EG25-G ANT_GNSS pin 47 dc input resistance

IoT Modules GNSS Module
1

I have an EG25-G installed in a phone. I can connect to the EG25-G on /dev/ttyusb2 and it outputs nmea sentences. Unfortunately it never finds any satellites. I removed the antenna (PIFA) and measured the cold, DC resistance of the transmission line connecting to the EG25-G, pin 47, ANT_GNSS pin. The transmission line resistance to ground measured electrically short with a DMM.

I’m wondering if I may have a shorted trace, causing the satellite acquisition failure. What should the pin 47 to ground resistance measure with a DMM?

Thanks.

2

Dear spartacus
1.Did you test indoors or outdoors? We recommend testing GNSS in an outdoor open sky environment.
2.Can you share your GNSS RF circuit? Let me check it for you.

Best Regards

3

Albert,

Thank you for the assistance. It is very appreciated. Since I made the post, I set my phone outside and watched gpsmon through a SSH connection. It took 30 minutes to find a satellite and 90 minutes to fix a location with 4 satellites. So, I think it is working.

I’m using a pine phone by pine64.org with a 1.2a version main board, which contains a EG25G. The schematic is downloadable at:

The GNSS circuit is on sheet 15 (see attached pic).

Screenshot 2020-12-16 at 8.09.47 PM
Screenshot 2020-12-16 at 8.09.47 PM981×399 21.6 KB

I think I need to work with the AGPS to get a faster lock. Is the pin 47 DC low resistance to ground normal? Since the main and diversity antenna inputs measured open to ground, I assumed the low resistance was an issue. At this point, just curious if the low resistance is normal.

Sincerely,
spartacus

4

Dear spartacus

  1. I tested that it is normal that pin 47 is shorted to GND, and it can be positioned normally.
  2. Can you provide us with your antenna specification? Have you tried another antenna? Help take a picture of the antenna and send it to me.
  3. In order to locate quickly, please refer to this command in the protocol manual: AT+QGPSCFG=“gnssconfig”, and configure it as GLONASS, Beidou, Galileo all on mode. “GSV” can only display GPS satellite information, if other satellite information can’t be displayed, you can check the “GSA” sentence or send AT+QGPSCFG=“outport”, “uartdebug” sentence to the debug uart port to check if there are GLONASS, Beidou and Galileo satellite information output.
  4. You can check whether there are interference sources on the circuit.

Best Regards