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Circuit detecting defined amplitude changes of defined duration - compares received signal with reference valve derived by demodulated signal fed to comparator via low-pass filter
Circuit detecting defined amplitude changes of defined duration - compares received signal with reference valve derived by demodulated signal fed to comparator via low-pass filter
A circuit for detecting defined amplitude changes with defined durations in a received signal is esp. for use in radio clocks and contains a comparator receiving signals, demodulated if necessary, at one input and a reference value at the other input. The evaluation of the received signal to derive time information for display is performed independently of its strength. The reference value is derived by passing the received demodulated signal to the reference comparator input via a low pass filter. For reception of signals with low levels of short duration compared to the cycle time of the carrier, the low pass filter has a d.c. voltage gain less than unity. It consists of a resistor in series with a parallel circuit contg. a capacitor and resistor.
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