Noise Suppression Method With Compressor/Expander Coupling for the Magnetic Recording and Playback of Analog Signals
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
An essential requirement for obtaining the original signal when a noise-suppressed magnetically recorded analog signal is played back is that the dynamic expansion during playback must be exactly synchronous with the dynamic compression during recording. As most known noise suppression systems are unsuited to meeting this requirement, an approximation is obtainable only by certain trade-offs. The problem of existing methods is that the playback expander does not directly and without delay control the recording compressor but that the control voltage has to be derived from the playback signal. However, the proposed method provides for the compressor/expander to be directly connected for control purposes. The figure is a block diagram of the recording system used.