GPS英文缩写

1 PPM - 1 Pulse Per Minute  1 PPS - 1 Pulse Per Second  14AF - 14th Air Force, USAF  19SOPS - 19th Space Operations Squadron, USAF  1-D - One-dimensional  1SOPS - 1st Space Operations Squadron, USAF  2-D - Two Dimensional  2DRMS - Two times the standard deviation or Twice Distance Root Mean  2SOPS - 2nd Satellite Operations Squadron, USAF  3-D - Three Dimensional  4-D - Four Dimensional (3-D plus time) A/C - Aircraft  A/D - Analog to Digital  A/J - Anti-Jamming  AAATS - Australian Advanced Air Traffic Services  ABAS - Aircraft-based Augmentation Systems  ABM - Abeam  ACI - Allocated Configuration Identification  ACU - Antenna Control Unit  ACSM - American Congress on Surveying and Mapping  A/D - Analog To Digital  ADC - Analog to digital converter  ADF - Automatic Direction Finder  ADI - Attitude Director lndicator  ADIU - Advanced Digital Interface Unit  ADP - Automated Data Processing  ADR - Accumulated Delta Range  ADS - Automatic Dependent Surveillance  AE - Antenna Electronics  AECB - Atomic Energy Control Board  AF - Air Force  AFB - Air Force Base  AFI - Automatic Fault Indication  AFSPC - Air Force Space Command  AGL - Above Ground Level  AHRS - Attitude Heading Reference System  AI - Artificial Intelligence  AIAA - American Institute of Aeronautics and Astronautics  AIS - Automated Information System  AJ - Antijamming  ALT - Alternate  ALT - Altitude  AM - Amplitude Modulation  AM/FM - Automated Mapping and Facilities Management  AMCS - Alternate Master Control Station  ANE - Autonomous Navigation Emulator  ANSI - American National Standards Institute  ANTB - Advanced Navigation Test Bed  AoA - Analysis of Alternatives  AOA - Airport Operations Area  AOA - Angle-of-Attack  AOC - Aeronautical Operation Control  AOC - Auxiliary Output Chip  AOC - Auxiliary Output Chip  AOCS - Attitude and Orbit Control System  AOM - Aircraft Operating Manual  AOO - Area of Operations  AOPA - Aircraft Owners And Pilots Association  AOR - Area of responsibility  AORP - Airfield Obstruction Reduction Program  AP - Acquisition Plan  APA - Airline Pilots Association  APMS - Automated Performance Measurement System  APPR - Approach/Approach Mode  APPS - Analytical Photogrammetric Positioning System  APR - April  APU - Auxiliary Power Unit  AQP - Advanced Qualification Program  ARGO - Automatic Ranging Grid Overlay  ARNS - Aeronautical Radio Navigation Service  ARPA - Advanced Research Projects Agency  ARR - Arrival  ARTCC - Air Route Traffic Control Center  ARTS - Automated Remote Tracking Station  ARTS - Automated Radar Terminal System  AS - AntiSpoofing  ASCII - American Standard Code for Interface and Interchange  ASF - Additional Secondary Factor (Loran-C)  ASI - Air Speed Indicator  ASIC - - Application Specific Integrated Circuit  ASPRS - American Society of Photogrammetry and Remote Sensing  ASR - Airport Surveillance Radar  ATA - Air Transport Association  ATC - Air Traffic Control ATCS - Advanced Train Control Systems  ATCSCC - Air Traffic Control System Command Center  ATE - Automatic Test Equipment  ATM - Air Transportation Management  ATON - Aids To Navigation  ATS - Automatic Throttle System  AUG - August  Autonav - Autonomous Navigation  AVAIL - Available  AVL - Automatic Vehicle Location  AVL - Automatic Vehicle Location -  AVLN - Automatic Vehicle Location And Navigation  AVM - Automatic Vehicle Monitoring  AWACS - Airborne Warning And Control System  AWAS - Automated Weather Advisory Station  AWIPS - Advanced Weather Interactive Processing System  B - Billion  BBS - Bulletin Board Service  BCD - Binary Code Decimal  BER - Bit Error Rate  BIPM - International Bureau of Weights