[ntp:questions] Re: Refclocks for the Ultra-Cheap

Richard B. Gilbert rgilbert88 at comcast.net
Fri May 6 23:08:05 UTC 2005

Will wrote:

>What are some extremely cheap options for locally attached
>refclocks, preferably under $400 total cost?   I don't need
>extreme accuracy.   Frankly accuracy to one second is sufficient.
>The application is Kerberos.    For various reasons the networks
>internal time server cannot easily use an NTP client, so I really
>prefer to find a locally attached refclock.
You can purchase a Motorla M12+T  GPS timing reciever with "hockey puck" 
antenna and evaualation circuit board for around $200 US.  This should 
work fairly well if you can site the antenna where it will have an 
unobstructed view of the sky.  See:

For more money, I don't know exactly how much, you can get the Motorola 
timing receiver combined with an antenna in a small plastic "radome" 
which will deliver a serial output to your computer via RS232 or RS422 
(supports up to 500 meters of cable)
See http://www.synergy-gps.com/GSynQ_EnTN-813.pdf for specs on this one.

You can find a lot of equipment on e-Bay.   Depending on where you are 
located, it may be possible for you to use a receiver for an HF or VLF 
time signal  WWV, WWVH, or WWVB in the US, CHU in Canada, etc.  The 
vagaries of radio propagation tend to make this a poor second choice for 
me but your mileage may vary.

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