LOGARITHMIC_LIMITER

Published:2009/7/21 22:38:00 Author:Jessie | From:SeekIC

Speech processor with logarithmic limiting makes noticeable improvement in speech readability of SSB transmitter. Adjustable-gain preamp U1 sets input level for soft limiting amplifier U2 in which nonlinear resistance characteristics of CR1 and CR2 supply increasingly heavier negative feedback as U2 output amplitude increases, thus providing logarithmic response. Low-pass active filter using U3 attenuates any frequencies above 2.8 kHz that may be generated in clipping process.-F. C. Getz, Audio-Frequency Speech Processor, Ham Radio, Aug. 1977, p 48-51.



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