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 MEASURED  EMISSIONS  DATA  FOR  USE  IN  EVALUATING  THE  ULTRA-  WIDEBAND  (UWB) 
 EMISSIONS  LIMITS  IN  THE  FREQUENCY  BANDS  USED  BY  THE  GLOBAL  POSITIONING  SYSTEM  (GPS) 
 ________________________________________________________________________ 


 Project  TRB  02-  02  Report 


 October  22,  2002 


 Technical  Research  Branch  Laboratory  Division 
 Office  of  Engineering  and  Technology  Federal  Communications  Commission 


 Prepared  by  Steven  K.  Jones 
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 TABLE  OF  CONTENTS 
 EXECUTIVE  SUMMARY  i 
 SECTION  ONE    INTRODUCTION  1  BACKGROUND  1 
 OBJECTIVE  3  APPROACH  3 


 SECTION  TWO    DESCRIPTION  AND  USE  OF  THE  FREQUENCY  BANDS  EXAMINED  5 
 GPS  APPLICATIONS  5  GPS  L1  FREQUENCY  BAND  5 
 GPS  L2  FREQUENCY  BAND  6  GPS  L5  FREQUENCY  BAND  7 
 ARNS  FREQUENCY  BAND  7 


 SECTION  THREE    DERIVATION  OF  THE  UWB  EMISSION  LIMIT  8 


 SECTION  FOUR    MEASUREMENT  SYSTEM  AND  PROCEDURES  11 
 MEASUREMENT  SYSTEM  DESCRIPTION  11  MEASUREMENT  SYSTEM  CALIBRATION  12 
 OVERALL  MEASUREMENT  SYSTEM  GAIN  14  MEASUREMENT  PROCEDURES  14 


 SECTION  FIVE    MEASURED  DATA  15  AMBIENT  EMISSIONS  MEASUREMENTS  15 
 Ambient  Emissions  Measurement  Locations  16  Ambient  Emissions  Measurement  Data  17 
 RADIATED  EMISSIONS  MEASUREMENTS  19  Consumer  Device  Sample  Set  20 
 Consumer  Device  Radiated  Measurement  Data  20 


 SECTION  SIX    RESULTS  22  AMBIENT  EMISSIONS  MEASUREMENTS  22 
 RADIATED  EMISSIONS  MEASUREMENTS  22 
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 SECTION  SEVEN    OBSERVATIONS  AND  CONCLUSIONS  30  OBSERVATIONS  30 
 Ambient  Emissions  Measurements  -  Outdoor  Sites  30  Ambient  Emissions  Measurements  -  Indoor  Sites  30 
 Radiated  Emissions  Measurements  31  CONCLUSIONS  32 


 APPENDIX  A    MEASUREMENT  SYSTEM  CALIBRATION  DATA  A-  1 


 APPENDIX  B    MEASUREMENT  PROCEDURES  B-  1 
 APPENDIX  C    DATA  FROM  AMBIENT  MEASUREMENTS  -  OUTDOOR  SITES  C-  1 


 APPENDIX  D    DATA  FROM  AMBIENT  MEASUREMENTS  -  INDOOR  SITES  D-  1 
 APPENDIX  E    DATA  FROM  RADIATED  EMISSIONS  MEASUREMENTS  E-  1 
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 MEASURED  EMISSIONS  DATA  FOR  USE  IN  EVALUATING  THE  ULTRA-  WIDEBAND  (UWB) 
 EMISSIONS  LIMITS  IN  THE  FREQUENCY  BANDS  USED  BY  THE  GLOBAL  POSITIONING  SYSTEM  (GPS) 


 EXECUTIVE  SUMMARY 
 On  February  14,  2002,  the  Federal  Communications  Commission  (FCC)  adopted  the  First  Report  and  Order  (R&  O)  authorizing  the  limited  use  of  Ultra-  Wideband  (UWB) 
 devices  on  an  unlicensed  basis  under  Part  15  of  the  FCC  rules.  UWB  devices  operate  by  employing  very  narrow  or  short-  duration  pulses  that  result  in  an  extremely  wideband 
 frequency  spectra.  UWB  technology  holds  great  promise  for  a  vast  array  of  new  applications  with  the  potential  for  providing  significant  benefits  to  public  safety 
 operations,  as  well  as  business  and  consumer  applications. 
 The  UWB  R&  O  establishes  average  limits  for  UWB  emissions  in  the  form  of  application-  based  emission  masks.  In  the  960-  1610  MHz  frequency  range,  the  emissions 
 limits  defined  by  these  masks  are  predicated  on  the  protection  of  current  and  future  Global  Positioning  System  (GPS)  operations.  Many  of  the  parties  providing  public 
 comments  within  the  UWB  proceeding  have  expressed  concerns  over  the  aggregation  of  conservative  assumptions  used  in  the  derivation  of  these  emissions  limits. 


 The  Commission  recognizes  the  growing  importance  of  GPS  in  everyday  life  and  is  committed  to  ensuring  that  the  GPS  signals  are  not  degraded  or  interrupted  as  a  result 
 of  radio  frequency  interference.  However,  the  Commission  is  also  committed  to  fostering  the  development  and  implementation  of  promising  new  radio  communications 
 technology.  As  such,  the  Commission  must  carefully  balance  the  need  to  protect  critical  services  like  GPS  from  interference  without  placing  unnecessary  burdens  on  developing 
 technologies  such  as  UWB. 
 The  following  statement  was  included  in  the  text  of  the  R&  O:  It  is  our  belief  that  the  standards  contained  in  this  Order  are  extremely  conservative.  These  standards  may 
 change  in  the  future  as  we  continue  to  collect  data  regarding  UWB  operations.  This  measurement  effort  represents  a  first  step  in  collecting  data  to  assist  in  an  assessment  of 
 these  standards  in  accordance  with  the  Commissions  commitment  to  re-  examine  the  UWB  rules  within  six  to  twelve  months  of  the  initial  release  of  the  R&  O.  Since  very  few 
 UWB  devices  had  actually  reached  the  marketplace  at  the  time  this  effort  was  initiated,  it  was  decided  that  this  first  step  assessment  would  focus  on  an  evaluation  of  some  of  the 
 assumptions  that  were  integral  to  the  derivation  of  the  emission  limits  for  UWB  devices.  In  particular,  this  effort  concentrates  on  an  examination  of  pre-  existing  emissions  and 
 associated  amplitude  (power  density)  levels  present  in  those  frequency  bands  that  were  identified  as  requiring  extreme  protection  from  UWB  operations. 


 A  measurement  approach  was  developed  to  determine  the  existing  level  of  ambient  RF  activity  within  these  specific  frequency  bands.  A  set  of  locations  was 
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 identified  from  which  to  perform  the  measurement  of  existing  ambient  RF  activity  based  on  the  likelihood  of  UWB-  to-  GPS  interactions.  These  locations  are  separated  into  two 
 distinct  categories,  outdoor  locations  and  indoor  locations.  Seven  outdoor  sites  were  identified  for  performing  these  measurements,  including  airports,  seaports,  train  yards, 
 and  industrial  sites.  These  sites  were  selected  primarily  because  GPS  has  been  cited  as  a  key  navigational  component  for  use  in  aviation,  maritime,  rail,  and  automotive 
 transportation  systems. 
 Eight  measurement  sites  were  selected  for  the  indoor  ambient  environment  measurements  consisting  primarily  of  office  buildings  and  factory  installations.  These 
 locations  were  selected  as  representative  of  environments  in  which  E-  911  enabled  handsets  (using  enhanced  GPS  technology)  are  anticipated  to  operate  coincident  with 
 UWB  devices. 
 A  measurement  system  was  designed  to  measure  and  record  the  existing  ambient  RF  activity  at  each  of  the  candidate  measurement  locations.  This  system  was  designed  to 
 detect  RF  emissions  down  to  the  very  low-  amplitude  levels  necessary  to  compare  with  the  conservative  GPS  receiver  susceptibility  threshold  assumed  in  the  derivation  of  the 
 UWB  emissions  limits.  The  measurement  system  was  transported  to  an  assortment  of  locations  where  existing  ambient  RF  emissions  were  measured  and  recorded  for 
 subsequent  analysis. 
 The  measurement  results  show  that  the  GPS  L1  and  L2  frequency  bands  are  quiet  with  respect  to  existing  ambient  emissions  at  those  outdoor  locations  where  tests  were 
 conducted.  However,  the  data  also  reveals  that  in  at  least  some  locations,  particularly  indoor  locations  similar  to  those  assumed  in  the  derivation  of  the  UWB  emission  limits, 
 the  ambient  noise  environment,  rather  than  the  GPS  receiver  thermal  noise  density,  may  actually  be  the  limitation  to  the  reception  of  the  low-  amplitude  GPS  signals. 


 The  measurement  system  developed  for  the  ambient  tests  was  also  used  at  the  FCC  Laboratory  facility  to  measure  and  record  radiated  emissions  and  associated  power 
 levels  produced  in  the  GPS  frequency  bands  by  common  consumer  electronic/  electrical  devices. 


 These  measurement  results  show  that  although  many  of  the  devices  tested  radiate  emissions  into  the  GPS  frequency  bands,  the  associated  amplitudes  were  at  much  lower 
 levels  than  permitted  by  the  applicable  limits.  However,  it  was  also  determined  that  the  amplitudes  associated  with  these  emissions  were  frequently  in  excess  of  the  limits 
 established  for  UWB  emissions. 
 As  part  of  this  measurement  effort,  the  ambient  noise  environment  in  the  lower  ARNS  (960-  1160  MHZ)  frequency  band  was  also  examined.  This  band  is  not  used  to 
 support  GPS  operations  nor  is  it  identified  for  use  in  the  GPS  modernization  plan.  Rather  this  frequency  band  is  used  to  support  terrestrial-  based  navigational  aids  such  as  the 
 Distance  Measuring  Equipment  (DME)  and  the  Air  Traffic  Control  Radio  Beacon  (ATCRBS).  NTIA  stated  that  "the  operational  limits  required  for  the  protection  of  the 
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 GPS  will  also  be  adequate  to  protect  DME  operations."  1  The  measurement  results  show  that  the  ambient  emissions  in  this  band  are  generally  above  the  adopted  UWB  emission 
 limits.  Thus  it  appears  that  the  limiting  factor  in  this  band  will  also  be  the  ambient  noise  environment  rather  than  the  limit  based  on  the  GPS  receiver  thermal  noise  density.  In 
 addition,  Table  6  in  the  NTIA  letter  shows  that  a  maximum  EIRP  of  -64  dBm/  MHz  is  required  to  protect  the  DME  system  under  the  most  conservative  assumptions,  which  is 
 well  above  both  the  adopted  UWB  limit  and  the  ambient  noise  environment  for  this  band."  2 


 1  Letter  from  United  States  Department  of  Commerce,  National  Telecommunications  and  Information 
 Administration/  William  T.  Hatch  to  Federal  Communications  Commission,  Office  of  Engineering  Technology/  Edmond  J.  Thomas,  dated  13  February  2002  (hereinafter  NTIA  Letter)  at  pp.  13  and  14. 
 2  See  NTIA  Letter,  Table  6. 
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 ACKNOWLEDGEMENTS 
 The  author  would  like  to  recognize  the  following  people  for  their  contributions  in  the  completion  of  this  effort.  Many  thanks  go  to  Mr.  Michael  Nicolay  of  the  FCC 
 Laboratory  for  his  technical  guidance  and  efforts  in  coordinating  access  to  many  of  the  sites  at  which  data  was  collected.  Mr.  David  Means  of  the  FCC  Laboratory  was  also 
 instrumental  in  coordinating  measurement  locations  for  this  effort.  Thanks  go  to  Mr.  Joe  Piekarski  of  Agilent  Technologies  for  his  efforts  in  providing  the  sensitive  measurement 
 instrumentation  necessitated  by  this  effort.  Finally,  thanks  to  all  of  those  who  permitted  access  to  their  facilities  in  support  of  the  data  collection  phase  of  this  project. 
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 SECTION  ONE  INTRODUCTION 
 BACKGROUND 
 On  February  14,  2002,  the  Federal  Communications  Commission  (FCC)  adopted  the  First  Report  and  Order  (R&  O)  authorizing  the  limited  use  of  Ultra-  Wideband 
 (UWB)  devices  on  an  unlicensed  basis  under  Part  15  of  the  FCC  rules.  3  UWB  devices  operate  by  employing  very  narrow  or  short-  duration  pulses  that  result  in  an  extremely 
 wideband  frequency  spectra.  UWB  technology  holds  great  promise  for  a  vast  array  of  new  applications  with  the  potential  for  providing  significant  benefits  to  public  safety 
 operations,  as  well  as  business  and  consumer  applications. 
 The  UWB  R&  O  establishes  average  limits  for  UWB  emissions  in  the  form  of  application-  based  emission  masks.  In  the  960-  1610  MHz  frequency  range,  the  emissions 
 limits  defined  by  these  masks  are  predicated  on  the  protection  of  current  and  future  Global  Positioning  System  (GPS)  operations 


 In  an  effort  to  determine  appropriate  UWB  emissions  limits  in  those  frequency  bands  in  which  GPS  operates,  the  Commission,  within  the  Notice  of  Proposed 
 Rulemaking  (NPRM),  encouraged  the  undertaking  of  measurement  efforts  to  assess  the  susceptibility  of  GPS  receivers  to  UWB  emissions.  4  Several  parties  performed 
 measurement  programs  to  assess  this  interference  potential  and  provided  the  data  and  analyses  as  a  part  of  the  record  in  this  proceeding.  5 


 General  agreement  was  obtained  from  each  of  these  studies  with  respect  to  the  interference  susceptibility  of  GPS  receivers  to  various  categories  of  UWB  emissions 
 (broadband  noise,  CW,  and  pulsed).  In  addition,  the  results  from  these  tests  were  consistent  with  GPS  protection  criteria  used  by  the  International  Telecommunications 
 Union-  Radiocommunications  Sector  (ITU-  R)  and  by  various  aeronautical  standards  organizations  e.  g.,  International  Civil  Aviation  Organization  (ICAO),  Federal  Aviation 
 Administration  (FAA),  RTCA  Inc,  etc. 
 NTIA  has  indicated  that  additional  protection  may  be  required  to  address  potential  interference  to  emerging  GPS  receiver  technology.  Enhanced  GPS  is  intended  for  use  in 


 3  FCC  02-  48,  Revision  of  Part  15  of  the  Commissions  Rules  Regarding  Ultra-  Wideband  Transmission 
 Systems,  First  Report  and  Order,  ET  Docket  98-  153,  April,  2002,  (hereinafter  UWB  R&  O).  4  FCC  00-  163,  Revision  of  Part  15  of  the  Commissions  Rules  Regarding  Ultra-  Wideband  Transmission 


 Systems,  Notice  of  Proposed  Rulemaking,  ET  Docket  No.  98-  153,  May  11,  2000,  (hereinafter  UWB  NPRM). 
 5  See  NTIA  Special  Publications  01-  45  and  01-  47,  Assessment  of  Compatibility  Between  Ultrawideband 
 (UWB)  Systems  and  Global  Positioning  System  (GPS)  Receivers,  February  2001  (initial  report)  and  November  2001  (addendum),  (hereinafter  NTIA  Report  and  NTIA  Report  Addendum),  University  of 


 Texas  at  Austin  Applied  Research  Laboratories,  Final  Report  Data  Collection  Campaign  for  Measuring  UWB/  GPS  Compatibility  Effects,  Feb.  26,  2001,  Stanford  University,  Potential  Interference  to  GPS  from 
 UWB  Transmitters  Phase  II  Test  Results,  March  16,  2001,  and  Johns  Hopkins  University/  Applied  Physics  Laboratory,  Final  Report  UWB-  GPS  Compatibility  Analysis  Project,  March  8,  2001. 
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 providing  location  information  as  a  solution  for  implementing  enhanced  911  (E-  911)  services  in  mobile  telephone  handsets.  Since  this  technology  was  not  available  at  the 
 time,  none  of  the  test  efforts  considered  the  potential  for  interference  from  UWB  emissions  to  this  type  of  GPS  receiver. 


 To  protect  for  this  new  GPS  technology,  NTIA  proposed  an  analytically  derived  protection  criterion  based  on  the  thermal  noise  floor  of  a  typical  GPS  receiver. 
 Specifically,  NTIA  recommended  a  receiver  susceptibility  mask  based  on  constraining  undesired  UWB  emissions  to  levels  6  dB  below  the  thermal  noise  floor  of  a  GPS 
 receiver.  6  In  addition,  NTIA  proposed  an  operational  scenario  assumed  to  be  representative  of  a  worst-  case  interference  interaction  between  a  UWB  emitter  and  a  GPS 
 receiver.  This  scenario  was  utilized  in  the  link-  budget  calculation  to  determine  the  maximum  UWB  emission  level  tolerable  by  this  class  of  GPS  receiver.  The  scenario 
 assumes  an  enhanced  GPS  receiver  (activated  by  placing  an  E-  911  call)  and  a  UWB  device  are  simultaneously  operating  with  an  unobstructed  signal  propagation  path  at  a 
 separation  distance  of  two  meters. 
 The  Commission  recognizes  the  growing  importance  of  GPS  in  everyday  life  and  is  committed  to  ensuring  that  the  GPS  signals  are  not  degraded  or  interrupted  as  a  result 
 of  radio  frequency  interference.  However,  the  Commission  is  also  committed  to  fostering  the  development  and  implementation  of  promising  new  radio  communications 
 technology.  As  such,  the  Commission  must  carefully  balance  the  need  to  protect  critical  services  like  GPS  from  interference  without  placing  unnecessary  burdens  on  developing 
 technologies  such  as  UWB.  It  is  in  the  public  interest  that  appropriate  limits  be  developed  to  provide  adequate  protection  but  not  overprotect  these  services,  particularly 
 to  an  extent  that  overly  encumbers  the  development  of  new  technologies. 
 The  following  statement  was  included  in  the  text  of  the  R&  O:  It  is  our  belief  that  the  standards  contained  in  this  Order  are  extremely  conservative.  These  standards  may 
 change  in  the  future  as  we  continue  to  collect  data  regarding  UWB  operations.  7  This  measurement  effort  represents  a  first  step  in  collecting  the  data  necessary  to  assess  these 
 standards  in  accordance  with  the  Commissions  commitment  to  re-  examine  the  UWB  rules  within  six  to  twelve  months  of  the  initial  release  of  the  R&  O.  Since  very  few  UWB 
 devices  had  actually  reached  the  marketplace  at  the  time  this  effort  was  initiated,  it  was  decided  that  this  first  step  assessment  would  focus  on  an  evaluation  of  some  of  the 
 assumptions  that  were  integral  to  the  derivation  of  the  emission  limits  for  UWB  devices.  In  particular,  this  effort  concentrates  on  an  examination  of  pre-  existing  emissions  and 
 associated  amplitude  (power  density)  levels  present  in  those  frequency  bands  that  were  identified  as  requiring  extreme  protection  from  UWB  operations. 


