Re: [time-nuts] Logging and correlating NMEA messages with TICC timestamp
Just a note about possible spurious pulses with the TICC. The input circuit is a 3.3v logic gate that's 5v-safe. Some PPS signals have much greater peak amplitude than that (e.g., the HP atomic clocks). Experience has shown that these pulses don't know have enough energy to damage the input, but the voltage can cause ringing that results in occasional double pulses. So use a scope to look at the pulse and if its peak is more than about 5v, use an attenuator to knock it down. Also, make sure the pulse is terminated in a 50 ohm load at the TICC input. John On Jun 24, 2019, 2:00 AM, at 2:00 AM, "Forrest Christian (List Account)" wrote: >I have a couple of GPS receivers I'm experimenting with that I've been >using a TICC to gather timestamps of the 1PPS output to ascertain >their relative quality. > >In the process of doing this, I've discovered that some of the 1PPS >outputs are not as stable as I'd like them to be. For instance, the >one currently on my bench emits stuff like this every once in a while: > >330364.902989667231 chA >330365.582893064933 chA >330365.584094826326 chA >330365.902989679840 chA > >Note the 2 inserted pulses between the two correct ones. > >I'd like to be able to look at a log of the GPS NMEA output at the >appropriate time for this and other events to determine if they >correspond to some sort of GPS event.In addition, I'd like to >gather the phase correction data (aka quantization error) from the GPS >(and which is spit out in a NMEA sentence as well) in a way that is >correlated to the TICC timestamp it goes with. > >I know I can hack together something in python or similar to open both >ports and log them together using a common timestamp. But this also >seems like something which is probably being done regularly in time >labs around the globe so there's likely some tool to do this that I'm >unaware of. > >So I guess I'm asking what everyone else is using to gather both >timestamp data and NMEA data in a correlated way > >Thanks for any input. > >-- >- Forrest > >___ >time-nuts mailing list -- time-nuts@lists.febo.com >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Logging and correlating NMEA messages with TICC timestamp
li...@packetflux.com said: > So I guess I'm asking what everyone else is using to gather both timestamp > data and NMEA data in a correlated way I have a hack that grabs everything and writes each line and a time stamp to a file per day. http://users.megapathdsl.net/~hmurray/time-nuts/Arctic/code/AAA-README http://users.megapathdsl.net/~hmurray/time-nuts/Arctic/code/grab-nmea.py I'd use two copies of it - one for the TICC and another for the NMEA. You can merge them on post processing. The time stamp is the end of line. If you know the baud rate and number of stop bits, you can calculate the start time. Again, post processing. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Logging and correlating NMEA messages with TICC timestamp
I have a couple of GPS receivers I'm experimenting with that I've been using a TICC to gather timestamps of the 1PPS output to ascertain their relative quality. In the process of doing this, I've discovered that some of the 1PPS outputs are not as stable as I'd like them to be. For instance, the one currently on my bench emits stuff like this every once in a while: 330364.902989667231 chA 330365.582893064933 chA 330365.584094826326 chA 330365.902989679840 chA Note the 2 inserted pulses between the two correct ones. I'd like to be able to look at a log of the GPS NMEA output at the appropriate time for this and other events to determine if they correspond to some sort of GPS event.In addition, I'd like to gather the phase correction data (aka quantization error) from the GPS (and which is spit out in a NMEA sentence as well) in a way that is correlated to the TICC timestamp it goes with. I know I can hack together something in python or similar to open both ports and log them together using a common timestamp. But this also seems like something which is probably being done regularly in time labs around the globe so there's likely some tool to do this that I'm unaware of. So I guess I'm asking what everyone else is using to gather both timestamp data and NMEA data in a correlated way Thanks for any input. -- - Forrest ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
