GPS RSSI (NMEA) using SLM app

[Ofir_A]

Hi,

We want to check how changing system voltage affects on GPS reception, for that we need to know the RSSI of each satellite the model use.

I know I can get the C2N/SNR from NMEA ($GPGSV) which GNSS sample gives me (and from that to calculate the RSSI), but, we are using the SLM application, so we need to know how to merge GNSS sample with the SLM app.

Is it possible to do so?

Do you have any other suggestion to test the strength of GPS signal in different operation modes (AT command or something)?

Thanks in advanced

[Charlie]

Hi Ofir,

Maybe nRF9160: Modem Shell — nRF Connect SDK 2.0.0 documentation (nordicsemi.com) could be a solution for your needs?

It is of course possible to add NEMA output support to SLM, it is just an alternative option for the current PVT output.

Best regards,

Charlie

[Ofir_A]

Hey Charlie,

Thank for your reply

Charlie said:

Maybe nRF9160: Modem Shell — nRF Connect SDK 2.0.0 documentation (nordicsemi.com) could be a solution for your needs?

I will look over it

Charlie said:

It is of course possible to add NEMA output support to SLM, it is just an alternative option for the current PVT output

how can I do that?

[Charlie]

Hi Ofir,

Ofir_A said:

how can I do that?

Sorry for the late reply, I just got time to have a look into the SLM source codes. You can follow the follow steps to add NMEA to the current GNSS commands.

First, you need to enable NMEA output. This can be done with  nrf_modem_gnss_nmea_mask_set(nmea_mask) as gnss sample does in main.c.

Then, you need to add on_gnss_evt_nmea in SLM sample slm_at_host.c file, which is similar to the existing on_gnss_evt_pvt function to read out NMEA information. 

At last, print NMEA at fix_rep_wk function, similar to the current pvt printout.

Best regards,

Charlie

[Ofir_A]

Hey Charlie,

Thanks so much

Problem solved

You can close the ticket