Noise compensating EAS antenna system
First Claim
1. An electronic article surveillance system comprising:
- a plurality of n antennas, each said antenna not overlapping with any other antenna and not electrically connected to any other antenna, one of said antennas operating as a reference antenna and the other n−
1 antennas operating as non-reference antennas;
a controller, said controller comprising;
a digital signal processor;
at least one analog to digital converter;
a plurality of n amplifier-filter circuits, each amplifier-filter circuit being dedicated to a given antenna;
a plurality of multi-function amplifier filters, this plurality equal to the summation of integers from 1 through n−
1, each said multi-function amplifier filter being dedicated to a given pair of said antennas; and
a plurality of digital potentiometers, the plurality equal to 1 plus (n−
1) squared, a set of n−
1 of said digital potentiometers being dedicated to each of said non-reference antennas;
wherein,the signal from each said antenna is directed through a respective amplifier filter circuit, the outputs of which are directed to said digital signal processor;
the signal from said reference antenna is also passed through a single respective digital potentiometer, the output of which is directed to n−
1 respective multi-function amplifier filters which pair said reference antenna with each said non-reference antenna;
the signal from each said non-reference antenna is passed separately through n−
1 digital potentiometers, the outputs of which are directed to n−
1 multi-function amplifier filters through which each said non-reference antenna is paired with each other said antenna;
each said multi-function amplifier filter performing a difference operation on the pair of signals it receives and directing the result to an analog to digital converter which in turn directs its output to said digital signal processor;
said controller performing a surveillance cycle comprising;
adjusting said digital potentiometers to minimize the output of each said multi-function amplifier filter,operating one of said n antennas to generate an interrogation field and then ceasing generating said field, andmonitoring said antennas to determine if said antennas receive an additional signal.
0 Assignments
0 Petitions
Accused Products
Abstract
An EAS system employs multiple antennas which are in separate electrical circuits and do not overlap to avoid magnetic coupling. Each antenna is paired with each other antenna. The controls for the system employ multi-function amplifier filters (MAF) to perform a difference operation on the signals in each pair. The results are converted from analog to digital and directed to a digital signal processor (DSP). The DSP adjusts digital potentiometers to minimize the differences at the MAFs. The controls then operate at least one antenna to pulse generate an interrogation field. The controls monitor the antenna signals for additional signal at the MAFs. The DSP performs pattern recognition on additional signals at the MAFs to distinguish types of EAS tags.
17 Citations
22 Claims
-
1. An electronic article surveillance system comprising:
-
a plurality of n antennas, each said antenna not overlapping with any other antenna and not electrically connected to any other antenna, one of said antennas operating as a reference antenna and the other n−
1 antennas operating as non-reference antennas;a controller, said controller comprising; a digital signal processor; at least one analog to digital converter; a plurality of n amplifier-filter circuits, each amplifier-filter circuit being dedicated to a given antenna; a plurality of multi-function amplifier filters, this plurality equal to the summation of integers from 1 through n−
1, each said multi-function amplifier filter being dedicated to a given pair of said antennas; anda plurality of digital potentiometers, the plurality equal to 1 plus (n−
1) squared, a set of n−
1 of said digital potentiometers being dedicated to each of said non-reference antennas;
wherein,the signal from each said antenna is directed through a respective amplifier filter circuit, the outputs of which are directed to said digital signal processor; the signal from said reference antenna is also passed through a single respective digital potentiometer, the output of which is directed to n−
1 respective multi-function amplifier filters which pair said reference antenna with each said non-reference antenna;the signal from each said non-reference antenna is passed separately through n−
1 digital potentiometers, the outputs of which are directed to n−
1 multi-function amplifier filters through which each said non-reference antenna is paired with each other said antenna;each said multi-function amplifier filter performing a difference operation on the pair of signals it receives and directing the result to an analog to digital converter which in turn directs its output to said digital signal processor; said controller performing a surveillance cycle comprising; adjusting said digital potentiometers to minimize the output of each said multi-function amplifier filter, operating one of said n antennas to generate an interrogation field and then ceasing generating said field, and monitoring said antennas to determine if said antennas receive an additional signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. An electronic article surveillance system comprising:
-
a plurality of antennas, each said antenna not overlapping with any other antenna and not electrically connected to any other antenna, one of said antennas operating as a reference antenna and the other antennas operating as non-reference antennas, each said antenna forming a pair with each other antenna; a controller; a digital signal processor; at least one analog to digital converter; an amplifier-filter circuit for each antenna, each amplifier-filter circuit being dedicated to a given antenna, the signal from each said antenna being directed through a respective amplifier filter circuit, the outputs of which are directed to said digital signal processor; a multi-function amplifier filter for each said pair of antennas, each multi-function amplifier filter receiving a signal from each antenna in its pair; a single digital potentiometer dedicated to said reference antenna, the signal from said reference antenna also being passed through said single digital potentiometer, the output of which is directed to the respective multi-function amplifier filters which pair said reference antenna with each said non-reference antenna; a digital potentiometer for each said non-reference antenna for each said pair, the signal from each said non-reference antenna being passed separately through a digital potentiometer for each said pair associated with a given antenna, the outputs of the digital potentiometers being directed to the respective multi-function amplifier filters through which each said non-reference antenna is paired with each other said antenna; each said multi-function amplifier filter performing a difference operation on the pair of signals it receives and directing the result to an analog to digital converter which in turn directs its output to said digital signal processor; said electronic article surveillance system performing a surveillance cycle comprising; said digital signal processor adjusting said digital potentiometers to minimize the output of each said multi-function amplifier filter, said controller operating one of said antennas to generate an interrogation field and then ceasing generating said interrogation field, and said digital signal processor monitoring said antennas to determine if said antennas receive an additional signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. An electronic article surveillance system comprising:
-
a plurality of antennas, each said antenna not overlapping with any other antenna and not electrically connected to any other antenna, one of said antennas operating as a reference antenna and the other antennas operating as non-reference antennas, each said antenna forming a pair with each other antenna; a controller; a digital signal processor; at least one analog to digital converter; an amplifier-filter circuit for each said antenna, said digital signal processor receiving the output from each said amplifier-filter circuit, each said amplifier-filter circuit receiving the output from a single one of said antennas; a multi-function amplifier filter for each said pair of antennas, each multi-function amplifier filter receiving a signal from each antenna in its pair, said signal from each antenna adjusted by a digital potentiometer, each said multi-function amplifier filter performing a difference operation on the pair of signals it receives and directing the resulting signal to an analog to digital converter, said digital signal processor receiving the analog to digital converted output from each said multi-function amplifier filter; a single digital potentiometer dedicated to said reference antenna, the signal from said reference antenna being passed through said single digital potentiometer, each said multi-function amplifier filter that has said reference antenna as one of its pair receiving the output of said single digital amplifier; a digital potentiometer for each said non-reference antenna for each said pair, the signal from each said non-reference antenna being passed separately through a digital potentiometer for each said pair with which a non-reference antenna is associated, the outputs of the digital potentiometers being directed to the respective multi-function amplifier filters through which each said non-reference antenna is paired with each other said antenna; said electronic article surveillance system performing a surveillance cycle comprising; said digital signal processor adjusting said digital potentiometers to minimize the output of each said multi-function amplifier circuits, said controller operating one of said antennas to generate an interrogation field and then ceasing generating said interrogation field, and said digital signal processor monitoring said antennas to determine if said antennas receive an additional signal.
-
Specification