Khz Gps
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 LOWRANCE M68C S MAP 200KHZ TM 116 03 HST WSU 116 032 $294.45 Time Remaining: 26d 22h 27m Buy It Now for only: $294.45 |
 Eagle FishElite 640C Fishfinder GPS Reciever 200 kHz Sonar Mapping Depthfinder $369.00 Time Remaining: 27d 20h 14m Buy It Now for only: $369.00 |
 Lowrance HDS 10 Fishfinder Base US with 83 200 kHz Transducer 140 00 $1,899.88 Time Remaining: 26d 16h 3m Buy It Now for only: $1,899.88 |
 NEW LOWRANCE ELITE 5 BASE FISHFINDER CHARTPLOTTER 83 200 kHz OPEN BOX 104 001 $499.95 Time Remaining: 9d 18h 50m Buy It Now for only: $499.95 |
 Lowrance HDS 7 7 Inch Waterproof Marine GPS Chartplotter 83 200kHz GREAT UNUSED $799.00 Time Remaining: 20d 3h 31m Buy It Now for only: $799.00 |
 NEW LOWRANCE MARK 5x DSI 5 LCD FISHFINDER 455 800 kHz 10233 001 $249.00 Time Remaining: 13d 17h 51m Buy It Now for only: $249.00 |
 Lowrance HDS 5 Fishfinder GPS Nautic Insight with 50 200kHz Transducer 140 20 $629.88 Time Remaining: 15d 14h 1m Buy It Now for only: $629.88 |
 Lowrance HDS 7 Gen2 Base US 83 200 kHz T M Transducer 000 10533 001 $999.00 Time Remaining: 7d 21h 17m Buy It Now for only: $999.00 |
 Lowrance Elite 5 Base Us Combo With 83 200 Khz 104 001 $525.98 Time Remaining: 13d 1h 32m Buy It Now for only: $525.98 |
 Lowrance HDS 7 Fishfinder USA Insight with 83 200 kHz Transducer Combo 140 12 $899.88 Time Remaining: 23d 1h 34m Buy It Now for only: $899.88 |
 LOWRANCE HDS 7 INSIGHT US 50 200 KHZ GPS FISHFINDER NEW 140 14 $1,149.99 Time Remaining: 25d 6h 37m Buy It Now for only: $1,149.99 |
 Lowrance HDS 7 Insight US Fishfinder with 50 200 Khz Transducer GPS 140 14 $999.88 Time Remaining: 1d 18h 29m Buy It Now for only: $999.88 |
 Lowrance Elite 5 Marine GPS Fishfinder w 83 200khz TDX $599.00 Time Remaining: 29d 11h 19m Buy It Now for only: $599.00 |
 Lowrance Hds 10 Gen2 Base Us 83 200 Khz T m Transducer 000 10625 001 $2,298.00 Time Remaining: 16d 16h 23m Buy It Now for only: $2,298.00 |
 Lowrance Elite 5 Gold Combo w 83 200 KHz TM Model 144 001 $619.00 Time Remaining: 26d 15h 49m Buy It Now for only: $619.00 |
 Lowrance Hds 7 Gen2 Insight Usa 83 200 Khz T m Transducer 000 10530 001 $1,098.88 Time Remaining: 11d 23h 56m Buy It Now for only: $1,098.88 |
 Lowrance Hds 5 Gen2 Nautic Insight 50 200 Khz Transducer 000 10519 001 $2,694.60 Time Remaining: 29d 15h 42m Buy It Now for only: $2,694.60 |
 Lowrance HDS 5 GEN2 Insight USA 83 200kHz Transducer 000 10515 001 $699.00 Time Remaining: 6d 16h 44m Buy It Now for only: $699.00 |
 LOWRANCE ELITE 5 BASE US COMBO WITH 83 200 KHZ 104 001 $549.00 Time Remaining: 15d 23h 32m Buy It Now for only: $549.00 |
 Lowrance 000 10515 001 Lowrance HDS 5 Gen2 Lake Insight w 83 200 kHz Transducer $714.78 Time Remaining: 29d 15h 21m Buy It Now for only: $714.78 |
 Lowrance HDS 7 Gen2 Insight USA 50 200 kHz T M Transducer $1,149.00 Time Remaining: 12d 17h 39m Buy It Now for only: $1,149.00 |
