A noise reduction system is connected to at least two input channels for receiving
input signals that have substantially identical program content but differing instantaneous
noise transients. The system selects a filtered input signal that has the lowest
instantaneous noise transient level. In another aspect, the noise reduction system
removes instantaneous transient noise from an input signal by way of a blanker.
The blanker includes a switch that opens whenever a band-pass filtered input signal
is greater than the average level of the signal by a predetermined proportional
amount. The input signal also includes continuous noise that is removed by a continuous
noise suppressor. The continuous noise is removed by a low pass filter whose corner
frequency is responsive to a differentiated input signal divided by the program
component signal, or vice versa. In another aspect, the noise reduction system
includes at least two of a switcher, blanker or continuous noise suppressor in
connected in series to remove both instantaneous noise transients and continuous
noise from an input signal.