Abstract: This paper focuses on the problem of the time consuming and poor anti-interference performance of traditional demodulate of modulation slope,the author advance a new demodulate method by using dichotomy,we first analyze the errors of the self-correlation estimation,then we use dichotomy on reasonable interval near the result,Through experiment,this mothed proofs effective and the coasting time reduce five times then the traditional demodulate.

Key words: demodulation;dichotomy;modulation slope;autocorrelation