All the below is with firmware 2.3.13 I have three units for testing, all are acting the same.
Test setup: Modules are set up with defaults other than a unique ID under “user”, and a correct fixed GPS location. Output is coupled onto a U/fl to SMA cable, into a 10dB pad, and then into a spectrum analyzer. Max input on the analyzer is +20dB, so the pad is required to protect the analyzer.
Power control: While I have seen settings of 30dBm, the chip won’t actually do more than 22. Just a limitation of the chip. Measuring with spectrum analyzer, it does seem that the power setting tracks the requested power up to 22dBm. Ok, no issue there.
Frequency slot: I’m leaving that at the default of 20, which puts me at 906.875. Usually that’s what I get. Using the spectrum analyzer, and max hold over a period of hours, it appears that the unit sometimes sends in slot 19, and sometimes 21. Repeatable across all my units. I sometimes catch it doing all three slots in what appears to be a single transmission. Of course this happens rarely and is hard to capture. Here is one such incident. Normally I would see a rectangular spectrum 250kHz wide Sorry, it will only let me put in one image…
Harmonics and general output issues: Sometimes the units appear to be transmitting except nothing shows up on the spectrum analyzer. Just no output at all. Sometimes I see harmonics at reasonable levels like -40dBc and other times +10 on the second harmonic and +15 on third harmonic.
I’d like to dig in and see what’s being passed to the appropriate functions.
Unfortunately I have had no luck tracking down the files needed to compile 2.3.13.
I see a lot of traffic in the same vein, is there a solid link to a file set that will compile?