and Measures  BITE - Built-in Test Equipment  BMCS - Backup Master Control Station (MCS)  Bps - Bits per second  BPSK - Binary Phase Shift Keying  BRG - Bearing  BRT - Brightness  BUMCS - Back-up Master Control Station  C - Centigrade  C&A - Certification and Accreditation  C/A - Coarse Acquisition Code  C/No - Carrier to Noise Ratio  C/PD - Cost/Pricing Data  C2 - Command and Control  C3 - Command, Control, and Communications  C3I - Command, Control, Communications, and Intelligence  CAD - Computer Aided Design  CASE - Computer Aided Software Engineering  CAT - Computer Aided Testing  CBD - Commerce Business Daily  CBT - Computer Based Training  CCB - Configuration Control Board  CCW - Continuous carrier wave  CCW - Coded Continuous Wave  CCZ - Coastal And Confluence Zone  CDMA - Code Division Multiple Access  CDU - Control Display Unit  CDMA - Code Division Multiple Access (GPS)  CEP - Circular error probable  CG - Center of Gravity  CGS - Centimeter-gram-second  Cl - Cost Index  CLR - Clear  cm - Centimeter  CM - Configuration Management  CMG - Command Managers Guide  CMOS - Complementary Metal Oxide Semiconductor  CMC - Central Maintenance Computer  CMP - Configuration Management Plan  CMS - Command Management Seminar  CNA - Computer Network Attack  CNS - Communications, Navigation, And Surveillance  CO - Contracting Officer; Change Order; Commanding Officer; Colorado  COE - Common Operating Environment; Center of Expertise  CONOPS - Concept of Operations  COP - Circle Of Position  CONUS - Continental United States  CORS - Continuously Operating Reference Station  COTS - Commercial Off-The-Shelf  CPU - Central Processing Unit  CRPA - Controlled Radiation Pattern Antenna  CRT - Cathode Ray Tube  CRYPTO - cryptographic  CS - Control Segment  CTR - Center  CSAT - Constellation System Assessment Team  CTRL - Control  CTS - Colorado Tracking Station  CUE - Common User Element  CVNS - carrier navigation systems  CW - Continuous Wave  CY - Calendar Year  D/A - Digital To Analog  D/D - Drift Down  DAC - Digital to Analog Converter  DATALINK - Digitized Information Transfer (air/ground)  dB - Decibel (X = 10 Log X dB)  DBS - Direct Broadcast Satellite  dBW - decibels per watt  DC - Direct Current Electricity  DEC - December  DECR - Decrement  DEG - degree  DEL - Delete  DEP - Departure  DEV - Deviation  DF - direction finding  DGIC - Differential GPS Integrity Channel  DGNS - Doppler GPS Navigation System  DGPS - Differential Global Positioning System  DH - Decision Height  DID - Data Item Description  DIS - Distance  DISCR - Discrepancy  DIST - Distance  DLL - Delay Lock Loop  DLM - Data Loader Module  DLR - Data Loader Receptable  DLS - Data Loader System  DLT - Data Link Terminal  DMA - Defense Mapping Agency  DME - Distance Measuring Equipment  DMU - Data Management Unit  DoD - Department Of Defense  DOE - Department of Energy  DOP - Dilution Of Precision  DoT - Department Of Transportation  DR - Dead Reckoning  DRMS - Distance Root Mean Square  DRS - Dead Reckoning System  DRU - Data Retrival Unit  DT&E - Development Test and Evaluation  DTG - Distance-to-go  E - East  EA - Electronic Attack; Evolutionary Acquisition  ECDIS - Electronic Chart Display And Information System  ECEF - Earth Centered, Earth Fixed  EDM - Electronic Distance Measurement  EGNOS - European Geostationary Navigation Overlay Service  EOS - Earth Orbiting System  EPROM - Erasable Programmable Read-Only Memory  EHF - Extremely High Frequency  ETA - Estimated Time Of Arrival  ECE - Earth-Centered-Earth-Fixed  ECEF - Earth Centered, Earth Fixed  ECM - Electronic Countermeasures  ECP - Engineering Change Proposal  ECS - Environmental Control System  EDM - Electronic Distance Measurement  EFIS - Electronic Flight Instrument System  EHF - Extremely High Frequency  EHSI - Electronic Horizontal Situation Indicator  EIU - Electronic Interface Unit  EKMS - Electronic Key Management System  ELEV - Elevation  ELT - Emergency Locator Transmitter  EM - Electro Magnetic  EMC - Electromagnetic Compatibility  EMCON - Emission Control  EMI - Electromagnetic Interference  EMP - Electromagnetic Pulse  EMS - Emergency Medical Services  ENG - Engine  EOL - End of Life  EOW - End of Week  EPR - Engine Pressure Ratio  EPROM - Erasable Programmable Read-Only Memory  EPS - Electric Power System  ES - Electronic Support  ESGN - Electrically Suspended Gyro Navigator  ESM - Electronic Support Measures  EST - Estimated  ETA - Estimated Time of Arrival  ETX - End of Transmission  EU - European Union  EW - Electronic Warfare  EXEC - Execute  Exp - Exponential Function  F - Fahrenheit  f - Frequency  FAA - Federal Aviation Administration  FAATC - FAA Technical Center - Atlantic City, New Jersey  FADEC - Full Authority Digital Engine Control  FANS - Future Air Navigation Systems  FAR - Federal Acquisition Regulation  FBO - Fixed Based Operator  FCC - Federal Communications Commission  FCC - Flight Control Computer  FCMDR - Flight Commander  FCU - Flight Control Unit  FD - Fault Detection  FDE - Fault Detection Equipment; Fault Detection and Exclusions  FDMA - Frequency Division Multiple Access -  FDR - Flight Data Recorder  FEB - February  FHWA - Federal Highway Administration  FLT - Flight  FI - Fault Isolation  FL - Florida  FM - Frequency Modulation  FMEA Failure Mode and Effects Analysis  FMS - Flight Management Systems  FO - First officer  FOC - Full Operational Capability  FOM - - Figure Of Merit  FOIA - Freedom of Information Act  FOUO - For Official Use Only  FPA - Focal Plane Array  FPM - Feet Per Minute  FQIS - Fuel Quantity Indicating System  FR - From  FRA - Federal Railroad Administration  FRA - Flap Retraction Altitude  FREQ - Frequency  FRP - Federal Radionavigation Plan  FRPA - Fixed Radiation Pattern Antenna  FRPA-GP - FRPA Ground Plane  FSS - Federal Supply Schedule  FT - Feet  FY - fiscal year  GA - General Aviation  GA - Ground Antenna  GANS - global access, navigation and safety  GAO - General Accounting Office  GATM - Global Air Traffic Management  GBAS - Ground-based augmentation system  Gbps - Gigabits per second  GDOP - Geometric Dilution Of Precision  GEO - Geosynchronous Earth Orbit  GEOREF - World Geographic Reference System  GHz - Gigahertz  GIAC - GPS Interagency Advisory Council  GIB - GPS Integrity Broadcast  GIC - GPS Integrity Channel  GIS - Geographic Information Systems  GLONASS - Global Navigation Satellite System  GMT - Greenwich Mean Time  GNSS - Global Navigation Satellite Systems  GPS - Global Positioning System  GPSE - GPS Enhancement  GPSIC - GPS Information Center  GRAS - Ground-based regional augmentation system  GRP - Geographical Reference Points  GRS - Geodetic Reference System  GS - Glide Slope  GS - Ground Speed  GSA - General Services Administration  GW - Gross Weight  GYRO - gyroscope  HADGPS - High Accuracy DGPS  HANU - High Accuracy Navigational Users  HD - High dynamic  HDG - Heading  HDG - SEL - Heading Select  HDOP - Horizontal Dilution of Precision  HF - High Frequency  HHA - Harbor And Harbor Approach  HF - high frequency  HIRS - High-Resolution Infrared Sounder  HMI - Hazardously Misleading Information  HR - relative height  HUD - Head-Up Display  HV - Host Vehicle  Hz - Hertz (cycles per second)  IALA - International Association Of Lighthouse Authorities  ICAO - International