The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 19, 2000
Filed:
Sep. 15, 1998
Li-Cheng Zai, San Jose, CA (US);
Trieu C Chieu, Scarsdale, NY (US);
Intermec IP Corp., Woodland Hills, CA (US);
Abstract
An RF/ID interrogator recovers a backscattered data signal from a moving RF/ID transponder by combining the received in-phase (I) and quadrature-phase (Q) components of the signal in a manner that cancels out the amplitude nulls and phase reversals caused by movement of the RF/ID transponder. More particularly, the RF/ID interrogator comprises a radio having a transmitter portion to provide an RF carrier signal and a receiver portion to receive the I and Q signals from the RF transponder. A bandpass filter is coupled to the radio to remove direct current (DC) components from the I and Q. A processor coupled to the radio and the filter executes stored instructions to combine the filtered I and Q signals and recover the original backscattered data signal therefrom. In an embodiment of the invention, the processor estimates a phase angle .beta.(t) between the I and Q signals and the RF carrier by calculating an arctangent of a ratio of the filtered Q and I signals. Thereafter, the processor recovers the backscattered data signal by summing a product of the filtered I signal and the cosine of the estimated phase angle .beta.(t) with a product of the filtered Q signal and the sine of the estimated phase angle .beta.(t).