 OBJECTIVE 
 6  NTIA  Letter  at  page  2. 
 7  NTIA  Letter  at  page  2. 
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 The  objective  of  this  effort  is  to  acquire  and  analyze  the  data  necessary  to  assess  existing  radio  frequency  emissions  and  associated  power  density  levels  within  specific 
 frequency  bands  in  the  960-  1610  MHz  portion  of  the  electromagnetic  spectrum. 


 APPROACH 
 Since  the  UWB  emission  limits  in  the  960-  1610  MHz  band  are  based  on  protection  of  GPS  receivers  to  levels  below  their  thermal  noise  floor,  an  obvious  question 
 is  will  a  GPS  receiver  realize  its  thermal  noise  floor  in  existing  electromagnetic  environments?  A  secondary  question  that  arises  as  a  result  of  the  small  separation 
 distance  assumed  in  the  derivation  is  what  emission  levels  are  currently  produced  within  the  GPS  frequency  bands  by  common  electronic  and  electrical  devices  at  a  distance  of 
 two  meters?  In  an  effort  to  address  these  questions,  the  FCC  Laboratory  examined  existing  RF  emission  levels  within  those  frequency  bands  over  which  the  GPS 
 interference  susceptibility  mask  was  applied  in  the  derivation  of  the  UWB  emission  limits. 


 In  order  to  address  the  first  question,  a  measurement  approach  was  developed  to  determine  the  existing  level  of  ambient  RF  activity  within  these  specific  frequency  bands. 
 A  set  of  locations  was  identified  from  which  to  perform  the  measurement  of  existing  ambient  RF  activity  based  on  the  likelihood  of  UWB-  to-  GPS  interactions.  These 
 locations  are  divided  into  two  distinct  categories;  outdoor  locations  and  indoor  locations.  The  outdoor  sites  identified  for  performing  these  measurements  include  airports,  seaports, 
 train  yards,  and  industrial  sites.  These  sites  were  selected  primarily  because  GPS  has  been  cited  as  a  key  navigational  component  for  use  in  aviation,  maritime,  rail,  and 
 automotive  transportation  systems. 
 The  measurement  sites  selected  for  the  indoor  ambient  environment  measurements  include  office  buildings  and  factory  installations.  These  locations  were 
 selected  as  representative  of  those  environments  in  which  enhanced  GPS  would  be  anticipated  to  operate  in  E-  911  applications  coincident  with  UWB  operations. 


 A  measurement  system  was  designed  to  measure  and  record  the  existing  ambient  RF  activity  at  each  of  the  candidate  measurement  locations.  This  system  was  designed  to 
 detect  RF  emission  levels  down  to  the  very  low  amplitudes  necessary  to  facilitate  a  comparison  to  the  conservative  GPS  receiver  susceptibility  threshold  used  in  the 
 derivation  of  the  UWB  emissions  limit.  The  measurement  system  was  transported  to  an  assortment  of  locations  where  existing  ambient  RF  emissions  were  measured  and 
 recorded  for  subsequent  analysis. 
 To  address  the  second  question,  a  measurement  system  was  developed  capable  of  detecting  radiated  emissions  from  existing  electronic/  electrical  devices  down  to  levels 
 equivalent  to  the  UWB  emission  limit.  This  measurement  system  was  used  at  the  FCC  Laboratory  facility  to  measure  and  record  spurious  emissions  and  associated  power  levels 
 produced  by  these  types  of  devices  in  the  frequency  bands  of  interest. 
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 Subsequent  to  the  data  collection  portion  of  this  effort,  an  analysis  was  performed  for  each  data  set.  Comments  are  provided  with  regard  to  any  identifiable  trends  observed 
 within  the  data  sets. 
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 SECTION  TWO  DESCRIPTION  AND  USE  OF  THE  FREQUENCY  BANDS 
 EXAMINED 


 GPS  APPLICATIONS 
 The  Global  Positioning  System  is  an  integral  component  in  a  wide  range  of  position  determination  and  timing  applications  worldwide.  GPS  has  become  an  essential 
 element  in  aviation  and  maritime  navigation  systems  and  is  also  routinely  being  implemented  in  navigational  systems  used  by  trains,  automobiles,  and  many  other 
 transportation  and  vehicular  applications.  The  telecommunications,  banking,  and  power  distribution  industries  have  become  reliant  on  the  ability  of  GPS  to  provide  very  precise 
 timing  information  necessary  for  managing  capacity  and  distribution  of  their  services. 
 Since  a  major  consideration  in  the  derivation  of  the  UWB  limits  applicable  to  the  960-  1610  MHz  was  the  protection  of  GPS  receivers  (both  existing  and  future 
 implementations),  this  effort  was  limited  to  an  assessment  of  the  existing  RF  activity  in  those  frequency  bands  in  which  GPS  either  currently  operates  or  plans  to  operate  in  the 
 future.  Additionally,  since  the  UWB  emission  limit,  although  predicated  on  the  protection  of  GPS  receivers,  is  also  applied  to  spectrum  that  is  not  currently  used  or 
 planned  for  use  in  GPS  operations,  it  was  determined  that  these  particular  band  segments  should  also  be  examined.  Specifically,  the  lower  Aeronautical  Radio  Navigation  Service 
 (ARNS)  band  between  960  and  1160  MHz  was  selected  for  examination  in  addition  to  the  three  GPS  frequency  bands.  The  following  paragraphs  briefly  discuss  characteristics 
 associated  with  each  of  the  frequency  bands  examined  within  this  measurement  effort. 


 GPS  L1  FREQUENCY  BAND 
 The  GPS  L1  frequency  band  is  contained  within  the  1559-  1610  MHz  restricted  band  of  operation.  The  1559-  1610  MHz  band  is  allocated  on  a  co-  primary  basis  to  the 
 Aeronautical  Radio  Navigation  Service  (ARNS)  and  the  Radio  Navigation  Satellite  Service  (RNSS).  The  upper  portion  of  the  band  is  used  to  host  downlinks  (space-  to-Earth) 
 from  the  Russian  GLONASS  satellite  navigation  system.  The  European  Union  is  finalizing  plans  to  build  and  launch  a  new  satellite  radio  navigation  system,  called 
 Galileo,  which  will  also  provide  one  or  more  downlink  signals  within  this  band. 
 The  GPS  L1  signal  is  transmitted  from  the  orbiting  GPS  satellites  on  a  center  frequency  of  1575.42  MHz.  The  total  bandwidth  registered  to  the  GPS  L1  signal  is  24 
 MHz  (i.  e.,  1575.42    12  MHz);  however,  typical  GPS  receivers  process  only  2-  12  MHz  of  the  signal.  The  L1  signal  provides  a  Standard  Positioning  Service  (SPS),  a  Precise 
 Positioning  Service  (PPS),  and  a  navigation  message.  The  L1  carrier  is  modulated  with  a  coarse  acquisition  (C/  A)  code  to  provide  the  SPS  and  is  the  only  signal  presently 
 guaranteed  to  be  available  to  civil  users  of  GPS.  The  L1  carrier  is  also  modulated  with  a  longer  precision  (P)  code,  in  phase  quadrature  with  the  C/  A-  code,  to  provide  the  PPS. 
12
 6 
 This  service  is  available  to  those  users  who  require  greater  precision,  with  the  use  of  specialized  GPS  receivers,  but  is  subject  to  being  made  unavailable  to  civil  users  at  any 
 time  by  modulation  with  the  encrypted  Y-  code. 
 The  FAA  and  other  international  aeronautical  administrations  are  planning  to  launch  geo-  stationary  orbiting  satellites  to  augment  the  GPS  constellation.  This  is  being 
 done  to  provide  the  satellite  availability  required  to  certify  GPS  for  use  as  a  sole-  means  of  aeronautical  radio  navigation.  The  domestic  augmentation  system  is  known  as  the 
 Wide  Area  Augmentation  System  (WAAS).  Similar  systems  are  also  being  planned  in  Europe  and  Japan.  Additionally,  the  FAA  is  planning  to  locally  augment  GPS  at  select 
 airports  with  a  system  know  as  the  Local  Area  Augmentation  System  (LAAS).  This  system  will  consist  of  terrestrial-  based  transmitters  to  augment  the  space-  based  GPS 
 signal  for  use  in  the  precision  landing  of  aircraft.  Both  of  these  systems  are  planned  for  operation  in  the  GPS  L1  frequency  band. 


 As  a  result  of  the  GPS  signals  originating  from  a  distant  point  in  space  (approximately  20,000  km),  the  signal  levels  are  very  low  when  they  reach  a  terrestrial 
 user.  The  minimum  guaranteed  GPS  signal  power  specification  for  the  C/  A-  code  is  -130  dBm  into  a  0  dBic  gain  antenna;  8  however,  the  actual  signal  levels  are  known  to  be  7-  10 
 dB  greater  than  the  minimum  level.  Nonetheless,  the  signals  are  very  weak  and  necessitate  the  use  of  signal  processing  techniques  in  order  to  recover  a  usable  signal. 
 The  GPS  signal  strength  can  be  further  reduced  before  arriving  at  a  user  receiver  from  signal  attenuation  associated  with  foliage,  terrain  and/  or  building  shielding. 


 Because  the  GPS  L1  band  is  within  a  restricted  band  of  operation  that  is  currently  used  exclusively  for  radio  navigation  satellite  downlinks,  there  are  no  authorized 
 frequency  assignments  to  terrestrial-  based  systems.  Therefore  it  is  hypothesized  that  any  existing  emissions  in  the  GPS  L1  band  will  be  a  result  of  spurious  (out-  of-  band  and/  or 
 harmonic)  emissions  from  intentional  radiators,  and/  or  low-  level  unintentional  or  incidental  emissions  from  electronic  and  electrical  devices  (i.  e.,  no  fundamental 
 emissions  are  expected  to  be  observed). 


 GPS  L2  FREQUENCY  BAND 
 The  GPS  L2  signal  is  contained  within  the  1215-  1240  MHz  restricted  band  of  operation,  which  is  allocated  on  a  co-  primary  basis  to  the  Radiolocation  Service  and  the 
 RNSS.  In  addition  to  the  L2  signal,  this  frequency  band  hosts  the  Joint  Surveillance  System  (JSS)  radar  system,  shared  by  the  Department  of  Defense  (DoD)  and  the  FAA. 
 These  radar  systems,  in  particular  the  Air  Route  Surveillance  Radars  (ARSRs),  are  used  by  the  FAA  for  en-  route  surveillance  of  commercial  aircraft  and  by  the  DoD  for  early 
 warning  air  defense.  To  accommodate  the  relatively  weak  GPS  signal,  the  radar  systems  operating  in  the  band  avoid  frequency  assignments  on  the  L2  center  frequency. 


 8  ARINC  Research  Corporation,  Navstar  GPS  Space  Segment/  Navigation  User  Interfaces,  Sept.  25,  1997, 
 at  page  13. 
13
 7 
 The  GPS  L2  signal  is  transmitted  on  a  center  frequency  of  1227.60  MHz.  The  registered  bandwidth  of  the  GPS  L2  signal  is  also  24  MHz  (1227.60    12  MHz). 
 Currently,  only  the  P-  code  (unencrypted)  or  Y-  code  (encrypted)  is  modulated  onto  the  GPS  L2  carrier. 


 Ongoing  GPS  modernization  efforts  include  the  addition  of  a  new  civil  signal  to  the  GPS  L2  carrier  providing  an  additional  channel  for  utilization  of  the  SPS.  9  This  new 
 signal  will  be  implemented  by  modulating  a  C/  A-  code  in  phase-  quadrature  with  the  existing  P-  or  Y-  code,  similar  to  the  structure  of  GPS  L1. 


 GPS  L5  FREQUENCY  BAND 
 The  implementation  of  a  GPS  L5  signal  is  also  part  of  the  ongoing  GPS  modernization  effort.  At  the  most  recent  World  Radio  Conference  (WRC-  2000)  an 
 allocation  to  RNSS  was  adopted  in  the  1164-  1215  MHz  segment  of  the  960-  1215  MHz  ARNS  frequency  band.  The  1164-  1188  MHz  segment  will  be  used  to  host  a  new  GPS 
 aviation-  specific  signal.  The  new  signal  is  denoted  L5  and  will  be  transmitted  on  1176.45  MHz  with  a  registered  bandwidth  of  24  MHz  (1176.45    12  MHz).  10  The  upper 
 segment  (1188-  1215  MHz)  will  be  used  to  host  a  Galileo  downlink  signal.  The  new  GPS  L5  signal  has  been  specifically  designed  to  support  aviation  applications  and  will 
 improve  on  known  shortcomings  of  the  existing  L1  signal.  As  a  result,  the  L5  signal  is  anticipated  to  be  a  more  robust  signal  (e.  g.,  6  dB  higher  power,  longer  code,  etc.)  and  less 
 susceptible  to  both  noise-  like  and  spectral  line  interference  than  the  existing  L1  signal. 


 ARNS  FREQUENCY  BAND 
 Prior  to  WRC-  2000,  the  960-  1215  MHz  band  was  allocated  exclusively  to  the  ARNS.  Traditionally,  this  band  has  been  used  to  support  navigational  aids  such  as  the 
 FAAs  Distance  Measuring  Equipment  (DME)  and  the  military  Tactical  Aeronautical  Navigation  (TACAN)  systems.  The  FAA  also  operates  the  Air  Traffic  Control  Radio 
 Beacon  System  (ATCRBS)  on  two  discrete  frequencies  (1030  and  1090  MHz)  within  this  band.  In  addition,  the  military  Joint  Tactical  Information  Distribution  System  (JTIDS) 
 operates  in  this  frequency  band.  At  WRC-  2000,  a  co-  primary  allocation  was  granted  to  RNSS  in  the  1164-  1215  MHz  portion  of  the  band  as  discussed  above.  In  this 
 measurement  effort,  the  960-  1164  MHz  portion  of  the  band  is  also  of  interest,  particularly  since  the  UWB  emission  limit,  although  based  on  the  protection  of  GPS  receivers,  is 
 applied,  although  GPS  does  not  currently  utilize  nor  has  plans  to  utilize  this  part  of  the  spectrum. 


 9  Press  Release  from  The  White  House,  Office  of  the  Vice  President,  Vice  President  Gore  Announces  New 
 Global  Positioning  System  Modernization  Initiative,  January  25,  1999.  10  Hegarty,  C.,  and  Van  Dierendonck,  A.  J.,  Civil  GPS/  WAAS  Signal  Design  and  Interference  Environment 


 at  1176.45  MHz:  Results  of  RTCA  SC159  WG1  Activities. 
14
 8 
 SECTION  THREE  DERIVATION  OF  THE  UWB  EMISSION  LIMIT 
 In  this  section,  the  methodology  and  assumptions  that  were  incorporated  in  the  derivation  of  the  emission  limits  applicable  to  UWB  devices  operating  over  the  960-  1610 
 MHz  region  of  the  electromagnetic  spectrum  will  be  presented  and  discussed.  In  this  measurement  effort,  elements  of  this  derivation,  particularly  the  GPS  receiver 
 susceptibility  threshold,  are  used  as  a  basis  for  comparison  to  existing  ambient  and  spurious  emission  levels. 