Civil Aviation Organization  ICD - Interface Control Document  ICS - Interim Control Segment  ID - Identifier  ICWG - Interface Control Working Group  IDD - Interface Design Document  IEEE - Institute Of Electrical And Electronics Engineers  IERS - International Earth Rotation Service  IF - Intermediate Frequency  IFF - Identification Friend or Foe  IFR - Instrument Flight Rules  IF - Intermediate Frequency  IGEB - Interagency GPS Executive Board  IG - Inspector General  IGS - International GNSS Service  ILS - Instrument Landing System  IMO - International Maritime Organization  INFO - Information  IFRB - International Frequency Registration Board  INIT - Initialization  INMARSAT - International Maritime Satellite  INR - Image Navigation and Registration  INS - Inertial Navigation System  INTC - Intercept  IOC - Initial Operational Capability  ION - Institute Of Navigation  IOT&E - Initial Operational Test and Evaluation  IP - Instrumentation Port  IPT - Integrated Product Team  IRD - Interface Requirements Document  IRS - Inertial Reference System  IRT - Independent Review Team  IRU - Inertial Reference Unit  ISA - International Standard Atmosphere  ISO - International Standards Organization  ITP - Integrated Test Plan  ITRF - International Terrestrial Reference Frame  ITS - Intelligent Transportation System  ITU - International Telecommunication Union  IV&V - Independent Verification and Validation  IVHS - Intelligent Vehicle Highway Systems IW Information Warfare  J/S - Jamming to Signal Ration  JAN - January  JCS - Joint Chiefs of Staff  JPALS - Joint Precision Approach and Landing System  JPL - Jet Propulsion Laboratory  JPO - Joint Program Office  JROC - Joint Requirements Oversight Council  JSRA - Joint Sponsored Research Agreement  JSST - J oint Space Support Team  JSTARS - Joint Surveillance, Target Attack Radar System  JTF - Joint Task Force  JTIDS - Joint Tactical Information Distribution System  JUL - July  JUN - June  K - Thousand  Kbps - Kilo bits per second  KG - Kilogram  kHz - kilohertz  KHz - Kilohertz  km - Kilometer  KT - (kts) - Knots  kW - Kilowatt  L - Link  L - Left  L1 - GPS Carrier Frequency, 1575.42 MHz  L2 - GPS Carrier Frequency, 1227.6 MHz  LAAS - Local Area Augmentation System  LAN - Local Area Network  Lat - Latitude  Lat/Lon - Latitude/Longitude  LBS - L Band System  L2C - Civil signal on L2  L2M - Military-code on L2  L5 - Link 5, carrier frequency = 1176.45 MHz  LAAFB - Los Angeles Air Force Base  LAAS - Local Area Augmentation System  LAN - Local Area Network  LAT - latitude  LCD - Liquid Crystal Display  LCN - Local Communications Network.  LED - Light Emitting Diode  LEO - Low Earth Orbit  LEP - Linear Error Probable  LED - Light emitting diodes  LEO - Low Earth Orbit  LEP - linear error probable  LF - low frequency  LFR - Low-frequency Radio Range  LIM - Limit  LIS - Land Information System  LF - Low Frequency  LO - Local Oscillator  LO - Low  LOC - Localizer Beam  Lon - Longitude  LOP - Line Of Position  Loran - Long Range Navigation  LOS - Line Of Sight  LRC - Long Range Cruise  LRU - Line Replaceable Unit  M - Mach Number  m - Meter(s)  M - Million  M/S - Meters per Second  MAG - Magnetic  MAINT - Maintenance  MAN - Manual  MAR - March  MAX - Maximum  mB - Millibar  Mbps - Mega bits per second  MC&G - mapping, charting, and geodesy  MCA - Minimum Crossing Altitude  MCDU - Multipurpose Control Display Unit  M-Code - Military Code  MCS - Master Control Station  MCT - Mean Corrective Maintenance Time  MCW - Modulated Continuous Wave  MCW - modulated continuous wave  MD - Maryland  MDL - Multipurpose Data Link  MEL - Minimum Equipment List  