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

David J Taylor david-taylor at blueyonder.co.uk.invalid
Sat Apr 2 05:41:47 UTC 2011

> I've done some more careful inspection of the Sure GPS comms trace:
> It really looks like the GPS does _not_ listen to commands by default, 
> instead the controlling program sends a solitary '0' char to ask for 
> "permission to talk".
> About 200 ms later the GPS boards drop the CD (Carrier Detect) line, and 
> then the gps.exe program sends the private NMEA message.
> As soon as the ending <CR><LF> arrives the GPS turns CD back on and 
> restarts the configured NMEA messages.
> If this sequence is required by default, then it must also be possible 
> to turn off such very non-standard GPS behavior, right?
> Terje

Fascinating!  I wonder whether that GPS "chip" is really intended for 
talking to a on-board microprocessor, and we're seeing the raw behaviour? 
As the board can forget any baud rate changes (although NTP works 
correctly at the default 9600 baud), perhaps it might forget any 
programming changes as well?  Presumably, you didn't get the programming 
manual as yet?


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