[ntp:questions] Sure Electronics GPS board: Amazing performance. :-)

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Mon Mar 14 11:52:18 UTC 2011

Terje Mathisen wrote:
> b) Since both the PPS and NMEA drivers have fudge flags to use a falling
> instead of the default rising edge of the DCD signal, I can use the
> first version of David's hack, i.e. from the official PPS header via the
> free RS232 level driver (U6 - pin 11->14). This should avoid the need to
> solder anything to U5 pin 8.

This worked perfectly, my (Windows) ntp.conf has the following lines:

# Sure Electronics GPS board: COM1, 18=(16+2)9600 baud GPGGA
server mode 18 minpoll 4 maxpoll 4 iburst prefer
# Enable PPS, enable falling edge (inverted PPS), disable kernel PPS,
# 0 ms PPS offset -100 ms NMEA offset
fudge flag1 1 flag2 1 flag3 0 time1 0.0 time2 0.100 refid 

> Terje
> PS. I've sent off emails to SkyNet, manufactor of the SkyLab gps chipset
> used, asking for documentation on how to manually determine both baud
> rate and which NMEA sentences should be sent each second.
> I got one test reply from admin at honestar.com, but no other response so far.

Still no reply, but I discovered by accident that if you leave the GPS 
board unplugged for some hours, it will revert to 9600 baud from 
whatever other speed setting you had previously selected.(I ran mine at 

I assume this also means that any command to turn on/off specific NMEA 
messages must be repeated.


- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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