TESEO-VIC3DA No Satellites Detected

[matthewshrike]

Hi there, 

We are troubleshooting an issue with our module where the GPGGA return shows no satellites detected. We have verified our circuitry according to the hardware instructions document on ST's website - https://www.st.com/resource/en/user_manual/um2832-teseovic3d-and-teseovic3da-hardware-instructions-stmicroelectronics.pdf

We are currently using a similar antenna that came with the GNSS dev kit. We know that there are satellites that can be picked up as the dev kit operates fines. 

If anyone has any troubleshooting recommendations, sharing them would be greatly appreciated.

The datasheet doesnt have explicit bring-up guidelines. As a result, i have only configured the PSTMINITGPS field, and nothing else. Are there other fields required to be configured out of the box? 

Also, our ANT_OFF pin is currently floating. I have measured 3.3V on the antenna itself though. 

[matthewshrike]

I should point out that I am getting GPGGA responses that are the same as the initial configuration sent in the PSTMINITGPS (ie its not updating positional info based on the initial command). I am certain of this because I configured it with a slightly offset position and date-time information compared to UTC. 

[GNSS-LeaT · Accepted solution]

Not connecting the ANT_OFF pin is fine as long as the VCC_RF is powering the antenna. Make sure the antenna that you are using is active and uses 3.3V to power the antenna's LNA. Some antennas have different power reqirements. If it is a passive antenna, VCC_RF should not be connected unless it is connected to an external LNA. Depending on the passive antenna, an external LNA may be required to get good performance. Match the input circuit for RF_IN as close to 50Ohm impedance as possible.

Check that all of the GND pins are connected and that VBAT and VCC are at 3.3V. 

[matthewshrike]

Thanks so much! The real reason was that the antenna wasn't grounded, my silly mistake. But your checks are useful for other engineers if they happent to have related issues.