Patent ID: 6891905
Filing Date: 2005-05-10
Classification: H04L

Abstract:
1. A frequency-shift-keyed (FSK) receiver comprising: demodulation circuitry capable of receiving an incoming FSK signal and generating therefrom a baseband signal comprising an amplitude modulated symbol stream of Logic 0 symbols and Logic 1 symbols having a data rate, R; auto-correlation circuitry capable of sampling said baseband signal S times during each symbol and generating an auto-correlation function comprising a sample stream of N-bit samples having a data rate, S×R, and having positive-going peaks approximately coinciding with the center of the Logic 1 symbol in a 010 sequence in said baseband signal and negative-going peaks approximately coinciding with the center of the Logic 0 symbols in a 101 sequence in said baseband signal; and decision circuitry capable of receiving said auto-correlation function and deciding a logic level of a first symbol as a function of: 1) a comparison of a signal level of a center sample of said first symbol and a mean signal level of said auto-correlation function; and 2) a comparison of said signal level of said center sample of said first symbol and a signal level of a center sample of a second symbol preceding said first symbol.