PPS NMEA sometimes does not follow the correct structure

IoT Modules GNSS Module
1

I have a strange behavior that happens sometimes (it’s random). The normal behavior is to receive the PPS signal and 180-200ms later to receive the NMEA data stream, that works fine, but sometimes this scheme is not respected and I receive the PPS signal, after 1 second I receive another PPS signal and 180ms later I receive the 2 frames of serial data. This is a problem when trying to use GPS as a time source. Is it an already known issue and is it fixable?

GPS model L80-M39 (L80GR01A10S) @ 57600 bauds (8N1), with PPS signal trough RING pin.

Normal behavior
03/13 11:22:56.994 PPS
03/13 11:22:57.182 $GPZDA,142257.000,13,03,2023,53
03/13 11:22:57.194 $GPGSA,A,3,21,31,27,28,10,08,32,04,01,03,1.13,0.78,0.8204
03/13 11:22:57.202 $GPGLL,2049.5323,S,06014.5963,W,142257.000,A,A50
03/13 11:22:57.208 $GPTXT,01,01,02,ANTSTATUS=OK3B
03/13 11:22:57.994 PPS
03/13 11:22:58.172 $GPZDA,142258.000,13,03,2023,5C
03/13 11:22:58.183 $GPGSA,A,3,21,31,27,28,10,08,32,04,01,03,1.13,0.78,0.8204
03/13 11:22:58.192 $GPGLL,2049.5323,S,06014.5963,W,142258.000,A,A5F
03/13 11:22:58.198 $GPTXT,01,01,02,ANTSTATUS=OK3B

Structure error
03/13 11:23:05.993 PPS
03/13 11:23:06.993 PPS
03/13 11:23:07.172 $GPZDA,142306.000,13,03,2023,56
03/13 11:23:07.183 $GPGSA,A,3,21,31,27,28,10,08,32,04,01,03,1.13,0.78,0.8204
03/13 11:23:07.192 $GPGLL,2049.5323,S,06014.5963,W,142306.000,A,A55
03/13 11:23:07.197 $GPTXT,01,01,02,ANTSTATUS=OK3B
03/13 11:23:07.203 $GPZDA,142307.000,13,03,2023,57
03/13 11:23:07.214 $GPGSA,A,3,21,31,27,28,10,08,32,04,01,03,1.13,0.78,0.8204
03/13 11:23:07.223 $GPGLL,2049.5323,S,06014.5963,W,142307.000,A,A54
03/13 11:23:07.229 $GPTXT,01,01,02,ANTSTATUS=OK3B
03/13 11:23:07.993 PPS
03/13 11:23:08.993 PPS
03/13 11:23:09.172 $GPZDA,142308.000,13,03,2023,58
03/13 11:23:09.183 $GPGSA,A,3,21,31,27,28,10,08,32,04,01,03,1.13,0.78,0.8204
03/13 11:23:09.192 $GPGLL,2049.5323,S,06014.5963,W,142308.000,A,A5B
03/13 11:23:09.197 $GPTXT,01,01,02,ANTSTATUS=OK3B
03/13 11:23:09.203 $GPZDA,142309.000,13,03,2023,59
03/13 11:23:09.214 $GPGSA,A,3,21,31,27,28,10,08,32,04,01,03,1.13,0.78,0.8204
03/13 11:23:09.223 $GPGLL,2049.5323,S,06014.5963,W,142309.000,A,A5A
03/13 11:23:09.229 $GPTXT,01,01,02,ANTSTATUS=OK3B

Thanks in advance !

2

Does anyone have any ideas on this?

3

Hi DavidAG,

I’m sorry. We don’t have records simillar to your problem. This problem will add to schedule. The problem appear randomly, so it will take long time for us to reappear.

Please share more about your test environment and configurations for L80 module. That will be very helpful.

Besides, common GNSS module doesn’t have a stable timing performance. If your project require for high timing accuracy, you can choose our timing module products like L26-T.

Best regards.