DIY Antenna GPS 10Hz ( chips: GPS NEOM8-N + Bluetooth JDY-30)

i tried to build this 10hz GPS antenna. I tried to pair with Racechrono, but it doesn't work.
with the Android app Serial Bluetooth i tried to connect on the DIYAntenna directly, this is the output:

09:00:40.479 $GNRMC,,V,,,,,,,,,,N*4D
09:00:40.479 $GNVTG,,,,,,,,,N*2E
09:00:40.479 $GNGGA,,,,,,0,00,99.99,,,,,,*56
09:00:40.479 $GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
09:00:40.586 $GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
09:00:40.586 $GPGSV,1,1,00*79
09:00:40.586 $GLGSV,1,1,00*65
09:00:40.610 $GNGLL,,,,,,V,N*7A
09:00:41.759 $GNRMC,,V,,,,,,,,,,N*4D
09:00:41.759 $GNVTG,,,,,,,,,N*2E
09:00:41.759 $GNGGA,,,,,,0,00,99.99,,,,,,*56
09:00:41.759 $GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
09:00:41.811 $GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
09:00:41.811 $GPGSV,1,1,00*79
09:00:41.811 $GLGSV,1,1,00*65
09:00:41.835 $GNGLL,,,,,,V,N*7A
09:00:42.494 $GNRMC,,V,,,,,,,,,,N*4D
09:00:42.494 $GNVTG,,,,,,,,,N*2E
09:00:42.494 $GNGGA,,,,,,0,00,99.99,,,,,,*56
09:00:42.494 $GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
09:00:42.584 $GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
09:00:42.584 $GPGSV,1,1,00*79
09:00:42.584 $GLGSV,1,1,00*65
09:00:42.606 $GNGLL,,,,,,V,N*7A

Have you any suggestions?

Thanks a lot

Luca from Italy


  • Configure it to output $GPRMC and $GPGGA. The rest are really not needed so you can disable them.
  • ok. perfect! i'll try to do it.
    thank you.
  • i tried to disable GLONASS and set UBX+NMEA+RMC in the output string. this is the output now:

    16:40:52.547 $GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30
    16:40:52.547 $GPRMC,,V,,,,,,,,,,N*53
    16:40:52.547 $GPVTG,,,,,,,,,N*30
    16:40:52.637 $GPGGA,,,,,,0,00,99.99,,,,,,*48
    16:40:52.637 $GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30
    16:40:52.637 $GPGSV,1,1,00*79

    Do you think could be right?

  • Looks right.
  • i need your help. :-(

    before making the changes you suggested, I performed a factory reset through the U-CENTER interface.
    Now it never locks on any satellite.

    Thank you
  • Hi, no idea unfortunately. I do have M8 chip here that I'm planning to try on my DIY stuff, maybe can answer this later...
  • I encountered similar behaviour, but it did start working again after a few minutes.
    In U-Center I did a CFG - "Revert to default configuration". Then it takes many minutes to get a lock to satellites again, even if you send the Almanac through 'A-GPS'.

    While my USB-GPS receivers function flawlessly (but not with RaceChrono - I should try to connect them to my phone!), my GPS module connected through a USB-serial connector behaves erratically in U-Center. A-GPS data is not always kept and the newer constellations (Beidou, Galileo) are not reported - but I think they are received.

    Also if you remove the GxGSV(?) records, U-Center does not report the satellites. So it may look like it is not receiving, but it does use them to calculate position.
  • What is the list of supported NMEA messages and talker id's ?
    * RMC and GGA are mentioned above: these 2 are pretty standard for a complete positioning decoding (HLT uses these)
    * GSA and GSV are used when available to display the constellation of satellites, perhaps optional? If used, can they be sent with a lower frequency (e.g. every 1, 2, 5 secs)?
    * I see that sending GPS, Glonass, and Galileo works - is anything but GP ignored? Should other talker be changed into GP talker id?
    * is GBS used?

    Thank you!
  • - Only GGA+RMC or RMC+VTG+ZDA combinations are used
    - GSA+GSV are optional
    - Sentences need to start with $GP
    - GBS sentence is not used (as stated above)
  • Hi,

    I found the solution.

    The problem was the internal GPS antenna.

    I tried to connect a simple electricwire and now it works.

  • hi,
    this is my output on RaceChrono
    it seems to be right, but I notice that the GPS update is not stable (14Hz is the GPS setting) it alternates between 6 and 13hz.
    Is it normal? Could be the of the serial communication? Now it is set 9600


  • Most definitely 9600 baud rate is not enough for 14 Hz NMEA. Try 19200 or 38400.
Sign In or Register to comment.