I am using SDRsharp to monitor air band with an RTL-SDR dongle. Sometimes I receive ATC voice clearly but at times it's distorted,
I am using RTL AGC gain of 29dB with no tuner gain. My filter bandwidth is 10 KHz but with 8-12Khz the results are identical. My antenna is a dipole placed outdoors.
What might cause reception to be distorted sometimes?