accelerating. Note the strength

of the 48.6 kHz test signal. Figure 3-31 shows an impulse

that has been produced by the locomotive. The impulse is as

much as 30 dB above the steady mine power-line harmonics and

is at least 50 dB above background levels between 100 Hz and

1000 Hz.

At the 4050 level, measurements were made close to the

working face area, at an area known as the "Y of 99 and 95Y."

This location was a hundred meters or so from the shaft area.

20
There was no mining activity in progress (measurements

were made on Saturday) . Figure 3-32 shows the spectrum obtained with the antenna axis horizontal, perpendicular to the

drift, and the tracks in the drift. The 4.2 and 8.4 kHz noise,

as previously seen in figure 3-26, appear clearly here also.

The spectrum taken with the antenna axis vertical showed about

6 dB less noise than figure 3-32. For the antenna axis horizontal and parallel to the tracks, the noise was below the

measurement system noise. Figure 3-33 shows the expanded

spectrum measured with the antenna axis vertical. Transients

were still in evidence at this location, possibly from the

hoist.

At this location near the face, it was clear that the

source of noise was primarily the two steel rails, and

secondarily, any other metal pipe in the drift. To demonstrate this, a measurement was taken with the antenna directly

adjacent to one of the rails. Figures 3-34 and 3-35 show

the result. Immediately apparent on figure 3-34 is the very

strong 48.6 kHz test signal inserted on the north rope at the

surface with a few watts of power.

3 . 4 Spectra Obtained from Cage Runs , Loop Antenna

3.4.1 Mine Not in Operation

To measure the fields on top of the cage as it traveled

the entire length of the shaft, a loop antenna was secured

to the top of the cage, next to the supporting hoist rope and

associated hardware. Because of the proximity of this rope,

levels of fields measured are not accurate field strength

values, but due to close coupling between antenna and hoist

rope, the values do reflect (on a relative basis) current

levels in the hoist rope.

21
On Saturday, August 25, 1973, the mine was not in operation. Figure 3-36 shows the noise measured at the zero level,

and figure 3-37 shows the noise measured at the 4050 level.

The noise levels shown are relatively low, and contain the

minor increase around 19 kHz which as previously noted, probably

comes from the hoist motor.

3.4.2 Mine in Operation

On Monday, August 27, 1973, when the mine was in full

operation, the measurement of fields on top of the cage was

repeated. Figure 3-38 shows the spectrum taken with the cage

stationary before starting down. Figure 3-39 shows the spectrum

just after starting down. Figure 3-40 shows the spectrum at

about 470 meters of depth. Figure 3-41 shows the spectrum

at about 1080 meters of depth. Immediately apparent from the

last four figures is the presence of a severe noise source

that was not present on Saturday when the mine was not operating.

This noise is from an unknown source and seemed to increase

with depth. Figure 3-41 is the last spectrum taken before

the recording equipment saturated. The signal monitors indicated the noise source was at or below the 4050 level. Laboratory replay of the analog recordings showed that this noise

has the following characteristics:

(1) The noise is made up of groups of about 4 to 8

individual impulses.

(2) The groups of impulses occur 120 times per second.

(3) The impulses within a group are not time synchronized.

(4) Alternating groups appear to have some similarity.

From the above characteristics, we speculate that this noise

source is an arc of some sort and is produced by 60 Hz single

phase, ac voltage.

22
On a second visit to this mine on February 8, 1974, this

same type of noise was received. Gains were set low enough

that saturation of the measurement system was avoided. The

spectra are similar in shape, and in the following figures,

absolute levels can be determined. This unknown source causes

noise many orders of magnitude stronger than any other source

of interference in this mine. It is not a transient, but

lasts seconds or minutes, and hence must be considered as

intermittent. Spectra are shown in figure 3-42 as recorded

from a loop antenna on top of a hoist cage . Another spectrum

of the same noise from the output of a ferrite loop around

the hoist rope into a 50-ohm load is shown in figure 3-43.

The spectral distribution varies with time as is shown by

comparing figure 3-44 with 3-42.

This source raises the noise level at least 40 to 60 dB

above background noise as shown in figure 3-45 over a wide

frequency range (50-100 kHz); figure 3-46 shows this noise

signal to be above system noise from 10 kHz to 200 kHz.

Transient events such as shown in figures 3-47, 3-48, and

3-49 are also present, but only for relatively short durations of time. Figure 3-50 shows a 20 kHz spectrum; it may

indicate a ground station at 18.6 kHz, but at the 1800 foot

level, this is doubtful.

23
O C E

o 'a -H . t-l <u -u to +J CO

to CO -H o •

. CJ O CO N

C O ^ .. ffi O iH 0^

"TJ « M », ,

0) 0) OJ c c; .H

•H -H ja

to S CO M a

o CO ^Jo

^^ ^ o

o w mam

N 0) H ffi 4J

iH 00

CO

CJ •H CO

4-1 -H

a o

•H c o u n^ a c o

CO QJ S N CO ^ o

o

iH S 4-1 P CO CO

4-1 C o

o <u x:

<U 4J

I CO

0) 3

too •H

CO 4-J •H 3

X rH

CO O

CO

0) (U >

•HU rH

•H CO

CO U

C 4-1 (U o

CO QJ

CO W

C

c

4-1 cn

CO C3^.

U CO

4J

CO3

bO3

-HIl/'aBcl a]i3i1-M3d- 1 ]Aiivi]a OP '^H 'i3A]i kiima nmm wimm-mi-mnm

m'mmnmi mm mi 'mm ii]d 3H3dWV0aDlW m Oi mim gp 'H 'Hi3N3HiS 013IJ 3li3NDVW m

24
CD

03

O

u

o

CO

— c o »o ^

in« CO

u

in

II C5<

o

K>

II if"*

II Q

cn

COo

in " .00

<M I in 03

. o

lo

c::>.

td iH

cdo

•H • O d u

o •H >-l iH 4J CO 13 K) > •H

cd 0) •H u O

C cc j:2 •H o

O o •H o *\ CO 4-i .H m 3

0) 0) a) iH ^ iH > O

U-l •H XI •H CO =3 CO 4-1 dJ OU-l bt Mi CJ

SI

S-J cc: o u §

iH o CO

4.) to U

o +J 00 •H e CO o

d cu

0) e c

o cn

to ^

t3

a

•H

4-1 0)d

60

COe

4-1o

i-4 4-1 o

(Ua.

cn

"4-1 d

CO •

to m

u •>

4-1 <U rH

cu cu

CO O CNJ

4J iH 4J P CO

»v U-l P

(U bO

CO 4-1 3

d CO <: o ^ -

CJ .

4-1 o p

CO u

CO o cu x; ^

CO 4J CO ••

CO > cr.

CM

I 0-!

CUd

bC

•H

1^4

3S10N QNV8 mm HOJ '^H IB-^A^Bci HBiBll-HBd-BHBdllVOHOlF^ 3N0

01 BAIIVIBH 8P '''h '13A31 U1SN3Q WnHiOBdS HlGNByiS-QlBlJ-OliBNOVH m

m-mwmm BiBdosio yod 'HBiBi'iyBd

BHBdWVOdOlW 3N0 Oi BAliVlBH 8P 'H 'HiONBHlS Q13U 0li3N0VW SNH

25
73 ». (U (U •H -H

CO X

C r^

CO CN

a. 3

O CO iH

'H «+j 60 piH -U C CO

(U

+-I o d

CO 3 -H 13 CO iH •> >-i <U N <U •H ffi CX

M-l ^ O

O O <U •H rH

4J iH ,Q

CU CO COO to 4-1 eg -U B N W

6

CO CNC . N

H CO

CO t~-. m

•Hc

o

•HP

3 m ,H

•H O

1^ CO

CO CL) u

3 CO

o (u e CO o

(U -U CO C CU

C/: CO 4-1

CU>

•H

4-i •H

CU a CO CO

m

I n

(U3

bC

•H

Oi 3MiV13M gP '""h '13A31 lilSN3Q Wnai03clS Hi3N3yiS-Q131J-01i3N3VI1 S

MO 'S310N3nD3HJ 3i3MSIQ HOJ 'M3i3W il3<j 3a3dWV0y01W 3N0 Oi 3MiV13a BP 'H 'Hi3N3yiS Q13I3 01i3N3VW SWH

26
OD0

U> 0

II 03

ir> to 0

u

in ^ *^

(^9

r CM

II

"'SO cfi CM .h; I ^ r- ^

CM — Q

CM I " m

CO 0

0

r^

en

CO ea

4-1 C

c nJ 0

u

cfl -a CD

cu M QJ M

•H 0) CI. CO d U) <^ >- bt Mi iH rs 0 H • Ll-I cd • 0= •HU

P4 C

4-» m A!

1-4

cfl CNC • •• N

•H

<4-l O

•H

4-1 (U

Cfl e

O

CJex

I m

(LI

bO

•H

CO

>-l QJ cfl fO

Oh 4-1 O

fo ,n

cfl o o

4-1

4-1 N CO X -HO o x:

<s- >,

cfl C

Pi OJ

(U B

4J Cfl

CO M-l

o

N

•H

>-l o

4::

CO •H O

X CO

cfl <UU

01> H •H 03M

4-1 O

OJa CO

3S10N QNva mm hoj '^Hiey^y^d ij3i3w-y3d-3y3ciwvoHoiw 3no

01 3AliV13y aP '''h '13A31 AilSN3Q Wnyi03dS HiON3yiS-Q1313-01i3N9Vl1 m

m •S310N3n03y3 3i3yOSlQ y03 'H3i3H y3d

3y3dWV0y01W 3N0 Ol 3MlV33y 8P 'H 'Hi9N3yiS Q131J 0ii3N0VN m

27
Oi ]AliV]3H aP 'Ml '13A31 UISN3Q WnHi03dS Hi0tJ3HiS-Q13lj-0li3N0V'il

HO '5310^3003^3 3i3H0SIQ H03 'H3i3W d3d

3d3di1V0y01W 3N0 Oi 3AllV13y SP 'H 'H13N3HiS 01313 0li3N0VW S'/IH

28
in

Q

•or- ir; o

LO

CNJ

C3

CD

C3>

LlJ

CDLO

C3

LO

o

O

6 - £

O

CO

OX)

tuO

-1-1 a

o 2 'o

(U ^

(-> nJ

(D

CD

+-> o

o

IT) in

00

-(-> o

O

O <u -I

+->

O (U a. c

CO

(U

so

^1 1-1

3S10NQNV9 QVOna H0J'MJ/'«3d U3i3W-H]d-3y3dliV0H0IW 3N0

Oi mrm HP '''h UISN3Q WdHlOBdS HiON3aiS-Q131J-01i"dli'JV« Sl\d

HO 'S3ION]n03Hd BIBHOSIQ BOd 'mi H3d

daBdWVOyOH'i 3N0 01 3AliV13a HP 'H 'HiONBHiS Q13ld 0li3l^3Vl1 m

29
I, CD

in

. . .(J,

•:;ao o

II

LO"

