48_Hz_12_STEP

Published:2009/7/10 5:50:00 Author:May | From:SeekIC

Used to provide 12 shades of gray for reception of satellite facsimile weather pictures. Input 1 is 2400-Hz square wave obtained from separate reference oscillator. Input 2 is 2400-Hz sine wave having 1 V P-P maximum voltage. U9 is 4-bit binary counter having special reset provided by U10A and U10B at count 12 to give desired 12 states. Outputs of U9 are used to adjust gain of U16A in 12 steps. Article describes operation in detail and gives circuits for reference oscillator and power supply.-R. Cawthon, Toward a More Perfect Weather Picture, 73 Magazine, April 1978, p 116-118.



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