GPS date issue

2 thoughts on “GPS date issue

  1. Hello,

    Right now I’m struggling with another GPS issue.

    To set the system clock of our handheld device after power-on, I’m trying to obtain GPS time and date as early as possible, i. e. before the actual fix. As soon as the date field in the $GPSACP response contains non-zero data, it’s transferred to the clock registers.

    Unfortunately, it turned out that we start with a completely wrong date, namely 870 days too early:

      First non-zero sentence: 092634.040,,,,,0,,,,231012,00
      …
      Correct date sentence: 093021.198,,,,,0,,,,100215,00
      …
      Final fix sentence containing all fields

    A handful of seconds after the first non-zero sentence, the date field flips over to the correct date.The 870 day offset appears to be constant – at least since yesterday when I first noticed the wrong date.

    One possible workaround is to wait until NSAT is non-zero, but this takes a lot longer than the first sentence containing the correct date.

    Is this a known issue? Is there a recommended workaround, ideally one that doesn’t involve updating GE864-GPS firmware?

    GE864-GPS firmware is 10.00.116.
    SiRF firmware is GSD4e_4.1.2-P5_CCK F+ 01/08/2013 8TELIT100.

    Best regards

    Harald Lenz

    1. Hello Harald,

       

      This issue has already been addressed to ts-emea by Burkhard Broehl. You can read my answer to his question below.

      In order to keep open one thread only, it would be better if we communicate through ts-emea. Please, give me your email address and I will I will put you in cc in the next messages. Thank you.

      When the receiver starts to see satellites, the first data that is been updated is the hour. To be sure to have a valid data, you should check the fix field, i.e. when you have a valid fix you can be sure that the data is correct. See below some sentences that show how hour and data change when the receiver starts to acquire signals and navigate.

      AT$gpsacp

      $GPSACP: 000000.000,,,,,0,,,,000000,00

      OK

      AT$gpsacp

      $GPSACP: 141751.647,,,,,0,,,,261012,00

      OK

      AT$gpsacp

      $GPSACP: 141753.652,,,,,0,,,,261012,00

      OK

      AT$gpsacp$GPSACP: 141756.647,,,,,0,,,,261012,00

      OK

      AT$gpsacp

      $GPSACP: 141757.652,,,,,0,,,,261012,00

      OK

      AT$gpsacp

      $GPSACP: 141759.647,,,,,0,,,,261012,00

      OK

      AT$gpsacp

      $GPSACP: 141800.647,,,,,0,,,,261012,00

      OK

      AT$gpsacp

      $GPSACP: 141801.652,,,,,0,,,,261012,00

      OK

      AT$gpsacp

      $GPSACP: 141802.652,3913.6605N,00904.1296E,1.2,36.1,3,186.43,0.28,0.15,130215,08

      OK

      AT$gpsacp

      $GPSACP: 141819.000,3913.6602N,00904.1291E,1.2,35.2,3,186.43,0.0,0.0,130215,08

      OK

      AT$gpsacp

      $GPSACP: 141821.000,3913.6602N,00904.1291E,1.2,35.2,3,186.43,0.0,0.0,130215,08

      OK

      AT$gpsacp

      $GPSACP: 141822.000,3913.6602N,00904.1290E,1.2,35.2,3,186.43,0.0,0.0,130215,08

       

      Can you please tell me the serial number of the GE864-GPS? Also the part number is OK.

       

      I need the commands sequence you sent to the module. I also need to see the C/N0 of the satellites. To provide it, you can send the AT$GPSNMUN=3,1,1,1,1,1,1 command and send me the output.

       

       

      Best regards,

      Federica Cara

      Technical Support – EMEA Application Engineering
      Telit Communications S.p.A.