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nRF9151 no GPS fix

Urmaz

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

  • 0 in reply to JONATHAN LL

    Yes, the 9160 was also custom board, same peripherials, same functions. Made 5 boards, all working ok. Now made upgrade to 9151, but stuck with GPS problem. 
    No, I didn't test in different location, can try tomorrow. I can't imagine, how it explains this pattern. When I move board inside a house, it finds less (...9) sat instead of 12, but this 2:10 and 6...7sek active pattern don't change.
    I don't have 9151DK. 
    Didn't mention it, but my board is powered by nPM1300, and I tried different Vdd voltages on GPIOs and LNA. All same. 

  • 0 in reply to Urmaz
    Urmaz said:
    Didn't mention it, but my board is powered by nPM1300, and I tried different Vdd voltages on GPIOs and LNA. All same. 

    Can you share the schematic of the nPM1300 and nRF9151 for your design? 


    Urmaz said:
    No, I didn't test in different location, can try tomorrow. I can't imagine, how it explains this pattern. When I move board inside a house, it finds less (...9) sat instead of 12, but this 2:10 and 6...7sek active pattern don't change.

    The GPS signal could be better. Could the you provide a log with the GNSS sample without A-GNSS, which shows the whole test run from boot? And make sure the LNA is enabled.


    Regards,
    Jonathan

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