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The search for intermodulation coupling in the ground Mitchell, Gerald George 1978

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The  Search  for  Coupling  Intermodulation  i n the Ground  by Gerald B.Sc,  A  of British  Columbia  SUBMITTED  IN P A R T I A L  FULFILLMENT  REQUIREMENTS MASTER  THE  FACULTY  Department  We  OF  FOR OF  THE D E G R E E  this  GRADUATE  thesis  the required  UNIVERSITY  OF  July,  Gerald  1975  OF  SCIENCE  of Geophysics  accept to  THE  Mitchell  University  THESIS THE  George  STUDIES  and Astronomy  as  conforming  standard  BRITISH  COLUMBIA  1978  George M i t c h e l l  1978  OF  In p r e s e n t i n g  this  thesis  an advanced degree at the I  Library shall  f u r t h e r agree  for  scholarly  by h i s of  this  written  make it  freely available  t h a t permission  It  is understood that  for financial  gain s h a l l  permission.  U n i v e r s i t y of B r i t i s h  T,  Columbia,  I agree  r e f e r e n c e and this  Columbia  not  copying or  for  that  study. thesis  purposes may be granted by the Head of my Department  2075 W e s b r o o k P l a c e V a n c o u v e r , Canada V6T 1W5  Date  for  the requirements  f o r e x t e n s i v e copying o f  Depa rtment The  fulfilment of  the U n i v e r s i t y of B r i t i s h  representatives. thesis  in p a r t i a l  or  publication  be allowed without my  ABSTRACT  The  assumption  electrical  network  that  i s tested with  sinusoids of current  simultaneously.  on  for  magnetic  the ground  tape.  Amplitude  intermodulation  coupling  indicate nonlinearity.  Tests  intermodulation  coupling.  massive  deposit,  sulfide  coupling.  This  test  instrument-electrode  detected  a field  are transmitted  The p o t e n t i a l  field  linear  experiment.  into  terms,  i s measured  and  test.  searched  campus d i d n o t d e t e c t  test,  at a  indicated significent  with  configuration.  and  recorded  the presence o f which  on t h e UBC  The f i r s t  Two  t h e ground  s p e c t r a a r e computed  was r e p e a t e d  i n the repeated  b e h a v e s as a  volcanogenic  intermodulation  a different  T h e r e was no c o u p l i n g  TABLE OF  CONTENTS  11  Abstract,  Table  of Contents  Table  of Figures  1  1  1  iv  Acknowledgment,  Chapter  1  Introduction  1  Chapter  2  Theory  18  A Test  for Linearity  19  Chapter  3...  Instrumentation  29  Chapter  4  Experiments  37  Tests  42  on t h e UBC Campus  Seneca  Chapter  4  Summary  Test  50  and C o n c l u s i o n s  57  Biblioigraphy.. . Appendix  61 Diagram o f the C o n t r o l  iii  Circuit...  65  Table  of  Figures  Array  for  response  of  Figure  1  Schlumberger  Figure  2  Electrical  Figure  3  D e c r e a s e i n impedance o f a s e r p e n t i n e at high charge d e n s i t y (Katsube 1973)  Figure  4  I n c r e a s e i n the d i s t o r t i o n c o e f f i c i e n t i n c r e a s i n g charge d e n s i t y f o r a galena sample (Katsube 1973)  Figure  5  Input-output  Figure  6  Two p o s s i b l e r e l a t i o n s h i p s & I(t)  Figure  7  The r e s p o n c e o f v a r i o u s s i n u s o i d a l input  networks  to  a  Figure  8  The r e s p o n s e i n p u t o f two  networks  to  an  Figure  9  Block  Figure  10  A.  of  an  point  Separate  electrical  the  array  f o r the  B.  a mineralized  of v a r i o u s sinusoids  diagram of  Electrode  resistivity  with  between  a common and  sample  with  network V(t)  instrumentation  input  ground  rocks  system  ground  output  circuits  points  Figure  11  A.  Output  signal  from  a  B.  Output  signal  from  a nonlinear  Figure  12  Amplitude of figure  Figure  13  Amplitude spectra o f the G e o p h y s i c s UBC  f o r the t e s t i n f r o n t and A s t r o n o m y B u i l d i n g  Figure  14  A diode connected nonlinearity  to  Figure  15  Amplitude connected  s p e c t r a f o r the n o n l i n e a r network to the ground ( f i g u r e 14)  Figure  16  Amplitude  spectra  Figure  17  Amplitude s p e c t r a f o r the t e s t at showing i n t e r m o d a t i o n coupling  spectra 11  linear  f o r the  the  f o r the  iv  network  linear  ground  network network  to  Seneca  induce  test Seneca  ACKNOWLEDGEMENT  I t h a n k D r . R.D. R u s s e l l  guiding  my work.  a problem  His ability  and t h e most  likely  help.  D r . R. C l o w e s l o a n e d  System  to this  field  trips  project  project.  t h e t o p i c and  t o immediately  see the heart o f  path  t o i t s s o l u t i o n was a g r e a t  the Digital  Marine Data  Recording  Mr. V. Ronka a s s i s t e d on one o f t h e  and c o n t r i b u t e d  was f u n d e d  f o r proposing  many u s e f u l  by t h e N a t i o n a l  #A720.  v  suggestions.  Research  Council  The  grant  CHAPTER  1  INTRODUCTION  Many p h y s i c a l  ferred  from  characteristics  a knowledge o f t h e E a r t h ' s  Measurement o f both  natural  provide  information  on t h e l a r g e  Earth's  crust  meters.  Studies  involve  function  at  structure  to depths  at depths  of the e l e c t r i c a l  of frequency  and e l e c t r o d e  i n some d e t a i l  within  kilo-  and  meters.  of the subsurface  o f t h e ground  configuration.  i n most  a few h u n d r e d  1  of the  t o a few hundred  as a  These  applied  t e x t b o o k s . Measurements o f t h e r e s i s t i v i t y  shallow depths,  signals  o f tens of  properties  be i n -  properties,  the structure  measurements o f t h e r e s i s t i v i t y  methods a r e d i s c u s s e d  sics  electrical  scale  t o determine  o f the rocks  may  a n d man-made e l e c t r i c a l  and u p p e r m a n t l e ,  It is possible  composition  o f the Earth  geophy-  o f the ground  meters o f surface,  have  applications  i n ground  water  investigations  and  mining  explorat ion.  D.C.  since  resistivity  t h e 1920s  surveys.  i n ground  in figure  electrodes  1^ and  I^-  between e l e c t r o d e s  resistivity  =  a  A  The  resistivity  extensively  exploration  t o the ground  I i s transmitted  resultant  potential  i s measured  determined  2  and  from  the  the  as  between  difference  apparent  relationship  1  2  11  the  apparent  of a hypothetical  produce  mining  current  P'  used  TTML -! ) v  is called  resistivity  of  1.  and  2  a  and  are connected  of the ground  (O  would  water  Four e l e c t r o d e s  illustrated  yO  methods have been  the observed  values  resistivity  because  homogeneous h a l f  results.  is unlikely  2  The  t o be  actual  space  i t i s the  which  distribution  homogeneous.  F i g u r e 1.  Schlumberger A r r a y f o r R e s i s t i v i t y  3  Soundings  From a k n o w l e d g e o f  tivity  tion  as a f u n c t i o n  of the  a probable  entire  of  the  This  face geophysics  behavior  of  the apparent  e l e c t r o d e geometry  and  of  i s the  the  actual  problem  techniques.  to  resistivity  the  posi-  determine  values  common t o a l l t y p e s  I t i s known a s  resis-  the  electrode array i t i s possible  distribution  the g r o u n d .  