MF - Medium Frequency  MGRS - Military Grid Reference System  MHz - Megahertz  MIDAS - Multi-discipline Data Analysis System  mil - unit of angular measurement equal to an angle having a tangent of 0.001  MILSPEC - Military Specifications  MIN - Minimum  MIN - Minutes  MLRS - multiple launch rocket system  MLS - Microwave Landing System  MLV - Medium Launch Vehicle  mm - millimeter  MMD - Mean Mission Duration  MMR - Multi-Mode Receiver  MN - Magnetic North  MNP - Master Navigation Plan  MNS - Mission Need Statement  MOA - Memorandum of Agreement  MOD - Modified/Modification  MODIS - Moderate-resolution Imaging Spectrometer  MOPS - Minimum Operational Performance Standards  MOU - Memorandum of Understanding  MP - Master Plan  MS - Monitor Station  MSAS - MTSAT Augmentation System  MSG - Message  MSK - Minimum Shift Keying  MSS - Mobile Satellite Service  MSL - Mean Sea Level  MTBF - Mean Time Between Failures  MTSAT - Multifunction Transport Satellite  MU - Management Unit  MWP - Meteorological Weather Processor  N - North  N/A - Not Applicable  NACA - National Advisory Committee for Aeronautics  NAD - North American Datum -  NADU - Notice Advisory to DGPS Users  NAGU - Notice Advisory to Glonass Users  NANU - Notice Advisory to Navstar Users  NAS - National Aircraft Standard  NAS - National Airspace System  NASA - National Aeronautics and Space Administration  NATCA - National Air Traffic Controllers Association  NATO - North Atlantic Treaty Organization  NAV - Navigation  NAVAID - Navigational Aid  NAV-msg - . - Navigation Message  NAVSTAR - Navigational Satellite Timing and Ranging  Navwar - Navigation Warfare  NCA - National Command Authority  ND - Navigation Display  NDB - Nondirectional Radio Beacon  NDGPS - Nationwide Differential Global Positioning System  NDS Nuclear Detection Subsystem  NESDIS - National Environmental Satellite, Data, and Information Service  NGS - National Geodetic Survey  NIMA - National Imagery and Mapping Agency  NIST - National Institute of Standards and Technology  Nl - Engine Revolutions per Minute (percent)  NLM - Network Loadable Module  NLR - National Research Laboratory (The Netherlands)  NM - Nautical Mile  Nm - Nautical Mile  NMC - National Meteorological Center  NNSS - Navy Navigation Satellite System (Transit)  NOAA - National Oceanic And Atmospheric Administration  NOS - National Ocean Survey  NRL - Naval Research Laboratory  Ns - Nanosecond  NOAA - National Oceanic and Atmospheric Administration  NOCC - National Operations Command Center (FAA)  NORAD - North American Aerospace Defense Command  NOTAM - Notice for Airman  NOV - November  NPA - Non-precision approach  NRL - Naval Research Laboratory  NRP - National Route Program  NS - Nanosecond  NSC - Non-standard C/A code  NSC - National Security Council  NSTC - National Science and Technology Council  NTIS - National Technical Information Service (Department of Commerce)  NTS - Navigation Technology Satellite  NTSB - National Transportation Safety Board  NW - Northwest Airlines  NWS - National Weather Service  OAB - Operational Advisory Broadcasts  OATS - Orbit and Attitude Tracking  OBE - Overtaken by Events  OBS - Omni Bearing Select  OCONUS - Outside the CONUS (Continental United States)  OCS - Operational Control Segment  OEM - Original Equipment Manufacturer  OGE - Operational Ground Equipment  OIS - Orbital Insertion System  OJT - On-the-Job Training  OMB - Office of Management and Budget  ONC - operational navigation chart  OP - Operational  OPCON - operational control  OPSCAP - Operational Status Capability  OPT - Optimum  ORD - Operational Requirements Document  ORRB - Operational