 As  previously  stated,  the  derived  UWB  limits  applicable  in  the  960-  1610  MHz  frequency  band  are  predicated  on  the  protection  GPS  receivers  from  harmful  interference. 
 Several  parties  to  the  UWB  rulemaking  performed  measurements  of  GPS  receiver  susceptibility  to  UWB  emissions.  General  agreement  was  observed  in  the  results  from 
 each  of  these  test  efforts.  Additionally,  these  results  were  shown  to  be  consistent  with  GPS  interference  protection  criteria  developed  by  the  United  States  delegation  to  WRC-2000 
 within  the  ITU-  R  11  and  by  RTCA  12  for  use  in  performing  GPS  interference  analyses.  The  threshold  for  broadband  noise  interference  developed  within  these  groups 
 is  based  on  maintaining  a  minimum  GPS  carrier-  to-  noise  density  (C/  N0)  of  34  dB-  Hz,  necessary  for  satellite  acquisition  (a  30  dB-  Hz  C/  N0  is  required  to  maintain  tracking  of  an 
 already  acquired  satellite),  assuming  the  minimum  specified  GPS  signal  strength  of  -130  dBm.  13  The  broadband  noise  interference  criterion  defined  in  these  documents  is 
 -110.5  dBm/  MHz.  This  criterion  was  developed  for  an  aviation  scenario  that  assumes  a  GPS  receive  antenna  gain  of  -4.5  dBi.  When  adjusted  for  use  in  land-  based  GPS  analyses 
 (i.  e.,  the  undesired  emitter  is  constrained  to  a  hemispherical  volume  with  respect  to  the  GPS  receiver  resulting  in  a  minimum  GPS  antenna  gain  of  0  dBi),  the  equivalent 
 threshold  is  -106  dBm/  MHz. 
 In  the  measurement  effort  undertaken  by  NTIA  to  assess  the  interference  susceptibility  of  GPS  receivers  to  UWB  emissions,  the  broadband  noise  interference 
 threshold  was  determined  to  range  between  -106  and  -100  dBm/  MHz  when  the  interference  metric  considered  was  satellite  break-  lock.  When  the  interference  metric 
 considered  was  a  degradation  in  reacquisition  time  the  interference  threshold  ranged  between  -106  and  -104.5  dBm/  MHz.  14  Regardless  of  the  interference  metric  assumed,  the 
 most  conservative  threshold  determined  from  the  NTIA  measurements  was 


 11  ITU-  R  Recommendation  M.  1477,  Technical  and  Performance  Characteristics  of  Current  and  Planned 
 Radionaviagation-  Satellite  Service  (Space-  to-  Earth)  and  Aeronautical  Radionavigation  Service  Receivers  to  Be  Considered  in  Interference  Studies  in  the  Band  1559-  1610  MHz,  2000,  (hereinafter  ITU-  R 


 M.  1477).  12  RTCA/  DO-  229B,  Minimum  Operational  Performance  Standard  for  GPS/  Wide  Area  Augmentation 
 System  Airborne  Equipment,  January,  1996.  13  See  ITU-  R  M.  1477. 
 14  See  NTIA  Report  Addendum,  Tables  2-  4  through  2-  6. 
15
 10 
 the  maximum  level  of  UWB  emissions  tolerable  to  this  class  of  GPS  receiver.  This  scenario  assumes  an  enhanced  GPS  receiver  (activated  by  placing  an  E-  911  call)  and  a 
 UWB  device  are  simultaneously  operating  with  an  unobstructed  signal  propagation  path  at  a  separation  distance  of  two  meters  20  . 


 Under  these  assumptions,  the  link  budget  for  indoor  UWB  applications  is: 
 Parameter  Value  Receiver  Susceptibility  Mask  (dBm/  MHz) 
 (Broadband  Noise)  -117.5  GPS  Antenna  Gain  in  Direction  of  RFI  Source  (dBi)  0 
 Propagation  Loss  (dB)  (Minimum  Distance  Separation  (meters))  42.2  (2) 
 Noise-  Like  RFI  Emission  Limit  (dBm/  MHz)  -75.3  47  C.  F.  R.  15.209  Emission  Limit  (dBm/  MHz)  -41.3 
 Additional  Attenuation  Required  (dB)  34.0 
 Thus,  the  average  emission  limit  applicable  indoor  UWB  devices  in  the  960-  1610  MHz  frequency  range  is  an  equivalent  isotropic  radiated  power  (EIRP)  of 
 -75.3  dBm/  MHz.  This  limit  is  applicable  in  the  960-  1610  MHz  band  to  the  following  UWB  applications:  Indoor  UWB  Applications  (Section  15.517),  Handheld  UWB 
 Applications  (Section  15.519),  and  Vehicular  Radar  Systems  (Section  15.515  ). 
 In  this  measurement  effort,  the  GPS  interference  susceptibility  threshold,  -117.5  dBm/  MHz,  is  used  as  a  basis  for  comparison  in  both  the  ambient  and  spurious 
 emissions  measurements.  A  display  line  is  used  to  depict  this  limit  on  the  spectrum  analyzer  plots  included  in  this  report. 


 For  the  ambient  emission  measurements,  the  display  line  at  117.5  dBm/  MHz  is  used  as  the  basis  for  comparison  to  the  measured  ambient  power  levels.  Since  the  source 
 of  the  ambient  emissions  is  not  always  known,  the  distance  between  the  source  and  the  measurement  antenna  cannot  be  determined.  Thus,  an  EIRP  cannot  be  calculated  to 
 compare  directly  to  the  UWB  limits  as  they  are  defined  in  the  rules.  However,  since  the  limits  were  derived  based  on  a  GPS  receiver  susceptibility  threshold  of 
 -117.5  dBm/  MHz,  a  comparison  to  this  level  is  equivalent  to  a  comparison  with  the  emission  limit.  The  underlying  assumption  is  that  the  measured  ambient  emissions 
 directly  correspond  to  what  would  be  detected  by  a  GPS  receiver  at  the  same  location  as  the  measurement  system  antenna. 


 For  the  spurious  radiated  emission  measurements,  the  display  line  value  (-  117.5  dBm/  MHz)  directly  represents  the  UWB  emission  limit  of  75.1  dBm/  MHz 
 (EIRP),  when  measured  at  a  distance  of  2  meters  within  a  1  MHz  measurement  bandwidth. 


 20  See  NTIA  Letter,  Table  2. 
17
 11 
 SECTION  FOUR  MEASUREMENT  SYSTEM  AND  PROCEDURES 
 MEASUREMENT  SYSTEM  DESCRIPTION 
 The  measurement  system  used  to  acquire  the  data  in  this  effort  is  shown  in  Figure  4-  1  below. 


 Figure  4-  1.  Measurement  System  Block  Diagram. 
 An  Agilent  model  E4440  PSA  spectrum  analyzer  was  the  primary  measurement  instrument  used  to  collect  the  data  in  this  effort.  This  analyzer  incorporates  a  true  RMS 
 detector  providing  a  means  to  acquire,  display,  and  store  a  continuous  trace  of  RMS  average  power  levels  across  the  frequency  bands  under  examination. 


 A  pair  of  low  noise  amplifiers  (LNAs)  was  cascaded  to  enable  the  detection  of  emissions  to  the  very  low  levels  necessary  to  compare  with  the  UWB  limit.  Two 
 different  measurement  systems  were  used  over  the  duration  of  this  effort,  differing  only  by  the  first  stage  LNA  employed.  Measurement  system  A  utilized  an  octave-  tuned  (1-  2 
 GHz),  pre-  amplifier  with  a  very  low  noise  figure  (NF)  of  0.6  dB.  Measurement  system  B  also  utilized  an  octave  tuned  (1-  2  GHz)  pre-  amplifier  but  with  a  NF  equal  to  1.0  dB.  In 
 both  systems,  the  first  stage  amplifier  effectively  establishes  the  noise  figure  of  the  entire  measurement  system.  The  second  stage  amplifier  is  a  broadband  amplifier  of  the  type 
 typically  used  in  a  compliance  measurement  set-  up.  A  10-  dB  attenuator  was  inserted  between  the  two  LNAs  to  provide  isolation. 


 Agilent  E4440 
 PSA 
 2  nd  Stage  LNA  NF  =  8  dB 
 F  =  0.5-  26.5  GHz  G  =  25  dB 
 1  st  Stage  LNA  NF  =  0.6  or  1.0  dB 
 F=  1-  2  GHz  G  =  45  or  42  dB 
 Variable  Tuned  Bandpass  Filter 
 F  =  0.75-  1.  5  GHz  LI  ~  1  dB 


 Isolation  Pad 


 Broadband  Horn  G  =  7-  9  dBi 
 F  =  1-  12  GHz 
18
 12 
 A  tunable  band-  pass  filter  (BPF)  was  included  in  the  measurement  system  ahead  of  the  first  stage  LNA  to  filter  out  signals  originating  outside  of  the  frequency  band  under 
 examination. 
 The  measurement  antenna  was  a  double-  ridge  broadband  horn  calibrated  for  use  in  the  1-  12  GHz  frequency  range.  This  type  of  antenna  was  determined  to  provide  the 
 greatest  flexibility  with  respect  to  polarization  and  broadband  frequency  characteristics,  while  also  producing  sufficient  gain  to  accommodate  the  measurement  of  emissions  to 
 the  low  levels  necessary  to  compare  to  the  UWB  limits.  It  should  be  noted  that  normalizing  the  data  collected  with  this  antenna  to  equate  to  a  GPS  antenna  can  result  in 
 an  under  estimate  of  the  ambient  levels  that  would  actually  be  seen  by  a  GPS  receiver,  particularly  when  the  emission  source  is  located  outside  the  main  beam  of  the 
 measurement  antenna. 
 Specific  information  for  each  component  of  the  measurement  system  and  the  equipment  used  for  calibration  is  presented  below  in  Table  4-  1. 


 TABLE  4-  1.  Test  and  Calibration  Equipment  Specifications. 
 EQUIPMENT  MANUFACTURER  and  MODEL  RELEVANT  SPECIFICATIONS 


 Spectrum  Analyzer  Agilent  E4440A  3  Hz  to  26.5  GHz 
 Signal  Generator  Agilent  E4437B  250  kHz  to  4  GHz 


 LNA  2  Hewlett-  Packard  HP83017A  0.5-  26.5  GHz  Gain  =  25  dB  (Min)  NF  =  8  dB  (Max) 


 LNA  1  (System  A)  MITEQ  AFS3-  01000200-  06-  10P-  6  1.0-  2.0  GHz  Gain  =  45  dB  (Min)  NF  =  0.6  dB  (Max) 
 LNA  1  (System  B)  MITEQ  AMF-  3B-  010020-  10-  25P  1.0-  2.0  GHz  Gain  =  42  dB  (Min)  NF  =  1.0  dB  (Max) 
 Tunable  Band  Pass  Filter  Texscan  5VF750/  1000-  5AA  0.75-  1.5  GHz 
 Receive  Antenna  EMCO  3105  Double  Ridge  Guide  Horn  1.0-  12.0  GHz 


 MEASUREMENT  SYSTEM  CALIBRATION 
 The  data  obtained  from  the  calibration  of  the  measurement  system  components  between  the  spectrum  analyzer  and  the  measurement  antenna  is  presented  in  APPENDIX 
 A.  The  following  tables  summarize  the  data  relevant  to  characterizing  the  measurement  system. 
19
 13 
 Tables  4-  2  and  4-  3  summarize  the  external  gain  as  measured  at  the  center  of  each  of  the  frequency  bands  under  examination  for  each  of  the  two  measurement  systems  used 
 in  this  effort.  The  external  gain  reported  in  the  tables  is  the  sum  of  the  cascaded  LNA  gains  less  the  attenuation  in  the  coaxial  cables,  connectors  and  the  isolation  pad,  and  the 
 insertion  loss  of  the  band  pass  filter. 
 TABLE  4-  2.  Measurement  System  External  Gain  (System  A). 
 CENTER  FREQUENCY 


 (MHz) 
 MEASUREMENT  SYSTEM  EXTERNAL  GAIN 
 (dB)  1575.4  64.8 
 1227.6  66.7  1176.0  66.4 
 985.0  68.0  1035.0  67.7 
 1085.0  67.3  1135.0  67.0 


 TABLE  4-  3.  Measurement  System  External  Gain  (System  B). 
 CENTER  FREQUENCY 


 (MHz) 
 MEASUREMENT  SYSTEM  EXTERNAL  GAIN 
 (dB)  1575.4  63.5 
 1227.6  64.7  1176.0  64.9 
 985.0  67.4  1035.0  66.7 
 1085.0  66.6  1135.0  66.2 


 MEASUREMENT  ANTENNA  CALIBRATION 
 TABLE  4-  4  lists  the  calibrated  antenna  gain  provided  by  the  manufacturer  of  the  double-  ridge  guide  horn  antenna  used  in  the  measurement  system. 


 TABLE  4-  4.  Measurement  Antenna  Gain. 
 FREQUENCY  (MHz)  ANTENNA  GAIN  (dBi) 


 1575.4  8.6  1227.6  7.2 
 1176.0  7.1  985.0  6.1 
 1035.0  6.4  1085.0  6.7 
 1135.0  6.9 
20
 14 
 OVERALL  MEASUREMENT  SYSTEM  GAIN 
 In  order  to  determine  the  true  amplitude  of  the  signals  impinging  on  the  measurement  antenna,  adjustments  to  the  displayed  amplitude  levels  are  necessary  to 
 account  for  the  amplification  in  the  measurement  system,  external  to  the  spectrum  analyzer.  This  amplification  is  necessary  to  detect  low-  amplitude  signals  but  must  be 
 removed  from  the  data  to  reveal  the  true  signal  level.  The  spectrum  analyzer  used  in  these  measurements  provides  the  capability  to  perform  these  corrections  internally,  but 
 the  user  must  enter  the  applicable  gain  values  in  order  to  adjust  the  data. 
 Tables  4-  5  and  4-  6  list  the  gain  values  determined  for  measurement  systems  A  and  B,  respectively.  The  overall  system  gain  reported  in  these  tables  are  the  values  that 
 were  input  to  the  spectrum  analyzer  to  facilitate  the  internal  correction  to  the  data  so  that  the  displayed  amplitudes  accurately  depict  the  actual  signal  levels  impinging  on  the 
 measurement  antenna.  The  overall  system  gain  was  determined  by  adding  the  measurement  system  external  gain  of  each  of  the  measurement  systems  and  the  antenna 
 gain  for  each  frequency  range  examined  as  a  part  of  this  effort. 
 TABLE  4-  5.  Total  System  Gain  (System  A). 
 FREQUENCY  (MHz)  EXTERNAL  GAIN  (dB)  ANTENNA  GAIN  (dBi)  OVERALL  SYSTEM  GAIN 
 (dB)  1575.4  64.8  8.6  73.4 


 1227.6  66.7  7.2  73.9  1176.0  66.4  7.1  73.5 
 985.0  68.0  6.1  74.1  1035.0  67.7  6.4  74.1 
 1085.0  67.3  6.7  74.0  1135.0  67.0  6.9  73.9 


 TABLE  4-  6.  Total  System  Gain  (System  B). 
 FREQUENCY  (MHz)  SYSTEM  GAIN  (dB)  ANTENNA  GAIN  (dBi)  OVERALL  SYSTEM  GAIN 
 (dB)  1575.4  63.5  8.6  72.1 


 1227.6  64.7  7.2  71.9  1176.0  64.9  7.1  72.0 
 985.0  67.4  6.1  73.5  1035.0  66.7  6.4  73.1 
 1085.0  66.6  6.7  73.3  1135.0  66.2  6.9  73.1 


 MEASUREMENT  PROCEDURES 
 The  procedures  implemented  for  measuring  both  existing  ambient  emissions  and  spurious  emissions  from  consumer  devices  are  defined  in  Appendix  B  of  this  document. 
21
 15 
 SECTION  FIVE  MEASURED  DATA 
 AMBIENT  EMISSIONS  MEASUREMENTS 
 Field  surveys  were  performed  at  those  locations  deemed  consistent  with  the  list  of  candidate  sites,  i.  e.,  airports,  shipyards,  train  yards,  industrial  areas  (outdoor  sites),  office 
 buildings  and  factory  floors  (indoor  sites).  These  surveys  were  performed  to  determine  the  presence  of  existing  ambient  emissions  and  the  associated  power  levels  within  the 
 frequency  bands  under  examination. 
 These  measurements  were  intended  to  determine  the  amplitude  of  existing  ambient  emissions  as  would  be  experienced  at  the  measurement  location  by  a  GPS 
 receiver.  The  measured  levels  were  then  compared  to  the  theoretical  GPS  interference  criterion  supported  by  NTIA  and  used  in  establishing  the  emission  limit  applicable  to 
 UWB  devices.  To  facilitate  this  comparison  the  measurement  system  was  configured  to  simulate  the  RF  front-  end  of  a  GPS  receiver.  The  resolution  bandwidth  of  the 
 measurement  receiver  (spectrum  analyzer)  was  set  to  1  MHz,  the  same  as  the  RF  bandwidth  of  many  GPS  receivers  and  also  to  give  results  in  dBm/  MHz,  consistent  with 
 the  specified  interference  threshold  units.  The  spectrum  analyzer  was  tuned  to  the  center  frequency  in  each  of  the  GPS  frequency  bands,  as  would  a  GPS  receiver,  but  was  also 
 used  to  span  the  entire  registered  bandwidth  of  the  GPS  signal.  The  ambient  emissions  were  measured  in  terms  of  RMS  average,  consistent  with  the  results  of  studies  performed 
 by  NTIA  and  others  showing  that  GPS  receivers  are  most  susceptible  to  average  power  interference.  Conventional  GPS  receivers  employ  an  integration  time  on  the  order  of 
 20  milliseconds;  however,  enhanced  GPS  receivers,  for  which  the  extreme  protection  criteria  was  deemed  necessary,  were  said  to    integrate  the  satellite  signal  over  a  longer 
 time  period,  allowing  the  receiver  to  obtain  a  20  to  30  dB  higher  processing  gain  than  a  conventional  GPS  receiver.  21  For  these  measurements,  an  effective  integration  time  of 
 100  milliseconds  was  utilized  in  performing  the  RMS  averaging  (one-  hundred  1-  msec  sweeps).  The  primary  distinction  between  the  measurement  system  and  the  RF  chain  of  a 
 GPS  receiver  was  the  receive  antenna.  The  measurement  system  utilized  an  antenna  that  is  more  directional  than  a  GPS  antenna  in  order  to  provide  sufficient  gain  to 
 accommodate  measurements  to  the  extremely  low  levels  necessary  to  compare  to  the  UWB  emission  limits  (i.  e.,  below  thermal  noise).  The  data  is  adjusted  to  equate  to  the 
 0-  dBi  gain  assumed  for  a  GPS  antenna  in  the  UWB-  to-  GPS  receiver  interaction  link  budget  analyses  of  UWB  interference  potential.  It  is  noted  that  this  normalization  of  the 
 antenna  gain  can  lead  to  an  underestimate  of  the  measured  ambient  signal  amplitudes,  particularly  when  the  emission  source(  s)  are  located  outside  of  the  measurement  antenna 
 main  beam. 
 In  these  ambient  measurements  no  concerted  effort  was  made  to  identify  the  source  of  the  emissions  observed.  Such  efforts  would  be  very  difficult,  particularly  since 
 many  of  the  emissions  present  in  these  frequency  bands  are  likely  to  be  spurious,  rather 
 21  See  UWB  R&  O  at  paragraph  99  and  NTIA  Letter  at  p.  8. 
22
 16 
 than  fundamental  emissions.  Therefore,  since  neither  the  emission  source  nor  its  physical  location  is  known,  it  is  not  possible  to  determine  the  EIRP  relative  to  the  source 
 emitter(  s).  Thus,  an  EIRP  cannot  be  calculated  that  could  be  compared  directly  to  the  UWB  limits  as  they  are  defined  in  the  rules.  However,  since  the  limits  were  derived 
 based  on  a  GPS  receiver  susceptibility  threshold  of  -117.5  dBm/  MHz,  a  comparison  to  this  level  represents  an  equivalent  metric.  The  underlying  assumption  is  that  the 
 measured  ambient  emissions  directly  correspond  to  what  would  be  detected  by  a  GPS  receiver  at  the  same  location  as  the  measurement  system  antenna.  Thus,  any  emissions  in 
 excess  of  the  susceptibility  threshold  would  be  expected  to  degrade  the  performance  of  those  GPS  receivers  considered  in  the  link  budget  analyses. 


