TWI551073B - Radio frequency identification device and method - Google Patents

Description

Radio frequency identification device and method Field of invention

This disclosure relates to radio frequency identification (RFID) systems. More particularly, the present disclosure discusses and presents a software-defined multi-mode RFID reading device.

Background of the invention

Conventional RFID devices operate on a single of a plurality of possible frequencies and employ one of a plurality of different coding schemes. For example, currently available systems operating at 125 kHz, 13.56 MHz, 915 MHz, and 2.4 GHz. The RFID tag attached to the item to be tracked operates only at a single frequency, and in addition, a unique and incompatible coding scheme can be used to transmit data at that frequency.

Currently RFID systems operate by coupling a transceiver or RFID reader antenna to one or more "tag" antennas attached to the item to be tracked. Conventional RFID readers are designed to work only on labels supplied by a particular supplier. The reader is not designed to read multi-type RFID tags universally. The current limitations of the reader can be attributed to the fact that it processes the response signal and decodes the tag information based on the hardware. A particular wireless circuit is used to sense information reflected from the RFID tag, filter the information, and shape the information before it is fed to the processor. While this technique is fairly straightforward, it lacks the flexibility to handle different types of tags, such as tags based on different frequencies and/or coding schemes.

Summary of invention

Embodiments described herein address the aforementioned problems by providing a different type of RFID tag that can handle different tag frequencies and/or coding schemes.

Several embodiments provide a method of reading an RFID tag. The method can include transmitting one or more search signals covering a plurality of RFID frequency bands. The method can further include detecting an indication of presence of one of the RFID tags of one of the plurality of RFID bands. The method can further include reading the RFID tag.

Several embodiments provide a method of reading an RFID tag. The method can include transmitting one or more search signals covering a plurality of RFID frequency bands. The method can further include detecting an indication of presence of one of the RFID tags of one of the plurality of RFID bands. The method can further include generating a query signal having a carrier frequency set to detect a frequency of the presence indication. The method can further include receiving a tag response signal from an RFID tag, the tag response signal including tag information associated with the RFID tag. The method may further include performing digital signal processing on the digital response signal based on the tag response signal to obtain the tag information.

Several embodiments provide an RFID reading device. The device can include an antenna. The apparatus can further include a processor configured to transmit one or more search signals covering the plurality of RFID frequency bands through the antenna. The processor can be further configured to detect an indication of the presence of one of the RFID tags of one of the plurality of RFID bands. The processor can be further configured to read the RFID tag based on a tag response signal received from the tag. The tag response signal can include tag information associated with the RFID tag. The processor can further include an analog to digital converter that is configured to generate a digital response signal based on the tag response signal. The processor can be further configured to perform digital signal processing on the digital response signal to obtain the label information.

It is to be understood that the foregoing description of the invention and the claims

Simple illustration

The accompanying drawings, which are incorporated in and in the claims In the drawings: Figure 1 is a block diagram showing an example of a multimode RFID reading device in accordance with several embodiments; and Figure 2 is a block diagram showing another example of a multimode RFID reading device in accordance with several embodiments; Yet another example of a multi-mode RFID reading device in accordance with several embodiments is shown in block diagram; FIG. 4 is a flow chart showing an example of a method for searching and reading RFID tags in a multi-RFID frequency band, in accordance with several embodiments; FIG. 5 is a flow chart showing an example of a method for generating and transmitting a modulated query signal to an RFID tag according to some embodiments; FIG. 6 is a flow chart showing a method for receiving and processing according to some embodiments. An example of a method for responding to a signal from an RFID tag; and FIG. 7 is a block diagram showing a computer system in which several embodiments may be embodied.

Detailed description of the preferred embodiment

Numerous specific details are set forth in the Detailed Description of the Detailed Description. It will be apparent to those skilled in the art that the embodiments may be practiced without the specific details. In other instances, well-known structural and technical details have not been shown in order to avoid unnecessarily obscuring the disclosure herein.

The term "institutive" is used herein to mean "as an instance, case or illustration." Any embodiment described herein as "exemplary" is not necessarily interpreted as preferred or advantageous over other embodiments or designs.

