METHOD FOR FREQUENCY DETECTION Russian patent published in 2000 - IPC

FIELD: radio engineering. SUBSTANCE: method involves dividing first periodic analog signal V3 at mean frequency by integer N using divider 33 in band-pass filter. Then, frequency-factored signal is sent to digital filter 48 as system clock signal. In addition, second periodic analog signal, which frequency should be also divided and slightly differs from mean frequency, is delayed by N periods in dynamic memory 54. Then, subtraction unit 56 subtracts second signal from delayed second signal and sends difference to digital filter 48. Output of digital filter corresponds to frequency of second signal, while mean frequency is subtracted. Filter may be used in requesting unit of electronic detection system, in which frequency of request signal is altered by small value, which corresponds to device to be detected. EFFECT: increased speed. 5 cl, 5 dwg, 1 tbl