Do I Need A Filter?

I run the newer dump978-fa. So much simpler and more reliable to run.
I haven’t managed to get an airspy to work well yet.
I currently use a V1 rtl-sdr with hardwired bias-t and a mast mount uputronics 978Mhzamp /filter, DPD antenna and a custom cavity filter(between the antenna and amp). I did run a pro stick(non-plus) with a custom 978Mhz cavity filter (and using a metal dongle case due to the interference)

Run wiedehopf’s graphs scripts to give you some idea of the range and signal levels

Remember that UAT/978Mhz aircraft tend to fly low. I barely get >90NM

Don’t ask me why I have lots of aircraft at max range.

It looks like you have 1090Mhz and 978Mhz on the same piaware so I can’t see what your range is like. Do you get any mlat timing errors? This could mean that the single USB 2.0 bus (on all RPI’s including the 4) is overloaded.

A metal case (for the RPI and dongles) could reduce noise(if that is your problem). I use 6" quality USB 3.0 extension “pigtails” as the RPI USB ports are too close together.

What is your setup like?