the  of  of  sur-  inversion  problem.  Advances  field  equipment  resistivity  and  procedures  method.  method have been  permitted  i n i n s t r u m e n t a t i o n have  The  in interpretation.  and  two  dimensional  Curve matching  generated  layered  between  catalogues of  the  4  of  use  in  the  of  computers  techniques  of  the  have  one  inversion.  field  resistivity  models c o n s t i t u t e d  i n the  Digital  of powerful  changes  inception  g r e a t e s t advances  the development  dimensional  s i n c e the  brought  first  data  and  curves  computer  calculated  of these  from  interpretation  techniques.  (Zohdy 1965,  O r e l l a n a and  Mooney 1966).  f o l l o w e d by the development o f a u t o m a t i c techniques.  curve  d a t a t o p r o b a b l e models.  a p p l i e s the l i n e a r i z e d  for direct  Oldenberg  i n v e r s e t h e o r y of Backus and  (1968) t o i n v e r t r e s i s t i v i t y  data.  The data i s i n v e r t e d  without  the n e c e s s i t y o f p r i o r  T h i s t e c h n i q u e produces  assumptions  i n v e r s i o n of induced p o l a r i z a t i o n  until and  the c l o s e s t  a satisfactory  of  resistivity  a t e c h n i q u e f o r the and  resistivity  data to  T h i s method compares the f i e l d  l a r g e l i b r a r y of forward problem the model g i v i n g  solutions.  f i t t o the f i e l d  two  data to a  The parameters d a t a are  f i t between i t s forward problem  the d a t a i s a c h i e v e d .  with  resistivity.  (1976) has d e v e l o p e d  d i m e n s i o n a l models.  a  a u t o m a t i c a l l y t o a p r o b a b l e model  v a l u e s or l a y e r s of homogeneous  Pelton  (1978)  Gilbert  one d i m e n s i o n a l model o f the v a r i a t i o n o f r e s i s t i v i t y depth.  was  matching  R e c e n t l y methods have been developed  i n v e r s i o n of f i e l d  This  of  varied  solution  The  observed  i n a tank  particles  N.J.,  induced  Seigal  at the Radio  a potential  and o t h e r s  disseminated  United  history  The  field  Pelton  Cole  and  After  phenomena  mineral  i n 1949.  I . P . phenomena  was o b s e r v e d  knowledge  i n the tank.  deposits i n the  southwestern  d i s c u s s i o n of the e a r l y  i n Overvoltage  Wait  Research  has been  (1972, 1978) h a s d e m o n s t r a t e d  (1941) t o p r e d i c t  i t sfrequency  s t u d i e d both i n  Recently  t h a t t h e I . P . phenomena  model p r o p o s e d  complex d i e l e c t i v e  and t i m e  and  1959.  i n rocks  by a r e l a x a t i o n  H.O.  t o the search f o r  and i n t h e l a b o r a t o r y s i n c e t h e 1 9 5 0 s .  be m o d e l l e d  metal  L a b o r a t o r i e s o f Boonton,  A complete  Applications,  and  was  t h e c e s s a t i o n o f an a p p l i e d  applied this  o f I.P. i s a v a i l a b l e  Geophysical  may  Frequency  discharge  metallic  States  or overvoltage  c o n t a i n i n g an a q u e o u s s o l u t i o n  U.S.A., i n 1946.  current,  the  polarization  domain r e s p o n s e  by C o l e and  behavior.  a r e shown  The model  in figure  Figure 2  (a)  A small s e c t i o n o f a m i n e r a l i z e d rock which b o t h b l o c k e d and u n b l o c k e d p o r e p a s s a g e s .  (b)  An e q u i v a l e n t c i r c u i t  (c)  Typical lent  (d)  f o r the mineralized  has  rock.  f r e q u e n c y domain r e s p o n s e f o r t h e e q u i v a -  circuit.  Time domain r e s p o n s e c o r r e s p o n d i n g t o t h e f r e q u e n c y domain r e s p o n s e p l o t t e d i n ( c ) .  From P e l t o n  1978  7  The  impedance o f  Z(w)  = Rod  this  - m(l  circuit  -  1 1  m  =  Pelton  indicate  =  0  (1977) has  between  values  and  of mineral  distinguish  type.  a  As  Pelton  some t y p e s  indicate  i t may  graphite  and  be  a wide r a n g e  each  deposit.  of  m  of  and  and  t may  be  deposits.  f u n c t i o n of  mineral  argues  of  field  results  useful  He  mineral  in  dis-  concludes  the  texture  texture... i s i n p a r t  i t should  deposits  from  be  which  rather  a function -  possible  others.  His  to  results  p o s s i b l e t o d i s t i n g u i s h between d e p o s i t s  massive  over  laboratory  types  t are  type,  (iwt)  X(R /m)l/c  criminating  than m i n e r a l  +  Ri/Rq  +  determinations  of m  )) c  1 1  t  is  of  sulphides  by  frequencies  measuring  and  8  complex  determining  m  of  impedance  and  t for  Recently  developed  techniques determine  a wide r a n g e  at several  interpreted  with  modulation coupling  ground.  This  electrical  the assumption  that  at the small  linearity  laboratory  experiments.  the laboratory  densities  This  experiment,  the assumption  in  involved,  o f the experiments  thesis  situations  was u n d e r t a k e n  that  densities  inter-  o f the  a l l work  the assumption  The a p p l i c a t i o n  uncertain.  network, a t c u r r e n t  t h e r e i s no  dealing  being  the ground i s  dealing  o f r o c k s and m i n e r a l s h a v e  to field  over  The r e s u l t s  nonlinearity  i n the ground,  Most  electrical  in  that  i s made i n v i r t u a l l y  current  linear.  o f the ground  frequencies.  due t o e l e c t r i c a l  signals  interpretation  The m e a s u r e m e n t s a r e made  harmonic  assumption  with  electrically  the frequency response  of frequencies.  simultaneously  are  i n s t r u m e n t a t i o n and  with the  been  of results obtained  i s always  to test,  the ground  somewhat  with a  field  behaves as a l i n e a r  o f t h e same o r d e r a s t h o s e  IP s u r v e y s . 9  used  Should  tures  some m i n e r a l s ,  conduct e l e c t r i c i t y  rock  types,  i n a nonlinear  or geologic  manner  i t i s conceiv-  able  t h a t an a c c u r a t e  lead  t o a method o f r e m o t e d e t e c t i o n o f t h e e l e m e n t  the  nonlinearity.  least  struc-  d e s c r i p t i o n o f the n o n l i n e a r i t y might  This p o s s i b i l i t y  s i n c e 1950, when  causing  has been r e c o g n i z e d a t  i t was t h e o b j e c t  of a United  States C  patent  a p p l i c a t i o n by O s c a r W e i s s and L u c i e n  Russian  studies  Geophysicists  of e l e c t r i c a l  published  nonlinearities  the  e a r l y 1970s.  Ryss  the  "Polarization  Curve Contact  is  made w i t h  transmitted  The  is  a massive  between  potential  drop  i n rocks  1973) d e s c r i b e s  Method".  sulphide  body  across  the massive  varying  across  10  a method  Electrical  called  contact  and l a r g e c u r r e n t s a r e  i n the host  DC c u r r e n t  the i n t e r f a c e .  of several  and m i n e r a l s i n  sulphide-host  t h e o r e body and t h e c u r r e n t  potential  the r e s u l t s  i t and an e l e c t r o d e  monitored. A slowly  through  (1971,  Masse.  rock  rocks.  interface  i s transmitted  i s p l o t t e d against the  Different  metallic  minerals  a t t h e i n t e r f a c e may  At  changes from  the i n t e r f a c e  reaction  taking  place  there.  reactions  chalcopyrite, galena  graphite,  and  laboratory.  