| US 7,508,890 B1 | ||
| Apparatus and method for FSK demodulation with integrated time and frequency tracking | ||
| Lawrence J. Malone, Carlsbad, Calif. (US); and Aaron D. Lamb, San Diego, Calif. (US) | ||
| Assigned to National Semiconductor Corporation, Santa Clara, Calif. (US) | ||
| Filed on May 09, 2005, as Appl. No. 11/124,913. | ||
| Application 11/124913 is a continuation of application No. 09/938018, filed on Aug. 23, 2001, granted, now 6,891,905, filed on May 10, 2005. | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. H03D 3/00 (2006.01); H04L 27/14 (2006.01) | ||
| U.S. Cl. 375—334 [375/272; 375/335; 375/275; 329/300] | 17 Claims |
| 1. A frequency-shift-keyed (FSK) receiver, comprising:
demodulation circuitry capable of receiving an incoming FSK signal and generating a baseband signal;
auto-correlation circuitry capable of sampling the baseband signal and generating an auto-correlation function, the auto-correlation
function having a positive-going peak approximately coinciding with a center of a Logic 1 symbol in the baseband signal and
having a negative-going peak approximately coinciding with a center of a Logic 0 symbol in the baseband signal; and
decision circuitry capable of deciding a logic level of a first symbol using the auto-correlation function wherein the decision
circuitry is capable of deciding the logic level of the first symbol by comparing a signal level of a center sample of the
first symbol and a mean signal level of the auto-correlation function.
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