[time-nuts] Jupiter GPS receiver

[Didier Juges]

Hi Johan,

I bought the Jupiter essentially to phase lock a 10 MHz reference, to be 
used to phase lock my test equipment (generators and counters). It has a 
10 kHz output that is much more convenient than the 1 pps of most other 
receivers.

But, since I have the thing working and hooked up, I wanted to see what 
it can do, so it was only a mild disapointment to find out the problem 
with the NMEA output.

What software do you use to interface the binary output to your NTP 
server? If it happens to be Linux software and the source code were 
available, I would be interested.

Didier KO4BB

Johan Swenker wrote:

>Hello,
>
>  
>
>>>Hello Didier,
>>>
>>>The Jupiter GPS receiver (if used in NMEA and not binary mode) has a known
>>>fault, that it can be 1 or 2 seconds delta to UTC, this is independent of
>>>the "leap-second" situation.
>>>      
>>>
>
>I use my Jupiter GPS to synchronize my ntp-server. When I ran it in 
>NMEA-mode, I had to fudge it 1.135 sec. A few days later I had to 
>fudge it 2.135 sec to give a time similar to public ntp-servers.
>
>The NTP newsgroup tells me that most consumer grade GPS-devices are 
>meant for navigation; giving an accurate time to the outside world is 
>not of primary importance. Thus I attributed the bad NMEA quality to 
>the unimportance of time to NMEA-engineers.
>
>I currently run my Jupiter in binary mode. According to ntpd the 
>offset is generally a few microseconds. I have no independant way to 
>check that claim.
>
>Regards, Johan Swenker
>
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>  
>