T h e y suggest  One  current  minerals  electrodes  that  i n the wall  this  method  of a - d r i l l  of  They c o n c l u d e  that  i n the presence of  could  hole,  of applying  i n the  be u s e d  to  b u t do n o t  t h e method  to  bodies.  o f the l i m i t i n g  density  reactions  (1976) have  i n the presence o f p y r i t e ,  t h e m s e l v e s on t h e s u b j e c t  entire ore  electrochemical  using  and g r a p h i t e .  sulphide  chalcopyrite  identify minerals  commit  i n the l a b o r a t o r y  to detect  curve.  The p o t e n t i a l d r o p  K l e i n and S h u e y  pyrite,  this  i n t e r f a c e the conduction  i s the p o t e n t i a l o f the  these  is possible  from  e l e c t r o n i c to i o n i c .  studied  it  identified  the orebody/host-rock  mechanism  across  be  required  observed  factors of this  to drive  by K l e i n  the  and S h u e y .  11  method  i s the  electrochemical  Their  experiments  large  required  tests  current  R y s s used  In  re ported  a 30kW, 250A  and g a l e n a .  different  "describing  high  function  analysis  For  sinusoidal  e x p e r i m e n t s on t h e  asbestos,  their  analysis  method  character  by  were t h e  f o rnon-linear  specimens",  Lissajous  pyrite,  on t h e  nonlinear  T h e m e t h o d s he u s e d  and low i m p e d a n c e  frequency  Survey o f Canada  he c o n c e n t r a t e d  analysing  methods.  f o rnonlinear  current,  Of t h e s e  and g a l e n a ,  In h i s f i e l d  transmitter.  nonlinearity of serpentine,  serpentine  method  2  t h e r e s u l t s o f some l a b o r a t o r y  cubanite  for  up t o 5mA/cm .  1973 K a t s u b e o f t h e G e o l o g i c a l  electrical  three  densities  the "ellipse  systems  analysis  f i g u r e s " , and t h e " d o u b l e  method".  the describing  function  waveform o f v o l t a g e ,  i n the case o f galena,  12  analysis, a  nondistorted  i n the case o f serpentine,  was a p p l i e d  and  t o t h e sample and  the r e s u l t i n g  an  applied  expressed  c u r r e n t or v o l t a g e monitored  sinusoidal  v o l t a g e the  =  I  y  Q  (I  n=l  I^  series.  w  iBn  between  the  density  i s d e f i n e d by  a  r  e  Sin  (nwt)  + I  B  n  and  and  n  resultant  recorded.  c u r r e n t may  For  be  as  I(t)  a Fourier  and  angular  frequency  to g i v e at l e a s t  e x p r e s s i o n and  (nwt))  n  t are  determined  Cos  the  Katsube  signal.  The  and  time  and  squares f i t  total  charge  as  w q = 1 A  where A  C ) o  Hz  the  between  t o 103  Sin  (wt)  Hz.  area of  the  Serpentine  .3 and  The  30  Cos  D  (wt))  dt  coulombs/cm  2  normalized  to  i n the  sample,  sample  volts  the  over  applied  voltage  a frequency  range  was  of  10  V l2 A  variation  I  impedence  Z =  was  +  1  i s the  For  varied  (I,  + 1  i2 B  i t s value  normalized  1 at  .3 v o l t s  at each  impedence. .as t h e 13  frequency.  applied  A  voltage  - 1  increased  was  taken  as  illustrates  Katsube's  analysis of  the  density,  Q  c r  *  evidence  results for  serpentine  of  10~8  coulombs/cra  J  c  r  the  is  and  in  the  distortion  cr  10~4  the  two  =  There  function  is a critical  above which  nonlinear.  The  charge  the  critical  sample  the  current  c o e f f i c e n t of  the  resultant voltage,  the  critical  charge  charge  density,  sample.  density  Figure  4.  d e n s i t i e s , 10~6  coulombs/cm2 a s s o c i a t e d  galena  describing  3  current  Q cr TTf  galena  plotted against  identifies  2  Figure  is  J  For  nonlinearty.  the  sample.  s a m p l e becomes e l e c t r i c a l l y  density,  of  with  nonlinear  is varied  E,  Katsube  coulombs/cm  phenomena  and  125  Figure  3.  Decrease at  io  7  .  i n impedance  high charge  id  density.  id  6  of  a  s e r p e n t i n e sample  (Katsube  id ,  5  4  1973)  io  3  TOTAL CHARGE DENSITY (COULOMBS/cm )  Figure  4.  Increase  i n the  increasing (Katsube  distortion  charge  197 3)  15  density  coefficient f o r a galena  with sample.  The " e l l i p s e  figures"  analyze  and t h e " d o u b l e  the specimens  describing  consists  of  less  function  than  1 Hz.  observed  signal  a t .3 v o l t s  charge  the f i e l d .  in  I.P. S u r v e y s .  densities  observed  used  f r e q u e n c y method  modulating  a  carrier  i s varied  signal  f o r the onset of  amperes  2  was  nonlin-  achieved  a r e commonly  For the case o f s e r p e n t i n e ,  o f 10~? c o u l o m b s / c m ,  a current  with a  of 1  range  t o a depth  o f 70  W h i t e made some l a b o r a t o r y  16  used  critical  ampere  a f r e q u e n c y o f .1 Hz w o u l d p r o v i d e a c h a r g e d e n s i t y  nonlinear  from  region.  i n the l a b , are e a s i l y  Currents of several  to  o b t a i n e d by t h e  o f the c a r r i e r  and n o n l i n e a r  lissajous  method"  The w a v e f o r m o f t h e m o d u l a t i o n  in  and  The d o u b l e  Katsube  density  frequency a n a l y s i s  The v o l t a g e  The c r i t i c a l  charge  for nonlinear  corroborated the r e s u l t s  i n the l i n e a r  which  method  method.  o f a 10^ Hz  .3 t o 30 v o l t s .  earity,  analysis  i n the  meters.  measurements o f  electrical  nonlinearities  Australia,  respects  will  discussed  Geophysics  of  development  modulation  and  of  the  Astronomy  the  of  initial  a system  required  for  MacQuarie  used  by  White  described  University,  is  i n some  in this  thesis.  It  later.  coupling  i s hoped  point  method  at  one  of  ground  and  the  first  made a t  the  first  studies  the  UBC  i n the  of  the  Department  field  of  nonlinearities .  One  obtained  method  the  properties  electrical  It  Thesis  thesis represents  electrical  effort  The  s i m i l a r to  be  M.Sc.  i n 1974.  This  of  i n an  that  i n the  future  this  the  objectives  capable  i n the  of  the  ground.  In  quickly  became  experience  course  of  of  this  investigations  17  the  gained  work may  in this  this  t h e s i s was  detection  terms of  of  the  the  inter-  time  and  principal objective.  and  the  form  area.  results  the  starting  CHAPTER  2  THEORY  A linear  which  of  the p r i n c i p l e  superposition  Consider  F(  X ] L  )  F(x ) 2  If  ie.  the  system o r network  F (  X  F(  X l  )  function  therefore  of superposition  may  be d e f i n e d  a function  be  defined  applies.  The  i n the f o l l o w i n g  F(x) such  as one  in  principle  way.  that  = A  = B  + x ^) = A  l  may  + B  + F ( x ) = F(x 2  F(x) obeys  a linear  1  +  x ) 2  the p r i n c i p l e  function  of  18  x.  of superposition  and i s  A Test  For  An  nonlinear  Linearity  electrical  by  an  superposition  input  of  is  an  input  of  the  experiment  that  is violated.  One  a sinusoid  current  network.  relationships  for a linear  by  NL.  nonlinear  for  the  network  network.  the  The  = a I(t) 1  determined  shows w h e t h e r  such  i s the  and  slope  the  linear  involves  resultant  output  two  possible  The  curve  may  take  i s the  only  any  the  5.  