Method and apparatus for spectrum spreading of a pulse-density modulated waveform

摘要

A spreading method and apparatus for spreading the spectral density of a pulse stream by summing a set of randomly selected zero-sum sequences to an incoming pulse stream and ensuring that the number of pulses output by the spreading method and apparatus is equal to the number of pulses input to the spreading method and apparatus.

主权项

1. A frequency spreading circuit comprising:LLL
a) an accumulator having an output port and four input ports, the first input port receiving a signal to be spread; b) a source of zero-sum sequences having an output port for outputting zero-sum sequences, the output port coupled to a second input port of the accumulator; c) an accumulator register having an output port and an input port, the input port being coupled to the output port of the accumulator and the output port being coupled to the third input port to the accumulator; d) a comparator having an input port and an output port, the input port coupled to the output port of the accumulator register, the output port of the comparator providing a stream of pulses, the number of pulses in the stream output from the comparator being equal to the number of pulses input to the first input port of the accumulator; and e) an inverter having an input port and an output port, the input port coupled to the output port of the comparator and the output port coupled to the fourth input port to the summer.