 LOWRANCE ELITE 5 GOLD COMBO BUNDLE W 83 200 KHZ TRANSOM MOUNT 144 001 $619.00 Time Remaining: 26d 19h 12m Buy It Now for only: $619.00 |
 Lowrance 000 10537 001 Lowrance HDS 8 Gen2 Insight USA 83 200 kHz T M Transducer $1,818.86 Time Remaining: 29d 15h 21m Buy It Now for only: $1,818.86 |
 LOWRANCE M68C S MAP 200KHZ TM 116 03 HST WSU 116 032 $308.03 Time Remaining: 15d 10h 20m Buy It Now for only: $308.03 |
 Lowrance Elite 5 Base US Combo Color w 200 kHz transducer 104 001 $549.00 Time Remaining: 20d 17h 34m Buy It Now for only: $549.00 |
 Lowrance Hds 7 Insight Usa Df 50 200 Khz T m Ducer $999.89 Time Remaining: 14d 17h 34m Buy It Now for only: $999.89 |
 NEW LOWRANCE HDS 7 INSIGHT USA FISHINDER GPS CHARTPLOTTER 83 200 kHz 140 12 $949.95 Time Remaining: 26d 19h 44m Buy It Now for only: $949.95 |
 Lowrance HDS 7 Gen2 Insight USA 50 200 kHz T M Transducer 000 10529 001 $1,149.00 Time Remaining: 5d 19h 15m Buy It Now for only: $1,149.00 |
 Lowrance HDS 5 Gen2 Lake Insight w 83 200 kHz LSS 2 Transducer 000 10868 001 $1,249.00 Time Remaining: 10d 1h 2m Buy It Now for only: $1,249.00 |
 Lowrance Hds 10 Gen2 Insight Usa 83 200 Khz T m Transducer 000 10542 001 $2,398.00 Time Remaining: 15d 2h 2m Buy It Now for only: $2,398.00 |
 Lowrance HDS 8 Gen2 Insight USA 50 200 kHz T M Transducer 000 10536 001 $1,849.00 Time Remaining: 10d 16h 42m Buy It Now for only: $1,849.00 |
 GARMIN OEM 200KHz TROLLING MOTOR TRANSDUCER for GPS 125 GSD 21 22 010 10200 00 $57.95 Time Remaining: 10d 17h 37m Buy It Now for only: $57.95 |
 Lowrance HDS 5 Gen2 Lake Insight w 83 200 kHz Transducer 000 10515 001 $699.00 Time Remaining: 5d 19h 37m Buy It Now for only: $699.00 |
 Lowrance HDS 8 Gen2 Base US 83 200 kHz T M Transducer 000 10624 001 $1,699.00 Time Remaining: 10d 16h 42m Buy It Now for only: $1,699.00 |
 Lowrance HDS 7 Insight 50 200 kHz Pre loaded Brand New $1,149.99 Time Remaining: 21d 22h 57m Buy It Now for only: $1,149.99 |
 Lowrance Hds 8 Insight Usa 83 200 Khz T m Ducer 140 07 $1,694.55 Time Remaining: 19d 19h 32m Buy It Now for only: $1,694.55 |
 Lowrance HDS 5 Gen2 Lake Insight w 83 200 kHz Transducer 000 10515 001 $699.00 Time Remaining: 2d 20h 57m Buy It Now for only: $699.00 |
 Lowrance HDS 8 Gen2 Insight USA 50 200 kHz T M Transducer 000 10536 001 $1,849.00 Time Remaining: 13d 12h 43m Buy It Now for only: $1,849.00 |
 Lowrance Hds 10 Insight Usa 83 200khz T m Ducer $2,070.00 Time Remaining: 19d 19h 21m Buy It Now for only: $2,070.00 |
 Lowrance Hds 10 Gen2 Insight Usa 50 200 Khz T m Transducer 000 10541 001 $2,341.49 Time Remaining: 16d 16h 23m Buy It Now for only: $2,341.49 |
 Lowrance HDS 5 Gen2 Lake Insight w 83 200 kHz Transducer 000 10515 001 $699.00 Time Remaining: 8d 19h 40m Buy It Now for only: $699.00 |
 Lowrance 000 10515 001 Lowrance HDS 5 Gen2 Lake Insight w 83 200 kHz Transducer $714.78 Time Remaining: 20d 6h 54m Buy It Now for only: $714.78 |
 Lowrance HDS 8 Gen2 Insight USA 83 200 kHz T M Transducer $1,799.00 Time Remaining: 13d 15h 49m Buy It Now for only: $1,799.00 |