I(t)  voltage  indicated  network  or  p r i n c i p l e of  figure  a nonlinear  NL  be  Consider  I(t).  curve  to  experiment  illustrates  and  is  form  by  L  indicated  for  a  a r b i t r a r y parameter  L.  represent  a power s e r i e s o f  V(t)  6  be  network.  V(t)  Figure  shape o f  may  the  and  straight line  We  by  to  between V ( t )  is  The  n e t w o r k may  the  the  +  r e l a t i o n s h i p between  I ( t ) and  V(t)  form  a I (t) 2  2  19  +  a I (t) 3  3  +  3  Electrical  Lit)  Figure  5.  Network  The  input  and  output  20  V(t)  o f an e l e c t r i c a l  network  For  the case  series  not  except  a ^ a r e 0.  network  a l l the c o e f f i c i e n t s  F o r the n o n l i n e a r network  of the  this is  the case.  Let  to  of the l i n e a r  the input,  I ( t ) , be a s i n u s o i d  o f amplitude  1 and a f r e q u e n c y o f  This  I(t)  =  V(t)  = a-jcosfwt) + a c o s  may  cos(wt)  be t r a n s f o r m e d  trigonometric  V(t)  2  2  into  (wt) + a ^ o s  the f o l l o w i n g  2  + 3a /8  + cos(wt)  +  4  {a  + 3a /4  1  + 3a /4  3  4  + cos(2wt)  ( a / 2 + 3a /8  + cos(3wt)  (a /4 +  )  + cos(4wt)  (a /9 +  )  2  4  3  4  +  21  +  (wt) +  form  identities  = a /2  3  +  through  equal  output  If the input t o a network i s a s i n u s o i d o f c u r r e n t  the  v o l t a g e can be d e s c r i b e d by e q u a t i o n  the  shape o f the output  t o +00  i n t e g r a l from -oo equation  waveform, i f i t has  4 w i l l a l l be  0 = a /2 2  The  being  no net  Whatever DC  term, i t s  z e r o , the even c o e f f i c i e n t s  zero, or  of  alternatively  + 3a /8 + 4  r e l a t i o n s h i p s between the  f o u r networks are l i n e a r provided  10.  illustrated  i n p u t s and  in f i g u r e  7.  t h a t the c u r r e n t amplitude  the o u t p u t s  Network 1 i s does not become so  g r e a t t h a t i t causes h e a t i n g problems i n the r e s i s t o r . o t h e r t h r e e networks are n o n l i n e a r .  Of the  networks, network 2, the s i n g l e d i o d e produces an output  with  t h a t t h i s network w i l l fundamental frequency  a net DC have both  odd  i n i t s output.  22  three  and  Equation  The  nonlinear  i s the o n l y one  term.  of  which  10 i n d i c a t e s  even harmonic's of  the  F i g u r e 7.  The response of v a r i o u s networks to a s i n u s o i d a l i n p u t .  The  presence  of  components  of  networks  2,  3 and  spectra  input  of  amplitude  4 which  figure  An  sinusoid.  input  To  transfer  the  problem  i s the  looking  of  function of  This  which  network  account  nonlinearity  sum  of  and  are  of  harmonic  they  that  problem  difficulty  If there  to the  output.  experimental  7 i s the  are  network  the  Let  (ignoring  exist  in  proof  t h a t the  principle  these  networks  are  the  test  illustrated  perfect  components p r e s e n t  going  their  t o be  present  in their  in  in  the  amplitudes  r e q u i r e s a knowledge of  the  due  to  the  network.  may  be  two  s i n u s o i d s of  power s e r i e s  I(t) = cos(wit)  phase  not  amplitude  transmitting a  avoided  by  equation  using  an  different  for intermodulation coupling  Consider  output  with  for a variation  the  do  constitute  superposition i s violated  nonlinear.  in  spectrams,  i n the  terms  input  signal  frequencies  i n the  output.  3.  + cos(w2t)  relations)  24  5  and  Substituting  equation  5 into  equation  3 and s i m p l i f y i n g  gives  6 V(t)  = a  2  + 9a /4  +  4  + cos(w t)  (a  + cos(w t)  (  1  2  1  + 9a /4  +  )  + 9a /4  +  )  3  a ; L  3  ( a _ / 2 + 2a  + cos(2w.t)  +  )  1 2 4 + cos(2w t) (a /2 + 2a +  )  A  2  2  + c o s ( (w_^  + cos((w  +  w  ^  )  t  4  )  - w )t)  2  1  +  +  (a  2  + 3a  + cos(3w t)  (a /4 +  )  + cos(3w t)  (a /4 +  .)  1  2  3  3  4  )  +  )  + cos((2  W l  + w )t)  (3a /4  +  )  + cos((2  W l  - w )t)  ( 3 a /4  +  )  2  2  3  + cos((2w  2  + w )t)  (3a /4  +  .)  + cos((2w  2  - w )t)  (3a /4  +  )  1  1  3  3  +  25  Output  Network  Input versus Output  2  8.  The response of v a r i o u s networks to the input of two s i n u s o i d s .  simultaneous  Amplitude Spectra  6 which  The  terms  (w^  + v ^ ) ) , are  called  intermodulation  The  presence  any  these  which  is  in equation  has  of  two  sinusoids  as  terms  both  coupling  i n the  i t s input  frequencies  terms.  output  proves  (i.e.  that  of  a  the  network  network  nonlinear.  8  Figure  spectra  the  of  include  f o r the  method  response  that  of  the  illustrates  four  the  networks  i s used  ground  obeys  that  is  detectable,  method  i f the  would  nonlinearity  ground  the  the  of  provide  using  spectrum  a better  than would  the  whether  the  and  amplitude  previously.  principle  is electrically  amplitude  output,  considered  to determine  A p o t e n t i a l advantage  is  input,  of  the  This  electrical  superposition.  two-frequency  nonlinear,  and  of  method  i f this  the  two  frequency  d e s c r i p t i o n of  the  nature  single  27  frequency  is  method.  of  There  the  are p a i r s  the  o f peaks  two-frequency  e t c . ) which  results  i n some l i n e a r i t y  University  t h e (w^ + w^)  degree  ly  method  of e l e c t r i c a l  he o n l y  observed  to that  i n an a t t e m p t  nonlinearity  8, o r i f a DC o f f s e t  dependent  method,  in this  applied  3 of figure  unless  there  work was u s e d  monitored  t o determine the  coupling  were p r e s e n t .  o f the input  8, w o u l d  was a DC o f f s e t  term  Consequent-  when t h e n o n -  was  White's  network,  network  no i n t e r m o d u l a t i o n c o u p l i n g  i n the input  28  diode  He d i s c o v e r e d i n  signal.  nonlinear  detect  by  the amplitude  as i n t h e c a s e o f t h e s i n g l e  to the obviously  number  of the  w i t h r o c k samples a t  t h e a m p l i t u d e o f t h e (w^ + w^)  on t h e DC o f f s e t  w^)  o f h i s samples.  intermodulation  of  that  used  White  was a s y m e t r i c a l ,  fact  and (w^ -  on t h e v a l i d i t y  experiments  linearity  figure  amplitudes i n  o f the system.  i n 1974.  term  identical  ( ( w ^ + w^)  s e r v e as a check  and t h e r e s o l u t i o n  Macquarie  of  s h o u l d have  spectrum  could  A similar  White  which  signal.  CHAPTER  3  INSTRUMENTATION  The  lation  instrumentation  coupling  transmission  potential  of  this  o f two  field  sinusoids  produced  diagram  spectra  This  to detect  requires  of current,  by t h e c u r r e n t ,  the simultaneous  the d e t e c t i o n  and t h e  of the p o t e n t i a l  of the i n s t r u m e n t a t i o n  intermodu-  of the  determination  field.  Figure  developed  9 is  to perform  experiment.  Current  500 power  current  supplies  was  T h e s e were  output  was  supplied  which  transducers.  supplies  power  designed  i n the ground.  