FSK_FOR_NRZ_INPUT

Published:2009/7/15 1:59:00 Author:Jessie | From:SeekIC

Crystal-controlled frequency-shift keyer accepts nonreturn-to-zero digital input and generates 5-V P-P FSK output signal having less than 3% total harmonic distortion, at standard 2.125- and 2.975-kHz radio-teletype frequencies. When input is low, counter A divides by seven; for high or logic 1 input, counter divides by five. Counter B divides by eight to produce required output frequencies. EXCLUSIVE-OR gates G1 and G2 generate fist approximation to desired sine-wave out-put, for filtering by three-pole active Butter-worth low-pass filter having 4.75-kHz cutoff.-K. Erickson, Frequency4hift Keyer Features Rock-Steady Operation, EDN Magazine, Jan. 5, 1977, p 44.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Basic_Circuit/FSK_FOR_NRZ_INPUT.html

Print this Page | Comments | Reading(3)