I bought a job lot of Polstar G-Mouse receivers to play with. These use the Sony CXD2951GA-4 chipset which has a PPS output but this is not made available at the end of the cable unfortunately. The units themselves are fully waterproof so they are happy to sit through all kinds of weather outside and cling like limpets to a metal surface even with the gusty winds we have been experiencing here. Now I have looked at the output of these which from a reset state run at 4800bd and produce the requisite NMEA 0183 protocol as expected. Looking at the TTL output on a scope there is a burst of data, at 4800bd, each second with a reasonable gap between each burst. Each packet of data starts with a $GPGGA message and time-stamping these shows they seem to occur at 1 second intervals. What I was thinking about building was a small circuit which would switch on the start of the data block and then time out at the end of the block thereby producing a 1Hz signal, albeit not 50% duty cycle, which could possibly be used to lock a ocxo via a phase-frequency detector, like a MC4044, and a low pass filter. Has anyone looked at this before and, perhaps discarded it or whatever? Yes, I know it is no substitute for a Thunderbolt but I don't have one of those yet and this may be a cheap and cheerful way to sync to GPS.
Be gentle Bruce :-) 73, Steve -- Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW Omnium finis imminet _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.