the amplitude  a block  was  supplied  connected  went d i r e c t l y  supply  two power  was  from  c a n be c o n n e c t e d  The  input  signal  as  to the input  t o t h e two  o f a summing  t o one o f t h e p o w e r  were  29  in series  BOP  power  generators.  amplifier  supplies.  by t h e same s i g n a l  connected  two K e p c o  voltage-to-  by two W a v e t e c f u n c t i o n  driven  supplies  t o t h e ground  The  i n antiphase.  with  whose  other  The  t h e common  E V to C  V Io C  INPUT  A LP  AMP  AMP  PS  AMP  PS  E  LP  OUTPUT  T A P E  TO  NULLED OUTPUT  _ J  (~)  Sine wave generator  fl]  Invertor Summing  DA  V to C Voltage to Current  amplifier  Differential  Figure 9.  Amplifier  PS  Phase S h i f t e r  L P  Low Pass F i l t e r  A to D  Analogue to D i g i t a l  Transducer  Convertor  Block diagram o f the i n s t r u m e n t a t i o n system. 30  connection  currents  small  also connected  were b a l a n c e d  current  ground  current  so that  this  and was o r i g i n a l l y  f o r t h e whole  separated  t o an e l e c t r o d e  system.  due t o p r o b l e m s  in this  ground  ground  intended  wire  very  t o be t h e common  related to  although  The  carried a  The p o t e n t i a l c i r c u i t  apparently  wire,  i n the ground.  this  was  later  non-negligable  current  was n o t  detected.  The  potential  with  potential field  electrodes  an i n p u t  potential  volts.  This  tape.  I t was a l s o  from  each  connected  impedance  electrodes  was m o n i t o r e d  was a m p l i f i e d  s i g n a l was d i g i t i z e d  and a v a r i a b l e g a i n  summing  amplifier.  sinusoids  on m a g n e t i c  amplifier.  and a m p l i t u d e  individually 31  The o u t p u t  was p u t t h r o u g h  a m p l i f i e r and i n p u t  The phase  were a d j u s t e d  The s i g n a l f r o m t h e  and r e c o r d e d  generators  shifter  amplifier  t o b e t w e e n +_ 2 a n d + 8  t o a summing  o f the f u n c t i o n  a pair of  to a d i f f e r e n t i a l  o f 100 megohms.  input  with  to this  o f each  t o produce  a phase  same  of the  a minimum  signal  only  at the output  nulls  produced  are  o f t h e summing  the fundamental  i n the ground  unaffected.  amplified  recorded  frequencies.  from  t o between + 2 v o l t s  tape.  The n u l l i n g  a t t h e low f r e q u e n c i e s  summing  a m p l i f i e r was m o n i t o r e d  so t h a t  sinusoids  cent  could  the phases  be a d j u s t e d  o f t h e two p r i m a r y  signal amplified  procedure  took  Results  electrical  the  i f they  digitized,  The o u t p u t  were  and  very  from the  two-channel  chart  and a m p l i t u d e s  o f each o f t h e  t o a minimum.  At l e a s t  another  97 p e r  25 t i m e s .  This  nulling  30 m i n u t e s p e r t e s t .  of laboratory  Survey  terms  a m p l i f i e r was  adjustments  on a B r u s h  s t u d i e s of the nonlinear  properties of galena  Geological  affects,  used.  coupling  s i g n a l s were n u l l e d o u t and t h e  remaining  about  t h e summing  operation  harmonics  and + 8 v o l t s ,  tedious  recorded  Any  This  and any i n t e r m o d u l a t i o n  The o u t p u t  on m a g n e t i c  amplifier.  and s e r p e n t i n e ,  o f Canada,  are present,  i n d i c a t e that  increase  32  by K a t s u b e o f  nonlinear  i n amplitude  with  decreasing  perform  this  on  frequency.  the  i t was  magnetic  signals  tests  tape.  recorded.  The  the  The  determined  500  power  milli-Amps  the  decided  In o r d e r  signals  using a Fast Fourier  the  periods of lowest  UBC  IBM  the  recorded  .065  Hz  370/168  and  was  to  to  r e c o r d them  spectra  of  the  Transform  of  the  frequency  selected  amplitude  had  t o be  to  selected  as  the  be  0.02  i n 20 m i n u t e s p r o v i d i n g  was  do  computer.  resolution lowest  frequency  resolution.  second  i t was  frequencies.  t o a c h i e v e good  24 p e r i o d s c o u l d be  required  low  reason  T h i s p e r m i t t e d the amplitude  a l g o r i t h m on  several  this  to d i g i t i z e  calculated  In o r d e r spectra  at very  necessary  t o be  computer  For  Hz.  the  frequency  of  sinusoid.  current amplitudes  used  to a degree  equipment  supplies  (160  mA  by  the  i n the  available.  have a maximum o u t p u t  peak-to-peak).  33  The  experiment  c u r r e n t of  were  The  BOP  80  current levels  were s e t  at  120 mA  order  peak-to-peak  to achieve  commonly  placed  to stay  current  occurring  well  this  limit.  d e n s i t i e s o f t h e same o r d e r  i n IP s u r v e y s  8 meters apart  within  the current  i n the f i e l d  tests.  In  as  electrodes  This  those  were  provides  a  -2 current  midway  density  between the c u r r e n t  The  shown  of approximately  electrode  and  the ground  The c u r r e n t  used  were p o r o u s p o t s ,  filled  s o l u t i o n o f CuSO^ and w a t e r , w i t h  suspended  i n the s o l u t i o n t o p r o v i d e  system.  of  erroneous  for  causing  the f i n a l  The  Configuration  t e s t s are  were b r a s s  The p o t e n t i a l  saturated  electronic  point  i n the f i e l d  electrodes  i n t o the ground.  electrode  at a  electrodes.  configuration  i n f i g u r e 10.  w h i c h were hammered  20 nA cm  rods  electrodes.  with  a  a copper rod  the connection  A o f f i g u r e 9 was  r e s u l t s and c o n f i g u r a t i o n B was  to the  suspected  adopted  tests.  tape  recording  and d i g i t i z i n g  34  system  was  t h e UBC  35  Department  Recording  of Geophysics  System.  convertor,  digital  tape  Three  a buffer  recorder.  t o be  eight  formatter  This  r e a d by  o f an  system  t h e UBC  Marine  and  channel analogue  a Kennedy n i n e  produces  IBM  S e i s m i c Data  370/168 c o m p u t i n g  the a m p l i f i e d  electrodes  and  the a m p l i f i e d  The  two  of  output  signal  these signals  filters  t o remove a l l s i g n a l s  Nyquist  frequency of  the  from  from  The  the  digitizer.  36  to the  potential  through  with frequencies  are  system.  input  the n u l l i n g  were p a s s e d  to  track  t a p e s which  c h a n n e l s o f d a t a were r e c o r d e d .  power s u p p l i e s ,  latter  Astronomy  It consists  digital  formatted  and  above  circuit.  low  the  pass  CHAPTER  3  EXPERIMENTS  Field  first  The  was  t h e lawn  second  sulphide  e x p e r i m e n t s were  site  in front  was  deposit  near  Harrison  the  system  tested  i s shown  works o f l i n e a r  and  lightbulbs  and  their  The  resistors.  f o r the  i n the  were u s e d  anticipated  Figure  transmitting  and  The  the Geophysics B u i l d i n g  Lake  B.C..  The  at  deposit  field  experiments  laboratory.  the  UBC.  is  A block  equipment  diagram  i n the previous chapter, f i g u r e  resistors,  first  sites.  deposit.  In p r e p a r a t i o n  carefully  a t two  i n a p i t at a v o l c a n o g e n i c massive  known as t h e S e n e c a  was  of  conducted  tests  11.  resistors  to test  and  d i o d e s , and  the system.  