Gps Cable
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 1 Car TV Digital DVB T FM Antenna Amp Booster 35MM connector hot free shipping  US $9.89
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 Lilliput 7 667GL 70NP H Y TFT LCD Monitor w HDMI YPbPr Input Fr Camera A1G US $159.56
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 GARMIN GA 30 GPS ANTENNA NEW US $25.99
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 Garmin StreetPilot 2610 Automotive GPS Receiver US $41.25
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 Garmin Nuvi 1450LMT GPS Receiver US $93.07
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 TomTom VIA 1505M 5 Inch Portable GPS Navigator with Lifetime Maps US $82.00
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 TomTom Via 1435TM US including Puerto Rico Canada Mexico Automotive US $94.00
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 CAR CHARGER TOMTOM GO 510 710 910 GPS SAT NAV LEAD NEW 12v 24v POWER PLUG US $10.99
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 Garmin nuvi 250W Automotive GPS Receiver FAULTY SPARES REPAIRS PARTS DAMAGED US $33.00
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 Garmin nuvi 755T Automotive GPS Receiver US $28.00
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 Garmin USB Sync Cable Works with Lots of Garmin Units US $2.99
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 43 Inch 43 Compact Premium GPS Carrying Case Cover for Garmin Nuvi 255W 43in US $4.95
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 USED ONLY ONE TIMEGarmin eTrex Vista HCX GPS Receiver US $149.99
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 Magellan Triton 300 GPS Receiver US $55.00
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 VOICE CAR RADAR LASER CAMERA GATSO DETECTOR WORLDWIDE US $47.13
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 TomTom ONE 3rd Edition US including Puerto Rico Canada Automotive GPS US $35.00
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 Rapid Fast Travel Battery Home Wall AC GPS Charger for Garmin Nuvi 1390 1390T US $1.99
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 Magellan Maestro 4350 43 Inch Bluetooth Portable GPS Navigator US $495.00
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 43 hard case cover bag for garmin nuvi 255w 255wt 265w 265wt 275w 1300 3790LMT US $4.95
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 Hard Case Cover Bag for Garmin Nuvi 255w 255wt 265w 265wt 275w 1300 1350 1370T US $4.95
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 TomTom XL Vehicle GPS Model N14644 US $22.49
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 Magellan Meridian Gold GPS Receiver US $26.72
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 Garmin Street Pilot 7200 GPS Reciever US $61.00
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 Rapid Fast Travel Battery Car Charger For Garmin Nuvi 1350T 265T 260W 250W 205W US $1.99
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 Garmin Forerunner 301 Black GPS Receiver US $68.00
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 ARKON GPS032 WEATHERPROOF GPS PHONE MOTORCYCLE MOUNT BIKE BICYCLE HANDLEBAR US $21.99
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 Trimble R7 GNSS Base Receiver US $15,500.00
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 Case CoverLCD Protector for Garmin Nuvi 255w 255wt 265wt 275w 1300 1350 1370T US $5.99
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 TomTom VIA 1405M Portable GPS Navigation System with 43 Touch Screen BRAND NEW US $99.99
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 Garmin StreetPilot c330 Automotive GPS Receiver US $48.62
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 43 TFT GPS Navigation WINCE 60 System 4GB SD With New Map Software US $92.12
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 Garmin GPSMAP 440s GPS Receiver US $228.25
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 ORIGINAL Garmin forerunner 305 405 watch AC DC power supply CHARGER USB CABLE US $6.84
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 CES10127 GPS Navigation System Text to Speech ML 500 US $91.50
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 NEW Magellan eXplorist 210 400 500 LE 600 GPS Data Cable US $11.99
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 Mio C320 Automotive GPS Receiver US $39.99
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 TOMTOM® 35 GPS NAVIGATION SYSTE US $150.00
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 Garmin GPS GTM 25 Receiver Car Boat Power Charger With US CAN Lifetime Traffic US $.90
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 Navman N40i Portable Navigation GPS Receiver NavPix Camera New in Box US $75.00
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 mini hard case cover bag for garmin nuvi 255w 265w 265wt 275w 1300 1350t 3790LMT US $4.95
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 Garmin eTrex Venture HC GPS Receiver US $71.00
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 Deluo USB GPS for laptop 31 311 01 US $59.99
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 Garmin GPSMAP 76Cx GPS Receiver used twice looks like new US $103.50
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 Garmin GPSMAP 478 GPS Receiver with motorcycle car boat XM Mem card Pkg US $685.00
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 Garmin Data Sync Cable for StreetPilot 2820 2730 2720 2650 2620 2610 GPS US $10.00
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 Garmin nüvi 1450LTM ORIGINAL BOX WITH ACCESORIES Free Lifetime Maps US $79.00
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 Garmin nuvi 750 Automotive GPS Receiver pin bloked US $35.00
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 7 Touch Screen GPS AnalogTV bluetooth AV INFM DDR128MWINCE60 free 4GB gps US $92.00
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 New 43 Car GPS Navigation FM Transimitter MTKCPU 500mHz Built in 4GB Map US $44.60
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 Garmin eTrex Legend GPS Receiver Works Great for Geocaching Waterproof WAAS EUC US $52.50
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 Garmin nuvi GPS w navigation mat bundled Fathers day dad travel car automotive US $75.00
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 Car Rear Mirror 43 GPS Navigation WIN CE50 New 4G Brand New Free Map New US $73.00
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 2012 7 Touch Screen car gps 4GBAnalog TV bluetooth AV INFM DDR128MWINCE60 US $90.00
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 Mobile Vision System 7 In Car VHS Recorder US $80.00
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 7 Touch Screen GPS AnalogTV bluetooth FM WINCE60 free 4gb gps US $84.00
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 Eclipse Avn 726e Stereo GPS Navigation Bluetooth iPod USB DVD Nice US $484.00