 Ambient  Emissions  Measurement  Locations 
 Table  5-  1  provides  a  list  of  the  outdoor  locations  where  the  ambient  emissions  measurements  were  performed  as  a  part  of  this  effort.  Table  5-  2  lists  the  indoor  locations 
 where  ambient  emissions  measurements  were  performed. 
 Table  5-  1.  Outdoor  Ambient  Emissions  Measurement  Sites.  SITE  DESCRIPTION  COORDINATES 


 BWI  Airport  Aircraft  Observation  Area  39  09.771  N  076  39.815  W 
 Dulles  International  Airport  Paige  General  Aviation  Terminal  38  57.170  N  077  26.638  W 
 Reagan  National  Airport  General  Aviation  Parking  Lot  38  50.748  N  077  02.668  W 
 Port  of  Baltimore  Security  Office  Parking  Lot  39  15.083  W  076  33.415  W 
 U.  S.  Coast  Guard  Yard  Buoy  Maintenance  Facility  39  12.027N  076  34.370W 
 Train  Yard  AMTRAK  Maintenance  Facility  38  55.055N  076  59.286W 
 Industrial  Location  Tysons  Corner,  VA  38  55.326N  077  14.008W 
23
 17 
 Table  5-  2.  Indoor  Ambient  Emissions  Measurement  Sites.  SITE  DESCRIPTION  COORDINATES 
 Office  Building  #1  Debt  Consolidation  Firm  Workspace  Area  39  11.547  N  076  49.014  W 
 Office  Building  #2  FCC  Portals  Large  LAN  Server  Room  38  52.967  W  077  01.578  W 
 Office  Building  #3  Scientific  Research  Facility  Central  Corridor  38  55.326  N  077  14.008  W 
 Office  Building  #4  Engineering  Research  Company  Small  LAN  Sever  Room  38  47.917  N  077  11.480  W 
 Office  Building  #5  Engineering  Research  Company  Typical  Office  Work  Space  38  47.917  N  077  11.480  W 
 Factory  Location  #1  Electro-  Optics  Manufacturer  Factory  Floor  39  10.948  N  076  48.767  W 
 Factory  Location  #2  Compact  Disc  (CD)  Manufacturer  Factory  Floor  39  10.686  N  077  15.047  W 
 Factory  Location  #3  Automotive  Assembly  Plant  Factory  Floor  39  16.024  N  076  32.695  W 


 Ambient  Emissions  Measurement  Data 
 The  spectrum  analyzer  plots  depicting  the  data  collected  at  each  measurement  site  are  presented  in  Appendices  C  (outdoor  sites)  and  D  (indoor  sites). 


 A  sample  spectrum  analyzer  plot  is  presented  below  as  an  aid  in  providing  an  explanation  of  how  to  read  and  interpret  the  data  presented  in  the  appendices.  In  these 
 plots,  the  upper  (yellow)  trace  depicts  the  ambient  emissions  measured  in  the  subject  frequency  band  using  a  peak  detector  and  the  maximum  hold  function  (i.  e.,  no  averaging 
 employed)  over  a  fifteen-  minute  period.  This  trace  was  generated  mainly  as  a  tool  for  orienting  the  measurement  antenna  and  for  determining  the  maximum  likely  emission 
 amplitudes  to  facilitate  decisions  pertaining  to  the  necessity  of  adding  additional  attenuation  in  the  measurement  system  so  as  to  prevent  overdriving  of  components.  This 
 data  was  not  used  for  any  analytical  purposes.  The  lower  (blue)  trace  represents  the  measured  RMS  average  emission  level  over  one  hundred  one-  millisecond  analyzer 
 sweeps  across  the  measurement  band.  This  is  the  data  used  to  compare  to  the  assumed  interference  threshold  for  enhanced  GPS  receivers.  The  constant  display  line  (green)  at  -117.5 
 dBm  is  used  as  the  basis  for  comparing  the  measured  data  to  the  theoretical  enhanced  GPS  interference  threshold. 


 All  external  measurement  system  parameters  (e.  g.,  amplifier  gains,  cable  loss,  and  antenna  gain)  are  accounted  for  in  the  spectrum  analyzer  display  and  are  provided  on 
 each  plot  under  the  tag  Ext  PG  located  at  the  top  of  the  display.  At  some  measurement  locations,  it  was  necessary  to  add  additional  attenuation  in  the  measurement  system  due 
 to  the  presence  of  relatively  high-  amplitude  signals.  In  those  cases  where  additional  external  attenuation  was  required,  the  Ext  PG  value  was  adjusted  accordingly.  Thus,  the 
24
 18 
 levels  shown  on  the  amplitude  axis  of  the  spectrum  analyzer  plots  represent  the  actual  RMS  average  power  as  measured  in  a  1  MHz  bandwidth  at  the  measurement  system 
 antenna. 


 Figure  5-  1.  Sample  Spectrum  Analyzer  Plot  from  Ambient  Emissions  Measurement. 
 In  these  plots,  the  horizontal  axis  represents  frequency  and  the  vertical  axis  represents  amplitude.  For  measurements  in  the  GPS  frequency  bands,  a  span  of  25  MHz 
 was  used  to  encompass  the  24  MHz  registered  frequency  band.  For  a  25  MHz  span,  each  vertical  graticule  line  represents  a  2.5  MHz  deviation  in  frequency  (25  MHz/  10  graticule 
 lines).  For  example,  in  the  sample  plot  of  Figure  5-  1,  the  center  vertical  graticule  line  represents  the  center  frequency  of  1575.42  MHz.  Each  vertical  graticule  line  to  the  left 
 of  the  center  represents  a  decrement  from  the  center  frequency  of  2.5  MHz  and  each  graticule  line  to  the  right  of  the  centerline  represents  a  2.5  MHz  increment  relative  to  the 
 center  frequency.  For  the  measurements  performed  in  the  960-  1160  MHz  (ARNS)  band,  a  span  of  50  MHz  was  used,  the  maximum  that  could  be  achieved  within  the  pass  band  of 
 the  pre-  select  filter.  In  these  plots,  each  vertical  graticule  line  represents  a  frequency  deviation  of  5  MHz  (50  MHz/  10  graticule  lines). 


 On  the  amplitude  axis,  each  horizontal  graticule  line  represents  a  10  dB  decrement  from  the  reference  level  amplitude  shown  in  the  upper  left-  hand  corner  of  the 
 plot.  As  an  example,  to  determine  the  maximum  amplitude  level  from  the  RMS  average  trace,  begin  with  the  reference  level  amplitude  of  -45  dBm  and  count  7.25  graticule  lines 
 down  to  the  highest  emission  level  shown  by  the  trace.  Since  each  graticule  line  is  10  dB 


 RMS  Average  Trace  Display  Line  =  -117.  5  dBm 
 Peak  Trace 
25
 19 
 (indicated  in  the  upper  left-  hand  margin  of  the  plot  by  10  dB/  ),  the  measured  level  is  72.5  dB  (7.25  x  10)  down  from  -45  dBm,  or  -117.5  dBm. 
 RADIATED  EMISSIONS  MEASUREMENTS 
 In  this  set  of  measurements,  spurious  emissions  generated  by  common  consumer  electronic  and  electrical  devices  are  examined  within  the  GPS  L1,  L2,  and  L5  frequency 
 bands.  The  ARNS  band  was  not  examined  primarily  due  to  questions  regarding  the  usefulness  of  this  type  of  measurement  in  assessing  those  assumptions  used  to  establish 
 the  UWB  limits  within  this  band.  As  discussed  in  Section  2  of  this  report,  GPS  does  not  operate,  nor  has  plans  to  operate  in  this  frequency  band.  Thus,  the  relevance  of  a 
 comparison  of  spurious  emissions  generated  from  consumer  devices  to  the  theoretical  GPS  interference  threshold  is  not  immediately  clear.  Further,  it  seems  questionable  that 
 the  types  of  consumer  devices  considered  in  this  effort  will  routinely  operate  within  two  meters  of  the  aviation  and  military  systems  that  utilize  this  frequency  band  (see  Section  2 
 for  a  description  of  these  systems). 
 The  radiated  spurious  emissions  measurements  were  performed  with  the  measurement  system  described  previously.  The  measurement  system  was  configured  as 
 it  would  be  to  determine  compliance  with  the  UWB  emission  limits.  The  device  under  test  (DUT)  was  placed  at  a  distance  of  two  meters  from  the  measurement  antenna.  This 
 distance  was  selected  to  maintain  consistency  with  the  interaction  distance  assumed  in  the  derivation  of  the  UWB  emission  limit  (see  Section  Three  for  details).  At  a  distance  of 
 2-  meters,  the  display  line  at  117.5  dBm  directly  relates  to  the  EIRP  limit  of  -75.3  dBm/  MHz  defined  within  the  rules. 


 Immediately  preceding  each  measurement  of  the  DUT-  radiated  spurious  emissions,  the  measurement  system  was  used  to  perform  a  check  of  the  background  or 
 ambient  RF  environment  in  which  the  DUT  was  tested.  This  background  measurement  was  performed  using  the  same  settings  as  used  in  the  radiated  emissions  test.  The 
 resultant  data  was  displayed  using  one  of  the  three  available  traces  of  the  spectrum  analyzer.  The  DUT  was  then  turned  on  and  the  radiated  spurious  emissions  measurement 
 was  performed.  The  data  from  this  measurement  is  displayed  using  another  of  the  available  analyzer  traces.  A  single  spectrum  analyzer  plot  showing  both  traces  was 
 generated  for  each  measurement  band.  The  lower  (yellow)  trace  represents  the  ambient  (background)  emission  levels  and  the  upper  (blue)  trace  represents  the  sum  of  the 
 ambient  emissions  and  the  spurious  emissions  originating  from  the  DUT. 
 An  important  consideration  in  the  interpretation  of  this  data  is  the  fact  that  the  radiated  spurious  power  captured  by  the  measurement  system  is  actually  the  sum  of  the 
 ambient  emissions  already  present  and  those  spurious  emissions  introduced  when  the  DUT  is  turned  on.  Since  the  emissions  under  consideration  in  this  study  are  often  very 
 close  to  the  ambient  noise  floor,  the  contribution  of  the  noise  floor  to  this  sum  can  be  significant.  Within  this  study,  if  the  difference  between  the  measured  ambient  level  and 
 the  corresponding  radiated-  plus-  ambient  level  is  3  dB,  then  the  DUT  emission  amplitude  level  is  interpreted  as  being  equivalent  to  the  ambient  level.  Accordingly,  if  the 
26
 20 
 difference  between  the  DUT  radiated-  plus-  ambient  emission  level  and  the  corresponding  ambient  emission  level  is  less  than  3  dB,  then  the  DUT  emission  level  is  interpreted  as 
 being  less  than  the  ambient  level.  Emissions  that  are  more  than  3  dB  above  the  corresponding  ambient  level  are  attributed  to  spurious  emissions  from  the  DUT. 


 Consumer  Device  Sample  Set 
 Table  3-  2  lists  the  consumer  electronic/  electrical  devices  measured  as  a  part  of  this  effort. 


 Table  3-  2.  Consumer  Electronic/  Electrical  Devices  Tested.  DEVICE  DESCRIPTION 
 Desktop  Computer  1  Pentium  IV  Desktop  Computer  2  Pentium  II 
 Desktop  Computer  3  Pentium  III  w/  WLAN  hub  Laptop  Computer  1  Pentium  III 
 Laptop  Computer  2  Pentium  I  Laptop  Computer  3  Pentium  II 
 Laptop  Computer  4  Pentium  II  Personal  Digital  Assistant 
 Pendant  Transmitter  Automotive  Remote  Keyless  Entry  Device  Electric  Drill  #1  Variable  speed  AC  motor 
 Electric  Drill  #2  Variable  speed  DC  motor  (cordless)  Electric  Hairdryer  #1  Single  speed  AC  motor 
 Electric  Hairdryer  #2  Two  speed  AC  motor  Electric  Vacuum  Cleaner  Single  speed  AC  motor 


 Consumer  Device  Radiated  Emissions  Measurement  Data 
 Appendix  E  presents  the  spectrum  analyzer  plots  depicting  the  data  collected  from  the  measurement  of  radiated  spurious  emissions  generated  by  those  electronic/  electrical 
 devices  contained  in  the  sample  set  identified  above  for  each  of  the  GPS  frequency  bands.  A  sample  plot  from  these  measurements  is  presented  below  and  used  to  facilitate 
 the  following  explanation  of  how  to  read  and  interpret  the  represented  data. 
 The  instructions  provided  earlier  in  this  section  for  reading  the  ambient  emission  measurement  analyzer  plots  are  also  applicable  to  reading  the  data  represented  in  these 
 plots.  The  following  discussion  highlights  subtle  differences  between  these  plots  and  those  depicting  the  ambient  emissions  measurements. 


 In  each  of  the  spectrum  analyzer  plots  presented  in  Appendix  E,  two  measurement  traces  are  shown.  The  lower  (yellow)  trace  represents  the  background  (ambient) 
 emissions  in  the  frequency  band  under  examination  with  the  DUT  turned  off.  The  upper  (blue)  trace  represents  the  sum  of  the  emissions  radiated  from  the  DUT  and  the  existing 
 background  (ambient)  emissions.  A  constant  display  line  (green)  is  also  shown  in  each 
 Radiated  Spurious  Emission  (RMS) 


 Display  Line  =  -117.  5  dBm 
27
 21 
 plot.  This  is  set  to  a  level  of  -117.5  dBm  to  represent  the  received  power  equivalent  to  the  UWB  EIRP  limit  of  -75.3  dBm/  MHz  at  a  distance  of  two  meters.  Some  of  the  plots 
 presented  in  Appendix  E  use  other  than  10  dB  per  vertical  division  (graticule  line).  This  was  done  to  facilitate  better  resolution  of  the  signals  under  examination.  These  plots  are 
 read  the  same  way  as  described  previously  except  that  each  vertical  line  may  represent  a  deviation  of  3  or  5  dB  from  the  reference  level.  The  dB-  per-  division  scale,  applicable  to 
 each  plot,  is  shown  in  the  upper  left-  hand  margin. 
28
 22 
 SECTION  SIX  RESULTS 
 AMBIENT  EMISSIONS  MEASUREMENTS 
 Tables  6-  1  and  6-  2  summarize  specific  data  points  from  the  spectrum  analyzer  traces  presented  in  Appendices  C  (outdoor  ambient  emissions  data)  and  D  (indoor 
 ambient  emissions  data).  While  it  is  difficult  to  characterize  all  of  the  information  provided  in  these  plots  within  a  single  table,  an  attempt  has  been  made  to  present  the 
 most  pertinent  data  points  from  each  plot  such  as  the  maximum  emission  amplitudes  observed  in  each  frequency  band,  the  associate  frequency  and  general  signal  structure, 
 and  the  measured  amplitude  at  the  GPS  center  frequency.  However,  the  data  in  these  tables  does  not  convey  information  such  as  the  number  of  emissions  observed  in  the  band 
 or  the  intermediate  amplitude  levels  (e.  g.,  those  emission  levels  less  than  the  maximum  observed  amplitude).  This  information  must  be  obtained  from  the  individual  spectral 
 plots  presented  in  the  appendices. 
 The  following  explanation  of  each  of  the  columns  in  these  tables  is  offered.  The  first  column  defines  the  frequency  band  that  the  subsequent  data  pertains  to.  Column  two 
 shows  the  maximum  emission  amplitude  (power  level)  observed  in  the  band.  The  values  in  column  three  compares  the  maximum  observed  emission  amplitude  to  the  GPS 
 interference  threshold  assumed  in  the  derivation  of  the  UWB  emission  limit.  Column  four  provides  the  frequency  associated  with  the  maximum  amplitude  emission  observed. 
 The  fifth  column  describes  the  general  emission  characteristic  in  terms  of  narrow  band  or  broadband  emissions.  The  final  column  shows  the  measured  emission  amplitude  at  the 
 center  frequency  of  each  of  the  GPS  bands.  There  are  no  entries  provided  in  this  column  for  the  data  collected  in  the  lower  ARNS  band,  since  GPS  neither  currently  operates  nor 
 has  a  future  plan  to  operate  in  this  band. 
 RADIATED  EMISSIONS  MEASUREMENTS 
 Table  6-  3  summarizes  the  specific  data  points  from  the  spectrum  analyzer  traces  from  the  measurements  of  radiated  spurious  emissions  produced  by  common  electronic 
 devices  into  the  GPS  frequency  bands.  The  complete  data  plots  are  presented  in  Appendix  E.  In  this  table,  the  column  descriptions  presented  above  apply. 
29
 23 
 TABLE 
 6-  1. 
 Summary 


 of 
 Outdoor 


 Ambient 
 Emissions 
 Measurement 


 Data. 