r e s p o n s e s a r e shown  N o n l i n e a r components  circuits  37  networks  in figures  of  Net-  resistors  These  w e r e made w i t h a n e t w o r k  receiving  8.  7 and  linear  i n the  were d e t e c t e d  of  by  the  8.  (  V  w 2  )  loC  V  to C  ^>  IOO  n  6  v  0  6  2  1  V to C V Io C  IKQ  100 Kfi  0  6  Figure  A. B.  A A A  A A A  A A A  11  Output  s i g n a l from a l i n e a r  Output  signal  network.  from a n o n l i n e a r  38  network.  presence of  the  linear  intermodulation  network.  constructed  Many o f  their  diagnosis  Due  causing  the  could  response  than  coupling  terms.  with  be  was  to  the  be  in results  Even  input, output  of  coupling  placed  was  coupling of i t s  i n t e r m i t t e n t , making  i n t e r m i t t e n t problem  i n the  in results  which  after  an  a  contained  fair  coupling  electrode  more  indicated a  linear  intermodulation  degree of  that  confidence  spent  turned  on  out  field  in  the  results  most p r o b a b l y  to  array.  determined  i s shown i n f i g u r e  and  instrumentation,  which  e s t a b l i s h e d much t i m e was  Experimentally  of r e s i s t o r s  from  error a circuit  intermodulation  possibility  intermodulation  due  output  difficult.  intermodulation  circuitry  no  and  i n the  n o n l i n e a r p r o b l e m s were  to the  confidence  terms  A f t e r much t r i a l  which produced  own.  coupling  n u l l e d output  39  amplitude  12.  are  spectra for  Amplitude  displayed  network  spectra of  for  the  the  e  (fl  -H  Input  •H  e  UL  i  0.05  1  r~  0.1  FREQUENCY  (HZ)  0.15  1  0.2  Output  i  0.05  i  0.1  FREQUENCY  Nulled  (HZ)  1  0.2  Output  0.D5  0.1  FREQUENCY  Figure  1  0.15  12.  Amplitude Spectra o f f i g u r e 11.  40  1  (HZ)  0.15  f o r the l i n e a r  1  0 2  network  network.  The  attenuated  nulled  and  the  output  rest  the o u t p u t .  The  Hz,  a digital  required  test.  both  dB  The  output  passed  per  very  low  above  the  low  1.22  and  pass  a corner  low  pass  filter  and  the e f f e c t s  Hz.  and  A  fundamental  spectrum  filters  .02  relative  Hz  and  15 m i n u t e s  output  signal  for  each  were  an  attenuation of  frequency of  .2  Hz.  was  digitizing  2.44  Hz,  wave a t  system  were n o t  spectra.  41  giving  .02  under  Hz  a  was  The  to  .065  with  square  of a l i a s i n g  at l e a s t  the n u l l e d  frequencies  amplified  f r e q u e n c i e s used,  frequency o f the d i g i t i z e r  frequency of  the  record of  signal  through  decade  of  has  20  sampling  Nyquist  input to  the  these c o n d i t i o n s  observed  i n the  amplitude  Tests  on  t h e UBC  Two  the  experiments  were c o n d u c t e d  Geophysics B u i l d i n g  configuration  of  Campus  this  test  transmitted  sum  each  o f two  illustrated  a r e shown  sinusoids  was  density  In the  the  i n f i g u r e 13.  current  o f 64  always  mA  at the p o i n t  Each  o f 128  i n f r o n t of  an  electrode  used.  The  power  supply  mA.  pk-pk. S i n c e  i n opposite  lawn  first,  i n f i g u r e 10 was  a peak-to-peak  electrode  current  a t UBC.  on  This  results  was  the c u r r e n t  polarity  the  from  the peak  midway ...between them was  approxi-  2 mately  125  nA  p e r cm  .  Two  p e a k - p e a k , were m o n i t o r e d resistivity  was  encountered  Most o f t h i s  potential  across  o f the ground,  Some t r o u b l e w i t h  was  sinusoids,  from  ground  circuitry  and  the  by  .92  volts  the p o t e n t i a l e l e c t r o d e s . equation  loops  when t h e e l e c t r o d e  eliminated  each  array  changes  system  42  in  1 i s 550  ^M.  the.instrumentation  was  first  i n design  ground  The  points.  of  connected.  the  After  CD  Cu E Input  20 -J •f-\  e  D.O  '  r  0-05  0.1  FREOUENCT  0.15  0.2  (HZ)  46 -J  Output o-23_|  >  0.0  0.05  ~~i—  0.1  FREQUENCY  0.15  (HZ)  ~1  0.2  CO -p  1  20"  -H  Nulled  Output  •rH E  icH  u  -r"  0.0  0.05  FREQUENCY  Figure  13.  1—  0.1  0.15  (HZ)  Amplitude Spectra f o r the test the G e o p h y s i c s b u i l d i n g , UBC.  43  0.2  i n front of  considerable  electrode  with  testing  array  amplitudes  potential  about  than  some v e r y  0.5  mV  T h e s e and  stimulus  The  Geophysics  involved  below  mV  i n the  the  similar  of  the  the  at  experiment  B u i l d i n g was  connecting  the  the  signals  at  the  result  n u l l e d output  the  of  level  in figure  proposed  a nonlinear  44  by  16  a signal  Mr.  element  figure  level  e l e c t r o d e s , and  of  the  in front  of  of  are  instrumenta-  represent  more s e n s i t i v e  conducted  of  intermodulation  potential  f o r f u r t h e r work w i t h  second  t o be  represent  detection  peaks  that  in  ground.  peaks  at  established  peak-to-peak  These peaks  peak-to-peak  t o be  1.0  considered  small  was  d e t e c t i o n system  spectrum  frequencies.  considered  tion.  coupling  amplitude  contains  coupling  than  e l e c t r o d e s were  The  confidence  potential  greater  intermodulation  13  and  enough  no  more  equipment.  the  V a i n o Ronka.  This  to the  as  ground  a  F i g u r e 14.  A d i o d e c o n n e c t e d t o the ground induce n o n l i n e a r i t y .  45  to  test  t o see  electrode  i f the  s y s t e m s were c a p a b l e  configuration  network are  illustrated  was  a diode  connected  ted  by  one  coupling  The  trodes,  conditions,  electrodes,  was  the  from  the  1.9  across  ground  the  electrodes,  line  by  the n o n l i n e a r  The  n o n l i n e a r element  two  electrodes, separa-  V,  by  intermodulation  was  the  in series  estimate,  based  was  with  on  .7  the  is  of  elec-  homogeneous  have  been  potential  reverse biased.  (conducting)  V.  diode  The  was  m e a s u r e m e n t s on  same l o c a t i o n ,  46  would  across the  biased  exceed  line  Assuming  diode  potential  forward  not  t o the  1 metre.  when t h e d i o d e  i t would  i n the  parallel  across  same as t h e  contacts  A reasonable  14.  of  introduced s i g n i f i c a n t  connected  When t h e d i o d e  potential  in figure  the p o t e n t i a l  approximately  position  The  output.  diode  offset  the  t o the ground  metre. T h i s  i n the  and  of d e t e c t i n g i t .  1000  the  resistance  of  not  measured.  other  sets of  Input  n  —,  1  ,  0.15  0.2  0.05  0.1  i  r  0.D5  0.1  0.15  FREQUENCY  (HZ)  Output  0.0  FREQUENCY  ~1 0.2  (HZ)  46H  Nulled  Output  o > •H  e  2 3-1  u  T  0.0  0.05  15.  Amplitude connected  AA. .  0 15  0.1  FREQUENCY  Figure  4-  Spectra f o r the nonlinear to t h e ground ( f i g u r e ] _ 4 ) 47  0.2  (HZ)  network  Disregarding  the  current  current  i n the diode,  i n the diode  transmitting  meter  by  potential  with  waveform  potential  output  current  mA  of  square  t o ground  circuit,  15  the  i s not  the  the presence  This  back-to-back  on  the  60  mV  f=0  of  Two  adjacent  the  in figure  term  other  the diode  same e x p e r i m e n t  diodes  but  data  the  current electrodes  corners of  would  a  1  other  produce  two  a  corners.  