 Lowrance HDS 7 Gen2 Insight USA 83 200 kHz T M Transducer 000 10530 001 $1,099.00 Time Remaining: 8d 19h 28m Buy It Now for only: $1,099.00 |
 Lowrance Hds 8 Gen2 Insight Usa 83 200 Khz T m Transducer 000 10537 001 $1,799.00 Time Remaining: 29d 15h 42m Buy It Now for only: $1,799.00 |
 Lowrance Elite 5 Base US Combo Color w 200 kHz $549.00 Time Remaining: 8d 21h 17m Buy It Now for only: $549.00 |
 Garmin 200kHz 12Deg Bronze Thru Hull 010 10217 00 $152.00 Time Remaining: 14d 17h 32m Buy It Now for only: $152.00 |
 Lowrance Hds 7 Insight Usa 83 200 Khz T m Ducer $1,078.56 Time Remaining: 19d 19h 21m Buy It Now for only: $1,078.56 |
 Lowrance HDS 8 Gen2 Base US 83 200 kHz T M Transducer 000 10624 001 NEW $1,750.00 Time Remaining: 29d 16h 34m Buy It Now for only: $1,750.00 |
 Lowrance Elite 5 Base US Combo Color w 200 kHz Transducer Model 104 001 $549.00 Time Remaining: 24d 18h 17m Buy It Now for only: $549.00 |
 Lowrance HDS 8 Gen2 Base US 83 200 kHz T M Transducer $1,699.00 Time Remaining: 13d 15h 56m Buy It Now for only: $1,699.00 |
 LOWRANCE HDS 7 GEN2 INSIGHT USA 83 200 KHZ T M TRANSDUCER 000 10530 001 $1,099.00 Time Remaining: 14d 17h 20m Buy It Now for only: $1,099.00 |
 FURUNO NAVNET 235DT PSE 235KHZ NYLON Thru Hull $187.00 Time Remaining: 26d 15h 7m Buy It Now for only: $187.00 |
 LOWRANCE ELITE 5 BASE US COMBO WITH 83 200 KHZ 104 001 $549.00 Time Remaining: 16d 1h 11m Buy It Now for only: $549.00 |
 GARMIN 200KHZ 12 DEG BRONZE THRU HULL DEPTH TEMP $141.00 Time Remaining: 48m Buy It Now for only: $141.00 |
 Lowrance 000 10530 001 Lowrance HDS 7 Gen2 Insight USA 83 200 kHz T M Transducer $1,033.58 Time Remaining: 27d 7h 1m Buy It Now for only: $1,033.58 |
 Lowrance 000 10537 001 Lowrance HDS 8 Gen2 Insight USA 83 200 kHz T M Transducer $1,818.86 Time Remaining: 28d 15h 34m Buy It Now for only: $1,818.86 |
 Lowrance HDS 8 Gen2 Base US 83 200 kHz T M Transducer Model 000 10624 001 $1,699.00 Time Remaining: 10d 18h 47m Buy It Now for only: $1,699.00 |
 LOWRANCE HDS 10 GEN2 INSIGHT USA 83 200 KHZ T M TRANSDUCER 000 10542 001 $2,399.00 Time Remaining: 10d 14h 20m Buy It Now for only: $2,399.00 |
 Lowrance 000 10530 001 Lowrance HDS 7 Gen2 Insight USA 83 200 kHz T M Transducer $1,116.27 Time Remaining: 28d 15h 32m Buy It Now for only: $1,116.27 |
 LOWRANCE HDS 7 GEN2 INSIGHT USA 50 200 KHZ T M TRANSDUCER 000 10529 001 $1,149.00 Time Remaining: 6d 17h 20m Buy It Now for only: $1,149.00 |
 LOWRANCE HDS 8 GEN2 INSIGHT USA 50 200 KHZ T M TRANSDUCER 000 10536 001 $1,849.00 Time Remaining: 12d 17h 20m Buy It Now for only: $1,849.00 |
 LOWRANCE HDS 8 GEN2 INSIGHT USA 83 200 KHZ T M TRANSDUCER 000 10537 001 $1,799.00 Time Remaining: 12d 17h 20m Buy It Now for only: $1,799.00 |
 Lowrance 000 10537 001 Lowrance HDS 8 Gen2 Insight USA 83 200 kHz T M Transducer $1,684.13 Time Remaining: 27d 7h 1m Buy It Now for only: $1,684.13 |
