US 7,321,289 B2
Systems and methods for reducing interference by modulating a reader transmittal signal within the transmission channel
Wayne E. Shanks, Baltimore, Md. (US)
Assigned to Symbol Technologies, Inc., Holtsville, N.Y. (US)
Filed on Jun. 30, 2005, as Appl. No. 11/169,701.
Prior Publication US 2007/0001848 A1, Jan. 04, 2007
Int. Cl. H04Q 5/22 (2006.01)
U.S. Cl. 340—10.1  [340/10.3; 340/10.4] 19 Claims
OG exemplary drawing
 
1. A method in a radio frequency identification (RFID) reader for communicating with an RFID tag within an operational frequency band, wherein the operational frequency band is divided into a plurality of operating channels, each operating channel having a center frequency, comprising:
selecting a carrier frequency, wherein the carrier frequency is approximately the center frequency of a selected operating channel of the plurality of operating channels;
initiating transmission of a symbol signal having a symbol transmission period;
beginning reception of a received signal during transmission of the symbol signal, wherein a period of reception of the received signal is a portion of the symbol transmission period;
frequency modulating a carrier signal within the selected operating channel during the symbol transmission period;
modulating the frequency modulated carrier signal with the symbol signal; and
transmitting the modulated symbol signal.