7.  drifting  i n the  the  spectrum  the  terms  of  integral  i n the  zero  i n the  the  nulled  of  of  the  spectrum,  i n t e r m o d u l a t i o n c o u p l i n g terms,  of  by  a homogeneous  550 ~H-M,  across  caused  approximation,  mA.  a measure o f  The  potential  surface of  c u r r e n t s and  i n the diode.  and  1.2  c u r r e n t on  a resistivity  of  i n the  a first  be  is illustrated  figure  harmonics  as  would  difference  Due  by  1.2  1 meter  half-space  The  the d e c r e a s e  are  the  caused  network.  was  was  48  performed  lost  due  with  a network  t o a tape  of  recorder  problem.  The  problem  equipment  had  been  to  the  test.  repeat  was  not  recognized  dismantled.  49  T h e r e was  until after  not  the  sufficient  time  Seneca  Test The  electrode  volcanogenic  massive  Vancouver.  pit.  In  10%  Highly  the  was  vicinity  from  the  Massive  zone  The  of  the  caused  rocks  electrode  and  the  are  array  stringers.  quartz,  electrode  is interpreted  have  of  seafloor  overlying  deposits  in Japan.  the  relative  they  metallic minerals  vent.  Seneca  p o s i t i o n s of  were  i n the  the  test  50  at  in  the  rocks  The  r e s t of  was  contain  the  clay  p i t , 15  set  been p a r t  i n the  of  the  in this  a  east  exposed  s e r e c i t e and  array  to  Seneca,  kilometers  for m e t a l l i f e r o u s hydrothermal  deposition  S e n e c a as  100  s p h a l e r i t e i s exposed  deposit  The  i n a p i t at  deposit  secondary  i n which  submarine vent  up  altered volcanic  i s predominantly  minerals.  set  sulphide  pyrite in disseminations  rock  at  array  meters  up.  of  a  solutions,  which  vent  and  on  i s s i m i l a r to  the  Kuruko  electrodes  UBC  were t h e  ( f i g u r e 10).  the  same  The  amplitudes of  giving  the  a total  potential  appears to  signal  from  be  resistivity  In  nulling  across  tive  i n the  was  circuit  to  the  to  had  potential  input  signals  1,  rock.  On  35  to  be  and  another  400  to  shifted  This  48  respectively.  was  occasion  51  the  The  resistivity  and  the  same  location  correct.  null  the  signals  The  for  values  the  been  phase  .02  the  signals  mineralization  The  in  i n phase  phenomenon has  anticipated.  These  pk-pk,  across  alteration  were r e t a r d e d  milliradions  mA  V pk-pk.  This  in phase.  disseminated  and  .64  ~ft,M i n t h e  be  64  signal  M.  amount o f  a proper  current.  The  500 ^TL  be  appear  were  waves o f  is  electrodes  a l 1973)  Hz  sine  current  pk-pk.  the  to  Voorhis  were  two  achieve  in areas of  required  mA  for  would  documented  et  128  determined  order  the  was  high  measurement  '  of  waves o f  equation  very  mineralization  the  sine  electrodes  resistivity,  so  two  Hz  rela-  well  (Van  shifts  and  were c a l c u l a t e d  .065  from  the  transfer function of  was  not  the  phase  The  phase  shifter  calibrated.  Figure  coupling  16  shows t h a t  terms w i t h  electrodes.  As  there  amplitudes  peak-to-peak present  i n the  in figure  13  their  attributed  intermodulation  tempting  to  to point  the  assessment  test  should  greater  amplitudes  are  await  the  c o n c l u s i o n which  that  there  no  .3%  of  the  the  primary  small  amplitude  or  test  can  intermodulation  10  parts  signals.  52  potential  too  more s e n s i t i v e  realistic  the  mV  some low  coupling  campus and  0.5  are  t o d i f f e r e n c e s i n the  on  intermodulation  than  across  there  only  are  were no  signal  p e a k s however  between  shifter.  be  t o be d e f i n a t e l y  i n the  ground.  It i s  low  amplitude  peaks  at  Seneca but  this  instrumentation.  made f r o m  coupling  per  amplitude  this  test  terms g r e a t e r  million  of  the  The  power  is  than  of  to Cu E <d  20A  Input •rH  E  0.05  0.0  0.1  FREQUENCY  0.15  (HZ)  10  rHl.O-l o >  Output  I  o.o  0.05  1—  0.1  FREQUENCY  0.15  (HZ)  '2CH io -P  Nulled  Output  rH  O >  -rH  _  KM  -rH  E  I  0.0  :  0.05  i  — 0.1  FREQUENCY  Figure  16.  Amplitude  Spectra  53  (HZ)  0.15  f o r the Seneca  test.  o.  An  earlier  significant  test  in  test  intermodulation  the electrode  the tests just  potential  field  campus t h e r e  ever  the test  17.  This  two  was v e r y  considerable  9b, d e s c r i b e d  coupling.  shown  How-  in figure  a m p l i f i e r as i n  section, failed to  The t r o u b l e  the electrode  prior  was m e a s u r e d  to starting  in this  the tape  54  A  with  was s u s p e c t e d  which  t o have  was a c t i n g a s  ground.  No c u r r e n t  checked  through  on t h e UBC  the potential f i e l d  i n the previous  The  i n the experiment.  and a d i f f e r e n t i a l  the n o n l i n e a r i t y .  been due t o c u r r e n t  common  measuring  than  t o the electrode  was t r i e d  the results  interest  In t h i s  i n f i g u r e 9a.  intermodulation  a t Seneca p r o d u c e d  o f the experiment  reproduce  the  little  this  was  different  was made r e l a t i v e  When  there  i n the ground.  I t i s shown  ground.  potential electrodes  figure  coupling  described.  measurement  caused  indicated that  c o n f i g u r a t i o n was s l i g h t l y  w h i c h was t h e s y s t e m  repeat  a t Seneca  circuit  recorder.  when i t was  The d e t e c t i o n  Cu  e  3  Input  204  •h  e o.o  T  1  -I  1  0.05  0.1  0.15  0.2  FREQUENCY  (HZ)  Output  ~0.05  o.o  Nulled  FREQUENCY  0.15  1 0.2  (HZ)  Output  0.05  0.0  Figure  1—  0.1  17 .  0.1  FREQUENCY  0.15  (HZ)  Amplitude s p e c t r a from t e s t a t Seneca showing i n t e r m o d u l a t i o n coupling.  55  0.2  limit jJA  so  of  the  there  loop.  multimeter  could  supplies drifted  After  obtaining  intermodulation  possible  of  experiment  removed.  the  was  No  second  the  the  the  for  repeated  significant  output  the  results  error.  prominent p o s s i b i l i t y  much a s  during  coupling,  sources  t o measure  have been as  It i s possible that  current  in  used  current  10JUh o f  level  of  which  introduced  was  intermodulation  56  one  of  10  in  the  the  strong  examined  point  nonlinearities  possible  measurement.  current  indicated  common g r o u n d  this  was  experiment.  experiment  The  with  this  source  coupling  for  appeared  so  of  was  a  the  error  detected  CHAPTER 4  SUMMARY AND  An  experiment  electrical  at  signals  two l o c a t i o n s .  front  to determine  i s that  Vancouver.  massive  the ground  superposition  sinusoids  at the U n i v e r s i t y of B r i t i s h  deposit  of a  100 k i l o m e t e r s  was l i n e a r  within  which  east o f  that the  the measuring  could  resolve  a  peak-to-peak.  used  to determine the e l e c t r i c a l  was a t e s t w h i c h  applied  of current,  respectively,  zone  the r e s u l t s i n d i c a t e d  o f the i n s t r u m e n t a t i o n ,  o f 1 mV  n e t w o r k was p e r f o r m e d  i n the b r e c c i a  At both l o c a t i o n s  The method  of  was  sulphide  response o f the ground  capability  response t o  One o f t h e s e l o c a t i o n s was on t h e lawn i n  and t h e o t h e r  volcanogenic  i f the ground's  of a linear  o f the Geophysics B u i l d i n g  Columbia  signal  CONCLUSIONS  determined  to e l e c t r i c a l  were t r a n s m i t t e d  i f the p r i n c i p l e o f  signals  with frequencies  i n the ground.  