 LOWRANCE HDS 8 GEN2 BASE US 83 200 KHZ T M TRANSDUCER 000 10624 001 $1,699.00 Time Remaining: 12d 17h 20m Buy It Now for only: $1,699.00 |
 LOWRANCE HDS 10 GEN2 BASE US 83 200 KHZ T M TRANSDUCER 000 10625 001 $2,299.00 Time Remaining: 11d 14h 30m Buy It Now for only: $2,299.00 |
 Lowrance HDS 5 Fishfinder+GPS Chartplotter Lake Insight 83 200kHZ 140 19 $699.99 Time Remaining: 10d 19h 8m Buy It Now for only: $699.99 |
 LOWRANCE HDS 5 GEN2 LAKE INSIGHT WITH 83 200 KHZ DUCER 000 10515 001 $699.00 Time Remaining: 6d 2h 20m Buy It Now for only: $699.00 |
 LOWRANCE HDS 7 GEN2 BASE US 83 200 KHZ T M TRANSDUCER 000 10533 001 $999.00 Time Remaining: 8d 2h 20m Buy It Now for only: $999.00 |
 LOWRANCE HDS 10 GEN2 INSIGHT USA 50 200 KHZ T M TRANSDUCER 000 10541 001 $2,449.00 Time Remaining: 15d 14h 35m Buy It Now for only: $2,449.00 |
 Lowrance HDS 10 Gen2 Base US 83 200 kHz T M Transducer $2,334.00 Time Remaining: 16d 3h 55m Buy It Now for only: $2,334.00 |
 Lowrance HDS 5 Gen2 Lake Insight w 83 200 kHz Transducer $719.25 Time Remaining: 16d 4h 2m Buy It Now for only: $719.25 |
 Lowrance HDS 7 Gen2 Insight USA 83 200 kHz T M Transducer $1,122.94 Time Remaining: 16d 3h 55m Buy It Now for only: $1,122.94 |
 Lowrance Elite 5 Base US Combo Color w 200 kHz $567.88 Time Remaining: 16d 4h 3m Buy It Now for only: $567.88 |
 Lowrance HDS 7 Gen2 Base US 83 200 kHz T M Transducer $1,022.01 Time Remaining: 16d 4h 3m Buy It Now for only: $1,022.01 |
 Lowrance HDS 7 Gen2 Insight USA 50 200 kHz T M Transducer $1,173.40 Time Remaining: 16d 3h 55m Buy It Now for only: $1,173.40 |
 Lowrance HDS 10 Gen2 Insight USA 83 200 kHz T M Transducer $2,434.91 Time Remaining: 16d 3h 56m Buy It Now for only: $2,434.91 |
 Lowrance HDS 10 Gen2 Insight USA 50 200 kHz T M Transducer $2,485.38 Time Remaining: 16d 4h 19m Buy It Now for only: $2,485.38 |
 Lowrance HDS 8 Gen2 Base US 83 200 kHz T M Transducer $1,728.47 Time Remaining: 16d 3h 55m Buy It Now for only: $1,728.47 |
 Lowrance HDS 8 Gen2 Insight USA 83 200 kHz T M Transducer $1,829.38 Time Remaining: 16d 4h 2m Buy It Now for only: $1,829.38 |
Ntp the Importance of External Time Reference
Network Time Protocol (NTP) is one of the Internet’s oldest protocols and is still the standard for time synchronisation. The success of NTP stems from its constant development (version 4 is currently in progress) and the accuracy that an NTP time server can boast in the synchronisation of networks.
Whilst an accuracy of 1/5000th of a second can be obtained on a network under the right conditions, this accuracy is solely reliant on whatever time reference NTP uses to synchronise with. This source could of course be unreliable, like a workstation clock as real time chips in most computers are prone to drift and are far less accurate than the average digital watch.
