MULTI-PROTOCOL RFID SYSTEM USING DYNAMIC RECONFIGURATION
A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGOTM RFID backscatter transponders, SEGOTM RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.
1 ) An RFID interrogator comprising:
(a) a computer comprising a storage memory area and a processor, the computer being arranged for storing and selectively retrieving configuration parameters associated with plural RFID protocols;
(b) a set of configuration parameter data for plural RFID protocols stored within the computer;
(c) a protocol schedule comprising information representing a sequence in which different protocols shall be implemented;
(d) a transceiver component connected to the computer via a data interface, where the transceiver component is arranged to alter its operation in response to configuration parameters received from the computer via the data interface;
(e) wherein the computer automatically switches transceiver component operation among two or more protocols by retrieving configuration parameter data and sending it via the data interface to the transceiver component in accordance with the protocol schedule.
2 ) The RFID interrogator of claim 1 wherein the configuration parameter is selected from the group consisting of: transmit depth of modulation; transmit duty cycle; transmit power; and receive sensitivity.
3 ) The RFID interrogator of claim 1 wherein the configuration parameter is transmit depth of modulation.
4 ) The RFID interrogator of claim 3 wherein the data interface comprises a digital to analog converter producing an output and the transceiver component comprises a switch which selects whether a transmitted signal is derived from the output of the digital to analog converter or a separate voltage reference.
5 ) The RFID interrogator of claim 1 wherein the configuration parameter is transmit duty cycle.
6 ) The RFID interrogator of claim 5 wherein the data interface comprises a microcontroller data register controlling a UART and the transceiver component comprises a UART output circuit.
7 ) The RFID interrogator of claim 1 wherein the configuration parameter is transmit power.
8 ) The RFID interrogator of claim 7 wherein the data interface comprises a digital to analog converter producing an output; and the transceiver component comprises a variable attenuator that varies an amplitude of a transmitted signal based upon the output of the digital to analog converter.
9 ) The RFID interrogator of claim 1 wherein the configuration parameter is receive sensitivity.
10 ) The RFID interrogator of claim 9 wherein the data interface comprises a digital control signal from the computer and the transceiver component comprises a variable attenuator which is controlled by the digital control signal.
11 ) The RFID interrogator of claim 1 wherein the computer advances to a next protocol in the protocol schedule in response to an externally received synchronization signal.
12 ) A system of RFID interrogators comprising a first interrogator which is the RFID interrogator of claim 1 and a second interrogator of which is the RFID interrogator of claim 11 wherein the first and second interrogator are connected by a synchronization circuit.
13 ) The system of claim 12 in which the first interrogator comprises a synchronization signal generator producing a system synchronization signal, and wherein the externally received synchronization signal of the second interrogator is the system synchronization signal and this signal is provided to the second interrogator via the synchronization circuit.
14 ) The system of claim 13 wherein the synchronization signal generator comprises a global positioning (GPS) receiver and the system synchronization signal is derived at least in part from a received GPS satellite signal.