LO

C5

LO

o

U -!->

X) ^3

tti Cud

tti M

d

o

• I-l uo

cm

O

J3Uo

0)

CO

I m

0)

00

13

(U

+-» oJuo

> O

o

o

o

o

o

LT) 0

• r-l

3SI0NQNV9 QVOlig y0i'lHJi:6/-y3d y3i3N-y3d-3y3dl1VC110IH TfiO

Oi 3MiV13y 9P '^W AilSNBQ WPiHlOBdS HiOtGHiS-Ql^lj-OliJl/JVii ^jIH

MO -SBION^nDBUi 313^0810 HOj 'H3i3W H3d 3M3dWV0M01W 3N0 01 3AliV13H QP 'H 'HiDN3HiS Q1313 01i3N0VW SUM

30
^ z

>^ in

.or- ^ S

C5

CD

IOO"

Lo"

LO

CNJ

O 0)

4-> C

do Hz 0

1—

1

o

nj sD

IT) •i-i a Fr US 0 bJO

in m

nju M <

u

0) j3

• r-l o

<L> a (U

^3 X,

• o CT' +J

OJ M-i o

0 o

engt 0) o

1—

1

a

^1

+->

• o

l-l 0

+J

:adf I—

<

er

0}

(U >

.1-1 m

0)

tic ax o

agne

tive

•(-> Oj T3

ving a

•r-l M<U

-(-> 0

<H-I a

0 sen

oca

a

1—

1

do

13 u

U

+-> O

+->

4-> ^

(UOh o 0 O 1—

<

m 1—

1

00

CO

CuO

3S10^J QNV9 QVOae H0J''JiiI6/' y3d }i3i3W-H3d-3H3dWV0H0IN 110

01 BMiVlBH aP '^H UISN3Q WOHIOBdS HiON3HiS-Q13IJ-01iTiijVii Slid

HO '8310^13003^3 313^0510 d03 'y3i3W H3d 3d3dNV0y01W 3N0 Oi 3Ai.iV13H 9P 'H 'HiON3diS Q13I3 01i3N3VK SWH

31
r o o

' CM

-4- KlU>

II CJ

OD U)

o

o

in

II o

r - oj "

M

Ll U)

as o o

K)- o

o

DG= m " * ^ T3 _"o O

I

•or- "CD

':cn -ro II °

LJ °

LO

oo"

LO

C3

<C5 LO

O (U

o K

o

LT)

0)

GJO ao

u

.1-1 •—

(M X

o

o

ill 0)

CO t!

<u >

O

0) +j

00

.1-1

CJ

(U

CD

oJ

CJo

5

CO

o

o

+-> o

(t3

!d

..-I >o

H

o

a

CO

fXO

U

3SI0NQIW9 QV0H8 HOj''ilJjj/'y](J mi-y^d-BHBdWVOHOIW

mmmm bno oi mm hp 'h 'wimm (\m mum m

32
in

CD

LO

r-

CO

C3>

Llj

LO

O

o

u

o

B ^

Vl ~ m

^+-> CO

.a ^

+-> +-> O nj

-(->

•>-> o

o

13o

o

to m o

I—

I CO

0)

fH

^3DO

03

O

T)

GO

..-I >O

t;^ TO o o

^

-I ^+->

SI o ^

o ^

o :^ <^

SI O 5

vO [ij <

un

d y b

3^

Oi 3AliV13M gp '^H '13A31 UISN3Q mm2£ Hi0I^3HiS-Q13lj-3li3N0Vi1 SilH

HO •S310N3nD3y3 3i3H0SlQ y03'y3i3Wy3d

3y3dWV0a01W 3N0 Oi 3AllV13y gp 'H 'Hi3N3yiS Q13I3 01i3N3VW m

33
o

cJ

in

II

fto

u

in o II o <o

II

II uc Ll.

t- o

°«- '1,

^Sf £

c —

CM . - °C\I „

«ir- ^ o

o

'— <^ s

CZif

Ll-I

lO

f—

CD

Cxj"

LO

O

O Nl

Oj O

13

a ^ O 0 cij

j5 1—

I

^ (U >> o

o u

• r-l +J Xi

.—I fu

• r-l

-)-> O

(U <U

J—I ^

OJ

X! U

CO

O

(U S

> °

CO O

o

U

CO

4-3

O

OJ

+-> COOB . < S

" CO

u

(-> o

i-U +J in a o

I

• I-l

. CO O +j O (U

1—

I

QNV9 QvoHa HQj'^H li^A m um-EHmmm bho

Oi BAliVlBH aP '^l AilSN3Q WPiHiOadS Hi3N3HiS-Q131J-01i3H0Vi^ SliH

yo 'S310N3nD3HJ 3i3aOSlQ a03 'a3i3W aid BBBdNVOHOIW 3N0 Oi BAliVlBH HP 'H 'HMiS Q13ld 0li3N3VW SWH

34
II

o

" cv; .

II u.

r- _

"cm 2

"CD

I' S

C3

LO" LU

LO

LO

C3LO

CNJ

sx u

0 d o 0) 1—

a u

0

<*-<

MH

th

(U

fl 0

.1-1 m nj 1

obt

rth

No

tuO

f:j (D t—

u a

+-> cn

ont

SI

1—

• H

!h

i-i O

o

.H

-(->

><! oj

tJJO ve am

+->

• r-l 0

a

0)

CO

+-> o

<V a 4-)

fM

1—

1 CO

cuu

&J0

O

0)

•7-1 ^

Q)

4-> •>

J-t nj T)

0) O

o

(U

-1-1 nj •

r-H O

O

CD

„ +->

. d a ^

CO

[si vD 3

ro I—

+^ O "5

SI '5 O

H! is r£3 7i ^

o

LT) <U

0) rti CO -I ^

3SIQN QNV9 GVOHH HQj'^H ir6AH3cj y3i3N-y3d-3y3dW3ll1 3t;0 Oi 3AliV13H 9P '^H AilSNBQ WfiyiOBdS Hi3NBMiS-OBj-3li];jOVl'i '311^

ao 'S3ION3nD3yj 3i3yOSIQ yOi 'a3i3N a3d 3a3dWV0a0IW 3N0 Oi 3MiV13y QP 'H 'HiON3MS Q13I3 0li3N3VN SWB

35
C3

oo"

C5

l-O

C3

U-l

L£2

r-o"

C3lO

o a O (D

o

o

(U

fH

+-> cn

I—

(U

• Ho

.1-1 +J

<D

SH&£) 03aO

a

13

Jh -MU

(U CO

CO

o

isl U

o

<uu

+-> CO

^-1

TJ

OJ U

o

D

+-> O

o

3

ill o

<v

fM

<

B ^ o

?.

+-> +j 0) o ^

X

o

in

s

o ^

r-H -(->

on

u

• r-l

'13A31 UISN3Q WP,}li03dS Hi3H3aiS-Q131j-01i3rjVi'! Sllli

HO S3ION3n03}lJ 3i3yOSIQ HOJ 'y3i3W M3d 3y3dWV0y01W 3N0 01 3MiV13H SP 'H 'HiON3HiS Q13li 0li3N3VW m

36
BSION 0MV9 OVOHa HQj '^HISlA M3d MBiBll-MBd-lHBdWVOMOIH 3N0

01 BWiviia ap '''h mm wnaioBds HiDN3Mis-Qi3ij-oii]Novn m

HO 'S3ION3nD3ll3 3i3yOSia MOJ 'H3i3H H3d 3a3dWV0a01W 3N0 Ol 3WiV13H ap 'H 'Hi3N3MiS Q13IJ OlidNOVH SWH

37
10 o

o

II OB

o • ^ in

CO «=. in «^ O II

o

» _O

*=»(<)

<M —

CM

CM

C3 ft

•rtQO

II if CD

II (JQ

CD

CMo

o

o

CM

U3

cr->

3S10N QNV9 QVOye HOJ '^H16-^AH3d y3i3N-M3d-3y3dWV0y011'l 3N0

AilSN3a nmm Hi0N3yiS-Q1313-0113N0V'/l S'/IH

HO •S310N3n03Hj 3i3yOSlQ HOi '^31311 y3d

3y3dWV0H01W 3N0 01 3AliV13y 9P 'H 'HiON3yiS Q1313 01i3N0VN SlIH

e

O

o

o (U CM

iH

ev

cd iH

CO

• N

C O 1 X o in

<i- iH

rH

(1) iH • c CO CO

•H 4J « c c CO u •H o •H

,ri N o •H C

>-i o

42 CO O •H U •a 4=

bO •H C u CO iH

re -u

OS u 03

CO ck (1)

>-l 'O 3 > iH H •H tfl 0) U >-i •H •H 4J

M-^ N CO O

Ed c (U o <u ft

•H CO CO

4-> m

0) CO & to uu

•

(U r~- e N 4J

<4-l an iH o OSt in B 4-1

ru na ot u

4J c CO a <u 3

4-1 bO

in

I m

•H

38
o II o

-i o

in

I—

I CO

CD

+-> O

O > m CO

o

•r-l +->

a

0) +J Co

CO V

• i-i —I u

<U CD

c;) U cn O

>-A cu

o

o

3?h r-l CO ^ 00 u

a

(U m Id

c^ <n <U ^ > h

s:; o • CU LT) C

cu 5 ?.