The alternative is to use a reliable UTC (Coordinated Universal Time) source. UTC is the standard for time synchronization. It was started in 1972 after the development of atomic clocks and allows the entire globe to synchronise to the same absolute time. This has not only made technologies such as the Internet, GPS and communication satellites possible, but also has allowed industries such as airlines and the stock market to trade globally.
The simplest way to synchronise a network to UTC has always been to use an Internet time reference. There are hundreds available such as nist.gov and most Windows software has a built in utility, Windows Time (win32.exe) to synchronise the system clock to a reference clock over the Internet.
However, Microsoft and others warn against using an Internet source as a time reference as authentication is not possible from these sources.
Authentication is the security measure that NTP uses to ensure that a time reference is trusted. Without authentication systems are vulnerable to malicious attacks such as hackers who could adjust a timestamp to commit fraud or a DDoS attack (Distributed Denial of Service usually caused by malicious software inundating the system).
Not only are Internet times sources unauthenticated but also a survey by Nelson Minar of MIT on over 900 Internet time references, discovered nearly half were offset by over ten seconds (one by a staggering 6 years – but there were fortunately not many peers) and less that a third where described as being “useful”.
The report also discovered that many Internet time reference hosts were too far away from their peers to allow accurate time synchronisation.
There are however, several ways of ensuring a NTP server is synchronised to a reliable and stable UTC time source that is both accurate and authenticated.
There are two systems available and both use relatively low cost equipment. The first option and often the easiest, is to connect to a GPS antenna and dedicated GPS time server to the network. This uses the UTC time code transmitted by the GPS satellites, as long as the antenna has a good view of the sky.
Alternatively specialist broadcast signals transmit a timestamp in several countries. In Britain it is referred to as MSF and broadcast from Cumbria by the National Physics Laboratory at 60 kHz but can be picked up as far away as 1000 km, although similar systems operate in Germany, France and the US. These radio referenced NTP servers are vulnerable to interference but traditionally were of a lower cost than GPS receivers however, advances in technology mean the difference is now minimal.
The integrity of a time source used by a NTP time server is therefore highly important and whist system administrators are all too willing to invest in expensive firewalls and anti-viral software to protect their networks many neglect their time server’s security which after all, may not be telling them the right time anyway!
About the Author
Copyright 2008 © Richard N Williams
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 for more information about NTP products and NTP servers