L76K cold start issues

IoT Modules GNSS Module
1

Hi,
I have isues with cold start on L76K module. It does not find enough satelites and no fix.
These are the messages I am getting.

00> 842795: $GNGGA,145228.000,0,00,25.5,72
00> 842824: $GPGSV,1,1,01,29,23,06E
00> 842853: $BDGSV,1,1,01,29,21,07D
00> 842874: $GLGSV,1,1,00,079
00> 842919: $GNRMC,145228.000,V,311223,N,V21
00> 842953: $GPTXT,01,01,01,ANTENNA OPEN25

Commands sent to the moulde are
‘$PCAS10,1’
‘$PCAS03,1,0,0,1,1,0,0,1,0,0,0,0’
‘$PCAS04,7’
NB: Cheksums are added to the abbove messages by transmit routine at runtime

Any additional document on L76K to help resolving the issue?
I see there is AGNSS document asn demo C++ code. That could be helpful.

Darko

2

Hi Darko,

Did you test in open sky environment? Please be aware that AGNSS can’t improve the TTFF duration in cases where the signal level is too low (either due to poor RF design, or signal reception quality).

What about the antenna you use on your device? Does it support the parameter below?

image
image901×714 69.4 KB

Best regards.

3

Hi Raphael,

Thanks for the reply.
At current setup - antenna is passive and according to the requrements.
RF design is being under investigation right now.
Environment is my home window. So not open sky, but not closed space either.
L76K is being tested against Garmin GPSMAP 66s and Samsung Note20 mobitel.
Both have lower TTFF than L76K.

Moost of the times L76K is being stucked at 3 GPS satelites and 1 GLONASS. That is why I think AGNSS should be of some help.

Regards,
Darko