Rotator Ground Station Noise

Hi all, I recently finished the construction of my rotator ground station and have begun testing.

I have been having some issues with observations. Currently, the station is equipped with a VHF Yagi-Uda a wideband LNA, and a genuine RTL-SDR. My biggest issue lays within the radio portion, I have not been able to get rtl_biast to work correctly (turns on for 10-15seconds then back off) so I opted to power the LNA using a 5v micro USB connection. Ill admit that I did not shield the stepper motor cables or any of the electronics from the SMA cable being used to connect the antenna to the LNA to the rpi. Before I go back and shield everything I want to get everybody else’s take on my weird issues. I have attached an image of noise that I am getting and it appears to be following some sort of pattern.

My observations are for the most part garbage, I have received some signals but the weird part is that my Yagi-Uda was pointing at the ground instead of the sky (plugged in stepper motor backwards)

Groundstation id is 2278 - FCNA2021


This is pretty classic switch-mode power supply noise. The drifting is due to the switching frequency drifting with load.

All I can suggest here is try powering things off one at a time and see if the noise goes away.


Thanks. Im going to try that tomorrow.

I went ahead and shielded all of the stepper motor cabling and moved the radio portion further up the mast. However I am still having a weird issue with passes. Could you take a look?

Still lots of noise, and the noise is varying throughout the pass, indicating that you’re probably seeing the noise source move through the pattern of your antenna as it moves.

Look further afield of your receive/antenna system. It could be anything in the vicinity.