nRF9151 no GPS fix

Hi,

My custom boards with nRF9151 don't get gps fix. I'm using the same GPS antenna and LNA as DK. Soft is from DevAcademi example, but tried also GGSN sample and some other samples, but never got fix. Same soft with nRF9160 board works ok (devicetree overlay is different). UART, SPI, I2C, sensors, flash, pMIC, all ok.

When GPS cycle starts, then always during 2minutes and 10sec nRF9151 finds only 0...3 satellites, all with cn0: 0. On 2:10 satellite count jumps to 12, all with good cn0. It lasts 6...7sek, then drops again to 0...3 sat, but this time cn0 is different from 0 (seems real). It repeats with every GPS cycle, never gets fix and always 2:10 from start and lasts 6...8sek. Current monitored with PPK2 seems normal. 

LNA is connected to COEX0, but tested it also with always power on - same result.

Tried modem FW 2.0.0, 2.0.2, SDK 2.7, 2.8, 2.9 - no diffrence.

Tried different LTE PS modes and values - same GPS pattern. 

Tried to set GPS priority over LTE - same.

Tried with two boards (same batch) - same pattern.

NRF9151-LACA-R7 bought from Mouser, details installed to PCB in factory.

Br 

Urmas

...

[00:02:13.645,202] <inf> gw2_2: Searching...

[00:02:13.649,810] <inf> gw2_2: Number of current satellites: 0

[00:02:14.569,488] <inf> gw2_2: Searching...

[00:02:14.574,066] <inf> gw2_2: Number of current satellites: 0

[00:02:15.573,944] <inf> gw2_2: Searching...

[00:02:15.578,521] <inf> gw2_2: Number of current satellites: 0

[00:02:16.574,371] <inf> gw2_2: Searching...

[00:02:16.578,979] <inf> gw2_2: sv: 4, cn0: 207, signal: 1

[00:02:16.584,838] <inf> gw2_2: sv: 11, cn0: 210, signal: 1

[00:02:16.590,759] <inf> gw2_2: sv: 16, cn0: 217, signal: 1

[00:02:16.596,710] <inf> gw2_2: sv: 3, cn0: 288, signal: 1

[00:02:16.602,569] <inf> gw2_2: sv: 31, cn0: 213, signal: 1

[00:02:16.608,489] <inf> gw2_2: sv: 1, cn0: 213, signal: 1

[00:02:16.614,349] <inf> gw2_2: sv: 24, cn0: 207, signal: 1

[00:02:16.620,269] <inf> gw2_2: sv: 30, cn0: 211, signal: 1

[00:02:16.626,220] <inf> gw2_2: sv: 23, cn0: 207, signal: 1

[00:02:16.632,171] <inf> gw2_2: sv: 7, cn0: 215, signal: 1

[00:02:16.638,000] <inf> gw2_2: sv: 199, cn0: 214, signal: 3

[00:02:16.644,042] <inf> gw2_2: sv: 25, cn0: 220, signal: 1

[00:02:16.649,963] <inf> gw2_2: Number of current satellites: 12

[00:02:17.574,401] <inf> gw2_2: Searching...

[00:02:17.579,010] <inf> gw2_2: sv: 4, cn0: 239, signal: 1

[00:02:17.584,869] <inf> gw2_2: sv: 11, cn0: 242, signal: 1

[00:02:17.590,820] <inf> gw2_2: sv: 16, cn0: 241, signal: 1

[00:02:17.596,740] <inf> gw2_2: sv: 3, cn0: 252, signal: 1

[00:02:17.602,600] <inf> gw2_2: sv: 31, cn0: 239, signal: 1

[00:02:17.608,551] <inf> gw2_2: sv: 1, cn0: 243, signal: 1

[00:02:17.614,379] <inf> gw2_2: sv: 24, cn0: 244, signal: 1

[00:02:17.620,330] <inf> gw2_2: sv: 30, cn0: 243, signal: 1

[00:02:17.626,281] <inf> gw2_2: sv: 23, cn0: 241, signal: 1

[00:02:17.632,202] <inf> gw2_2: sv: 7, cn0: 242, signal: 1

[00:02:17.638,061] <inf> gw2_2: sv: 199, cn0: 242, signal: 3

[00:02:17.644,104] <inf> gw2_2: sv: 25, cn0: 244, signal: 1

[00:02:17.650,024] <inf> gw2_2: Number of current satellites: 12

[00:02:18.573,486] <inf> gw2_2: Searching...

...

[00:02:22.574,523] <inf> gw2_2: sv: 4, cn0: 246, signal: 1

[00:02:22.580,383] <inf> gw2_2: sv: 6, cn0: 255, signal: 1

[00:02:22.586,242] <inf> gw2_2: sv: 16, cn0: 243, signal: 1

[00:02:22.592,163] <inf> gw2_2: sv: 31, cn0: 244, signal: 1

[00:02:22.598,114] <inf> gw2_2: sv: 1, cn0: 246, signal: 1

[00:02:22.603,973] <inf> gw2_2: sv: 24, cn0: 246, signal: 1

[00:02:22.609,893] <inf> gw2_2: sv: 30, cn0: 245, signal: 1

[00:02:22.615,844] <inf> gw2_2: sv: 23, cn0: 247, signal: 1

[00:02:22.621,765] <inf> gw2_2: sv: 7, cn0: 249, signal: 1

[00:02:22.627,624] <inf> gw2_2: sv: 199, cn0: 243, signal: 3

[00:02:22.633,636] <inf> gw2_2: sv: 25, cn0: 242, signal: 1

[00:02:22.639,587] <inf> gw2_2: Number of current satellites: 11

[00:02:23.568,969] <inf> gw2_2: Searching...

[00:02:23.573,577] <inf> gw2_2: sv: 6, cn0: 249, signal: 1

[00:02:23.579,437] <inf> gw2_2: Number of current satellites: 1

[00:02:24.568,847] <inf> gw2_2: Searching...

[00:02:24.573,455] <inf> gw2_2: sv: 6, cn0: 249, signal: 1

[00:02:24.579,315] <inf> gw2_2: Number of current satellites: 1

[00:02:25.568,420] <inf> gw2_2: Searching...

[00:02:25.573,028] <inf> gw2_2: Number of current satellites: 0

Parents Reply
  • Antenna selection is ok, and I am not aware of any issues in the location so not sure what is the issue, but I will continue digging to see if there is anything. 


    You say that things work on the 9160, is that also a custom board? I assume that this is the case so I also assume that the 9151 HW is ok. 


    It does sound strange that you experience the same pattern of  seeing 12 satellites after a given time, have you tested in more then one location? 

    and do you have the option to test on a 9151DK ?

    Regards,
    Jonathan

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