 MEASUREMENT  BAND  (MHz) 
 MAXIMUM  EMISSION  AMPLITUDE  (dBm) 
 EMISSION  AMPLITUDE  RELATIVE  TO  THRESHOLD  (dB) 
 EMISSION  FREQUENCY  (MHz) 


 EMISSION  CHARACTERISITC 
 MEASURED 
 AMPLITUDE  at  GPS  CENTER  FREQUENCY  (dBm) 


 Measurement 
 Location: 
 Baltimore- 
 Washington 


 International 


 Airport 


 GPS 
 L1 


 -117.  5 


 0 
 1564 


 Narrow 
 Band 


 -122.  0 


 GPS 
 L2 


 -120.  0 


 -2. 
 5 


 1215-  1240 


 Broad 
 Band 


 -122.  0 


 GPS 
 L5 


 -62.  0 


 55.  5 
 1185 


 Narrow 
 Band 


 -118.  0 


 960- 
 1010 


 -112.  0 


 5.5 
 984 
 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -83.0 
 34. 
 5 


 1030 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -94.0 
 23. 
 5 


 1090 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -87.0 
 30. 
 5 


 1122 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Ronald 
 Reagan 
 National 


 Airport 


 GPS 
 L1 


 -122.  0 


 -4. 
 5 


 1563-  1588 


 Broad 
 Band 


 -122.  0 


 GPS 
 L2 


 -120.  0 


 -2. 
 5 


 1215-  1240 


 Broad 
 Band 


 -122.  0 


 GPS 
 L5 


 -118.  0 


 -0.  5 
 1165 


 Narrow 
 Band 


 -122.  0 


 960- 
 1010 


 -82.  0 


 35.  5 
 1008 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -95.0 
 22. 
 5 


 1030 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -76.0 
 41. 
 5 


 1072 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -90.0 
 27. 
 5 


 1149 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Dulles 
 International 


 Airport 


 GPS 
 L1 


 -122.  0 


 -4. 
 5 


 1563-  1588 


 Broad 
 Band 


 -122.  0 


 GPS 
 L2 


 -121.  0 


 -3. 
 5 


 1215-  1240 


 Broad 
 Band 


 -122.  0 


 GPS 
 L5 


 -87.  0 


 30.  5 
 1169 


 Narrow 
 Band 


 -122.  0 


 960- 
 1010 


 -119.  0 


 -1. 
 5 


 960- 
 1010 


 Broad 
 Band 


 N/  A 


 1010-  1060 
 -80.0 
 37. 
 5 


 1028 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -79.0 
 38. 
 5 


 1106 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -94.0 
 23. 
 5 


 1122 
 & 
 1114 


 Narrow 
 Band 


 N/  A 
30
 24 
 TABLE 
 6- 
 1 
 (continued). 


 Summary 
 of 
 Outdoor 


 Ambient 
 Emissions 
 Measurement 


 Data. 


 MEASUREMENT  BAND  (MHz) 
 MAXIMUM  EMISSION  AMPLITUDE  (dBm) 
 EMISSION  AMPLITUDE  RELATIVE  TO  THRESHOLD  (dB) 
 EMISSION  FREQUENCY  (MHz) 


 EMISSION  CHARACTERISITC 
 MEASURED 
 AMPLITUDE  at  GPS  CENTER  FREQUENCY  (dBm) 


 Measurement 
 Location: 
 Port 
 of 
 Baltimore 


 GPS 
 L1 


 -118.  0 


 -0. 
 5 


 1563-  1588 


 Broad 
 Band 


 -117.  5 


 GPS 
 L2 


 -117.  0 


 0.5 
 1215-  1240 


 Broad 
 Band 


 -117.  0 


 GPS 
 L5 


 -85.  0 


 32.  5 
 1185 


 Narrow 
 Band 


 -117.  0 


 960- 
 1010 


 -115.  0 


 2.5 
 960- 
 1010 


 Broad 
 Band 


 N/  A 


 1010-  1060 
 -80.0 
 37. 
 5 


 1030 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -82.0 
 35. 
 5 


 1090 
 & 
 1102 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -95.0 
 22. 
 5 


 1125 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 U. 
 S. 
 Coast 


 Guard 


 Yard 


 GPS 
 L1 


 -117.  0 


 0.5 
 1563-  1588 


 Broad 
 Band 


 -117.  0 


 GPS 
 L2 


 -117.  0 


 0.5 
 1215-  1240 


 Broad 
 Band 


 -117.  0 


 GPS 
 L5 


 -96.  0 


 11.  5 
 1185 


 Narrow 
 Band 


 -117.  0 


 960- 
 1010 


 -111.  0 


 6.5 
 975 
 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -85.0 
 32. 
 5 


 1030 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -84.0 
 33. 
 5 


 1071 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -83.0 
 34. 
 5 


 1134 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 AMTRAK 
 Maintenance 


 Facility 


 GPS 
 L1 


 -117.  0 


 0.  5 
 1570 


 Narrow 
 Band 


 -121.  0 


 GPS 
 L2 


 -116.  0 


 1.  5 
 1234 


 Narrow 
 Band 


 -120.  0 


 GPS 
 L5 


 -113.  0 


 4.  5 
 1181 


 Narrow 
 Band 


 -119.  0 


 960- 
 1010 


 -95.0 


 12. 
 5 


 960 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -109.  0 
 8.  5 
 1030 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -95.0 
 12. 
 5 


 1090 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -91.0 
 16. 
 5 


 1116 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Urban 
 (Industrial) 


 Area 


 GPS 
 L1 


 -118.  0 


 -0.  5 
 1575 


 Narrow 
 Band 


 -118.  0 


 GPS 
 L2 


 -117.  5 


 0.  0 
 1226 


 Narrow 
 Band 


 -117.  5 


 GPS 
 L5 


 -100.  0 


 17.  5 
 1164 


 Narrow 
 Band 


 -117.  5 


 960- 
 1010 


 -77.0 


 40. 
 5 


 960 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -86.0 
 31. 
 5 


 1041 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -90.0 
 27. 
 5 


 1090 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -95.0 
 22. 
 5 


 1122 


 Narrow 
 Band 


 N/  A 
31
 25 
 TABLE 
 6-  2. 
 Summary 


 of 
 Indoor 


 Ambient 


 Emissions 
 Measurement 


 Data. 


 MEASUREMENT  BAND  (MHz) 
 MAXIMUM  EMISSION  AMPLITUDE  (dBm) 
 EMISSION  AMPLITUDE  RELATIVE  TO  THRESHOLD  (dB) 
 EMISSION  FREQUENCY  (MHz) 


 EMISSION  CHARACTERISITC 
 MEASURED 
 AMPLITUDE  at  GPS  CENTER  FREQUENCY  (dBm) 


 Measurement 
 Location: 
 Office 
 Location 


 #1 


 GPS 
 L1 


 -108.  0 


 9.  5 
 1573 


 Narrow 
 Band 


 -113.  0 


 GPS 
 L2 


 -104.  0 


 13.  5 
 1220 


 Narrow 
 Band 


 -109.  0 


 GPS 
 L5 


 -94.  0 


 23.  5 
 1181 


 Narrow 
 Band 


 -106.  0 


 960- 
 1010 


 -91.0 


 26. 
 5 


 998 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -99.0 
 18. 
 5 


 1040 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -93.0 
 24. 
 5 


 1062 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -95.0 
 22. 
 5 


 1119 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Office 
 Location 


 #2 


 GPS 
 L1 


 -99.  0 


 18.  5 
 1575 


 Narrow 
 Band 


 -101.  0 


 GPS 
 L2 


 -94.  0 


 23.  5 
 1222 


 Narrow 
 Band 


 -108.  0 


 GPS 
 L5 


 -93.0 


 24. 
 5 


 1169 


 Narrow 
 Band 


 -98.0 


 960- 
 1010 


 -84.  0 


 33.  5 
 1009 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -85.0 
 32. 
 5 


 1036 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -83.0 
 34. 
 5 


 1063 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -92.0 
 25. 
 5 


 1125 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Office 
 Location 


 #3 


 GPS 
 L1 


 -109.  0 


 8.  5 
 1572 


 Narrow 
 Band 


 -113.  0 


 GPS 
 L2 


 -115.  0 


 2.5 
 1215-  1240 


 Broad 
 Band 


 -115.  0 


 GPS 
 L5 


 -114.  0 


 3.  5 
 1175 


 Narrow 
 Band 


 -116.  0 


 960- 
 1010 


 -105.  0 


 12.  5 
 989 
 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -110.  0 
 7.  5 
 1020 
 & 
 1050 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -106.  0 
 11.  5 
 1090 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -110.  0 
 7.  5 
 1125 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Office 
 Location 


 #4 


 GPS 
 L1 


 -97.  0 


 20.  5 
 1566 


 Narrow 
 Band 


 -110.  0 


 GPS 
 L2 


 -91.  0 


 26.  5 
 1233 


 Narrow 
 Band 


 -108.  0 


 GPS 
 L5 


 -81.  0 


 36.  5 
 1166 


 Narrow 
 Band 


 -107.  0 


 960- 
 1010 


 -84.0 


 33. 
 5 


 966 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -84.0 
 33. 
 5 


 1033 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -84.0 
 33. 
 5 


 1100 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -90.0 
 27. 
 5 


 1133 


 Narrow 
 Band 


 N/  A 
32
 26 
 TABLE 
 6- 
 2 
 (continued). 


 Summary 
 of 
 Indoor 


 Ambient 


 Emissions 
 Measurement 


 Data. 


 MEASUREMENT  BAND  (MHz) 
 MAXIMUM  EMISSION  AMPLITUDE  (dBm) 
 EMISSION  AMPLITUDE  RELATIVE  TO  THRESHOLD  (dB) 
 EMISSION  FREQUENCY  (MHz) 


 EMISSION  CHARACTERISITC 
 MEASURED 
 AMPLITUDE  ON  GPS  CENTER  FREQUENCY  (dBm) 


 Measurement 
 Location: 
 Office 
 Location 


 #5 


 GPS 
 L1 


 -107.  0 


 10.  5 
 1571 


 Narrow 
 Band 


 -115.  0 


 GPS 
 L2 


 -106.  0 


 11.  5 
 1236 


 Narrow 
 Band 


 -114.  0 


 GPS 
 L5 


 -102.  0 


 15.  5 
 1164 


 Narrow 
 Band 


 -114.  0 


 960- 
 1010 


 -102.  0 


 15.  5 
 1002 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -102.  0 
 15.  5 
 1040 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -101.  0 
 16.  5 
 1104 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -103.  0 
 14.  5 
 1136 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Factory 
 Location 


 #1 


 GPS 
 L1 


 -105.  0 


 12.  5 
 1568 


 Narrow 
 Band 


 -114.  0 


 GPS 
 L2 


 -106.  0 


 11.  5 
 1225 


 Narrow 
 Band 


 -109.  0 


 960- 
 1010 


 -100.  0 


 17.  5 
 995- 
 1000 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -101.  0 
 16.  5 
 1038 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -94.0 
 23. 
 5 


 1088 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -105.  0 
 12.  5 
 1117 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Factory 
 Location 


 #2 


 GPS 
 L1 


 -120.  0 


 -2. 
 5 


 1563-  1588 


 Broad 
 Band 


 -120.  0 


 GPS 
 L2 


 -115.  0 


 2.  5 
 1229 


 Narrow 
 Band 


 -118.  0 


 GPS 
 L5 


 -117.  5 


 0.0 
 1164-  1189 


 Broad 
 Band 


 -118.  0 


 960- 
 1010 


 -114.  0 


 3.5 
 998 
 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -114.  0 
 3.  5 
 1049 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -113.  0 
 4.  5 
 1088 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -104.  0 
 13.  5 
 1147 


 Narrow 
 Band 


 N/  A 


 Measurement 
 Location: 
 Factory 
 Location 


 #3 


 GPS 
 L1 


 -94.  0 


 23.  5 
 1574 


 Narrow 
 Band 


 -105.  0 


 GPS 
 L2 


 -80.  0 


 37.  5 
 1227 


 Narrow 
 Band 


 -104.  0 


 GPS 
 L5 


 -97.  0 


 20.  5 
 1170 


 Narrow 
 Band 


 -106.  0 


 960- 
 1010 


 -91.0 


 26. 
 5 


 984 


 Narrow 
 Band 


 N/  A 


 1010-  1060 
 -95.0 
 22. 
 5 


 1023 


 Narrow 
 Band 


 N/  A 


 1060-  1110 
 -93.0 
 24. 
 5 


 1091 


 Narrow 
 Band 


 N/  A 


 1110-  1160 
 -90.0 
 27. 
 5 


 1134 


 Narrow 
 Band 


 N/  A 
33
 27 
 TABLE 
 6-  3. 
 Summary 


 of 
 Radiated 


 Spurious 
 Emissions 
 Measurement 


 Data. 


 MEASUREMENT  BAND  (MHz) 
 MAXIMUM  EMISSION  AMPLITUDE  (dBm) 
 EMISSION  AMPLITUDE  RELATIVE  TO  THRESHOLD  (dB) 
 EMISSION  FREQUENCY  (MHz) 


 EMISSION  CHARACTERISITC 
 MEASURED 
 AMPLITUDE  ON  GPS  CENTER  FREQUENCY  (dBm) 


 DUT: 
 Desktop 


 Computer 


 1 


 GPS 
 L1 


 -103.  0 


 14.  5 
 1584 


 Narrow 
 Band 


 -118.  0 


 GPS 
 L2 


 -115.  0 


 2.  5 
 1224 


 Narrow 
 Band 


 -116.  0 


 GPS 
 L5 


 -110.  0 


 7.  5 
 1165 


 Narrow 
 Band 


 -116.  0 


 DUT: 
 Desktop 


 Computer 


 2 


 GPS 
 L1 


 -119.  0 


 -1.  5 
 1573 
 Narrow 
 Band 
 (Ambient) 


 -120.  0 


 GPS 
 L2 


 -116.  0 


 1.  5 
 1222 


 Narrow 
 Band 


 -119.  0 


 GPS 
 L5 


 -114.  0 


 3.  5 
 1167 


 Narrow 
 Band 


 -118.  0 


 DUT: 
 Desktop 


 Computer 


 3 


 GPS 
 L1 


 -113.  0 


 4.  5 
 1563 


 Narrow 
 Band 


 -118.  0 


 GPS 
 L2 


 -109.  0 


 8.  5 
 1216 


 Narrow 
 Band 


 -114.  0 


 GPS 
 L5 


 -111.  0 


 6.  5 
 1166 


 Narrow 
 Band 


 -115.  0 


 DUT: 
 Laptop 
 Computer 


 1 


 GPS 
 L1 


 -113.  0 


 4.  5 
 1563 


 Narrow 
 Band 


 -118.  0 


 GPS 
 L2 


 -111.  0 


 6.  5 
 1227 


 Narrow 
 Band 


 -116.  0 


 GPS 
 L5 


 -114.  0 


 3.  5 
 1164 


 Narrow 
 Band 


 -118.  0 


 DUT: 
 Laptop 
 Computer 


 2 


 GPS 
 L1 


 -112.  0 


 5.  5 
 1564 


 Narrow 
 Band 


 -118.  0 


 GPS 
 L2 


 -103.  0 


 14.  5 
 1238 


 Narrow 
 Band 


 -118.  0 


 GPS 
 L5 


 -109.  0 


 8.  5 
 1173 


 Narrow 
 Band 


 -118.  0 


 DUT: 
 Laptop 
 Computer 


 3 


 GPS 
 L1 


 -116.  0 


 1.  5 
 1584 


 Narrow 
 Band 


 -117.  5 


 GPS 
 L2 


 -109.  0 


 8.  5 
 1235 


 Narrow 
 Band 


 -116.  0 


 GPS 
 L5 


 -104.  0 


 13.  5 
 1170 


 Narrow 
 Band 


 -115.  0 


 DUT: 
 Laptop 
 Computer 


 4 


 GPS 
 L1 


 -114.  0 


 3.  5 
 1563 


 Narrow 
 Band 


 -119.  0 


 GPS 
 L2 


 -112.  0 


 5.  5 
 1238 


 Narrow 
 Band 


 -119.  0 


 GPS 
 L5 


 -106.  0 


 11.  5 
 1173 


 Narrow 
 Band 


 -118.  0 
34
 28 
 TABLE 
 6-  3 
 (continued). 


