Spread spectrum frequency hopping reader system
First Claim
1. A reader for use in an interrogation system, the reader generating a radio frequency signal to be returned by an electronic tag when the tag enters a predefined envelope region associated with the reader, the reader comprising:
- a radio frequency source outputting a radio frequency signal at one of a plurality of frequencies within a frequency range;
means for hopping the radio frequency signal according to a first sequence among the plurality of frequencies in the frequency range;
a detector for detecting destructive interference in a return signal from an electronic tag located within an envelope region associated with the reader; and
a controller operating to vary the hopping upon the detection of destructive interference in the return signal.
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Accused Products
Abstract
An apparatus for sourcing an interrogation signal for use in a object identification system including a frequency hopping source for generation of an interrogation signal which is coupled to a homo dyne radio for transmission by a bi-directional antenna to a tag. Upon receipt, the tag provides a return signal that is backscatter modulated to include tag identification or other data which is processed by the sourcing system. The frequency hopping source includes a voltage controller oscillator which is driven by a pseudo random code generator for selecting one of a plurality of hopping frequencies at which the interrogation signal is to be generated based on the available bandwidth.
172 Citations
20 Claims
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1. A reader for use in an interrogation system, the reader generating a radio frequency signal to be returned by an electronic tag when the tag enters a predefined envelope region associated with the reader, the reader comprising:
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a radio frequency source outputting a radio frequency signal at one of a plurality of frequencies within a frequency range; means for hopping the radio frequency signal according to a first sequence among the plurality of frequencies in the frequency range; a detector for detecting destructive interference in a return signal from an electronic tag located within an envelope region associated with the reader; and a controller operating to vary the hopping upon the detection of destructive interference in the return signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A reader for reading data from an electronic tag comprising:
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a bi-directional antenna; a frequency hopping source for generating an interrogation signal at a frequency within a frequency range according to a first sequence; a homodyne radio for transmitting the interrogation signal to the electronic tag through the antenna and for receiving a radio frequency signal returned from the electronic tag; means for processing the radio frequency signal to decode the data from the electronic tag; and a controller operating to vary the hopping of the frequency hopping source to minimize occurrences of interference among adjacent readers.
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Specification