S: (n) clutter (unwanted echoes that interfere with the observation of signals on a radar screen)
S: (n) background, background signal (extraneous signals that can be confused with the phenomenon to be observed or measured) "they got a bad connection and could hardly hear one another over the background signals"
S: (n) crosstalk, XT (the presence of an unwanted signal via an accidental coupling)
S: (n) fadeout (a gradual temporary loss of a transmitted signal due to electrical disturbances)
S: (n) jitter (small rapid variations in a waveform resulting from fluctuations in the voltage supply or mechanical vibrations or other sources)