+j O

cti >—

mwam mm m y^d y3i]w-y3dOi HMiVlBH 8P '^1 '13A31 UISN3Q mim Hi3N3HiS-Q131j-01i3tl3V,l -liH

HO 'S310r!3flD3M3 3i3M0SlQ M03 '^31311 y3d 3y3dWV0M01W 3N0 01 3AliV13a 9P 'H 'HiON3iJiS Q13I3 0li3N3VH SUM

39
(\m mm m ' 'hjqv^pj M3i]ii-!j]d-3M3diTvuajih oi 3/\iivi3y 8P '^11 '13A31 UISN3Q m)\im m\im-mi-m\im

MO 'S310N3nD3y3 3i3H0Sia MOJ 'M3i3W H3d'

3y3di'iwyoiw 3N0 Oi 3AiiV"i3y gp 'H 'wimm mi mmv,\ m

40
^5 si

a. ^

o o

a ^

^ .2

• r-l !—

I

o

o

4-> fO

CO O

5

o

o

O

+->

O

+->Hio

03

r-l <D

•1-1

B ^

—i 1—1>

> a

00

1—

I

I

0)M.1-1 h

>< H-1

0) M-l

Cifl o

^ >o

(U IT)

1=1 o

cr* ro

cu

^1 0)

u

o

o

cu

H'^HJ5^^y3d y3i3W-y3d-3H3dmoyOIW 3110

Oi 3MiV13H 9P '^1 ''13^31 UISN3Q W(lHi03dS Hi3N3MiS-Q13lJ-01i]l!'JVl'i Gliy

" ao 'S3ION3llD3a^ 3i3aOSIQ yOJ 'y3i3W M3d

3d3dWV0})0IW 3N0 Oi 3MiV13a 9P 'H 'HiDN3diS Q13IJ 0li3H3VW SWH

41
42
ro rr~> uO CO r-—

3SI0:i 0NV9 QVOHfl m '^HieiA M3d a3i3l1-a3d-3a3()WV0H01W 3H0

Oi 3MiV13H aP '^H '13A31 AilSN3Q Wnai03dS Hi9N3aiS-Q13IJ-01i3NDVW S m 'S3io:i3nD3a3 3i3aosiQ ao3 'y3i3w a3d 3a3dWVOaOIW 3N0 oi 3AliV13a 8P 'H 'Hi3N3ai8 Q13I3 0li3N3VW m

tH

1 o (U ro o o >

•H •

igure

4-1 n

a •H O CO a iH o (U in

0)c

0)

na CM <

•H •H 4-1 CO IS CO d

o +J 4-1 d •H rn d 4J o CO CO CO <: CJ X. •H (Loi

4-1 (-1 bO • C > 0

(U a) • • u iH CO N

CJ m c

1-5 in O

t3 o • • » iH C«

<u N iH

•H

<4-l cn CO u •H o O o C/1 •H o 0 d

4-1 TS IS o

QJ •H O 4-1 4-1

4-1 IW 3

CO CO tH e N ^ 4J O

CD d CD o CD o N yt iH 4-J •H e d S-( CO o O CO M C m x: i-t 4J 4J O 0) C CO o

QJ 4J 0) •H cu P- d p. X

un CO o CO

o

CM

I cn

cuu

d

bC

•H

43
II OB , a*"

O

u

ir> o O

CO o O

sin

•CsJ a wi

<M I

II

II O

(X) -DO

I o

o

o

o

ino

o

in CO

o

U-J is

Ll-J U_l

CJP

LXJ

CO

CO

ro

to

CO

3810N QNva QV0H9 Hoj '^H m/^m mm-m-mmmm m

Oi BAliVlBH aP ''^H '13A31 AilSNBQ Wnyi03dS HiGN3yiS-Q131J-01i3N9VW SNH

HO •s3iON3no3y3 3i3yosia hoj 'y3i3w m

3y3dWV0y01W 3N0 oi 3MiV'l3y 9P 'H 'Hi9N3yiS Q13I3 0li3N3VW SWH

o

o

c

o

•H

oM -H u

4-1 >^

CO ^

o

1-J

0)

CO

r-l

I ro

00

Cd CM c

C 4-1 (U CO

4-1 S

C M

CO 3

cu •H "

<4-l N

trl a ^ •H

+j CO

cuc o M 4-)

cfl

o c

4J C

o cu

cu 4J tn CO

CM

I CO

cuu

00

•H

iH CO

CO •> CO

>-i /-^ -H o cn Old ^3 !Z O

4-1 4-1

<4-l iH 3

Cd Cd iH ^ 4-1 O

C CO O (U N M

H

o

CO u

3

o cd CD X >-l 4-1 C CO cj 0) -H (U o cd c«

44
5?

a,o ^

o o

o

fi •H

CO

4-1

<+-l

bO ft,

0) •H K

^ >

O

3 O

O

N

in

CO

3

<1

CO in . CN N

CO

COO CO •H -H

O O

•H

•U rH

CUC O

W) +J

CM

I CO

3

•H

CO ,c

4-1 3

O

CDC

a)a

o

CO 3

CO CO<U

0) i-i >

•H rH

+J CO •H !-i CO 4J C CJ

(U CU CO CL

cn

COC

C . CU ro

4J

CO rH

3AliV13a 8P '''h '13A31 JlilSN3Q Nnai03dS Hi0N3HiS-ai31J-0li3N3V11 S

MO •S3ION3n03H3 3i3H0SIQ mi 'M3i3W M3d

3a3dNV0li3IW 3N0 Oi 3WiV13a 9P 'H 'HiON3MiS Q13IJ 31i3N3VW m

45
II

*:o

u CJ • •»» lO m a O 91 <

<M ^

1 o

•« «=» t— CV

II U.

a. o

ino

o

o

CVJ

Csi

ODo

foil Q

CD

•CO o

** II •nQD

•in ;f o

CP z

oj u-i

U-I

o

o

o

•H

n)

4-1 ^ IS o

J-l XI

bO -H

0)u

4J

m

CNl w •> 4J O M-l CO

14-1 3 u o 00 o a <; ^6

u . CU tfl 4-t rt lo • & (N N

.. ffi

•> iH iH iH rH

0) On > " •

O

•H

4-1 c

CO

O

o

•H

4-1

»-l >

m cfi 3

M -H iH O X O

O cfl W

01 4J >

Cfi 4-1

3 cti

4-1 C

o <u

0) 4J

CO

CM

I CO

<uu

•rl

CO

S U £ QJ (1) 4-J 03 CU 3 cn o CO

cn C

C • C (U CO

OJ 4-1 r-- O CO rH

isioN QNva mm mi '^hi^a yad HHiBw-yHd-BHBdwvoHoiw bno

mmmm m oi bmivihh ap 'h 'HiONBHis oiBid oubnovw swh

46
N

oc

)-l o 0) o o CO C/3 iH B (J u tC •H C 4J p; o c )^ Q

c u 1^ •rH o 1 > a

1 u CO ,—1 (U tH w

c c O CO •H •H > CO CD CO J4 u O

.a > rH o CO •H CO 13 4-J ^

•H •H O

bO fa C (U C > (U a

(U (U CD CO ^ rH O CO 3 O C •

T in C

o (U iH Cl

01 N c iH

•H X CO

M-l in O o o

•H c o C U <-\ T3 •H

0) •U CO c o 4-J CO u M-l ;-i ma N

ha

a. <! w 0

=) CO

CJ OJ

CO

CN

I m

dJ

Cl3

•H

fa

U

3

O

COC

OJo

I n a CO

(-1 c:c

0) CM

i-> ..

CO iH 5 ^

]S10NaNV9QVOHayCj'^Hr?i,^«]d y3i3H-H]d-]H3dWV0li0IW 3tl0 01 3MiV13y aP '13A31 AilSN3Q WnHiOldS H13N3MiS-ai3IJ-0li3N0VM SM)1 aO 'S3l3:J3n03aJ 3i3H0SIQ MOJ 'y3i3W H3d 3y3dWV0a0IM 3N0 Oi 3,MiV13a HP 'H 'HiDN3aiS Q131J 01i3N3VW SMH

47
OB

o

u

ino

o•• OD La_l in CO

in

LJ_I

cc:

U-i

U)

ODo

tn- - • o

u

rj —

cCVJ

OS

CM •

II Q

CD

"Oo•«»

I o

o

o

o

^ o

CO

CO

lO

c:3

0) • n

o CU iH o cC CO iH "4-1 O •H o Co •Hu

4J o u o

CU •H O o > 4-1 ^4

14-1 4-* CO iH

ne • rHO xi OS •H CU ?» CO <U

cd q

v-l u •H o (U IS > iH o -d" •H CO >^ 4J M

CO •H 4J u •^3 iH CO a

bO •H 0) C CU C Vj ?;

(U Ph

4) CU CO W

U iH

4J >^ m

1^ O • in c

•T3 o CU piH 4-1 a^

CU G iH

•H CO

14-1 N COVj in O o tlO CM

•H o c

4J en Td •H i-i CU 4-1 CO c o 4-J CO 3

4-1 >-l bO

CO CU N Ph <:

tc CO o

o c • 1

B §

•

cc o Pu CO C CO C 00 a CU C CU CN

CU 4-1 CU 4-J Ph c CO iH

cc o

in

I CO

CUu

d

•H

Pt4

3S10N QNva Qvona m 'w^/'UBd m3w-y3d-3y3dwvoyoiw bno

Oi HAliVlBH eP '^H '13A3"1 AilSIOQ Wn}]i03dS Hi3N3yiS-Q]313-01i3N0VW SWH

m •S3ION3n03H3 3i3yOSIQ y03 'y3i3W d3d

3y3dHV0y01W m Ol 3AliV13y aP 'H 'HiGN3diS Q1313 01i3N3VW m

48
o >

O 0) iH r-l COc

CO O C

LO cu C O 4J 0 C!

CO

01 (U » C C bp

•H -H

CO S -H M 4J ^ CO O U

x; -H a WHO

^1 ^ 4-1 O

k4

•J

CO • N

.-j •< 4-J <U N CO

fi O

COE N

CO

o

^-1

g >-> 3 CO 01

4-1 d 0)

(J 0) e

Q) 4J Ph s o

CO cd iH

CM

V43

00

•H

00 . 00

CO CD a -H

•H

4-J fiO

<U -H > 4Jd

•H O

X CO

CO QJ

0)> .H

•H CO

4-J M

•H 4J

Cfi O

C 0)

Cfi CO

aO 'S3ION3nDlJ 3i3M0Sia MOJ 'H3i3W a3d 3a3dWV0y01W 3I!0 Oi 3MiV13a 8P 'H 'Hi3N3aiS Q13IJ 0li3N3VW

SWd

49
cvi o

r>

•- <n

O

" CVJ . >^ If)

ff> >• o

I <M

CO

II

II

00

2^

CDo

o

o

o

•in

N 4-1

Ll-I

—

A,

BSior^ QNva ovona HOJ i6VH3cj H3i3ii-y3d-3y]d;ivoHoiw m

Oi 3AliV13y 9P '''h '13A31 UISN3a HiON3yiS-Q1313-01i3N3VW SWH

HO •S310N3n03y3 3i3yOSlQ y03 'y3i3W m

'm^mWk 3N0 Oi 3AliV13y aP 'H 'HOTIS Q131J 0li3N3VW m

«s iH O iH O CO QJ • tH > CO CO

OJ PI

tfl H c 0^ rH

(U iH 1-* O 4J O ino in Ft . <r CNJ (U

P) 4-1 Cm •H

cS

ne in 1—

U •H 4J bO O

,o CO •H o u

4-* (U CO ^ CO u Id o • O

bO •H

5-1 • QJ CO •

5-1 N U

iH O 5-1 iH

=) (U CO tH p-4 4J • (U CO cn

•H

IW N CO CO o •H

CJ 4-1 •H

•H 4-1 4-1 CO !-i o

(U 0) •H & to > 4J

CO e CO iH B N o •H O

!-i CO

14-1 CO <U O C 5-1 •o- cn cu

5-1 > iH

CO (U •H CO 4J 4-1 5-1 4-J 0) •H 4J o 0) B CJ

cu 4J c (U p- o cu

CO tH w CO

(N

I cn

CU54bO •H

50
3SI0NQNV8 QVOMa MOJ '^HIlZ-HBd M3ei-a]d-3H3dWVOyOIW ]N0

Oi 3MlV13y aP '^H '13A31 AilSN3Q Nnai03dS Hi3N31jiS-Q13IJ-0li3N0VM SH

HO 'S3ION3nD3a3 3i3yOSia HOJ 'M3i3W H3d 3a3dWV0a0IM 3N0 Ci 3AliV13a 8P 'H 'Hi3N3aiS Q131J 01i3N3VW SWH

