Poor reception and excessive noise are classic symptoms of Antenna or VSWR problems.
In this case you say both systems are affected. How many aerials does your machine have? if its two seperate systems with seperate aerials and feeders its unlikely that they both have exactly the same defect so isolate the common component, the control panel for instance, check that its correctly fitted and connected and if possible swap that with a known good one.
If the aerial is common a VSWR check will tell you if its good or not, and a time domain reflectometer can be used to isolate any problems with the feeder cable.
To help troubleshooting,
When did the defect arise? did it just appear or was it a gradual thing?
Could both systems have been disturbed on a recent hangar visit?