Re: GPS units

Fred Hillhouse

What is the port? I am trying it this morning and I am not located yet.


What are you doing at field day that requires the accuracy from NTP? I would think the GPS would provide a satisfactory time stamp.


Fred N7FMH



From: aprsisce@... [mailto:aprsisce@...] On Behalf Of Steve Daniels
Sent: Tuesday, January 28, 2014 8:17 PM
To: aprsisce@...
Subject: RE: [aprsisce] GPS units



Those wanting to try GPSD or even my NTP server can do, the IP address is it’s a static address.

Obviously only for testing as GPSD will give my location, and you would be better of using a proper time server.

My NTP system is really to try and get a reasonable time on a non internet connected system, such as Field day.

If you are attaching a GPS to a pi you might as well do as much as possible with it.


As you can see PPS jitter is good GPS time data not so good. Obviously a bit of work to do. For comparison I am linked to a UK ntp pool hence the other info.

The GPS is not designed for time reference but does have a PPS output.



Lynn is you want to connect to GPSD for testing please do it should be running 24/7 APRSIS32 uses it just fine

Steve Daniels

Amateur Radio Callsign G6UIM

Torbay Freecycle  Owner

APRSISCE/32 Beta tester and WIKI editor


From: aprsisce@... [mailto:aprsisce@...] On Behalf Of Steve Daniels
Sent: 28 January 2014 00:15
To: aprsisce@...
Subject: RE: [aprsisce] GPS units



I need to test in a better way to be absolutely sure. And I will port
forward my router so people can see for themselves.
My current setup provides GPS location to any device or software capable of
receiving location and time data from a GPSD system. APRSIS32 is capable of
NTP time for access from any device. Using the PPS in kernel mode rather
than user mode.
Also a samba install to allow monitoring from a windows pc.
And SNMP for remote monitoring as this is intended as a headless system.

Currently showing a bit of jitter on the GPS time as expected, but zero
jitter on the PPS.

I can create an image of the SD card. And torrent if people are interested.

Steve Daniels
Amateur Radio Callsign G6UIM
Torbay Freecycle Owner
APRSISCE/32 Beta tester and WIKI editor

-----Original Message-----
From: aprsisce@... [mailto:aprsisce@...] On Behalf
Of Gary Sanders
Sent: 27 January 2014 17:11
To: aprsisce@...
Subject: Re: [aprsisce] GPS units

Don't know if you've seen this:

I did similar, and never could tame the thing down - the jitter was
really bad - to the point that it really wasn't usable.

I was driving the PPS with the PPS output from a Trimble Thunderbolt
GPSDO, so I know the PPS was good. I understand that the RasPi
occasionally strips out some Oscillator clock pulses for some reason,
and I suspect that may be the cause.

More later - have to go to an appointment.

Gary Sanders

On 1/27/2014 6:24 AM, Steve Daniels wrote:
> Well I got asked to do data modes for the Olympics in Weymouth, to find
> the laptop time was out enough that JT-65 did not work.
> Using an adafruit breakout board GPS, that will run from 5V or 3.3V.
> Enable input and fix output. Handy for balloons.
> Cold starts very quickly. To the point that I have not sorted the
> battery backup.
> Have had it supplying APRSIS32 via GPSD with location. And time via the
> normal NMEA sentences.
> Got it running in user mode for NTP time easily, Which to be honest is
> good enough.
> But attempting to get the more accurate kernel mode working, which is
> more of a problem. On my second 10 hour long compile!!
> When it's working will torrent an image for everyone, as I will with an
> added TNC-Pi setup using XASTIR.
> I am hoping we can get APRSISMO working on the Pi. Currently there is a
> graphics driver issue that stops it running. To do with 3D hardware
> acceleration if I recall.
> Steve Daniels


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