51
in

" to

11 -*

ir>»2 ft " co

" CNJ . in

»r» «» O „

r - (O ^ <

-8

CD

QDo

KV

»15

o

in

1 • II

o o

O lDo

isl

oJ" Ll_l

u-i

ex:

ro

01

3S10N QNva mm m '^h leiA^Bd y3i3w-a3d-3H3dwvoyoiw hno

]AliVl]y aP '"^H '13A31 A11SN3Q Nnai03dS Hi0N3yiS-Q1313-0li3N9VW SWH

HO •S3ION3nD3a3 3i3yOSIQ m 'y3i3W y3d

3y3dWV0y01W 3N0 Ol 3AliV13H SP 'H 'Hi9N3yiS Q1313 0li3N9VW SWH

^ tsl

DC

+->

^ o .

i:2 ^

^ w o

(U r-H

^ 2

o O

°1

1^

0)

fM

;3 (Ti

a, c

m -

(U

.1-1

r-l S

52
a. (u o >

O (U

•H

4-J O

o

o

cC C O

in iH c o

O vj- QJ _^ tH

'O « -H CCS •H -H

CO S 0)

4-J >

O CC +JO

U U O M fn o

C O

•U O H-i w a O

I—I " (U 0) N >

•H ffi -H

M-l ^ S-i

CJ O

•H C 13

N

» 00

a CO •H -H

•UU C

(U o

> -Hu

m 3 •^-^

(1) 0) >-( >

•H

4-t cd

cn +j C o

(U (U

CO

t/i

c .

4-1 r~-. C ON

cfl CM

cuc o

bO 4J S NX 14-1 ^

O

4-1 CO bO3

<1

3 CO c

^ C CO

^-> C a <u a,

0) 4J o C o

CO CO rH

o

rn

I CO

(U3

•H

P4

0)Oc

CO bOC

•H

3 CJ^ CL in

CO rH

•H iH

'Hll/^y]d IJ3i3W-W<j-l]dKV

Oi ]MiV13H flP "'H '1]A31 UISN3Q Wnai03dS Hi3N3!JiS-Q131J-0li3tl3VN S

yo 'S3ioN3nD3H3 3i3aosia HOJ 'mm y3d 3H3dWV0a01W 3N0 Oi 3WiV13y 8P 'H 'HiDN3yiS 01313 0li3tJ3VW SWH

53
00

o

" CM . CB^ If)

I « • O ,1

II if ^

.o JT o m ^ o

3S10N QNVO Qvona yoj '^h le^AnBd y3i3ii-y3d-3y3dwvoyoiw 3No

Oi 3AliV13y aP '^H '13A31 U1SN3Q Wnyi33dS Hi9N3yiS-Q1313-01i3N3VN SWH

HO •S310N3n03y3 3i3yosiayo3'y3i3wy3d

3H3dWV0H01W 3N0 01 3AliV13y OP 'H 'Hi3N3yiS Q1313 01i3N3Vl1 SWH

>

•H

(u e

> o

OJ o

iH O

iH C C

o m 0) O tH

TS 'H

0) ^

C •> 13 •H (U

CC C <U 4J -H >

,JQ S -rl O U

O

4J 'O O

bO -H O

C M O

CU pt, iH,

4-1 t>^ M-l n ^ o

o

CU >

•H •> -H

•H 'O

<u 3 Coo

CO rt 6 N

o o

c/5 nJ iH

I

(Ud

•H

[14

OH

4-1 U

(U o

> -H

4J

CO 3

•H rH X O

n) cn

(U >

•H iH

4J rt •H H

W 4-» c a

(1) (U

C

0) CO

4->

u in

CO CM a

0) w

o S)

ccbO • c e

•H . »H CO d a,

in

•H iH

54
o >

O QJ

cC O

d o

o o0) 0)

CO

0^

4-1

•Uo m

N CM

•H

>-l o

CO •H

CO60

•H <|

cC ».

P! > •

(U •H CO •

4-1 N

+J CJ •H

Cfi 3 CO m

rH

•13 o

tH «v CO rH 00

(U N

•H CO ft c CO CO

p: rH •H

CJ o (U •H •H c 4-1 CO PI tJ rH >-l O

<U CO •H

Pi o O 4J bO 4-1 «\ 4-1 CO CO rH e N 0) yi o

>-l CO CO

14-1 CO rH (U o !-i rH CU O

o •H rH

CO CO nd CO d Pi U

+J a CU +J o cu V4 o

QJ 4J CO U 0) ft 0) CU ft eo c CI. C/3

CMcn

•A

3SI0NQM QVOffl DOJ 'w/^H]d l!3i]N-a3d-3a]dWV0a0IW ]N0

Oi 3AliVl]y 8P '^H '13A31 U1SN3Q WnMi03dS Hi3N3aiS-Q131J-0li3N3¥N Sl'lM HO 'S313'13n03HJ 3i3M0Sia HOJ 'H3i3W H3d 3a3dWV0d0IW 3N0 Oi 3MiV13H 9P 'H 'Hi3N3MiS Q131J 0li3N3VW SWH

55
I'.

cvi o

o

U-l CO

o

U-I is

U-l

LlJ

KV

o

<i:>

c:? >—

cr5

o

CVJ —

sin

»o QD

II OQ

o

o

o

o

Oh •> O .H CO o (U I—

ev O

• O I—

o in CO o a I—

•H On

(LJ 4J • d U CO

*rlCO fi > CO •U •H •H

CO o •5^ O

CO CO •H

4J •H > iH

(1) fa •H O

4-1 CO

4-J •H CD

CO ck SU>-i

cu rH

I—

hJ CO CO

cu !-l •H 4-1 N s O

c (U

CJ Ph •H 4-1 CO

4-1 CO c

CO o

4J rn

to CO N CU ON

J-i .H

<4-l CO o c

(U in i

o CM

CO CO C 4-1 4J

+j C! CO o OJ

(U 4-J CO a QJC

COon

I CO

(U

bO

•H

3S1QN QNVa QVQH9 HQj '^H IG'^AHBd HBlBW-HBd-BHBdWVOHOlW 3N0

01 3AliV13y aP ''^H AilSN3Q Wnyi03dS Hi0N3yiS-Q13lJ-0li3N0VW m

m '83101^3(103^3 3i3yosia yo3 'y3i3w y3d

3y3dWV0y01W 3N0 Ol 3AliV13y 9P 'H 'HOTiS Q1313 0li3N9VW SWH

56
a.o

o

o

'O

0)c

•H

4-1 O

4-1 bOC

So

CO •H

O

dJ CO

•H

4-(

^ CO u

CO c^J

o

cu

CO

(U

•H

(X4

4-1 CO3

60

3

(U u

d

CO

o •> o •

•

•\ CO

CO

0) m

!-i <r

co

0)u

CO 3 oc o

•H cn

]SiOfnf;ve ovcvia hoj '^hisiA Hid H^iBii-v.Bd-iiiwvoMoiw biio Oi 3AliVl]M ai' '^H '13A31 AilSN]0 MUm Hi3N3!iiS-013IJ-01i3N9Vli m

3H3dWVOaOIW 3N0 Oi 3M1V13M HP 'li 'Hi9N3yiS 01313 01i3N3VW SWy

57
II

00

CM

I r~ cvj

CJ

in

II

U)

00o

KV

z; o

u

CO o O

"=»i n

CJ —

CVJ CM

CM >

II Q

CDo

o

o

o

o

<r> >—

O iH O (U -H >

0)

c o

o

(UC •> •H (U

03 C

O

M -H

0)

H

•H

14-1 a

•H

4J

CUc o

bO 4-t COB N

X

«4-l 0 o

1 CO U C

o <u a c W CO

in

0)

bO

•H

CO u

O

O Oh

CO CO

O iH

4-»

C CM

(Uo u

CO

COC •

CU e C CO

CO

o

O O rH rH rH . 00

•> n

CO O-

<u 3 m

' o

CU p. o

CO e 4J w 2 p

V-i -H O

CO |x! CO

(U CO (U G G u

CO

I I I 3SioNaNvaQvoyeyoj'zHi6LAy]d ra-y3d-3y3dwvoaoiw m

Oi 3AllV13y aP ' H '13A31 AilSN3Q imiW Hi3N3yiS-Q13U-0!i3N0VN SWH

HO S3ION3nD3yj 3i3yOSia H03'y3i3W y3d m^mm 3no oi 3Aiivi3y ap 'h 'mmm qi3ij oii3Novw m

58
~ o °

doo Pi

iration. nte

nJ • N

on p- •

(U o

"Xi c d

•H

• (U •H O oc

P! on

•H

cd

not CM w

4-1 •H O •H

mine

>-< O

fi •H

4-J 4-1 bO >-> iH d

rH

(U O r-i +J O

C CO 4J >

o 0) m N

N H ri rH

iH H!

;ro o Cfl (U )-J •H 4-1 iw c a c N •H 0) O iH p. •H

4-1 O

0) 4-1 o

4-1 > • bC N •H

to X > 4-) 0) r-l si ON

iH C 0) d

o rH

M-l 0)

cn in §

O

«

04

n3

PI d 4-1 +J Pi O d cn O 0) 4J 3

(U 4J 4-1 bC

p. Pi g

d

n3

CO

ro

d

^H19I/ H3d y3i3M-a]d-3a3dWV0M0IW 3i;o '13A31 UISN3Q Wnai03dS Hi3N311iS-Q13IJ-0ll3tlDV11 Sl!ll

'S3ION3nD3H3 313aOSlQ H03 'y3i3W M3d

10 Oi 3MiV13H aP 'H 'Hi3N3aiS Q131J 0li3N0VW m

59
•"CM !^ o

"SOD o.

Oh CO O PI o c

CO

1=1 o

0)

c

o

•HU

COU

<Uo

c

•H

CO >^ 4J •P CO o ^ 13 C

O

c

•H c ^ 01 o «

cn >

N iH

OJ ^ O

•H in

M-l O O

•H «

+J o n

<U 4J O

C +J bO N CO

CO W >

"+H O 0) O iH e " o

3 CO

>-i P! p. c o

OJ 4-1

• N

(i r-f

CNJ CO •H

" o w

iH

CO 4JC

O

•H

>-l O

X.

CO •H

CJ W CO

I

X P.

CO c/:

> . •H sj- •H a^

CO iH

e!

