Lack of information with NMEA frame read by ardupilot

Hi, I’m new to this, and I’m a bit lost.
Could someone tell me what are the specific NMEA GPS frames ardupilot uses to establish position?

Thank you very much.
Best regards.

I suppose AP uses gga, rmc, vtg. My m8n also sends gsv, gsa, gll - maybe it affects accuracy.
Frequency must be 5hz or higher.

The frequency of the transmitting signal is above 5hz. What could be happening?

Rx/tx are messed up? GPS_TYPE not 5? Wrong baudrate? Wrong data?
You can check received data with serial port monitor and AP passthrough feature:

Yes, I’m at 4800 bps, but I seem to have GPS for a while, then it goes away, then comes back, and so on constantly. Is this normal?

I had a similar problem until I added a rmc message to protocol.
Or it can be buffer overflow.

I have RMC message, which buffer?

It can be tx buffer at your device or rx buffer at your flight controller.
Have you checked my link? Is the data flow correct?

Yes, I fixed it. It was a frame-to-frame send time bug.

Thank you very much.