Requirements Review Board  ORWG - Operational Requirements Working Group  OS - Operational Stability  OSCARS - Optimum Satellite Constellation Assessment Report Summary  OSD - Office of the Secretary of Defense  P-Code - Precision/Protected Code  PADS - Position Azimuth Determining System  PAFB - Peterson Air Force Base, Colorado Springs, CO  PALS - Precision Approach Landing System  PC - Personal Computer  PDD - Presidential Decision Directive  PDOP - Position Dilution Of Precision  PE - Probable error  PERF - Performance  PHARE - Program for Harmonized ATC Research in Europe  PHIBUF - Performance Buffet Limit  PHMI - Probability of Hazardously Misleading Information  PHINOM - Nominal Bank Angle  PINS - Precise Integrated Navigation System  PLGR - Precise Lightweight GPS Receiver  PMI - Preventative Maintenance Instructions  PMS - Performance Management System  PNT - Position, navigation and time  POC - Point of Contact  POS - Position  POS REF - Position Reference  Pos/Nav - positioning/navigation  PPM - Parts Per Million  PPM - Parts Per Million  PPOS - Present Position  PPS - Precise Positioning Service  PPS - Pulse Per Second  PR - Pseudorange  PREV - Previous  PRN - Pseudo Random Noise  PROM - Programmable Read-Only Memory  PTTI - precise time and time interval  PVT - Position, Velocity and Time  PY - Prior Year  QA - Quality Assurance  QC - Quality Control  QTY - Quantity  QUAD - Quadrant  R - Right  R&D - Research and Development  RAD - Radial  RAIM - Receiver Autonomous Integrity Monitoring  RAM - Random Access Memory  RAP - Reserve Auxiliary Payload  RCVR - Receiver  RDF - Radio Direction Finder  RDOP - Relative Dilution of Precision  RDSS - Radio Determination Satellite Systems  REF - Reference  RF - Radio Frequency  RFI - Radio Frequency Interference  RINEX - Receiver INdependent EXchange format  RLG - ring laser gyro  RMS - Root Mean Square  RNAV - Area Navigation  RNP - Required Navigation Performance  ROM - Read-Only Memory  ROV - Remotely Operated Vehicle  RTCA - Radio Technical Commission for Aeronautics  RTCA-SC - Radio Technical Comission for Aeronautics, Special Committee  RTCM - Radio Technical Commission for Maritime Services  RTK - Real-Time Kinematic  RSS - Root Sum Square  RTCA - - Radio Technical Commission for Aeronautics  RTCM - Ratio Technical Commission for Maritime Services  RTE - Route  RTS - Remote Tracking Station  RVR - Runway Visual Range  S - South  S/A - Selective Availability  SA - Selective Availability  SA - Situation Awareness  SA/A-S - selective availability/anti-spoof  SAASM - Selective Availability and Anti-Spoofing Module  SAFB - Schriever Air Force Base (Colorado)  SAR - Selected Acquisition Report; Subsequent Application Review; Search and Rescue; Safety Assessment Report; Special Access Required  SARPS - Standards and Recommended Practices  SATCOM - Satellite Communications  SATNAV - Satellite Navigation  SBIR - Space Based Infrared System; Small Business Innovation Research Program  SC - Special Committee  SCA - Satellite Control Authority/Architecture  SCAT I - Special Category I  SCATANA - Security Control of Air Traffic and Navigation Aids  SCCB - Software Configuration Control Board  SCI - Sensitive Compartmented Information  SCSS - Satellite Control Simulation System  SDLS - Satellite Data Link Standard  SE - Systems Engineering; Support Equipment  sec - Second(s)  SEL - Selected  SEP - - Spherical Error Probable  SES - Severely Errored Seconds  SF - Sub Frame  SGLS - Space-Ground Link Subsystem  SHF - Super High Frequency  SIGMET - Significant Meteorological Information  SIGSEC - Signal Security  SINS - Shipborne INS  SIS - Signal-In-Space  