CO m

CM

COd 4-1 P! CO

CO <:

u

Oi 3l\liV13a 9P H 'Mm mm wnyi03ds Hi3i«HiS-Qi3ii-o:::;;jy/s s

!0 'S3ION3f1D3HJ 3i3yOSIQ HOJ 'M H3d 3N0 01 3MiV13H 9P 'H 'Hi9N3HiS Q131J 01i3WI Sl\a

60
=0

o

o

•HB

cd cu

COc

4-1 c

<U C M-l ^

•S s ^ ^ ^

CO g

O 13

•H

(U ^ QJ u o

0)

""^

T3

0) ffi bC <

O

a o

•H .H

(U O K) C 4-1 bO 0)

CC N >-i e K O

cu o o ,n

oN

•H

<tCO CO

CN CO

i-H -H

4J C

U 0)

CU 4J

c/: CO

00m

I ro

CU

bO

•r(

4J

' '-H

cn

4-1 3

CO iH ^ o

cu Cfi cx cu o u

Oi BAliVlBH 9P '''h '13A31 AilSNBQ mim Hi3H3aiS-Q131J-01i3N3VW SWH

MO 'S310N3n03aJ 3i3yOSlQ a03 'M3i3M ^3(1 3H3dWV0M01W 3N0 01 3W1V13M 9P 'H 'Hi3N3aiS Q13IJ 01i3N3VW SWH

61
a O

ID 0 P-H 0

r—

1

in O

T)

(U

£3 (Ti .1-1 a

+-> u

qo

>>

+->

(J

re -1

+-> CO

SI

1—1 3 • r-l <+H o

U o r-l 1—

1

+-> (U to

So O

a

I—

1

!h

+-> U 0)

(UPh

COm

GO

o

05u

+-> o

oim

CO

O

cn

1—I oJ , >

d; O CO

i-H SI

3olOKlf/9 QVOMS HOJ '^HI8i/ H3j y3i3W-y3d-3H3dWV0H0lli 3110 Oi 3MiV13H 9P '^1 '13,\31 Ail3N3Q linai03dS Hi3W3yiS-Q131J-0ll3H0Vll S

HO 'S310N3ilD3a3 313^0510 lj03 'mi i]3d 3d3dl<V0M0!W 3N0 Oi 3AliV13« 8P 'H 'Hi3tJ3HiS Q13IJ 0li3N3VW SUH 62
QJ> & OJ •H

,

1 4.J o si

n3 r-l

rn }-l o 4-1

tfl CJ tj Ui tu QJ p! i—

1

p.

f3 nlw

•H 'ST' < 4-1 n) Pi • m

Q

M 0-. x: Q .H

4-1 r-iH •r-l 00 4_) #t pi r~

(U CM

j_i (J 0)a 4-1

1 1 o US c bO N •H 3

a) <C

•H

M-l c • o •H ^ N

CJ O e

•H rH T

•u w

O • d 4-) cc

01 rH r--

IS! 0) T3 4J cn

cn

on •H O C S-i N c

iH 0) •H o

e 4-1 U •H

0) O 4-1

!-i c e

4-1 c I-', CJ 01 c CO O

OJ 4J •H cn c <^ X <y cn 03 S-i o

I m

(U

•r-J

Oi ]MiVI3H 9P ''h '13A31 AilSN3Q Wniii03dS Hi3N3l!iS-Q1313-3li3N3VW S

MO 'S310N3(1D3MJ 3i3aOSIQ a03 'y3i3WM3d

3H3dWVOd01W 3N0 Oi 3WiV13a 8P 'H 'Hi3N3HiS Q131J 0li3OW m

63
rH 0)> > •H o 0) 4-1 o iH •H iH O

CDC

CO O 0) iH

CD CO 0 m U

O CO 4J g O

T3 0)

0) c <U cx

CJ •H 4-1 •H s d

rt CO

j-t • rCl CO m

O 13 C

•H o

x: U •H

4-1 4-1 CO

>-i OJ d) CM

>-i •u o 4J m hj d

US 'd •H bO

iH N 3

(U !^ (1) <: •H 2 c

<4-l •H o e a o ix: •H iH «\ 4-1 /~\ w

(U O •

4-1 0) CO

rH

CO N CO

4-1 CD m s rs on •H o o 0) N d

rH •p •H o

•H

CO g o 4J d 3

4-1 o H

a 0) CO CD O

cu +J o •H CD d. c iH X 0)

CO CO U

I CO

u

3

'H19I/ t]3d y]i3W-M3d-13dWV0H01W 3N0 3M1V13H 8P ""H '13A31 UISN3Q WnMi03dS Hi3N3yiS-Q13IJ-01i3N3VW SWd

I 'S3ION3nD3HJ 313^0510 UOJ '^31311 H3d

NO 01 3AliV13H 8P 'H 'HiOEHiS Q13IJ 0li3H3VW Slid

64
t9 o

a o

Ho

u

•j-> •

+-> C! CO O

(U o

O

•r-l

-12

-3 °°

^3

^^1

O (U

^ S

O cti +->

4-> O

d o

(U

O

0) ^

^, CO

4-1

CO

O

5 H

•

(J

tsl O

CO

C! O :5o

C! 0 C!3

SI 60C

2

O

5-1 4J CO CO dC

cd O B

!-i o

mh u

<D

U-(

CO •H

cu

cd o too •H

CO

^3 r—

1

>

<u o +-> CM >0 at

X) CO

f-i • 1-1

1—

1

(U > &c

03

C/J •r-J u

p 3J 'HJSl/-!J3d ffli3W-'ti]d-3y3dNV0y31W 31^0 Oi 3MiV13y 8P '^H '13A31 AilSN3a Wnai03dS Hi9N3yiS-a]3IJ 0li3IJ0V>1

HO 'S310N3nD3HJ 3i3aOSIQ HOJ 'y3i3W a3d

3ll]dWV0y3IW 3N0 Oi 3AliV13y 8P 'H 'Hi3N3diS Q13I3 mwm m

65
5 ""CM

13 •*->

00

o

CO o

a,o

+-> CO

oo

in

o :3 u

^ :3 !h CO •-2 -1 ^

OJ h CI

H

0)

o

o

„ O

CO o 2 a;

O CO >O OX)

0) !sl >O

(Ti O

o

?! O

U >

+-> U <D (U ^

O

CO

I

OJO

CO m

o

r—I >

asG

•H

c/2

s >

CO o TO lD

.5 "5 H CO> (1) u

<U <U u

;ri oJ O

:^ u "

>> i

nJ • o

•rf °^ ?

3S10N QNVG Qvoya mi ' %\A d3d noAOHOiw 3N0 01 mmbp '13A31 AilSNBQ WnOdS .13Vi10A Sl'IH

SWHO 05 SSOyOV ilOAOyOiil ],';0 01 ];\!J'/l];j a? '3DV1 -OA m

66
(U

CD CO

1 1, j r—

O OJ (t (u

asiot) Q[ Oi 3MiVl]H H 13A31 AilSfJ3Q WnHi33dS Hi3N3iiiS-Q13IJ-0ll]WVtj Sill! HO 'S310N3nD3H3 3i3H0SIQ d03 'lj3i3W Ei

m Oi 3AliV13y eP 'H 'Hi3N3HiS 01313 0li3N3Vl«i Si'id

67
CO

• r-l o

u

r*

:no o

-t-> .1-1

<L) Dh nQ 0 1-1 >H r—

1

Oj

-i-> O

CO

• (U o a H o 0) 1—

1

.a a0

o O O

in he

Ph

+->

cn 0

0 >

1—1 o

:ro CD

+-> u i-i u m

0) u ;h

0) (U

GJO -(-> nj QJ +J

I—

1

a 0 CO >

• r-l

0

(Dtm d

a

-<-) I—

1

bo 0 (Ti u >

+-> CO u

.1-4

(U a, +-> 0

CO m o

0 1—1

<J

00

o

l-< +-> nJo

o

oX

tri

CO

ao

lO

u

o

•rl

4-) cd

0)o

•H

•HS

00

00 a

O M

M d

CO

CO CO •H

<u

CI. CO a, -H d

0) > H do

• M

cuo

3SI0N QNva avoya aoj ' ssiA a3d iimm m oi 3Aiivi]a e? '13A31 AIM WnHi03dS33VilOASWa

MO 'S3l'}t;3nD3aJ 3i3dr'3IG 'dOJ SHHO OS SS0M3V ilOAOiiOii'i 3fi0 Oi 3A"V^^::1 3P '3DVl"iOA m

68
" .1-4

S O

O -" m

t3 +^

cu

to

j2

O

4-> S

CO O

' J-l o o w

.r-l .r-l

n) >

O C

>^ « ^ CO

Oj - 13

CD U

O <U

cn ^ H

4-> o

o

(U •• o ^

I

(U

•

OJo

rO

hr-i no03 o

o knoa

0

+->

tsl S

o

cd a0 o

fr fr^

0)

bJO is

^1 0)BO O •H

in

:3a"

1—

1

>

fr

1—

1

QJ o

LD

(NJ

^1> -(-» o 03M

.1-1 1-1 1—1a D

>

cn

• r-l

03 U

QNV9 QVOna mi 'HJS^ y]d M3i3W-M3d-3a3dWV0y0IW 3110

01 3MiV"13y 9P '^l 'l3^31 AilSN3Q Wnyi03dS Hi3N3aiS-QBJ-01i:iN0VH

yo 'S310N3flD3y3 3i3H0SIQ MOJ 'y3i3W M3d 3y3dWV0H0IW 3N0 01 3MlVTda 8P 'W 'HOTIS Q131J 3113N3VW SWH

69
S O

O --I

a

o

•i-i +->

.1-1

o

+-> m

CuO

PR^ 00 o

O ,^

O nj

4-> ^ O

C o

o ^

S

° O +j

O ;3

+-> t3 5 s

CO cn

a a

o o ^ m

cm

SH r-l

.r-l o CO

<u

cr' <u

o

I m

0)

GO

.1-4

03

>o

o . uT) 0)

CO

2 H

tn

•r-l .r-l ^

r—( >

03 0)--; > M ^ o3 --i

]S10N GNVa

Oi 3MiV13H gP '13A31 U1SN3Q Wnai03dS HiOfJ3yiS-Q13IJ-01i3IJ'jVW ol.J

aO 'S3ION3n03H3 3i31iOSlQ dOJ 'a3i31'l ll3d 3H3dl'JV0M0IW 3N0 01 3MiV13M BP 'H 'HlSN3diS 01313 0li3N0VN m

70
o

o

0)

CD

O

O

o

o

(U

o

u

o

-M

•r-l

1

1 o

U

0)

go o n

U 3

u

eb anS

o

-(-> 5-1 M-l

<U

.on ar

-)-> 0} o H

u o nJ

Lo- I—

00

•H

cn

•M

3SI0N 0NV8 avoye m ' ^ygj/^ y^d iioAo-i;i m oi ^Aiivi^a op

HO S^MnOHwj HJJaO^IGm

SWHO 05 SSOHOV HOAOHDIH M Oi MVTO 6? '39VilOA S^Jd

71
;2 "

o

CM

II tn

",;cr) cr o

o

U3 o

11 u

C J o

0)

o ^

CO

u

m

O ^

u

00

oo

in O

CD

CuO a

u

o <u o >o

3 =

o

^ - S

O cn

O

s

CDW) 3i o

^

a 3

o ^ >

<Uu

r-l

•H

O

00

4-1 •o

IS

• o

BSION QNV8 QV0H8 Wi ' 9Ql/ M3d ilOAOyOIW 3N0 Oi 3MiV13y BP '13A31 AilSN3(l Wnyi03dS ^lOASWy

yO •S3ION3nD3y3 3i3y031G yoj swHo OS ssoyov hoaohoiw m Oi 3Aiivi]y gp '30ViioA m

72
(35 in

; —

in

-VI

r

• -* ^ < ^ "r ^ >

CP

uri"

