| US 7,577,412 B2 | ||
| System and method for detecting narrow bandwidth signal content to determine channel occupancy | ||
| John Jorgenson, Cedar Rapids, Iowa (US); David Eastburn, Cedar Rapids, Iowa (US); and Hunter Leland, Cedar Rapids, Iowa (US) | ||
| Assigned to Intermec IP Corp., Everett, Wash. (US) | ||
| Filed on Dec. 23, 2005, as Appl. No. 11/318,348. | ||
| Prior Publication US 2007/0149155 A1, Jun. 28, 2007 | ||
| Int. Cl. H04B 17/00 (2006.01) | ||
| U.S. Cl. 455—226.1 [455/67.11; 455/182.1; 455/266] | 16 Claims |
| 1. A receiver system for detecting the presence of a signal on a channel, comprising:
an antenna;
a local oscillator having an output with a controllable frequency within a band of frequencies defined by the channel;
a frequency mixer connected to receive signals from the antenna and the local oscillator as inputs, and to output a baseband
signal having a frequency indicative of a difference between a frequency of signals from the antenna and a frequency of signals
from the local oscillator; and
a tone detector coupled to the frequency mixer to determine whether the signals received by the antenna are less than a threshold
frequency apart from the frequency of the local oscillator output, the threshold frequency being less than a bandwidth of
the band of frequencies defined by the channel.
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