H - Electricity – 04 – L
Patent
H - Electricity
04
L
325/32
H04L 27/14 (2006.01) H04L 27/16 (2006.01) H04L 27/26 (2006.01) H04Q 7/16 (2006.01)
Patent
CA 1301846
DECODING OF SIGNALS USING COPHASE AND DIFFERENTIATING SIGNAL DETECTION Abstract of the Disclosure The disclosed decoder (14) produces an output signal when a receiver (12) signal contains frequencies that are sequentially within a predetermined passband surrounding detection frequencies f1 and f2. The receiver signal is mixed at exclusive-OR logic gates (52, 54) with cophase reference signals R1 and R2, which are produced by a reference tone generator (18) and have a frequency fr that corresponds to the desired tone detection frequency f1 or f2 and a phase difference of 90°. The outputs of gates (52, 54) are applied to low pass filters (56, 58), which produce outputs having a frequency of equal to the absolute value of the difference between the input and reference frequencies fi and fr, provided that .DELTA.f is below the filter's cutoff frequency fc1. A cophase detection circuit (60, 62, 64, and 66) produces a high logic output when signals are passed by filters (56, 58), indicating that the frequency of the receiver signal differs from the desired tone detection frequency by less than fc1. To further enhance the accuracy of tone detection, a differentiating tone detection arrangement (68 through 84) is provided to determine whether .DELTA.f is less than some second cutoff frequency fc2 or greater than fc1. Two differentiating circuits (68, 70) receivethe outputs of filters (56, 58) and produce bidirectional square waves having magnitudes corresponding to .DELTA.f. These square waves are then compared with some predetermined threshold to produce an output only when .DELTA.f is below fc2 or above fc1. The cophase and differentiating tone detection outputs are combined to produce an output when a tone corresponding to the detection frequency f1 or f2 has been detected.
582727
Rothenbuhler Engineering Co.
Smart & Biggar
LandOfFree
Decoding of signals using cophase and differentiating signal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Decoding of signals using cophase and differentiating signal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Decoding of signals using cophase and differentiating signal... will most certainly appreciate the feedback.
Profile ID: LFCA-PAI-O-1192487