C3o

o

o

o

a ^

(U CO

-t-> o

0)

• r-l

o

H-1 00

U

CD

0)

0

tuO

. nj

O

% ^

5 o

o ^

H

-t-> O ti

I fO

0)

H-I O

tsl cn 5 S

° H

ISI O

in

]SICIJ QNVO QVOHa mi 'W_9^ H3d y3i3W-H3d-3H3dWV01i01W 3I'J0 Oi 3MiV13a 8P "^H '13A31 AilSN3Q Wnai03dS Hi3N3HiS-Q131j-0IJ]iim< 'jli' HO'S3IOmy3 313yOSia HOJ 'M3i3W H3d

]y3d'/jvoaoiH 3IJ0 oi 3Aiivi3H ap 'H 'HMis Q13IJ oii3NOvw swy

73
4. AMPLITUDE PROBABILITY DISTRIBUTION MEASUREMENTS

4 . 1 Introduction and Uncertainties

The amplitude probability distribution (APD) of the received noise signal magnitude is one of the most useful

statistical descriptions of the noise process for the design

and evaluation of a telecommunications system operating in a noisy environment [5,6,7].

By plotting the cumulative APD on Rayleigh graph paper,

one can show clearly the fraction of time that noise exceeds

various levels. Rayleigh graph paper is chosen with scales

so that Gaussian noise (e.g., thermal noise) plots as a straight line with slope of -1/2. Noise with rapid large

changes in amplitude (e.g., impulsive noise) then has a much steeper slope, typically -4 or -5, depending on the

receiver bandwidth.

All APD measurements are reported in absolute quantities.

The estimated limits of error for the APD noise measurements are ± 5 dB. Several sources of error that are critical

to the overall accuracy of our measurements are listed below:

1. Use of a discrete, digital level counter (le.vels are

6 dB apart) contributes ± 1-dB quantization error limit.

One-decibel step attenuators are used to achieve the

± one decibel . 2. The system, i.e., recording, data transcribing, and

data processing, has a calibration uncertainty of

± 0.5 dB [3]

.

3. The estimated uncertainty involved in using the portable and the laboratory tape recorders for record and

playback is ± 0.5 dB due to harmonic distortion, flutter,

dropout, cross-talk, gain instability, etc.

74
4. The gain instability during measurements, gain

changes between measurements and calibration, and the

non-linearity of electromagnetic interference and field

strength (EIFS) meters and mixers, all combined, contribute ± 0.5 dB uncertainty.

5. The gain instability and non-linearity of the digital

level counter, the tuned frequency converter, the amplifier, and attenuators, all combined, contribute ± 0.5 dB

uncertainty

.

6. Connector losses and BNC cable losses, particularly

at higher frequencies above 100 kHz, contribute ± 2.0 dB

uncertainty

.

4 . 2 Results

APD measurements were made on August 27, 1973, and on

February 8, 1974, during operation in the Lucky Friday Mine

located near Wallace, Idaho. Descriptions of the Lucky

Friday Mine are given in section 1.2. APD measurements were

made at four locations. The first set of APD measurements at

four frequencies was made on August 27 at the head-frame on

the surface. APD ' s are shown in figures 4-1 through 4-9 for

two antenna orientations. The second set of APD measurements

at four frequencies was made on August 27, 1973, at the 1450

foot (427 m) level. These APD's are shown in figures 4-9

through 4-16. The third set of APD measurements at three

frequencies was made on August 27, 1973, at the 3050 foot

(930 m) level. APD's are shown in figures 4-17 through 4-22.

In these sets of APD measurements, both the vertical and

horizontal components of magnetic field were measured. The

fourth set of APD measurements at three frequencies was made

on February 8, 1974, at the 3650 foot (1113 m) level, during

operation. The 3650 level was a working level with light

activity. APD's are shown in figures 4-23 through 4-28.

75
In all cases except for the 3650 working level, the

horizontal component is about 10 dB stronger than the vertical

component. This is probably because the horizontal orientation

of the antenna coupled more strongly to the nearby hoist ropes

(the apparent source of noise) than did the vertical orientation. At the working level, the strongest noise source was

not the hoist ropes but was machinery at the level. Somewhat

higher levels were also measured at the 3650 level than at

other levels. Whether the 20 minute time interval for each

recording was sufficient for statistical validity needs to be

determined from further analysis.

Also, at the 3650 level, the noise amplitude tended to

increase with increasing frequency, while at all other locations at this mine, it tended to decrease with increasing

frequency

.

4.3 RMS and Average Values

The APD's are integrated to give rms and average values

of the field strength, according to the equations

CO H = - J H dp(H) avg •' ^

>

and

H

rms

-/ dp(H)

where H represents the magnetic field strength of the noise,

and p is the probability that the measured field strength

exceeds the value H. These quantities are also dependent

upon the measurement bandwidth, the length of the data run,

and possibly other parameters. Finite series are used for

the numerical integration. The rms and average values so

76
arrived at are identified on each graph and are time averages

(23 minutes) o£ these time -dependent parameters. If the

tapes are played into ordinary rms -reading meters, the meter

readings will vary 10 to 20 dB over fractions of a second.

The rms value is directly relatable to noise power. Withi

these wide variations of field strength with time, the most

suitable presentations are statistical ones.

4 . 4 Summary Curves

Excursions of field strength between 0.001 and 99 percent,

as well as rms and average values, are shown in figures 4-29

through 4-36. The predetection bandwidth for these APD

measurements is either 1 kHz or is normalized to 1 kHz.

Figure 4-29 is a summary of the figures 4-1 through 4-4,

at the headframe, the horizontal (N-S) component. Figure 4-30

is a summary of figures 4-5 through 4-8, at the headframe,

vertical component. Figure 4-31 is a summary of figures 4-9

through 4-12, at the 1450-foot level, vertical component.

Figure 4-32 is a summary of figures 4-13 through 4-16, at the

1450-foot level, horizontal (N-S) component. Figure 4-33 is

a summary of figures 4-17 through 4-19, at the 3050-foot

level, horizontal (N-S) component. Figure 4-34 is a summary

of figures 4-20 through 4-22, at the 3050-foot level, vertical component. Figure 4-35 is a summary of figures 4-23

through 4-25, at the 3650-foot level, horizontal (N-S) component. Figure 4-36 is a summary of figures 4-26 through 4-28,

at the 3650-foot level, vertical component.

77
Linear by - y logi^C-lnp)

cr

a

i_a.E

o

o

(b>

o

<b

QD

•c

i0;c

O

.0001 .001 .01 .5 1 5 10 20 30 40 50 60 70 80 85 90 95 Percent of Time Ordinate is Exceeded

99

Figure 4-1 APD, Magnetic field strength, 3 0 kHz, Horizontal

(North-South) component, Headframe, Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 11:00 a.m.,

August 27, 1973.

78
Linear by - j log,Q(-lnp)

4Q| I I II I I Mi l I I M i l I I I I I I I I I I I I—\

1

30

.0001.001.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99 Percent of Time Ordinate is Exceeded

Figure 4-Z APD, Magnetic field strength, 70 kHz, Horizontal

(North-South) connponent, Headframe, Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 11:00 a.m.,

August 27, 1973.

79
40

30

^ 20

10

-10

-20

-30

-40

-50

t

-60

.OOOi .001 .01

Mine Generated Noise

14

RM

1

AVG

^.1

TTITT "1 System Noise

4!

4-

.5 5 10

-4

1

! ^.

Figur

20 30 40 50 60 TO 80 85 90 95 98 99 Percent of Time Ordinate is Exceeded

e 4-3 APD, Magnetic field strength, 150 kHz, Horizontal

(North-South) component, Headframe, Lucky Friday Mi

1.2 kHz predetection bandwidth. Time was 11:00 a.m

August 27, 1973.
40

Linear by - y log (-In p)

30

.0001.001.01 .1 .5 i 5 10 20 30 40 50 60 70 80 85 90 95 98 99 Percent of Time Ordinate is Exceeded

Figure 4-4 APD, Magnetic field strength, 250 kHz, Horizontal

(North-South) component, Headframe, Lucky Friday Mine,

1.2 kHz predetection bandwidth. Time was 11:00 a.m.,

August 27, 1973

81
20 30 40 50 60 TO 80 85 90 95 Percent of Time Ordinate is Exceeded

Figure 4-5 APD, Magnetic field strength, 30 kHz, Vertical component, Headframe, Lucky Friday Mine, 1 kHz predetection bandwidth. Time was 10:30 a.m., August 27, 1973

82
Lineor by - j log|Q(-lnp)

Percent of Time Ordinate is Exceeded

Figure 4-6 APD, Magnetic field strength, 70 kHz, Vertical component,

Headframe, Lucky Friday Mine, 1 kHz predetection

bandwidth. Time was 10:30 a.m., August Z7, 1973.

83
Linear by - j log|Q(-inp)

20| M M I I I iiiiiiii I I I UN '

I rn 1

.0001.001.01 .1 .5 I 5 10 M ^0 40 50 60 70 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-7 APD, Magnetic field strength, 150 kHz, Vertical component, Headframe, Lucky Friday Mine, l.Z kHz predetec-

' tion bandwidth. Time was 10:30 a.m., August 27, 1973.

84
Lineor by - j log|g(-lnp)

.0001.001.01 ,1 .5 1 5 10 20 30 40 50 60 TO 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-8 APD, Magnetic field strength, 250 kHz, Vertical component, Headfranne, Lucky Friday Mine, l.Z kHzpredetection bandwidth. Time was 10:30 a.m., August 27, 1973.

85
Percent of Time Ordinate is Exceeded

Figure 4-9 APD, Magnetic field strength, 30 kHz, Vertical component, 1450 level. Lucky Friday Mine, 1 kHz predetecti on bandwidth. Time was 1:00 p.m., August 27, 1973.

86
-80 I I I I I ll l lll I \ ±nmA I I U I M M M I I l l l lii m ill Mi ll I L_J 1

.0001.001.01 .1 ,5 1 5 10 20 30 40 50 60 TO 80 85 90 95 98 99 Percent of Time Ordinate is Exceeded

Figure 4-10 APD, Magnetic field strength, 70 kHz, Vertical component, 1450 level, Lucky Friday Mine, 1 kHz predetection bandwidth. Time was 1:00 p.m., August 27, 1973.