 Summary 
 of 
 Radiated 


 Spurious 
 Emissions 
 Measurement 


 Data. 


 MEASUREMENT  BAND  (MHz) 
 MAXIMUM  EMISSION  AMPLITUDE  (dBm) 
 EMISSION  AMPLITUDE  RELATIVE  TO  THRESHOLD  (dB) 
 EMISSION  FREQUENCY  (MHz) 


 EMISSION  CHARACTERISITC 
 MEASURED 
 AMPLITUDE  ON  GPS  CENTER  FREQUENCY  (dBm) 


 DUT: 
 PDA 


 GPS 
 L1 


 -118.  0 


 -0. 
 5 


 1563-  1588 


 Broad 
 Band 


 -118.  0 


 GPS 
 L2 


 -109.  0 


 8.  5 
 1216 


 Narrow 
 Band 


 -114.  0 


 GPS 
 L5 


 -111.  0 


 6.  5 
 1166 


 Narrow 
 Band 


 -115.  0 


 DUT: 
 Pendant 


 Transmitter 


 GPS 
 L1 


 -90.0 


 27. 
 5 


 1575 


 Narrow 
 Band 


 -95.0 


 DUT: 
 Electric 


 Drill 
 #1 


 GPS 
 L1 


 -100.  0 


 17. 
 5 


 1574 
 Impulsive- 
 Broad 
 Band 


 -110.  0 


 GPS 
 L2 


 -87.0 


 30. 
 5 


 1239 
 Impulsive- 
 Broad 
 Band 


 -105.  0 


 GPS 
 L5 


 -84.0 


 34. 
 5 


 1188 
 Impulsive- 
 Broad 
 Band 


 -90.0 


 DUT: 
 Electric 


 Drill 
 #2 


 GPS 
 L1 


 Impulsive 


 GPS 
 L2 


 -110.  0 


 7.5 
 1233 


 Impulsive 


 -117.  5 


 GPS 
 L5 


 -113.  0 


 4.5 
 1167 


 Impulsive 


 -117.  5 


 DUT: 
 Electric 


 Hair 
 Dryer 


 #1 


 GPS 
 L1 


 -100.  0 


 17. 
 5 


 1589 
 Impulsive- 
 Broad 
 Band 


 -111.  0 


 GPS 
 L2 


 -99.0 


 18. 
 5 


 1217 
 Impulsive- 
 Broad 
 Band 


 -116.  0 


 GPS 
 L5 


 -95.0 


 22. 
 5 


 1182 
 Impulsive- 
 Broad 
 Band 


 -111.  0 


 DUT: 
 Electric 


 Hair 
 Dryer 


 #2 


 GPS 
 L1 


 -106.  0 


 11.  5 
 1577 


 Impulsive 


 -119.  0 


 GPS 
 L2 


 -110.  0 


 7.5 
 1235 


 Impulsive 


 -117.  5 


 GPS 
 L5 


 -111.  0 


 6.5 
 1165 


 Impulsive 


 -117.  0 


 DUT: 
 Electric 


 Vacuum 
 Cleaner 


 GPS 
 L1 


 -103.  0 


 14. 
 5 


 1578 
 Impulsive- 
 Broad 
 Band 


 -106.  0 


 GPS 
 L2 


 -102.  0 


 15. 
 5 


 1238 
 Impulsive- 
 Broad 
 Band 


 -103.  0 


 GPS 
 L5 


 -100.  0 


 17. 
 5 


 1169 
 Impulsive- 
 Broad 
 Band 


 -102.  0 
35
 29 
 SECTION  SEVEN  OBSERVATIONS,  CONCLUSIONS 
 AND  RECOMMENDATIONS 
 OBSERVATIONS 
 Ambient  Emissions  Measurements  -  Outdoor  Sites 
 The  ambient  emissions  measurements  performed  in  the  GPS  L1  and  L2  frequency  bands  reveal  these  two  bands  to  be  relatively  quiet  with  respect  to  existing  RF  activity. 
 At  most  of  the  outdoor  locations,  no  emissions  exceeding  the  sensitivity  of  the  measurement  system  were  detected.  At  those  few  locations  where  emissions  were 
 observed,  the  associated  power  levels  were  determined  to  be  very  low,  and  in  all  cases,  less  than  the  interference  threshold  assumed  for  GPS  receivers  in  the  derivation  of  the 
 UWB  limits  applicable  in  these  frequency  bands. 
 Ambient  emissions  measurements  performed  in  the  GPS  L5  frequency  band  disclose  a  greater  level  of  RF  activity  than  in  the  GPS  L1  and  L2  frequency  bands. 
 Existing  ambient  emissions  were  observed  in  this  band  at  many  of  the  measurement  locations;  however,  they  appear  to  be  associated  with  frequency  assignments  to  what  are 
 assumed  to  be  authorized  systems  operating  in  the  band.  In  all  locations,  the  emissions  detected  in  this  band  were  removed  in  frequency  from  the  GPS  L5  center  frequency.  The 
 waveforms  associated  with  these  emissions  were  observed  to  decrease  to  amplitude  levels  less  than  the  assumed  GPS  interference  threshold  within  the  likely  pass  band  of  a  GPS  L5 
 receiver. 
 The  ambient  emissions  measurements  performed  in  the  lower  ARNS  band  (960-  1160  MHz)  show  a  high  level  of  RF  activity  within  this  region  of  the  spectrum.  At  all 
 measurement  sites  significant  emissions  were  observed  in  the  band  with  associated  power  levels  well  in  excess  of  the  assumed  interference  threshold.  Existing  ambient  emissions 
 were  observed  in  the  band,  at  levels  up  to  35  dB  (more  than  3000  times)  greater  than  the  interference  threshold  assumed  in  deriving  the  UWB  emission  limits  applicable  to  the 
 band.  For  some  of  these  observed  emissions  the  source(  s)  were  readily  identifiable  (e.  g.,  the  Air  Traffic  Control  Radio  Beacon  System  interrogator  and  reply);  however,  for  many 
 others  the  source  was  not  readily  known. 
 Ambient  Emissions  Measurements  -  Indoor  Sites 
 When  the  measurement  system  was  moved  indoors  to  detect  the  presence  and  amplitude  of  existing  ambient  emissions  at  those  locations  consistent  with  the  operational 
 scenario  assumed  in  the  derivation  of  the  UWB  emission  limits  (e.  g.,  inside  office  buildings,  factories,  etc),  a  different  trend  emerged.  In  the  outdoor  measurements,  no 
 distinct  emissions  were  observed  in  either  the  GPS  L1  or  L2  frequency  bands.  However,  at  many  of  the  indoor  measurement  locations,  narrow-  band  emissions  were  observed  at 
 amplitudes  exceeding  the  assumed  GPS  interference  threshold  by  as  much  as  37.5  dB 
36
 30 
 (i.  e.,  by  more  than  5600  times).  It  was  beyond  the  scope  of  this  effort  to  identify  the  source  of  these  emissions;  however,  it  was  presumed  that  they  emanate  from  existing 
 electronic  devices  (e.  g.,  computers  and  peripherals,  copiers,  etc)  and  other  man-  made  noise  generated  by  a  variety  of  other  office  equipment  including  electric  motors.  The 
 magnitude  of  these  emissions  was  observed  to  be  related  to  the  density  and  distribution  of  the  electronic  systems  present  within  the  immediate  measurement  environment. 


 It  is  recognized  that  a  comparison,  in  terms  of  interference  potential,  between  a  narrow-  band  ambient  emission  and  a  UWB  emission  is  specious  unless  the  narrow  band 
 signal  is  coincident  with  the  pass  band  of  a  GPS  receiver.  However,  at  several  of  the  indoor  measurement  sites  the  maximum-  amplitude  narrow-  band  emission  was  indeed 
 detected  at  frequencies  coincident  with  the  pass  band  of  a  GPS  receiver  (e.  g.,  Office  Location  #2,  and  Factory  Location  #3).  In  other  cases,  although  the  maximum-  amplitude 
 emission  did  not  fall  within  the  pass  band,  one  of  the  intermediate-  amplitude  emissions  did. 


 Finally,  a  comparison  between  the  values  presented  in  the  last  columns  of  Tables  6-  1  and  6-  2  reveal  that  the  measurement  system  experienced  some  level  of 
 desensitization  at  all  but  one  of  the  indoor  measurement  sites.  For  the  outdoor  measurement  locations,  the  minimum  detectable  ambient  signal  was  typically  limited 
 only  by  the  sensitivity  of  the  measurement  system.  However,  for  all  but  one  of  the  indoor  measurement  locations  the  minimum  detectable  signal  was  limited  not  by  the 
 measurement  system  sensitivity,  but  by  the  existing  ambient  noise  environment.  This  measurement  system  desensitization  ranged  between  2  and  24  dB,  depending  on  the 
 measurement  band  and  location.  Since  the  measurement  system  was  configured  to  simulate  the  RF  front-  end  of  a  GPS  receiver,  it  is  reasonable  to  expect  that  a  GPS 
 receiver  would  likely  experience  a  similar  desensitization. 
 Similar  results  were  observed  in  both  the  GPS  L5  and  the  lower  ARNS  band.  At  least  some  of  the  ambient  emissions  detected  in  the  ARNS  band  were  attributed  to  known 
 systems  (e.  g.,  ATCRBS)  but  at  reduced  amplitudes  (relative  to  the  outdoor  measurement  data)  as  a  result  of  signal  attenuation  through  the  building  walls. 


 Radiated  Emissions  Measurements 
 Narrow-  band  spurious  emissions,  radiating  from  those  consumer-  grade  electronic  devices  tested  as  a  part  of  this  effort,  were  observed  in  each  of  the  GPS  frequency  bands. 
 The  power  density  levels  associated  with  these  emissions  were  typically  low  relative  to  the  applicable  emissions  limit  (e.  g.,  Part  15.109  22  ),  but  were  nonetheless  in  excess  of  the 
 UWB  emission  limits  by  as  much  as  27.5  dB  (more  than  500  times  greater).  Stated  another  way,  each  of  the  devices  measured  complies  with  the  applicable  emission  limits 
 in  the  frequency  bands  under  examination;  however,  if  they  were  subjected  to  the  emission  limits  for  UWB,  most  of  the  devices  examined  would  fail  a  compliance  test. 


 22  47  C.  F.  R.  Chapter  15,  Part  15,  Subpart  B,    15.  109. 
37
 31 
 All  of  the  radiated  spurious  emissions  observed  from  the  consumer-  grade  electronic  devices  were  narrow  band  in  structure.  As  stated  previously,  a  comparison,  in 
 terms  of  interference  potential,  between  a  narrow-  band  ambient  emission  and  a  UWB  emission  is  specious  unless  the  narrow  band  signal  is  coincident  with  the  pass  band  of  a 
 GPS  receiver.  Such  was  the  case  for  two  of  the  devices  examined  (Laptop  Computer  #2  and  the  Pendant  Transmitter).  Based  on  these  observations,  it  is  reasonable  to  suspect 
 that  other  unlicensed  electronic  devices  exist,  although  not  examined  within  this  effort,  whose  circuitry  also  generates  spurious  emissions  into  these  bands,  and  perhaps  also 
 within  the  GPS  receiver  pass  band. 
 Emissions  were  also  observed  from  the  consumer-  grade  electrical  devices  in  all  of  the  measurement  bands  at  various  amplitude  levels,  most  of  which  exceeded  the  GPS 
 receiver  interference  threshold  assumed  in  the  derivation  of  the  UWB  limit.  The  emissions  observed  from  these  measurements  are  all  attributed  to  electromagnetic  energy 
 resulting  from  the  armature-  stator  interaction  common  to  all  electric  motors.  These  types  of  emission  sources  are  deemed  incidental  radiators  since  their  function  does  not  require 
 the  generation  of  radio  frequency  signals.  The  power  density  associated  with  these  types  of  emissions  attenuates  rapidly  with  separation  distance,  and  thus  they  are  not  usually 
 considered  in  interference  analyses  to  electronic  systems.  Because  of  the  low  potential  for  interference  from  these  types  of  devices  to  electronic-  communication  systems,  the 
 FCC  does  not  regulate  them.  The  following  statement  from  the  Code  of  Federal  Regulations  is  the  only  applicable  regulation  with  regard  to  these  devices: 
 Manufacturers  of  these  devices  shall  employ  good  engineering  practices  to  minimize  the  risk  of  harmful  interference.  23  However,  under  extremely  conservative  assumptions, 
 such  as  the  two-  meter  interaction  distance  assumed  in  deriving  the  UWB  emission  limits,  these  types  of  devices  can  also  be  considered  as  potential  interferers. 


 The  data  collected  from  this  part  of  the  effort  shows  that  when  measured  at  a  distance  of  two  meters,  the  radiated  emission  amplitudes  from  the  consumer-  grade 
 electrical  devices  were  as  much  as  34.5  dB  (more  than  2800  times)  greater  than  the  assumed  interference  threshold  within  the  GPS  registered  frequency  bands.  The  data 
 further  shows  that  these  emission  amplitudes  were  as  much  as  27.5  dB  (more  than  560  times)  greater  than  the  theoretical  GPS  interference  threshold  within  the  pass  band  of  a 
 GPS  receiver. 
 CONCLUSIONS 
 The  following  statement  was  included  in  the  NTIA  letter  and  was  incorporated  into  the  UWB  R&  O.  ,  the  minimum  level  of  the  GPS  signal  that  can  be  used  for  an 
 E-  911  position  determination  will  be  determined  by  the  receiver  system  noise  density.  24  The  ambient  measurement  results  show  that  the  GPS  L1  and  L2  frequency  bands  are 
 quiet  with  respect  to  existing  ambient  emissions  at  those  outdoor  locations  where  tests  were  conducted.  However,  the  data  also  reveals  that  in  at  least  some  locations, 
 particularly  indoor  locations  similar  to  those  assumed  in  the  derivation  of  the  UWB 
 23  47  C.  F.  R.  Chapter  15,  Part  15,  Subpart  B,    15.  13. 
 24  NTIA  Letter  at  p.  9,  and  UWB  R&  O  at  par.  101. 
38
 32 
 emission  limits,  the  ambient  noise  environment,  rather  than  the  GPS  receiver  thermal  noise  density,  may  actually  be  the  limitation  to  the  reception  of  the  low-  amplitude  GPS 
 signals. 
 The  radiated  emissions  measurement  results  show  that  although  many  of  the  devices  tested  radiate  emissions  into  the  GPS  frequency  bands,  the  associated  amplitudes 
 were  at  much  lower  levels  than  permitted  by  the  applicable  limits.  However,  it  was  also  determined  that  the  amplitudes  (power  density)  associated  with  these  emissions  were 
 frequently  in  excess  of  the  limits  established  for  UWB  emissions. 
 As  part  of  this  measurement  effort,  the  ambient  noise  environment  in  the  lower  ARNS  (960-  1160  MHZ)  frequency  band  was  also  examined.  This  band  is  not  used  to 
 support  GPS  operations  nor  is  it  identified  for  use  in  the  GPS  modernization  plan.  Rather  this  frequency  band  is  used  to  support  terrestrial-  based  navigational  aids  such  as  the 
 Distance  Measuring  Equipment  (DME)  and  the  Air  Traffic  Control  Radio  Beacon  (ATCRBS).  NTIA  stated  that  "the  operational  limits  required  for  the  protection  of  the 
 GPS  will  also  be  adequate  to  protect  DME  operations."  The  measurement  results  show  that  the  ambient  emissions  in  this  band  are  generally  above  the  adopted  UWB  emission 
 limits.  Thus  it  appears  that  the  limiting  factor  in  this  band  will  also  be  the  ambient  noise  environment  rather  than  the  limit  based  on  the  GPS  receiver  thermal  noise  density.  In 
 addition,  Table  6  in  the  NTIA  letter  shows  that  a  maximum  EIRP  of  -64  dBm/  MHz  is  required  to  protect  the  DME  system  under  the  most  conservative  assumptions,  which  is 
 well  above  both  the  adopted  UWB  limit  and  the  ambient  noise  environment  for  this  band." 
39
 1 
 APPENDIX  A  MEASURMENT  SYSTEM  CALIBRATION  DATA 
 In  this  appendix,  the  spectrum  analyzer  plots  produced  from  the  calibration  of  the  RF  front-  end  (between  the  antenna  input  and  the  spectrum  analyzer  input)  of  the  two 
 measurement  systems  used  to  collect  the  data  in  this  effort  are  presented.  This  calibration  was  performed  by  inserting  a  known-  amplitude  continuous  wave  (CW)  signal  into  the 
 antenna  input  of  the  measurement  system.  The  signal  was  swept  across  each  of  the  frequency  bands  under  examination  in  this  measurement  effort.  The  spectrum  analyzer 
 was  used  to  record  the  resultant  power  as  a  function  of  frequency.  A  calibrated  signal  generator  was  used  to  provide  the  CW  signal.  The  input  amplitude  was  set  at  80  dBm 
 for  the  calibration  of  System  A  and  at    65  dBm  for  the  calibration  of  System  B.  The  resultant  spectrum  analyzer  trace  depicts  the  signal  gain  (or  loss)  in  the  RF  chain  over  the 
 frequency  range  under  examination  and  is  reported  in  Tables  A-  1  and  A-  2  as  the  measurement  system  external  gain.  This  external  gain  is  the  sum  of  the  gain  provided  by 
 the  cascaded  low  noise  amplifiers  less  the  attenuation  in  the  coaxial  cables,  connectors,  isolation  pad,  and  the  insertion  loss  of  the  band  pass  filter. 