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 SkyGolf SkyCaddie SG35 Sports GPS Receiver US $84.99
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 CAR RADAR LASER CAMERA GATSO DETECTOR WORLDWIDE US $33.00
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 TomTom XL 340S Used Great Condition US $55.00
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 Garmin nuvi 265 Automotive GPS Receiver US $95.00
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 Garmin nuvi 1690 Automotive GPS Receiver Gray Bundle w Extras PARTS REPAIR ONLY US $9.99
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 New Garmin nüvi 2555LMT Automotive GPS Receiver US $145.00
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 Garmin GPSMAP 3205 GPS Receiver w northeast inland lakes data card US $435.00
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 GARMIN NUVI ZUMO GPS GTM25 POWER CHARGE CABLE W TRAFFIC RECEIVER FOR USACANADA US $8.98
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 New Garmin Edge 500 Red Bundle Cycling GPS Computer Bid Now US $309.99
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 Motorcycle Car GPS 35 Touch Waterproof Navigator Brand New in Box Fast Ship US $199.99
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 GARMIN StreetPilot 2820 Lot of Two US $69.20
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 Magellan RoadMate 2036 MU Automotive GPS Receiver Navigation System US $9.99
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 7 TFT LCD Stand Color Car Rearview Headrest Screen Monitor DVD VCR Rear view L US $19.99
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 Early Warning EW3200 Radar Laser Detector with Safety Alert US $58.33
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 Magellan RoadMate 2035 Automotive GPS Receiver US $45.99
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 Battery Home Wall AC Charger for Garmin Nuvi 1490 1450T US $1.99
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 TomTom One XL N14644 Automotive GPS Receiver US $18.50
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 70 HD SIRF5 GPS4GB US CA MAPWireless Reversing CameraTTSMP3SPEED CAMERA US $109.95
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 Garmin GPS 60 personal navigator US $100.00
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 NEW Rapid Travel Battery Car Charger for Garmin Nuvi 200 205 250 255 710 750 760 US $1.99
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 Garmin nuvi 1300LM 43 Portable GPS with Case2 Vehicle Mounts 2 Vehicle cables US $159.99
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 BRAND NEW Garmin GPSMAP 62s GPS Receiver US $251.00
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 Teletrac MC 56 GPS Commercial Tracking Devices US $750.00
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 Garmin StreetPilot c340 Automotive GPS Receiver US $25.00
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Installing a Ntp Server Using a GPS Timing Source
Network Time Protocol (NTP) is one of the Internet’s oldest protocols still used, invented by Dr David Mills from the University of Delaware, it has been in utilized since 1985. NTP is a protocol designed to synchronize the clocks on computers and networks across the Internet or Local Area Networks (LANs).
NTP (version 4) can maintain time over the public Internet to within 10 milliseconds (1/100th of a second) and can perform even better over LANs with accuracies of 200 microseconds (1/5000th of a second) under ideal conditions.
NTP works within the TCP/IP suite and relies on UDP, a less complex form of NTP exists called Simple Network Time Protocol (SNTP) that does not require the storing of information about previous communications, needed by NTP. It is used in some devices and applications where high accuracy timing is not as important.
Time synchronisation with NTP is relatively simple, it synchronises time with reference to a reliable clock source. This source could be relative (a computer’s internal clock or the time on a wrist-watch) or absolute (A UTC - Universal Coordinated Time - clock source that is accurate as is humanely possible).
Atomic clocks are the most absolute time-keeping devices; however, they are extremely expensive and are generally only to be found in large-scale physics laboratories. However, NTP can synchronise networks to an atomic clock by using either the Global Positioning system (GPS) network, a specialist radio transmission or over the Internet. However, it must be noted that Microsoft strongly recommends that an external based timing should be used rather than Internet based, as these can’t be authenticated.
GPS is an ideal time and frequency source because it can provide highly accurate time anywhere in the world using relatively cheap components. Each GPS satellite transmits in two frequencies L2 for the military use and L1 for use by civilians transmitted at 1575 MHz, Low-cost GPS antennas and receivers are now widely available.
The signal transmitted by the satellite can pass through windows but can be blocked by buildings so the ideal location for a GPS antenna is on a rooftop with a good view of the sky. The more satellites it can receive from the better the signal. However, roof-mounted antennas can be prone to lighting strikes or other voltage surges, so installation of a suppressor inline on the GPS cable is highly recommend.
The cable between the GPS antenna and receiver is also critical. The maximum distance that a cable can run is normally only 20-30 metres but a high quality coax cable combined with a GPS amplifier placed in-line to boost the gain of the antenna can allow in excess of 100 metre cable runs.
A GPS receiver then decodes the GPS signal sent from the antenna to a computer readable protocol which can be utilised by most time servers and operating systems including, Windows, LINUX and UNIX.
The GPS receiver also outputs a precise pulse every second that GPS Network Time Protocol (NTP) servers and computer time servers may utilise to provide ultra-precise timing. The pulse-per-second timing on most receivers is accurate to within 0.001 of a second of UTC.
GPS is ideal in providing NTP time servers or stand-alone computers with a highly accurate external reference for synchronisation. Even with relatively low cost equipment, accuracy of hundred nanoseconds (a nanosecond = a billionth of a second) can be reasonably achieved using GPS as an external reference.
About the Author
Richard N Williams is a technical author and a specialist in the telecommunications and network time synchronisation industry helping to develop dedicated time server products; ethernet clocks, GPS time servers, NTP servers, digital wall clocks, atomic clock servers and SNTP time servers. Please visit us for more information about NTP products and NTP servers