87
Linear by - j log (-In p)

w

+-

a>E

Q.

a

E

o

o

0)>o

a*

i_ CO

T3

C

(b

L

o%

co

.0001 .001 .01 .5 1 5 10 20 30 40 50 60 70 80 85 90 95 Percent of Time Ordinate is Exceeded

Figure 4-11 APD, Magnetic field strength, 150 kHz, Vertical component, 1450 level, Lucky Friday Mine, 1.2 kHz predetection bandwidth. Time was 1:00 p.m., August Z7, 1973.

88
Linear by - j log J-lnp)

O)

a:

%

E

V.a.

a.E

oo

01>

o

01 m

T3

c

CO

0)

0;c

D

.0001.001,01 .1 .5 5 10 20 30 40 50 60 70 80 85 90 95 Percent of Time Ordinate is Exceeded

99

Figure 4-12 APD, Magnetic field strength, 250 kHz, Vertical component, 1450 level. Lucky Friday Mine, 1.2 kHz predetection bandwidth. Time was 1:00 p.m., August 27, 1973.

89
.0001 .001 .01 Percent of Time Ordinate is Exceeded

Figure 4-13 APD, Magnetic field strength, 3 0 kHz, Horizontal

(North-South) component, 1450 level, Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 1:3 0 p.m.,

August 27, 1973.

90
Linear by -j log,Q(-lnp)

.0001.001.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99 Percent of Time Ordinate is Exceeded

Figure 4-14 APD, Magnetic field strength, 70 kHz, Horizontal

(North -South) component, 1450 level, Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 1:3 0 p.m.,

August 27, 1974.
Percent of Time Ordinate is Exceeded

Figure 4-15 APD, Magnetic field strength, 150 kHz, Horizontal

(North -South) component, 1450 level, Lucky Friday Mine,

1.2 kHz predetection bandwidth. Time was 1:30 p.m.,

August 27, 1973.

92
.0001.001.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99 Percent of Time Ordinate is Exceeded

Figure 4-16 APD, Magnetic field strength, 250 kHz, Horizontal

(North -South) component, 1450 level. Lucky Friday Mine,

1.2 kHz predetection bandwidth. Time was 1:30 p.m.,

August 27, 1973.
Linear by - y log|Q{-ln p)

.OOOi.OOI.OI I .5 I 10 20 30 40 50 60 70 80 85 90 91) 98 99 Percent of Time Ordinate is Exceeded

Figure 4-17 APD, Magnetic field strength, 30 kHz, Horizontal

(North-South) component, 3050 level. Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 3:00 p.m.,

August 27, 1973.

94
Linear by - j log|Q(-ln p)

-80 ' 'I ' I n il " I I Ill ' I ' ' ' I I I I I I 1

.0001.001.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-18 APD, Magnetic field strength, 70 kHz, Horizontal

(North-South) component, 3050 level, Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 3:00 p.m.,

August 27, 1973.

95
Lineor by -

-g log|Q(-ln p)

<\

\

-V

Mine Generated Noise

RP

AV G

<

1 11em 3i s e —

i—

r

.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99 Percent of Time Ordinate is Exceeded

ure 4-19 APD, Magnetic field strength, 150 kHz, Horizontal

(North-South) component, 3050 level. Lucky Friday Mine,

1.2 kHz predetection bandwidth. Time was 3:00 p.m.,

August 27, 1973.

96
Linear by - j log,Q{-lnp)

10

40

50

\

\\

iT

1\

1\

\ j \ -4

i

' i\/I i rl 1 fit? c rr1 \m 1 1 c f> i c C

- 1- \

.1. RMS

1

—I- 4—

!

.0001.001.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-20 APD, Magnetic field strength, 30 kHz, Vertical component, 3 050 level. Lucky Friday Mine, 1 kHz predetection bandwidth. Time was 2:30 p.m., August 27, 1973.

97
-70

-80' 'I 'I I NMI I I M l I I L_J 1

.0001.001.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-21 APD, Magnetic field strength, 70 kHz, Vertical component, 3 050 level, Lucky Friday Mine, 1 kHz predetection bandwidth. Time was 2:30 p.m., August 27, 1973.

98
Lineor by - y logiJ-lnp)

10

20

40

50

60

70

T

TTT

III 111

III m

TTT

TTT

TTT

TTT

1||. .

L TTT V>

TTT TT^

III tH^

i "I1 jiyiine Generated Noise

1 \

II —

1

j

1

1 ||.

i[- RMS

||-

fQ

||- —

r II- s 5t e 1 1 )i S(3

-

1 ll—

1

-1

1

"T —

'

-i

.0001.001.01 .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

ure 4-22 APD, Magnetic field strength, 150 kHz, Vertical component, 3050 level, Lucky Friday Mine, 1.2 kHz predetection bandwidth. Time was 2:30 p.m., August 27,

1973.

99
40

Linear by - log (-Inp)

30

.0001.001.01 .1 ,5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-23 APD, Magnetic field strength, 3 5 kHz, Horizontal

(North-South) component, 3 650 level, Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 10:00 a.m.,

February 8, 1974.

100
Lineor by --^ log^{-lnp)

DOOI.OOI.OI Percent of Time Ordinate is Exceeded

Figure 4-24 APD, Magnetic field strength, 75 kHz, Horizontal

(North-South) component, 3650 level, Lucky Friday Mine,

1 kHz predetection bandwidth. Time was 10:00 a.m. , February 8, 1974.

101
Linear by log (-In p) 40. I M l I I I I I , I

: 1,

1

20

10

-10

20

30

40

50

\ ^1i ? Sen e •0 t e d SI oise

Lf

-/ \ /(3-

System fMoise —

JOOOI.OOI.OI .1 .5 I 5 10 20 30 40 50 60 70 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-25 APD, Magnetic field strength, 200 kHz, Horizontal

(North-South) component, 3650 level, Lucky Friday Mine,

1.2 kHz predetection bandwidth. Time was 10:00 a.m.,

February 8, 1974.

102
Linear by - j logi^C-lnp)

ID

tr

E

a>Q.

a>

<uQ.

E

o

o

(U>o

a>

k. mD

C

in

a>

c

o

.01 J .5 I 5 10 20 30 40 50 60 70 85 90 95 98 Percent of Time Ordinate is Exceeded

Figure 4-26 APD, Magnetic field strength, 3 5 kHz, Vertical component, 3 650 level, Lucky Friday Mine, 1 kHz predetection

bandwidth. Time was 10:30 a. m,, February 8, 1974.

103
Linear by - j log|Q(-lnp)

(A

a:

-V- 0)E

ka>a

a

E

o

o

>

o

0)

V. CD

T3

C

CO

c

cno

.0001 .001 .01 Percent of Time Ordinate is Exceeded

Figure 4-27 APD, Magnetic field strength, 75 kHz, Vertical component, 3650 level. Lucky Friday Mine, 1 kHz predetection

bandwidth. Time was 10:30 a.m., February 8, 1974.

104
Linear by - j log|Q(-lnp)

-40 1 ! i IT IN i ll L-lLI I II I I I M 1 1 1 M M I I llml l l 1 1 M I rTT J

I I" i— .0001.001.01 .1 .5 I 6 10 20 50 40 50 60 TO 80 85 90 95 98 99

Percent of Time Ordinate is Exceeded

Figure 4-28 APD, Magnetic field strength, 200 kHz, Vertical conaponent, 3650 level. Lucky Friday Mine, 1.2 kHz predetection

bandwidth. Time was 10:30 a.m., February 8, 1974.

105
X to ijj

X • O <

U

O (U o

S ° I

+j U t—

I

tu "+^

<4H C

0)

O

St?

O O

• i-i "

^3

CIO

X u

0)

r-l

c? o o o o o

I I

I (SWa M3i3W HBd BHBdHVOyOIW I Oi 3AliV13y 9P)

H'Hi9N3aiS 01313 0li3N9VW

106
im UBIBN UBd HHBdNVOHOIN I 01 BAIiV13H 8P)

H 'HiONaUiS Q13U OliBNOYN

u

(Uu

HP ^

-i-> ro

0)o

ao

o

1—

I

a

u

CO Xi 03 >

<x) o

h-] C> o

Hi o

I

0)

•T-l

00

en

^3

107
my3i3H m 3M3dwvoyoiw i oi 3Aiivi3y m

H 'Hi9N3aiS 01313 0li3N9VW

O D

m

O

CIO

o

U <^

CO o

.1-1

-l-> u

(U >

Pi S

m O .r^ O o !-i

d

on

<^ r-i '"^ r-- d !=!

^ ID W)

CO ^ ^ <H

;3 CO

108
<l

05

"SE. *«: ^

^ ^ S z

Z C3£ ^ Z

X • O <

o

O OJ

CO m

3

°

0) o

+-> o

M CO

mi S

t-< CJ

•r-l

;3o

I

+-> uo

o

• -Iuo

o

to '73

00

CD>U

. o >^ o

CTi

\^ ^

CO

CJ d

5^

CO

I

.1-1

a;

X2

>

.—

o

LTl

ido

o

u

(SWy H3i3H M3d 3M3dHV0a0IW I Oi BAIiVlBH 8P) H *Hi9N3MiS Q13IJ OliBNSVH

109
03

>< CO S

- X O <

O

• 1-1 cn0

u

0)

• -1

-i-> CJ

(P ^

u

Hi

<D O

O

O

to

O

0) d

+^

n) O ^ m O •r' O

X) ^ Cfi >u

Hio ^

>^ o

HI w

CO

CO

I

CD

Hi

r-l

CJ

+->

Hi

Cfi Hi

Hi

CD

h:o

C3 O O

(SWy y3i]W M3d 3H3dWV0M0IW I Oi ]AliV13M 9P)

H 'HiONByiSQlBIJ OliBNOVH

110
T T

0903

S S2 => X— ^= CO I I ^

^Z ac= ^ >•

xc ^Z

X • o <

-•>

en

(SNH HBlBWUBd BHBdWVOHOIW I 01 BAIiVl]^

H'HiONBMiS ai3IJ0li3N9VW

o

CD

I OO

o

d

cr o (U

r-l fH M-i

ur of x

*r-l 4->

+-> U

C!

