Hi there,
I have a Quectel L76K which sees a lot of satellites, but does not provide a fix. Sometimes it takes 30s, but sometimes the fix takes tens of minutes. I created a parser for the GPS data to see whats going on and I have multiple satellites with no SNR. I don’t know what the problem is, maybe can I update the firmware of the module, is that possible?
This is the output:
001543090: Baidu:
001543090: Satellites in view: 2
001543090: List of active satellites ids:
001543090: List of satellites in view:
001543090: id: 24 elevation: 11 deg azimuth: 195 deg snr: 0 dbHz
001543091: id: 34 elevation: 68 deg azimuth: 284 deg snr: 0 dbHz
001543091: GPS:
001543091: Satellites in view: 10
001543091: List of active satellites ids:
001543092: List of satellites in view:
001543092: id: 2 elevation: 6 deg azimuth: 62 deg snr: 0 dbHz
001543092: id: 7 elevation: 14 deg azimuth: 316 deg snr: 0 dbHz
001543093: id: 8 elevation: 28 deg azimuth: 290 deg snr: 0 dbHz
001543093: id: 10 elevation: 38 deg azimuth: 154 deg snr: 0 dbHz
001543094: id: 15 elevation: 10 deg azimuth: 57 deg snr: 0 dbHz
001543094: id: 16 elevation: 67 deg azimuth: 226 deg snr: 28 dbHz
001543094: id: 18 elevation: 44 deg azimuth: 60 deg snr: 0 dbHz
001543095: id: 23 elevation: 51 deg azimuth: 106 deg snr: 0 dbHz
001543095: id: 26 elevation: 37 deg azimuth: 181 deg snr: 0 dbHz
001543096: id: 27 elevation: 62 deg azimuth: 296 deg snr: 29 dbHz
001543096: GLONASS:
001543096: Satellites in view: 0
001543096: List of active satellites ids:
001543096: List of satellites in view:
Hi Stegmaf,
About the satellites with elevation and azimuth, but no SNR.
Those information of satellites maybe saved from last fix. The ephemeris( data of satellites ) will be automatically saved when module get fixed. The information store in RAM and the module will prioritize these information for locating while start up.
However, if the GNSS receiver does not have a good sight of satellites( the sky is block, or indoors ), those information are useless for location. So please confirm the module is working in a good environment.
Besides, L76K is a ROM version so that it doesn’t have a firmware.
Best regards.
Hi Raphel-Q,
thanks for the reply, it helps me to further understand how the module works. In the datasheet and here in the forum I have read, that I can transfer AGNS data to the module. The other post mentioned, that I should ask my responsible FAI, but as a maker, I don’t have a direct contact to quectel. Who can I ask, if I want to use the AGNS feature on this module?
Kind Regards
stegmaf
Hi Stegmaf,
I will send you an AGNSS Application Note to help you know more about the function.
You can contact with me no matter on Forums or emails. Anything emergency can send to my email raphael.wu@quectel.com . I will reply to you ASAP.
Best regards.
Hi Raphael-Q,
thanks for the application node, I will take a look at it. Its not urged, but thanks for the offer 
Kind Regards
stegmaf
Hi Raphel-Q,
I’m trying to decode the examples in the ANGSS application node. It seems for me that the example on page 15 is not correct. The example payload is:
// Send:
BA CE 38 00 0B 01 00 00 00 80 EB D1 3F 40 00 00 00 40 0A 47 5D 40 00 00 00 00 00 00 00 00 00 00
00 00 A0 A1 15 41 00 00 00 00 00 00 00 00 00 00 00 3F 00 00 00 00 E5 07 00 00 62 08 00 23 14 CB BD
// ACK:
BA CE 04 00 05 01 0B 01 00 00 0F 01 05 01
I have always miss a byte, thats what I’ve got:
FrameStart: BA CE
Length (LSB first): 38 00
Class: 0B
ID: 01
Lat: 00 00 00 80 EB D1 3F 40
Lng: 00 00 00 40 0A 47 5D 40
Alt: 00 00 00 00 00 00 00 00
TOW: 00 00 00 00 A0 A1 15 41
FreqBias: 00 00 00 00
pAcc: 00 00 00 00
tAcc: 00 00 00 3F
fAcc: 00 00 00 00
Res: E5 07 00 00
Wn: 62 08
TimerSource: 00
Flasgs: THIS BYTE IS MISSING
Checksum: 23 14 CB BD
Can you please check? I tried it 5 times and I don’t find the problem
Hi Stegmaf,
Thank you for reply. It maybe a mistake for this document.
I also test on my evaluation board. And the tool sends:
BA CE 38 00 0B 01】 【d1 28 fa cf dc 44 39 40】 【69 06 0a 1f 7e 95 5b 40】 【cd cc cc cc cc cc 1a c0】 【00 00 00 00 60 c3 0a 41】 【00 00 00 00】 【00 00 00 00】 【00 00 00 00】 【00 00 00 00】 【00 00 00 00】 【cf 08】 【00】【23】 94 6f 96 61
And I also compared with the data string of example. The bytes are matched.
Best regards.
Hi Raphel-Q,
thanks for your verification, I’ll take this as example.
I have questions to the field WN and TOW:
- What is the purpose of the first byte in the WN?
- How do I calcualte the TOW?
Kind Regards
Frederik
Hi Stegmaf,
I will send you C++ demo. Please take reference.
Best regards.
Hi Raphael-Q,
thank you very much, I’ll take a look at it.
Kind Regards
