Patent ID: 6700931
Filing Date: 2004-03-02
Classification: H04L

Abstract:
An apparatus for initiating and maintaining synchronization of a pulse position modulation (PPM) decoder with a received PPM signal, comprising:a bit counter comprising a modulo-n counter having data inputs, a clock input, a reset input and a Q output, and a carry flip-flop having a data input, a clock input, a reset input and a Q-not output; and a bit window counter comprising a modulo-p counter having a clock input, a set input and a plurality of outputs; wherein the data inputs of the modulo-n counter are adapted to receive a reload value from a calibration/reload function, the clock input of the modulo-n counter is adapted to receive an internal oscillator clock signal, the Q output of the modulo-n counter is connected to the clock input of the carry flipflop, the Q-not output of the carry flipflop is connected to the data input of the carry flipflop and the clock input of the modulo-p counter, the reset inputs of the modulo-n counter and the carry flipflop are adapted to resynch the modulo-n counter and the carry flipflop at a rising edge of a PPM pulse, and the set input of the modulo-p counter is adapted to set the modulo-p counter at a rising edge of a last pulse of a calibration symbol.