 Table  A-  1  summarizes  the  data  obtained  from  the  calibration  curves  for  Measurement  System  A,  given  in  figures  A-  1  through  A-  7.  Table  A-  2  summarizes  the 
 data  obtained  from  the  calibration  of  Measurement  System  B,  with  the  complete  data  provided  in  Figures  A-  8  through  A-  14. 


 TABLE  A-  1.  Measurement  System  External  Gain  (System  A).  CENTER 
 FREQUENCY  (MHz)  MEASUREMENT  SYSTEM  EXTERNAL  GAIN  (dB) 
 1575.4  64.8  1227.6  66.7 
 1176.0  66.4  985.0  68.0 
 1035.0  67.7  1085.0  67.3 
 1135.0  67.0 
 TABLE  4-  3.  Measurement  System  External  Gain  (System  B).  CENTER 
 FREQUENCY  (MHz)  MEASUREMENT  SYSTEM  EXTERNAL  GAIN  (dB) 
 1575.4  63.5  1227.6  64.7 
 1176.0  64.9  985.0  67.4 
 1035.0  66.7  1085.0  66.6 
 1135.0  66.2 
40
 A-  2 
 Figure  A-  1.  Measurement  System  A  Calibration  Over  GPS  L1  Frequency  Band. 
 Figure  A-  2.  Measurement  System  A  Calibration  Over  GPS  L2  Frequency  Band. 
41
 A-  3 
 Figure  A-  3.  Measurement  System  A  Calibration  Over  GPS  L5  Frequency  Band. 
 Figure  A-  4.  Measurement  System  A  Calibration  Over  960-  1010  MHz  Frequency  Band. 
42
 A-  4 
 Figure  A-  5.  Measurement  System  A  Calibration  Over  1010-  1060  MHz  Frequency  Band. 
 Figure  A-  6.  Measurement  System  A  Calibration  Over  1060-  1110  MHz  Frequency  Band. 
43
 A-  5 
 Figure  A-  7.  Measurement  System  A  Calibration  Over  1110-  1160  MHz  Frequency  Band. 
 Figure  A-  8.  Measurement  System  B  Calibration  Over  GPS  L1  Frequency  Band. 
44
 A-  6 
 Figure  A-  9.  Measurement  System  B  Calibration  Over  GPS  L2  Frequency  Band. 
 Figure  A-  10.  Measurement  System  B  Calibration  Over  GPS  L5  Frequency  Band. 
45
 A-  7 
 Figure  A-  11.  Measurement  System  B  Calibration  Over  960-  1010  MHz  Frequency  Band. 
 Figure  A-  12.  Measurement  System  B  Calibration  Over  1010-  1060  MHz  Frequency  Band. 
46
 A-  8 
 Figure  A-  13.  Measurement  System  B  Calibration  Over  1060-  1110  MHz  Frequency  Band. 
 Figure  A-  14.  Measurement  System  B  Calibration  Over  1110-  1160  MHz  Frequency  Band. 
47
 1 
 APPENDIX  B  MEASUREMENT  PROCEDURES 
 This  appendix  presents  the  procedures  used  for  collection  of  the  data  utilized  in  this  report. 
 AMBIENT  EMISSIONS  MEASUREMENT  PROCEDURES 
 The  following  procedures  were  applied  in  performing  the  measurements  at  each  ambient  emissions  measurement  location: 


 1.  Set-  up  the  measurement  system  as  shown  in  Figure  2-  1. 
 2.  Set  measurement  antenna  to  a  nominal  height  of  four  feet  above  ground  level  (roughly  equivalent  to  typical  height  of  a  hand-  held  GPS  receiver  or  E-  911 
 enabled  cell  phone) 
 3.  Orient  the  measurement  antenna  in  vertical  polarization  and  rotate  through  360  observing  peak  signals  and  probable  direction. 


 4.  Repeat  with  antenna  oriented  in  horizontal  polarization. 
 5.  Review  the  collected  data  to  determine  antenna  polarization  and  the  bearing  that  maximizes  the  received  emission  levels. 


 6.  Using  the  data  obtained  from  the  previous  steps,  set  up  the  spectrum  analyzer  display  (e.  g.,  reference  level,  amplitude  scale,  attenuation  levels,  etc.)  to 
 accommodate  all  subsequent  measurements.  Set  the  analyzer  display  line  to  117.5  dBm. 


 7.  Sequentially  measure  over  each  of  the  frequency  bands  under  consideration  (i.  e.,  GPS  L1,  L2,  and  L5,  and  ARNS  band  segment)  collecting  peak  emission 
 traces  and  RMS  average  emission  traces,  by  utilizing  two  of  the  three  available  analyzer  traces. 


 8.  When  relatively  high  emission  levels  are  observed,  perform  a  system  saturation  test  by  inputting  an  additional  10-  dB  attenuator  at  the  spectrum 
 analyzer  input  and  verifying  that  the  received  signal  is  attenuated  by  10  dB. 
 9.  Store  the  composite  analyzer  displays  and  associated  trace  data  onto  computer  disk. 


 10.  Record  the  relevant  measurement  site  information,  i.  e.,  GPS  coordinates,  street  address,  site  description,  date,  time,  and  antenna  bearing. 
48
 2 
 RADIATED  EMISSIONS  MEASUREMENT  PROCEDURES 
 The  following  procedures  were  implemented  in  the  measurement  of  radiated  emissions  from  common  consumer  electronic  and  electrical  devices  into  the  GPS 
 frequency  bands: 
 1.  Assemble  measurement  system  as  shown  in  Figure  2-  1. 
 2.  Place  the  device  under  test  (DUT)  in  the  center  of  a  non-  conductive  turntable  and  turn  power  on. 


 3.  Place  the  measurement  antenna  at  a  distance  of  two  meters  from  the  DUT. 
 4.  Use  turntable  to  rotate  the  DUT  through  360  with  the  measurement  antenna  oriented  in  vertical  polarization. 


 5.  Re-  orient  the  measurement  antenna  to  horizontal  polarization  and  again  rotate  the  DUT  through  360. 
 6.  Review  the  data  and  observe  the  antenna  polarization  and  the  azimuth  with  respect  to  the  DUT  that  produces  the  maximum  emission  levels.  Use  this 
 polarization  and  DUT  orientation  for  the  remainder  of  the  test. 
 7.  With  DUT  radiating,  move  the  measurement  antenna  up  and  down  (between  approximately  1  and  3  meters)  to  determine  the  antenna  height  at  which  the 
 emissions  are  maximized.  Set  the  antenna  to  the  height  determined  from  this  procedure. 


 8.  Using  the  data  acquired  in  the  previous  steps,  set  up  the  spectrum  analyzer  display  (e.  g.,  reference  level,  amplitude  scale,  attenuation  levels,  etc.)  to 
 accommodate  all  subsequent  measurements.  Set  the  analyzer  display  line  to  117.5  dBm. 


 9.  Turn  the  DUT  off  and  use  the  spectrum  analyzers  trace  1  feature  to  record  the  ambient  RF  background. 
 10.  Turn  the  DUT  on  and  tune  the  spectrum  analyzer  to  one  of  the  frequency  bands  under  consideration.  Use  analyzer  trace  2  to  record  the  RMS  average 
 emission  from  the  DUT  and  use  trace  3  to  record  the  Log  average  measured  emissions. 


 11.  Store  the  composite  analyzer  trace  and  associated  trace  data  to  computer  disk. 
 12.  Repeat  steps  9-  11  for  each  of  the  frequency  bands  under  consideration. 
49
 1 
 APPENDIX  C  OUTDOOR  AMBIENT  EMISSIONS  MEASUREMENT  DATA 
 The  data  plots  recorded  from  the  measurement  of  existing  ambient  emissions  at  outdoor  sites  such  as  airports,  shipyards,  train  yards,  and  urban/  industrial  locations  are 
 presented  in  this  appendix.  The  following  paragraphs  provide  guidance  on  reading  and  interpreting  these  plots. 


 In  each  of  the  figures  presented  in  this  appendix,  the  upper  (yellow)  trace  depicts  the  ambient  emissions  measured  in  the  subject  frequency  band  using  a  peak  detector  and 
 the  maximum  hold  function  (i.  e.,  no  averaging  employed)  over  a  fifteen-  minute  period.  This  trace  was  generated  mainly  as  a  tool  for  orienting  the  measurement  antenna  and  for 
 determining  the  maximum  likely  emission  amplitudes  to  facilitate  decisions  pertaining  to  the  necessity  of  adding  additional  attenuation  in  the  measurement  system  so  as  to  prevent 
 overdriving  of  components.  This  data  was  not  used  for  any  analytical  purposes.  The  lower  (blue)  trace  represents  the  measured  RMS  average  emission  level  over  one  hundred 
 one-  millisecond  analyzer  sweeps  across  the  measurement  band.  This  is  the  data  used  to  compare  to  the  assumed  interference  threshold  for  enhanced  GPS  receivers.  The  constant 
 display  line  (green)  at  -117.5  dBm  is  used  as  the  basis  for  comparing  the  measured  data  to  the  theoretical  enhanced  GPS  interference  threshold. 


 All  external  measurement  system  parameters  (e.  g.,  amplifier  gains,  cable  loss,  and  antenna  gain)  are  accounted  for  in  the  spectrum  analyzer  display  and  are  provided  on 
 each  plot  under  the  tag  Ext  PG  located  at  the  top  of  the  display.  At  some  measurement  locations,  it  was  necessary  to  add  additional  attenuation  in  the  measurement  system  due 
 to  the  presence  of  relatively  high-  amplitude  signals.  In  those  cases  where  additional  external  attenuation  was  required,  the  Ext  PG  value  was  adjusted  accordingly.  Thus,  the 
 levels  shown  on  the  amplitude  axis  of  the  spectrum  analyzer  plots  represent  the  actual  RMS  average  power  as  measured  in  a  1  MHz  bandwidth  at  the  measurement  system 
 antenna. 
 In  each  of  these  plots,  the  horizontal  axis  represents  frequency  and  the  vertical  axis  represents  amplitude.  For  measurements  in  the  GPS  frequency  bands,  a  span  of  25 
 MHz  was  used  to  encompass  the  24  MHz  registered  frequency  band.  For  a  25  MHz  span,  each  vertical  graticule  line  represents  a  2.5  MHz  deviation  in  frequency  (25  MHz/  10 
 graticule  lines).  For  the  measurements  performed  in  the  960-  1160  MHz  (ARNS)  band,  a  span  of  50  MHz  was  used,  the  maximum  that  could  be  achieved  within  the  pass  band  of 
 the  pre-  select  filter.  In  these  plots,  each  vertical  graticule  line  represents  a  frequency  deviation  of  5  MHz  (50  MHz/  10  graticule  lines). 


 On  the  amplitude  axis,  each  horizontal  graticule  line  represents  a  10  dB  decrement  from  the  reference  level  amplitude  shown  in  the  upper  left-  hand  corner  of  the 
 plot. 
50
 2 
 Figure  C-  15.  Ambient  Emissions  in  the  GPS  L1  Frequency  Band  at  BWI  Airport. 
 Figure  C-  16.  Ambient  Emissions  in  the  GPS  L2  Frequency  Band  at  BWI  Airport. 
51
 3 
 Figure  C-  17.  Ambient  Emissions  in  the  GPS  L5  Frequency  Band  at  BWI  Airport. 
 Figure  C-  18.  Ambient  Emissions  in  the  960-  1010  MHz  Frequency  Band  at  BWI  Airport. 
52
 4 
 Figure  C-  19.  Ambient  Emissions  in  the  1010-  1060  MHz  Frequency  Band  at  BWI  Airport. 
 Figure  C-  20.  Ambient  Emissions  in  the  1060-  1110  MHz  Frequency  Band  at  BWI  Airport. 
53
 5 
 Figure  C-  21.  Ambient  Emissions  in  the  1110-  1160  MHz  Frequency  Band  at  BWI  Airport. 
54
 6 
 Figure  C-  22.  Ambient  Emissions  in  the  GPS  L1  Frequency  Band  at  Reagan  National  Airport. 
 Figure  C-  23.  Ambient  Emissions  in  the  GPS  L2  Frequency  Band  at  Reagan  National  Airport. 
55
 7 
 Figure  C-  24.  Ambient  Emissions  in  the  GPS  L5  Frequency  Band  at  Reagan  National  Airport. 
 Figure  C-  25.  Ambient  Emissions  in  the  960-  1010  MHz  Frequency  Band  at  Reagan  National  Airport. 
56
 8 
 Figure  C-  26.  Ambient  Emissions  in  the  1010-  1060  MHz  Frequency  Band  at  National  Airport. 
 Figure  C-  27.  Ambient  Emissions  in  the  1060-  1110  MHz  Frequency  Band  at  National  Airport. 
57
 9 
 Figure  C-  28.  Ambient  Emissions  in  the  1110-  1160  MHz  Frequency  Band  at  National  Airport. 
58
 10 
 Figure  C-  29.  Ambient  Emissions  in  the  GPS  L1  Frequency  Band  at  Dulles  International  Airport. 
 Figure  C-  30.  Ambient  Emissions  in  the  GPS  L2  Frequency  Band  at  Dulles  International  Airport. 
59
 11 
 Figure  C-  31.  Ambient  Emissions  in  the  GPS  L5  Frequency  Band  at  Dulles  International  Airport. 
 Figure  C-  32.  Ambient  Emissions  in  the  960-  1010  MHz  Frequency  Band  at  Dulles  Airport. 
60
 12 
 Figure  C-  33.  Ambient  Emissions  in  the  1010-  1060  MHz  Frequency  Band  at  Dulles  Airport. 
 Figure  C-  34.  Ambient  Emissions  in  the  1060-  1110  MHz  Frequency  Band  at  Dulles  Airport. 
61
 13 
 Figure  C-  35.  Ambient  Emissions  in  the  1110-  1160  MHz  Frequency  Band  at  Dulles  Airport. 
62
 14 
 Figure  C-  36.  Ambient  Emissions  in  the  GPS  L1  Frequency  Band  at  the  Port  of  Baltimore. 
 Figure  C-  37.  Ambient  Emissions  in  the  GPS  L2  Frequency  Band  at  the  Port  of  Baltimore. 
63
 15 
 Figure  C-  38.  Ambient  Emissions  in  the  GPS  L5  Frequency  Band  at  the  Port  of  Baltimore. 
 Figure  C-  39.  Ambient  Emissions  in  the  960-  1010  MHz  Frequency  Band  at  the  Port  of  Baltimore. 
64
 16 
 Figure  C-  40.  Ambient  Emissions  in  the  1010-  1060  MHz  Frequency  Band  at  the  Port  of  Baltimore. 
 Figure  C-  41.  Ambient  Emissions  in  the  1060-  1110  MHz  Frequency  Band  at  the  Port  of  Baltimore. 
65
 17 
 Figure  C-  42.  Ambient  Emissions  in  the  1110-  1160  MHz  Frequency  Band  at  the  Port  of  Baltimore. 
66
 18 
 Figure  C-  43.  Ambient  Emissions  in  the  GPS  L1  Frequency  Band  at  the  U.  S.  Coast  Guard  Yard. 
 Figure  C-  44.  Ambient  Emissions  in  the  GPS  L2  Frequency  Band  at  the  U.  S.  Coast  Guard  Yard. 
67
 19 
 Figure  C-  45.  Ambient  Emissions  in  the  GPS  L5  Frequency  Band  at  the  U.  S.  Coast  Guard  Yard. 
 Figure  C-  46.  Ambient  Emissions  in  the  960-  1010  MHz  Frequency  Band  at  the  Coast  Guard  Yard. 
68
 20 
 Figure  C-  47.  Ambient  Emissions  in  the  1010-  1060  MHz  Frequency  Band  at  the  Coast  Guard  Yard. 
 Figure  C-  48.  Ambient  Emissions  in  the  1060-  1110  MHz  Frequency  Band  at  the  Coast  Guard  Yard. 
69
 21 
 Figure  C-  49.  Ambient  Emissions  in  the  1110-  1160  MHz  Frequency  Band  at  the  Coast  Guard  Yard. 
70
 22 
 Figure  C-  50.  Ambient  Emissions  in  the  GPS  L1  Frequency  Band  at  the  AMTRAK  Train  Yard. 
 Figure  C-  51.  Ambient  Emissions  in  the  GPS  L2  Frequency  Band  at  the  AMTRAK  Train  Yard. 
71
 23 
 Figure  C-  52.  Ambient  Emissions  in  the  GPS  L5  Frequency  Band  at  the  AMTRAK  Train  Yard. 
 Figure  C-  53.  Ambient  Emissions  in  the  960-  1010  MHz  Frequency  Band  at  the  Train  Yard. 
72
 24 
 Figure  C-  54.  Ambient  Emissions  in  the  1010-  1060  MHz  Frequency  Band  at  the  Train  Yard. 
 Figure  C-  55.  Ambient  Emissions  in  the  1060-  1110  MHz  Frequency  Band  at  the  Train  Yard. 
73
 25 
 Figure  C-  56.  Ambient  Emissions  in  the  1110-  1160  MHz  Frequency  Band  at  the  Train  Yard. 
74
 26 
 Figure  C-  57.  Ambient  Emissions  in  the  GPS  L1  Frequency  Band  at  Urban/  Industrial  Site. 
 Figure  C-  58.  Ambient  Emissions  in  the  GPS  L2  Frequency  Band  at  Urban/  Industrial  Site. 
75
 27 
 Figure  C-  59.  Ambient  Emissions  in  the  GPS  L5  Frequency  Band  at  Urban/  Industrial  Site. 
 Figure  C-  60.  Ambient  Emissions  in  the  960-  1010  MHz  Frequency  Band  at  Urban/  Industrial  Site. 
76
 28 
 Figure  C-  61.  Ambient  Emissions  in  the  1010-  1060  MHz  Frequency  Band  at  Urban/  Industrial  Site. 
 Figure  C-  62.  Ambient  Emissions  in  the  1060-  1110  MHz  Frequency  Band  at  Urban/  Industrial  Site. 
77
 29 
 Figure  C-  63.  Ambient  Emissions  in  the  1110-  1160  MHz  Frequency  Band  at  Urban/  Industrial  Site. 
78
 1 
 APPENDIX  D  INDOOR  AMBIENT  EMISSIONS  MEASUREMENT  DATA 
 The  data  plots  recorded  from  the  measurement  of  existing  ambient  emissions  at  indoor  sites  such  as  office  buildings  and  factory  facilities  are  presented  in  this  appendix. 
 The  following  paragraphs  provide  guidance  on  reading  and  interpreting  these  plots. 
 In  each  of  the  figures  presented  in  this  appendix,  the  upper  (yellow)  trace  depicts  the  ambient  emissions  measured  in  the  subject  frequency  band  using  a  peak  detector  and 
 the  maximum  hold  function  (i.  e.,  no  averaging  employed)  over  a  fifteen-  minute  period.  This  trace  was  generated  mainly  as  a  tool  for  orienting  the  measurement  antenna  and  for 
 determining  the  maximum  likely  emission  amplitudes  to  facilitate  decisions  pertaining  to  the  necessity  of  adding  additional  attenuation  in  the  measurement  system  so  as  to  prevent 
 overdriving  of  components.  This  data  was  not  used  for  any  analytical  purposes.  The  lower  (blue)  trace  represents  the  measured  RMS  average  emission  level  over  one  hundred 
 one-  millisecond  analyzer  sweeps  across  the  measurement  band.  This  is  the  data  used  to  compare  to  the  assumed  interference  threshold  for  enhanced  GPS  receivers.  The  constant 
 display  line  (green)  at  -117.5  dBm  is  used  as  the  basis  for  comparing  the  measured  data  to  the  theoretical  enhanced  GPS  interference  threshold. 


