| US 7,590,398 B2 | ||
| Method and apparatus for finding digitally modulated signals | ||
| John Eck, Kenosha, Ill. (US) | ||
| Assigned to Zenith Electronics LLC, Lincolnshire, Ill. (US) | ||
| Filed on Aug. 21, 2007, as Appl. No. 11/842,609. | ||
| Application 11/842609 is a division of application No. 09/474911, filed on Dec. 28, 1999, granted, now 7,376,387. | ||
| Prior Publication US 2007/0287377 A1, Dec. 13, 2007 | ||
| Int. Cl. H04B 1/18 (2006.01) | ||
| U.S. Cl. 455—183.1 | 26 Claims |
| 1. A method of finding digitally modulated signals, wherein each of the digitally modulated signals has a corresponding frequency
in a frequency spectrum, the method comprising the following steps:
a) stepping through the frequency spectrum by frequency increments;
b) testing each frequency increment for timing lock; and,
c) determining that one of the digitally modulated signals is found at each frequency increment where timing lock is detected
as a result of step b),
wherein step c) comprises the step of determining a center frequency of a digitally modulated signal corresponding to each
frequency increment where timing lock is found as a result of step b),
wherein the frequency increments are first frequency increments, and wherein the center frequency determining step comprises
the following steps:
estimating the center frequency of the corresponding digitally modulated signal; and,
determining a true center frequency of the corresponding digitally modulated signal by performing a zig-zag frequency search
from the estimated center frequency using a plurality of second frequency increments, wherein each of the second frequency
increments is less than the first frequency increments.
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