[time-nuts] thunderbolt for ntpd or gpsd

John Ackermann N8UR jra at febo.com
Fri Aug 15 08:17:40 EDT 2008


Yes, sadly this was a layout error that didn't get caught until too late 
  (I'm still not sure why the rules check in the board layout software 
didn't catch it).  Removing R4 if you're using DTR for power is the 
correct answer.

John
----

Scott Mace wrote:
> I found that on the two FatPPS units I have, pin 2 on the female DE-9 connector
> is tied to the DC-IN. This was causing noise from the thunderbolt RS-232
> TX to get into the PPS output.  It basically made it totally unusable.
> I removed R4 since I use DTR for power and it works perfectly.
> 
> 	Scott
> 
> Tim Cwik wrote:
>> Wayne Knowles wrote:
>>> Tim, Chris,
>>>
>>> Over a month ago I experimented with getting GPSD and the Tunderbolt working 
>>> together.
>>> I quickly added support for the missing TSIP packet types, and was able to get 
>>> xgps to display lat, long, time  and constellation status.   I did manage to 
>>> get NTP to work, have not invested the time into getting the 1PPS signal 
>>> working under FreeBSD yet.
>>>
>>> I have attached my patches against the gpsd source repository.   Note that I 
>>> did not invest much time understanding the internals of gpsd beforehand so 
>>> some aspects may not be fully implemented.
>>>
>>>   
>> Thanks Wayne and Chris and Chris.
>>
>> I have discovered the even though cgps does not report position or time 
>> using the Thunderbolt, the stock gpsd is getting enough timing data to 
>> update ntp. Gpsd is selected as the sys.peer with a jitter of about .8. 
>> It looks like the PPS pulse is too narrow to be detected on DCD, I am 
>> going to investigate a pulse stretcher available from TAPR 
>> http://tapr.org/kits_fatpps.html and will see if that helps. FWIW, 
>> Centos 5.1 selinux allows gpsd to update the ntp shared memory segment 
>> out of the box.
>>
>>
>> 73,
>>
>>
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> 
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