Patent ID: 6255901
Filing Date: 2001-07-03
Classification: H04L

Abstract:
A demodulator circuit for demodulating a signal ASK-modulated with modulation pulses equal in duration, and having a small depth of modulation and large dynamic range comprising an amplitude limiter (10) through which an amplitude-dependent current flows when the amplitude of the signal to be demodulated exceeds its limiting threshold value, an envelope detector (12) to the input of which said signal to be demodulated is applied, a differentiating network (14) configured so that it differentiates the output signal of said envelope detector (12) and outputs a signal pulse only when the change in amplitude of this output signal is in one direction, a bandpass filter (18) passing, from a signal derived from said amplitude-dependent current from said amplitude limiter (10), the frequency component attributed to the duration of the modulation pulses, a comparator (20) comparing the output signal of said bandpass filter (18) to a fixed threshold value and outputting a signal pulse when said output signal exceeds the threshold value, and a logic circuit (15) outputting the signal pulse existing in each case as the demodulated signal.