Two  o f .02 Hz and .065 Hz  i n t o the ground  57  linearity  simultan-  eously and  and t h e r e s u l t i n g  recorded  on t a p e .  peak-to-peak.  with  field  The c u r r e n t  amplitudes  A Fourier transform  t a p e was p e r f o r m e d  using  a fast  produced by t h i s  frequencies.  intermodulation  coupling  t e r m s was t a k e n network.  L=4M a n d  routine  spectra  f o r terms a t t h e  coupling  coupling  array with  The a m p l i t u d e  intermodulation  intermodulation  w e r e 64 mA  o f t h e t i m e s e r i e s on  r o u t i n e were s e a r c h e d  ground b e h a v e d as a l i n e a r  digitized,  Fourier transform  t h e UBC IBM 3 7 0 / 1 6 8 c o m p u t e r .  detecting  monitored,  The S c h l u m b e r g e r e l e c t r o d e  1=0.5M was u s e d . the  potential  The a b s e n c e o f as p r o o f  that the  The s y s t e m was c a p a b l e terms t h a t were  t h a n 1 mV p e a k - t o - p e a k o r 0.3% o f t h e a m p l i t u d e  of  greater  of the primary  signal.  The e x p e r i m e n t s two s p e c i f i c similar  locations.  in this There  study  current  densities  at other  locations  and f r e q u e n c i e s .  58  out at only  i s no e v i d e n c e t o a s s u m e  r e s u l t s w o u l d be o b t a i n e d  different  were c a r r i e d  that  or with  If  priority  work c o n t i n u e s  be  placed  ment w h i c h w i l l  sensitivity  faithfully  .03%  of  on  field  of  the  of  geologic environments  structure  with  may  be  a  as  nonlinear  effects  the  l a b and  I recommend  rock  units  are  59  instru-  capable  be  of  that  are  directed  toward  t h a t a rock  type  ultra-basic  work.  in serpentine at  high  signals.  i n hopes  a target for further  these  be  peak-to-peak  should  the  a  I f p o s s i b l e the  intermodulation c o u p l i n g amplitude  identified.  Hope a r e a  mV  primary  different  should  that  automated  results.  0.1  measurements  I recommend  compact,  on-the-spot  signals  amplitude  Future  a  detection circuit  resolving  of the  area,  developing  provide  the  in this  low  Katsube  or  spectrum  rocks  in  the  detected  current densities  highly serpentinized.  in  Bibliography  A n d e r s o n , L.A. and K e l l e r ,  polarization;  Geophysics,  G.V.,  1964, A s t u d y  V 29, p  858-915  B a c k u s , G. and G i l b e r t ,  F., 1968, The r e s o l v i n g  earth  Journal of the Royal  data; Geophysical  i n induced  power o f g r o s s  Astronomical  S o c i e t y , V 16, p 169-205  D e W i t t , G.W.,  presented  Hallof,  W.R.,  at the annual  P.G.,  coupling;  Sill,  meeting  1974, The p h a s e  Geophysics,  Katsube, T.J. , Ahern,  nonlinear  Parametric  phenomena  s t u d i e s o f IP s p e c t r a ;  o f t h e SEG,  1976  I P m e a s u r e m e n t and i n d u c t i v e  V 39, p 650-665  R.H.  and C o l l e t t ,  i n rocks; Geophysics  60  L . S . , 1973,  V 38, p  Electrical  106-124  Bibliography Klein, of  J.D.  and  t h e complex  presented Houston  MacMillian,  D.W.,  Resistivity  for  1976,  A laboratory  investigati  ion  of m i n e r a l - e l e c t r o l y t e i n t e r f a c e s ; i n t e r n a t i o n a l meeting  of the  SEG,  1976  Non-linear  New  c o n t r o l systems  Analysis;  York  1978,  Interpretation of Direct  Measurements;  E . , and  vertical  Madrid,  impedance  R.H.,  Pergamon P r e s s ,  Orellana  W.H.,  a t the 46th a n n u a l  Texas,  Oldenburg,  Pelton,  - cont'd  Geophysics, V  Mooney, H.M.,  Electrical  1966.  Soundings  I n t e r s c i e n c i a 150  p  66  Over  tables.  61  43, p  Current  610-625  M a s t e r T a b l e s and Layered  Curves  Structures.  Bibliography  P e l t o n , W.H.,  P.H.,  Ward, S.H.,  1976, I n - s i t u  American M i n e r a l  the  Sill,  Complex R e s i s t i v i t y  Deposits:  presented  W.R.  and N e l s o n ,  studies o f North  a t the annual meeting o f  SEG 19 76.  Induction  coupling with  D i s c r i m i n a t i o n and Removal o f  MultiFrequency  I P ; G e o p h y s i c s , V 43,  588-609  P e l t o n , W.H. , R i t j o , dimensional at  cont'd  H a l l o f , P.G.,  , 1978, M i n e r a l  p  -  induced  L. S w i f t ,  CM.  polarization  J r . , 1976., I n v e r s i o n  and r e s i s t i v i t y  data;  o f two presented  t h e a n n u a l m e e t i n g o f t h e SEG 19 76.  Pelton,  W.H.,  S m i t h , B.D.  complex r e s i s t i v i t y  and S i l l ,  and d i e l e c t r i c  a n n u a l m e e t i n g o f t h e SEG  19 74.  W.R., data;  1974, I n v e r s i o n presented  a t the  of  Bibliography  Ryss,  Y.S.,  1971,  Borehole Mining  editors,  Leningrad,  by  Volosyuk  and  N.I.  in  Safranov,  Nedra.  1973,  The  and  Search  West, G.F.,  synthetic  high r e s i t i v i t y  sulfides;  Geophysics,  V o o r h i s , G.D.,  and  Exploration  for  Ore  of P o l a r i z a t i o n Curves;  V  38,  V  p  1969,  rocks  34 p  Nelson,  resistivity  Geophysics  P o l a r i z a t i o n Curves;  Nedra.  S c o t t , W.J.,  Complex  cont'd  of  G.K.  t h e C o n t a c t Method  Leningrad,  Van  Method  Geophysics;  ,  Bodies  Contact  -  spectra  Induced  containing  p o l a r i z a t i o n of  disseminated  87-100  P.H.,  and  Drake, T.L.,  of porphyry  49-60.  63  copper  1973,  mineralization;  Bibliography  Wait,  J.R.,  1959, O v e r v o l t a g e  Appliations;  Weiss,  0.,  New  York,  - cont'd  Research  Pergman  Press.  and M a s s e , L . , E l e c t r i c a l  Geological  Exploration;  and i t s G e o p h y s i c a l  1954 U.S.  method  patent  and a p p a r a t u s f o r  number  2,690,537.  W h i t e , R.M.S., 1974, A s t u d y o f n o n l i n e a r e l e c t r i c a l  i n m i n e r a l i z e d r o c k s ; M.S.  thesis,  Macquarie  effects  University,  Australia.  Wynn, J . C . and Zonge, K.L., EM  its  removal  49,  p 831-851.  Zohdy, A.R.,  sounding  Zarrouk  and t h e c u l t u r a l  coupling, i t s i n t r i n s i c  c o u p l i n g problem;  1965, The a u x i l i a r y  interpretation  parameters;  point  method  and i t s r e l a t i o n s h i p  Geophysics,  V 64  30 p  value,  Geophysics,  of  electrical  t o t h e Dar  644-660  V  Bibliography  -  cont'd  Zonge, K.L.,  and Wynn, J . C . 1975,  applications  i n complex r e s i s t i v i t y  V 40, p 851-864  65  R e c e n t a d v a n c e s and  measurements;  Geophy  Appendix  Diagram o f the C o n t r o l  66  Circuitry  Output from the B u f f e r V(  iv > w  2  Q t o V toC* 2  V( w,+ u»j) Q to V to C * l  IOK  5 x Nulled  Output  Nulled  Output w  0  ond A Io D Converter 25 x N u l l e d  Output  PHASE SHIFTER  9  - ( 1 8 0 ° + 2tan -wRC)  NULLING CIRCUIT  2  

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