 All  external  measurement  system  parameters  (e.  g.,  amplifier  gains,  cable  loss,  and  antenna  gain)  are  accounted  for  in  the  spectrum  analyzer  display  and  are  provided  on 
 each  plot  under  the  tag  Ext  PG  located  at  the  top  of  the  display.  At  some  measurement  locations,  it  was  necessary  to  add  additional  attenuation  in  the  measurement  system  due 
 to  the  presence  of  relatively  high-  amplitude  signals.  In  those  cases  where  additional  external  attenuation  was  required,  the  Ext  PG  value  was  adjusted  accordingly.  Thus,  the 
 levels  shown  on  the  amplitude  axis  of  the  spectrum  analyzer  plots  represent  the  actual  RMS  average  power  as  measured  in  a  1  MHz  bandwidth  at  the  measurement  system 
 antenna. 
 In  each  of  these  plots,  the  horizontal  axis  represents  frequency  and  the  vertical  axis  represents  amplitude.  For  measurements  in  the  GPS  frequency  bands,  a  span  of  25 
 MHz  was  used  to  encompass  the  24  MHz  registered  frequency  band.  For  a  25  MHz  span,  each  vertical  graticule  line  represents  a  2.5  MHz  deviation  in  frequency  (25  MHz/  10 
 graticule  lines).  For  the  measurements  performed  in  the  960-  1160  MHz  (ARNS)  band,  a  span  of  50  MHz  was  used,  the  maximum  that  could  be  achieved  within  the  pass  band  of 
 the  pre-  select  filter.  In  these  plots,  each  vertical  graticule  line  represents  a  frequency  deviation  of  5  MHz  (50  MHz/  10  graticule  lines). 


 On  the  amplitude  axis,  each  horizontal  graticule  line  represents  a  10  dB  decrement  from  the  reference  level  amplitude  shown  in  the  upper  left-  hand  corner  of  the 
 plot. 
79
 2 
 Figure  D-  64.  Ambient  Emissions  in  GPS  L1  Frequency  Band  Office  Building  #1. 
 Figure  D-  65.  Ambient  Emissions  in  GPS  L2  Frequency  Band  Office  Building  #1. 
80
 3 
 Figure  D-  66.  Ambient  Emissions  in  GPS  L5  Frequency  Band  Office  Building  #1. 
 Figure  D-  67.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Office  Building  #1. 
81
 4 
 Figure  D-  68.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Office  Site  #1. 
 Figure  D-  69.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Office  Site  #1. 
82
 5 
 Figure  D-  70.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Office  Site  #1. 
83
 6 
 Figure  D-  71.  Ambient  Emissions  in  GPS  L1  Frequency  Band  at  Office  Site  #2. 
 Figure  D-  72.  Ambient  Emissions  in  GPS  L2  Frequency  Band  at  Office  Site  #2. 
84
 7 
 Figure  D-  73.  Ambient  Emissions  in  GPS  L5  Frequency  Band  at  Office  Site  #2. 
 Figure  D-  74.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Office  Site  #2. 
85
 8 
 Figure  D-  75.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Office  Site  #2. 
 Figure  D-  76.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Office  Site  #2. 
86
 9 
 Figure  D-  77.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Office  Site  #2. 
87
 10 
 Figure  D-  78.  Ambient  Emissions  in  GPS  L1  Frequency  Band  at  Office  Site  #3. 
 Figure  D-  79.  Ambient  Emissions  in  GPS  L2  Frequency  Band  at  Office  Site  #3. 
88
 11 
 Figure  D-  80.  Ambient  Emissions  in  GPS  L5  Frequency  Band  at  Office  Site  #3. 
 Figure  D-  81.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Office  Site  #3. 
89
 12 
 Figure  D-  82.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Office  Site  #3. 
 Figure  D-  83.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Office  Site  #3. 
90
 13 
 Figure  D-  84.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Office  Site  #3. 
91
 14 
 Figure  D-  85.  Ambient  Emissions  in  GPS  L1  Frequency  Band  at  Office  Site  #4. 
 Figure  D-  86.  Ambient  Emissions  in  GPS  L2  Frequency  Band  at  Office  Site  #4. 
92
 15 
 Figure  D-  87.  Ambient  Emissions  in  GPS  L5  Frequency  Band  at  Office  Site  #4. 
 Figure  D-  88.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Office  Site  #4. 
93
 16 
 Figure  D-  89.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Office  Site  #4. 
 Figure  D-  90.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Office  Site  #4. 
94
 17 
 Figure  D-  91.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Office  Site  #4. 
95
 18 
 Figure  D-  92.  Ambient  Emissions  in  GPS  L1  Frequency  Band  at  Office  Site  #5. 
 Figure  D-  93.  Ambient  Emissions  in  GPS  L2  Frequency  Band  at  Office  Site  #5. 
96
 19 
 Figure  D-  94.  Ambient  Emissions  in  GPS  L5  Frequency  Band  at  Office  Site  #5. 
 Figure  D-  95.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Office  Site  #5. 
97
 20 
 Figure  D-  96.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Office  Site  #5. 
 Figure  D-  97.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Office  Site  #5. 
98
 21 
 Figure  D-  98.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Office  Site  #5. 
99
 22 
 Figure  D-  99.  Ambient  Emissions  in  GPS  L1  Frequency  Band  at  Factory  Site  #1. 
 Figure  D-  100.  Ambient  Emissions  in  GPS  L2  Frequency  Band  at  Factory  Site  #1. 
100
 23 
 Figure  D-  101.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Factory  Site  #1. 
 Figure  D-  102.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Factory  Site  #1. 
101
 24 
 Figure  D-  103.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Factory  Site  #1. 
 Figure  D-  104.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Factory  Site  #1. 
102
 25 
 Figure  D-  105.  Ambient  Emissions  in  GPS  L1  Frequency  Band  at  Factory  Site  #2. 
 Figure  D-  106.  Ambient  Emissions  in  GPS  L2  Frequency  Band  at  Factory  Site  #2. 
103
 26 
 Figure  D-  107.  Ambient  Emissions  in  GPS  L5  Frequency  Band  at  Factory  Site  #2. 
 Figure  D-  108.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Factory  Site  #2. 
104
 27 
 Figure  D-  109.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Factory  Site  #2. 
 Figure  D-  110.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Factory  Site  #2. 
105
 28 
 Figure  D-  111.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Factory  Site  #2. 
106
 29 
 Figure  D-  112.  Ambient  Emissions  in  GPS  L1  Frequency  Band  at  Factory  Site  #3. 
 Figure  D-  113.  Ambient  Emissions  in  GPS  L2  Frequency  Band  at  Factory  Site  #3. 
107
 30 
 Figure  D-  114.  Ambient  Emissions  in  GPS  L5  Frequency  Band  at  Factory  Site  #3. 
 Figure  D-  115.  Ambient  Emissions  in  960-  1010  MHz  Frequency  Band  at  Factory  Site  #3. 
108
 31 
 Figure  D-  116.  Ambient  Emissions  in  1010-  1060  MHz  Frequency  Band  at  Factory  Site  #3. 
 Figure  D-  117.  Ambient  Emissions  in  1060-  1110  MHz  Frequency  Band  at  Factory  Site  #3. 
109
 32 
 Figure  D-  118.  Ambient  Emissions  in  1110-  1160  MHz  Frequency  Band  at  Factory  Site  #3. 
110
 1 
 APPENDIX  E  RADIATED  EMISSIONS  MEASUREMENT  DATA 
 The  data  plots  recorded  from  the  measurements  of  radiated  emissions  from  common  consumer  electronic/  electrical  devices  are  presented  in  this  appendix. 
 In  each  of  the  spectrum  analyzer  plots  presented  in  this  Appendix,  two  measurement  traces  are  shown.  The  lower  (yellow)  trace  represents  the  background 
 (ambient)  emissions  in  the  frequency  band  under  examination  with  the  DUT  turned  off.  The  upper  (blue)  trace  represents  the  sum  of  the  RMS  average  emissions  radiated  from 
 the  DUT  and  the  existing  background  (ambient)  emissions.  A  constant  display  line  (green)  is  also  shown  in  each  plot.  This  is  set  to  a  level  of  -117.5  dBm  to  represent  the 
 received  power  equivalent  to  the  UWB  EIRP  limit  of  -75.3  dBm/  MHz  at  a  distance  of  two  meters. 


 All  external  measurement  system  parameters  (e.  g.,  amplifier  gains,  cable  loss,  and  antenna  gain)  are  accounted  for  in  the  spectrum  analyzer  display  and  are  provided  on 
 each  plot  under  the  tag  Ext  PG  located  at  the  top  of  the  display. 
 In  each  of  these  plots,  the  horizontal  axis  represents  frequency  and  the  vertical  axis  represents  amplitude.  A  span  of  25  MHz  was  used  to  encompass  the  24  MHz 
 registered  GPS  frequency  band.  For  a  25  MHz  span,  each  vertical  graticule  line  represents  a  2.5  MHz  deviation  in  frequency  (25  MHz/  10  graticule  lines).  On  the 
 amplitude  axis,  each  horizontal  graticule  line  represents  a  10  dB  decrement  from  the  reference  level  amplitude  shown  in  the  upper  left-  hand  corner  of  the  plot.  Note  that  some 
 of  these  plots  utilize  other  than  10  dB  per  vertical  division  (graticule  line).  This  was  done  to  facilitate  better  resolution  of  the  signals  under  examination.  These  plots  are  read  the 
 same  way  as  described  previously  except  that  each  vertical  line  may  represent  a  deviation  of  2,  3,  or  5  dB  from  the  reference  level.  The  dB-  per-  division  scale,  applicable  to  each 
 plot,  is  shown  in  the  upper  left-  hand  margin. 
 An  important  consideration  in  the  interpretation  of  this  data  is  the  fact  that  the  radiated  spurious  power  captured  by  the  measurement  system  is  actually  the  sum  of  the 
 ambient  emissions  already  present  and  those  spurious  emissions  introduced  when  the  DUT  is  turned  on.  Since  the  emissions  under  consideration  in  this  study  are  often  very 
 close  to  the  ambient  noise  floor,  the  contribution  of  the  noise  floor  to  this  sum  can  be  significant.  Within  this  study,  if  the  difference  between  the  measured  ambient  level  and 
 the  corresponding  radiated-  plus-  ambient  level  is  3  dB,  then  the  DUT  emission  amplitude  level  is  interpreted  as  being  equivalent  to  the  ambient  level.  Accordingly,  if  the 
 difference  between  the  DUT  radiated-  plus-  ambient  emission  level  and  the  corresponding  ambient  emission  level  is  less  than  3  dB,  then  the  DUT  emission  level  is  interpreted  as 
 being  less  than  the  ambient  level.  Emissions  that  are  more  than  3  dB  above  the  corresponding  ambient  level  are  attributed  to  spurious  emissions  from  the  DUT. 
111
 2 
 Figure  E-  119.  Desktop  Computer  #1  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  120.  Desktop  Computer  #1  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
112
 3 
 Figure  E-  121.  Desktop  Computer  #1  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
113
 4 
 Figure  E-  122.  Desktop  Computer  #2  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  123.  Desktop  Computer  #2  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
114
 5 
115
 6 
 Figure  E-  124.  Desktop  Computer  #2  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
116
 7 
 Figure  E-  125.  Desktop  Computer  #3  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  126.  Desktop  Computer  #3  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
117
 8 
 Figure  E-  127.  Desktop  Computer  #3  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
118
 9 
 Figure  E-  128.  Laptop  Computer  #1  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  129.  Laptop  Computer  #1  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
119
 10 
 Figure  E-  130.  Laptop  Computer  #1  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
120
 11 
 Figure  E-  131.  Laptop  Computer  #2  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  132.  Laptop  Computer  #2  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
121
 12 
 Figure  E-  133.  Laptop  Computer  #2  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
122
 13 
 Figure  E-  134.  Laptop  Computer  #3  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  135.  Laptop  Computer  #3  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
123
 14 
 Figure  E-  136.  Laptop  Computer  #3  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
124
 15 
 Figure  E-  137.  Laptop  Computer  #4  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  138.  Laptop  Computer  #4  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
125
 16 
 Figure  E-  139.  Laptop  Computer  #4  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
 Note  #1:  In  this  spectral  plot,  the  ambient  or  background  emission  level  is  shown  as  greater  than  the  sum  of  the  radiated  emissions  and  the  background  emissions  in  the  highlighted  frequency  range.  Although  this 
 apparent  inconsistency  was  not  thoroughly  examined,  the  most  likely  explanation  is  as  follows:  the  background  measurement  and  the  radiated  measurements  were  performed  sequentially  rather  than 
 simultaneously.  The  ambient  emission  was  higher  when  the  background  measurement  was  performed  than  it  was  when  the  radiated  measurement  was  made.  This  can  be  attributed  to  one  or  more  of  the  following 
 phenomena.  An  antenna  rotation  associated  with  the  ambient  transmitter  (e.  g.,  transmit  antenna  was  pointed  in  the  direction  of  the  test  facility  when  the  background  measurement  was  made,  but  pointed  away 
 during  the  radiated  emissions  measurement)  or  fading  due  to  the  occurrence  of  multi-  path  signal  arrival  at  the  measurement  antenna. 


 See  Note  #1  Below 
126
 17 
 Figure  E-  140.  Personal  Digital  Assistant  (PDA)  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  141.  Personal  Digital  Assistant  (PDA)  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
127
 18 
 Figure  E-  142.  Personal  Digital  Assistant  (PDA)  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
 Figure  E-  143.  Pendant  Transmitter  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
128
 19 
 Figure  E-  144.  Electric  Drill  #1  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  145.  Electric  Drill  #1  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
129
 20 
 Figure  E-  146.  Electric  Drill  #1  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
130
 21 
 Figure  E-  147.  Electric  Drill  #2  Radiated  Emissions  in  GPS  L1  Frequency  Band. 
 Figure  E-  148.  Electric  Drill  #2  Radiated  Emissions  in  GPS  L2  Frequency  Band. 
131
 22 
 Figure  E-  149.  Electric  Drill  #2  Radiated  Emissions  in  GPS  L5  Frequency  Band. 
132
 23 
 Figure  E-  150.  Electric  Hairdryer  #1  Radiated  Emissions  in  the  GPS  L1  Frequency  Band. 
 Figure  E-  151.  Electric  Hairdryer  #1  Radiated  Emissions  in  the  GPS  L2  Frequency  Band. 
133
 24 
 Figure  E-  152.  Electric  Hairdryer  #1  Radiated  Emissions  in  the  GPS  L5  Frequency  Band. 
134
 25 
 Figure  E-  153.  Electric  Hairdryer  #2  Radiated  Emissions  in  the  GPS  L1  Frequency  Band. 
 Figure  E-  154.  Electric  Hairdryer  #2  Radiated  Emissions  in  the  GPS  L2  Frequency  Band. 
135
 26 
 Figure  E-  155.  Electric  Hairdryer  #2  Radiated  Emissions  in  the  GPS  L5  Frequency  Band. 
136
 27 
 Figure  E-  156.  Electric  Vacuum  Cleaner  Radiated  Emissions  in  the  GPS  L1  Frequency  Band. 
 Figure  E-  157.  Electric  Vacuum  Cleaner  Radiated  Emissions  in  the  GPS  L2  Frequency  Band. 
137
 28 
 Figure  E-  158.  Electric  Vacuum  Cleaner  Radiated  Emissions  in  the  GPS  L5  Frequency  Band. 
138