[ntp:questions] How to debug GPS PPS?

David Lord snews at lordynet.org
Wed Dec 30 23:37:55 UTC 2009


unruh wrote:
> On 2009-12-30, David Lord <snews at lordynet.org> wrote:
>> xyz-2041 wrote:
>>> On Dec 28, 7:59 am, Thomas Laus <lau... at acm.org> wrote:
> .......
> 
>>> If not, does anyone have some other suggestions?  Would I be able
>>> to use this Motorola antenna with another GPS unit?  Other low-cost
>>> ways of getting GPS accuracy on this FreeBSD/NTP box?
> 
> the standard is the Garmin GPS18xLVC unit. Cost about $60, plus some
> soldering of a serial port  and usb port plug(for power)  onto the
> wires.
> 

Mine was good for 1us during period I had it setup in summer
but when I tested more recently PPS was very erratic, I suspect
because it's TTL level with borderline pull down when temperature
drops (can also see this from MSF receiver also TTL outputs). So
depending on serial port of pc it may need PPS signal converting
to rs232.

David




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