Hi all,
We are testing with the nrf9151 (mfw 202) on custom hardware with an external active antenna (molex 206640) and a slightly altered SLM (from SDK 2.7.0).
Most important modifications are the use of softsim (and custom AT-commands), enabling of scheduled downloads, allowing low-accuracy fix, and activating NMEA logs.
When the SLM application start and gets a fix we observe quite lage differences between the $GPGGA and the XGPS (PVT) data:
Using the following AT-commands after boot:
AT+CEREG=5
AT%XSYSTEMMODE=1,0,1,1
AT+CFUN=31
AT#XGPS=1,0,10
We see quite big difference in fix-data:
$GPGGA,115028.35,5223.38685,N,00454.21081,E,1,03,100.00,122.29,M,,M,,*7A $GPGSA,A,3,03,17,19,,,,,,,,,,100.00,100.00,100.00,1*13 $GPGGA,115029.35,5223.38663,N,00454.21077,E,1,03,100.00,122.24,M,,M,,*77 $GPGGA,115030.35,5223.38674,N,00454.21057,E,1,03,100.00,122.25,M,,M,,*7A #XGPS: 52.389774,4.903509,122.284439,41.691196,15.915215,0.847988,3.765412,0.055654,0.813594,187.960800,119.907867,100.000000,100.000000,100.000000,100.000000,0.000000,0.000000,0.000000,0.000000"0050-31-489700816 1078604260:2320198794:1075027249" $GPGSV,2,2,8,17,40,243,21,19,41,279,25,25,01,010,,28,19,044,10,1*5A $GPGGA,115031.35,5223.38644,N,00454.21056,E,1,03,100.00,122.28,M,,M,,*74 $GPGSA,A,3,03,17,19,,,,,,,,,,100.00,100.00,100.00,1*13 $GPGGA,115032.35,5223.38572,N,00454.21082,E,1,03,100.00,122.31,M,,M,,*70 $GPGSA,A,3,03,17,19,,,,,,,,,,100.00,100.00,100.00,1*13 $GPGGA,115033.35,5223.38568,N,00454.21192,E,1,03,100.00,122.32,M,,M,,*79 $GPGSV,2,1,8,1,43,136,,2,15,140,,3,71,067,29,4,58,176,09,1*51 $GPGGA,115034.35,5223.38590,N,00454.21178,E,1,03,100.00,122.42,M,,M,,*7A $GPGGA,115035.35,5223.38569,N,00454.21191,E,1,03,100.00,122.38,M,,M,,*77 $GPGGA,115036.35,5223.38636,N,00454.21133,E,1,03,100.00,122.37,M,,M,,*7A $GPGSA,A,3,03,17,19,,,,,,,,,,100.00,100.00,100.00,1*13 $GPGGA,115037.35,5223.38634,N,00454.21193,E,1,03,100.00,122.38,M,,M,,*7C $GPGGA,115038.35,5223.38571,N,00454.21340,E,1,03,100.00,122.39,M,,M,,*7C $GPGLL,5223.38571,N,00454.21340,E,115038.35,A,A*6E $GPGGA,115039.35,5223.38538,N,00454.21453,E,1,03,100.00,122.39,M,,M,,*75 #XGPS: 52.389757,4.903599,122.395164,46.143543,17.095324,0.544477,3.780228,0.050574,0.815002,187.960800,180.000000,100.000000,100.000000,100.000000,100.000000,0.000000,0.000000,0.000000,0.000000"0050-41-2327204724 1078604259:562462907:1075027273" $GPGGA,115040.35,5223.38498,N,00454.21529,E,1,03,100.00,122.41,M,,M,,*73 #XGPS: 1,2 $GPGSA,A,3,03,17,19,,,,,,,,,,100.00,100.00,100.00,1*13 $GPGGA,115041.35,5223.38539,N,00454.21596,E,1,03,100.00,122.40,M,,M,,*7D $GPGGA,115042.35,5223.38581,N,00454.21625,E,1,03,100.00,122.44,M,,M,,*72 $GPGGA,115050.57,,,,,0,,99.99,,M,,M,,*64 #XGPS: 52.389718,4.903626,122.528717,69.901436,18.345539,0.470053,4.803012,0.005579,0.833977,187.960800,180.000000,100.000000,100.000000,100.000000,100.000000,0.000000,0.000000,0.000000,0.000000"0050-52-1177549626 1078604258:190884630:1075027280" #XGPS: 1,4 #XGPS: 1,2 $GPGSV,2,1,8,1,42,137,,2,14,140,,3,70,067,,4,59,175,,1*51 $GPGGA,115051.57,,,,,0,,99.99,,M,,M,,*65 $GPGGA,115052.57,5223.38307,N,00454.21754,E,1,03,100.00,122.53,M,,M,,*7E #XGPS: 52.389606,4.903622,122.567596,72.052505,19.387293,0.779464,4.737854,-0.000449,0.837156,187.960800,180.000000,100.000000,100.000000,100.000000,100.000000,0.000000,0.000000,0.000000,0.000000"0051-02-2567315469 1078604254:300233275:1075027279"
The PVT / XGPS data seems to be the correct location.
Is someone able to explain why we see this big differences? Does the nrf-modem do some internal filtering on the NMEA data to get PVT?
Kind regards,
Hessel
