u/I_FELL_ipe

Hey, I've been designing a software-defined radio system from scratch and collected some data connected to a ~38.2 MHz dipole. I am getting these weird, semi-constant lines every 70 kHz or so and have not been able to figure out where they're coming from (not the high-amplitude lines at 38.2, 39.5 MHz, etc, I mean the stripe-like lines that go through the whole spectrogram).

I have tried switching the power supply for a battery, I'm not using any switching supplies, I have tried shielding the circuit inside a metal box, and changing the FFT parameters, but nothing gets rid of them. They still appear even when the PCB is not connected to any antenna.

Any help would be highly appreciated, thanks.