(Uu

-t-)

I—

111 OJ

• r-l MH s

• 1-1 o +->

• f-l +-> <u

i1 +-> m

0

so

-0

0)>

uru 1—

>> o

o

o

a

£

CD^

+-> 0)

o

Ohao

o

1—

o

• -I

+-> u

03

CO

bjo

I

• H

111
(swy H3i3w m 3y3ciwvoyoiw i oi BAiiviay 8P) H 'Hi9N3yiS Q13IJ 0li3N9VW

o^^

a; g

g o 5

X

^ ^

o

-3 ni

cn

I—

I

+-> (u

O

SI

• r-( O

X

^ o :S

°°

o ^ j3 a;

. o 1-1 h

<^ ^ '—I +-> > 0)o

a5 i o ^

LT) (U vD Q m ^ m (J

u

•r-<

112
• o

^ ^ i X CO Lij == ^Z cr: ^ ><<: =SE

X • O <

m

O

uo

X

0)

Um

-»-> qj

5 o

o o

13 O 0)

I

u

• i-i

o

s

oo

- CO U

—

1

o q; - a >

.1-1

00

0) >^ > u

<u oj

in ^

o o o CIS cr> o o <0 CSJ ^ CO

m M3i3W y3cJ 3M3dHV0H0IW I Oi 3AliV13y 9P)

H'Hi9N3MiS 01313 0li3N9VW

113
5. NOISE AND ATTENUATION MEASUREMENTS ALONG THE HOIST ROPE

5.1 Noise Measurements

Measurements were made on two different days. On one day

the mine was in operation; on the other day it was not. On

the day the mine was in operation, measurements were made

while the cage was in motion; when the mine was not in operation, measurements were made with the cage stopped at a number

of levels . The cage was shorted to water pipes , and both

"open" and "short" measurements were made. At 35 kHz, the

readings were rather erratic, indicating either substantial

variations with time, or nearby sources. The 50 kHz data

showed standing wave patterns similar to those obtained in

the attenuation measurements.

Values are in dB with respect to one microvolt across

50 ohms; the uncertainty is estimated as ± 5 dB. The aircore loop values could be calibrated in terms of microamperes

per meter, but the field strength is really controlled by the

current in the hoist rope (although coupling is not as tight

as with the ferrite core), so only voltage units will be given.

The noise data for the time when the mine was not operating are shown in figures 5-1, 5-2, 5-3, and 5-4; data taken

when the mine was in operation are shown in figures 5-5, 5-6,

5-7, and 5-8. Noise is somewhat higher during operation, but

the variations indicate the basic problem with this type of

measurement - - the cw measurement system is responding to the

time variations, but in a way that masks the statistical range

of values caused by transients and intermit tents . The APD

section gives data at some levels, but APD's were not recorded

on the hoist

.

114
5 . 2 Attenuation Measurements

Discrete -frequency signals were injected at the headframe

and signal strength measurements were made of the current at

the cage at a number of levels . The plots show standing wave

patterns. Either the short has some inductance, or the open

has some capacitance, or both, as the equal -amplitude mark is

at about 3600 feet (- 1100 meters) for 50 kHz, and if there

were no stray effects, the equal amplitude (- A/8) point

should be at about 2500 feet (750 meters).

Actual attenuation is relatively low, only a few dB over

the 4000 foot (1200 meter) length of cable. The standing

waves due to an unterminated transmission line are clearly a more serious problem. Up to 20 dB variation may be expected

from maxima to minima.

The signal-to-noise ratio looks very encouraging, unless

the intermittent noise from the strong unknown source (plus

60 dB noise) combines with a minimum in a standing wave pattern (minus 20 dB signal). Even this worst case may be handled,

but the margin is significantly reduced, especially near the

working levels when the mine is in operation and where noise

levels are highest.

115
116
pool UOS ssojov A^^ I 9Aoqv gp

117
o

pDonuoS ssojov I aAoqv gp

118
o

^ to C\J — — CVJ pDO-| uoQ ssojoy I 9Aoqv QP

119
o

o

1 I

1 1 lO

pDO-| lyog ssojov A"^ I SAoqy

120
121
122
123
pDO-| uoQ ssojov I 9Aoqv gP

124
o

poo-] lyoQ ssojov A"^! aAoqv gP

125
6. CONCLUSIONS

The electromagnetic interference in Lucky Friday Mine is

somewhat lower than many other mines, most of the time. However, there is some unknown source of noise that is present

on an intermittent basis, and during these times, the spectrum

from 10 kHz to 200 kHz is subject to levels 60 dB above

ambient from 50 to 100 kHz. This noise may last seconds or

even minutes; it is not similar in nature to noise from very

short- duration transients.

Noise near neon lights such as are common in cities cause

considerably higher power-line harmonics than occur in most

rural areas. We have now obtained absolute data on this type

of noise.

Unterminated transmission lines formed by hoist ropes

give strong standing waves.

7. RECOMMENDATIONS

Effort should be made to determine the source of the

high-level noise. On hoist phones, standing wave variations

must be taken into account in designs .

8 . ACKNOWLEDGMENTS

Those making significant contributions to this program

are as follows: laboratory development and field use of measurement equipment, Ed Neisen, Doug Schulze, and Tom Bremer;

data processing, Anne Rumfelt, Nancy Tomoeda, Frank Cowley, and

David Stearns. Those making valuable but less time-consuming

contributions are Gerry Reeve, Bob Matheson, Don Spaulding,

John Chukoski, Lorne Matheson, Dave Lewis, and Sharon Foote.

Sharon Foote and Janet Jasa typed tirelessly through

many versions. Jocelyn Spencer and Barbara Bolton provided

drafting assistance.

Finally, none of this would have been possible without

excellent cooperation from various people in the Hecla Mining

Company. For arrangements we thank Wallace Crandall, George

Wilhelm, and Art Brown; for much special assistance we thank

Don Beck

.

126
9. REFERENCES

Bensema, W.D., Kanda, M. , Adams, J.W., Electromagnetic

Noise in Robena No. 4 Coal Mine, NBS Tech. Note 654

(April 1974)

.

IEEE Dictionary of Electrical and Electronic Terms,

The Institute of Electrical and Electronic Engineers,

Inc . , Std. 100 (1972)

.

Taggart , H.E. and Workman, J.L., Calibration Principles

and Procedures for Field Strength Meters (30 Hz to 1 GHz)

,

NBS Tech. Note 370 (March 1969).

Adams, J.W., Bensema, W.D., Kanda, M. , Electromagnetic

Noise in Grace Hardrock Mine, NBS Tech. Note 657 (June

1974)

.

Crichlow, W.Q., et al . , Amplitude -Probability Distributions for Atmospheric Radio Noise, NBS Monograph 23

(1960b).

Thompsom, W.I., III, Bibliography of Ground Vehicle Communications and Control, AKWIC index. Report No. DOTTSC-UMTA-71-3 (July 1971).

Spaulding, A.D. and Disney, R.T., Man-Made Radio Noise.

Part 1: Estimates for Business, Residential, and Rural

Areas, OT Report 74-38 (June 1974).

127
10. APPENDIX

Decoding of Spectrum Captions

Spectrum captions are generally organized into the following format

First line: MP NDT NZS NDA NPO RC DF date, time, frame, serial,

where ^ MP = Two's power of length of Fourier transform, example,

2^^ where MP = 12

NDT = Detrending option, example, 0 (dc removed)

NZS = Restart spectral average after output, example, 0

(restarted)

NDA = Data segment advance increment, example, 2048

NPO = Number of spectra averaged between output calls,

example, 20

RC = Integration time in seconds per spectra, example, 0.168

DF = Resolution bandwidth, spectral estimate spacing in

hertz, example, 62.5

Date = Date of computer processing, example, 03/21/73

Time = Time of computer processing, example, 15:06:34

Frame= Frame set number, example, 10

Serial = Film frame serial number, example, 42.

Second line: DTA DA(1) DA(2) DA(3) NSA NRP NPP, where

DTA = Detrending filter parameter a, example, 0.00195

DACl) = Detrending filter average, K=l , example, 59.4

DA(2) = Detrending filter average, K=2, example, 0

DA(3) = Detrending filter average, K=3, example, 0

NSA = Number of periodograms averaged, example, 20

NRP = Number of data points processed since spectrum

initialization, example, 43008

NPP = Number of data points processed since data initialization, example, 43008.

128
Third line: RUN, SESSION, MONTH, DAY, YEAR Gain corr. , rec. = tot. constr. =, where

Run and Session = the title of the portrayed frame identifying

the digitizing session and run number,

example, 21 8 3

Month, Day, Year = date data were recorded in the mine,

example , 8 25 73

Gain corr. rec. = receiver gain correction, example, -6

tot. const. = constant gain correction of entire system,

example , 46.4

Fourth line: C = , RG = , DG = , FG = , AG = , where

C = correction curve used with data, example, 25

RG = receiver gain and accompanying correction in dB added to

the data, example, 200 (-6 dB)

DG = digitizer gain, example, 0

FG = filter gain in dB , often rounded to nearest single digit,

example , 0

AG = absolute gain correction added to data, example, 52

Fifth line: Top of Scale, Standard Error, Spectral Peak, where

Top of Scale = largest scale marking for computer drawn

graph, example, 1.000 + 004 (1.0 x 10"*)

Standard Error = standard error of curve, example, 0.3162

Spectral Peak = largest spectral peak observed, example,

4.108+003 (4.108 x 10^)

129
NB5-1 14A (REV. 7-73)

U .S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. public;ation or report no. NBSIR 74-391

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TiTLF AND SUBTITLE

Electromagnetic Noise in Lucky Friday Mine

5. Publication Date October 1974

6. Performing Organization Code

7. AUTHOR(S)

W.W. Scott, J.W. Adams, W.D. Bensema, H. Dobroski

8. Performing Organ. Report No.

9. PLRFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Prqiect/Task/Work Unit No. 2768412

11. Contract/Grant No.

12. Sponsoring Organ izatipn N^mc and Complete Address (Street, City, State, ZIP)

U.S. Bureau of Mines

Pittsburgh Mining and Safety Research Center

4800 Forbes Avenue

Pittsburgh, Pennsylvania 15213

13. Type of Report & Period Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT' (A 200-word or less (actual summary of most signidcant information. If document includes a significant

bibliography or literature survey, mention it here.) Measurements of the absolute value of electromagnetic noise and attenuation along a hoist rope were made in an operating hard-rock mine,

Lucky Friday Mine, located near Wallace, Idaho. Spectra of electromagnetic noise generated by various pieces of equipment, spectra of specific

noise signals at various depths, and noise and attenuation on the 4250

foot (1295 meter) hoist, were measured. Three techniques were used to

make the measurements. First, noise was measured over the entire electromagnetic spectrum of interest for brief time periods. Data were recorded using broadband analog magnetic tape for later transformation to

spectral plots. Second, noise amplitudes were recorded at several discrete frequencies for a sufficient amount of time to provide data for

amplitude probability distributions. A third technique gave attenuation

data through the direct measurement of field strength at various depths.

The specific measured results are given in a number of spectral

plots, amplitude probability distribution plots and amplitude curves

as a function of depth.

17. KEY WORDS (six to twelve entries, alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) Amplitude probability distribution; digital data, electromagnetic interference; electromagnetic noise; emergency communications; Fast Fourier

Transform; Gaussiam distribution; impulsive noise; magnetic field strength; measurement

instrumentation; mine noise; spectral density; time-dependent: .<^perfra1 dpn.m'

18. AX'AILABILITY rX Unlimited

[ Eor Official Distribution. Do Not Release to NTIS

[ Order I'riim Sup. of Doc, U.S. Government Printing Office Washington, D.C;. 20402, SD Cat. No. CI 3 ["2 Order E rom National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Price

USCdMM KRI. USCOMM-DC 29042-P74