SKYNET - Skynet Communications Satellite  SLEP - Service Life Extension Program  SLR - Satellite Laser Ranging  SLS - Satellite Launch Squadron  SM - Security Module  SME - Subject Matter Experts  SNAPM - Satellite-Based Navigation Accuracy Performance Model  SNR - Signal To Noise Ratio  SOC - Satellite Operations Center  SOIT - Satellite Operational Implementation Team  SONAR - sound navigation ranging  SOP - Standard Operating Procedure  SOPS - Satellite Operations Squadron  SORD - System of Operational Requirements Document  SP - Space  SPS - Standard Positioning Service  SPU - Spacecraft Processor Unit  SQL - Structured Query Language  SRP - Selected Reference Point  SS - Space Segment  SSG - Senior Steering Group  SSM - Sign Status Matrix  SSN - Space surveillance network  SPS - Standard Positioning Service  STB - System Test Bed  STD - Standard  STS - Space Transportation System  STS - System Telecommunication Simulator, Block IIF  STS/TSM - Satellite Telecommunications Simulator (Block IIF)/Telecom Simulator  SV - Space Vehicle  SVN - Space Vehicle NAVSTAR, Space Vehicle Number  T - Trillion; Time  T&E - Test and Evaluation  TACAN - Tactical Air Navigation  TAI - International Atomic Time  TBD - To Be Determined  TCA - Terminal Control Area  TCAS - Traffic Alert & Collision Avoidance System  TD - Time Difference  TDMA - Time Division Multiple Access  TDOP - Time Dilution of Precision  TE - Test Equipment  TEMP - Temperature  THDG - True Heading  TN - True North  TO T - echnical Order  TOA - Time of Arrival  TOD - Time Of Day  TOPEX - The Ocean Topography Experiment  TOT - Total  TQM - Total Quality Management  TRACON - Terminal Radar Approach Control Facility.  TRANS - Transition  TSO - Technical Standard Order  UAV - Unmanned Aerial Vehicle  UE - User Equipment  UERE - User Equivalent Range Error  UEE - User Equipment Error  UHF - Ultra High Frequency  UNK - Unknown(s)  URE - User Range Error  US - User Segment  USAF - United States Air Force  USCG - United States Coast Guard  USGIC - US GPS Industry Council  USGS - US Geological Survey  USNO - US Naval Observatory  UT - Universal Time  UTC - Coordinated Universal Time  UTC (USNO) - Coordinated Universal Time as maintained by the USNO  V - Velocity  V&V - Verification and Validation  VAR - Variation  VAR - Visual-aural Radio Range  VDOP - Vertical Dilution of Precision  VE - Value Engineering  VFR - Visual Flight Rules  VHF - Very-high Frequency  VLF - very low frequency  VLM - Vehicle Location Monitoring VMC - Visual Meteorological Conditions  VNAV - Vertical  VOM - Volt-ohm-milliammeter  VOR - very high frequency omnidirectional range station  VOR/DME - Very High Frequency Omnidirectional Range/Distance Measuring Equipment  VORTAC - VHF Omni Range Radio/Tactical Air Navagation  VPATH - Vertical Path  VREF - Reference Velocity  VTC - Vessel Traffic Center  VTOL - Vertical Takeoff and Landing  VTR - Variable Takeoff Rating  VTS - Vessel Traffic Services  W - West  WAAS - Wide Area Augmentation System  WADGPS - Wide Area Differential GPS  WAGE - Wide Area GPS Enhancement  WAN - Wide Area Network  Waypoint - Position in space usually on aircraft's flight plan  WGS - World Geodetic System  WGS 84 - World Geodetic System 1984  WPT - Way point  WRC - World Radio Conference WT - Weight  WWV WWVH - time station call letters  WX - Weather  WXR - Weather Radar  X-BAND - The frequency range between 8000 and 12500 MHz  XCVR - Transceiver  XFR - Transfer  XLTR - Translator  XMIT - Transmit  XMITR - Transmitter  Y code - Precise code (GPS)  Y2K - Year 2000  YD - Yaw Damper  YSAS - Yaw Stability Augmentation System  Z - Zulu (GMT time)