Embodiments of the present disclosure address and address the problems of conventional RFID systems that are typically only available for single type RFID tags. Embodiments of the present disclosure provide multi-mode RFID reading devices that can process multi-type RFID tags based on different target frequencies (eg, 125 kHz, 13.56 MHz, 915 MHz, and 2.4 GH) and/or encoding schemes (eg, ISO 18000). Such a device employs a processor that performs at least several functions conventionally performed by a dedicated single frequency hardware component in software. Such functions may include, but are not limited to, generation and modulation of carrier signals; and demodulation, filtering, and decoding of tag information from RFID response signals. Several embodiments of multi-mode RFID reading devices are configured to demodulate and decode different RFID systems operating within the total bandwidth of their capabilities, process multi-frequency RFID tags, and process any defined coded deductive rules. In addition, the new frequency and coding scheme can be added to its capabilities by re-planning the processor without making hardware modifications.

1 is a block diagram illustrating a multimode RFID reading device 100 in accordance with several embodiments. The device 100 includes a processor 101, an antenna set 103, an antenna selection switch 105, a local oscillator 113, a digital to analog converter (DAC) 114, a modulator 115, an output amplifier 117, and an input amplifier. 121, a demodulator 123, and an analog to digital converter (ADC) 125. In some embodiments, modulator 115 and demodulator 123 are quadrature modulators and quadrature demodulator, respectively.

The first output of the processor 101 is coupled to the control input of the local oscillator 113, the second output of the processor 101 is coupled to the digital input of the D/A converter 115, and the third output of the processor 101. The end is coupled to the selection input of the antenna selection switch 105. The signal output end of the local oscillator 113 is coupled to the first (carrier) input of the quadrature modulator 115, and the analog output of the D/A converter 114 is coupled to the second of the modulator 115 (modulation) ) Input. The output of the modulator 115 is coupled to the input of the output amplifier 117, and the output of the output amplifier 117 is coupled to the common terminal of the antenna select switch 105. A selectable set of terminals of the antenna selection switch 105 is coupled to the antenna set 103. The common terminal of the antenna selection switch 105 is also coupled to the input of the input amplifier 121. The output of input amplifier 121 is coupled to a first input of quadrature demodulator 123. The second input of demodulator 123 is coupled to the signal output of demodulator 123. The output of demodulator 123 is coupled to an analog input of A/D converter 125. The digital output of A/D converter 125 is coupled to the input port of processor 101.

The processor 101 is assembled (e.g., planned) to search for and read a multi-type RFID tag. An example of the search operation of the RFID reading device 100 will now be described. The processor 101 transmits a search signal through a plurality of RFID frequency bands. As used herein, a "search signal" may include an RFID band search signal set that encompasses a plurality of RFID bands to be searched for. For example, the search signal may include a first search signal of the first RFID frequency band, a second search signal of the second RFID frequency band, and a third search signal of the third RFID frequency band. For example, assume that the RFID reading device 100 is designed to read three RFID bands, namely 125 kHz, 13.56 MHz, and 915 MHz. The processor 100 transmits a first search signal for 125 kHz and an indication of the presence of an RFID tag. In the case of passive RFID (eg, a tag that does not contain its own power source), due to the short circuit of the antenna in the RFID tag, the tag presence indication can be in the form of a sharp drop in the reflected search signal. If the indication of the presence of the tag is detected within the 125 kHz bandwidth, the processor 101 attempts to read the RFID tag by means of an inquiry signal or an excitation signal transmitted at the target frequency (e.g., the frequency at which the tag is detected), as will be described later.

The search signal for a particular RFID band may be a relatively wideband signal covering the entire bandwidth of the frequency band of one transmission (e.g., from about 900 MHz to about 928 MHz for the 915 MHz band). Additionally, the search signal can include a collection of relatively narrowband search signals (e.g., sliced slices) that are sequentially transmitted to sweep the entire bandwidth. The foregoing steps are for other bandwidths such as 13.56 MHz and 914 MHz repetition.

It should be noted that in several embodiments, multiple antennas are provided, such as antenna set 103 shown in FIG. The reason is that the transceiver antenna that can transmit and receive signals (such as search signals or interrogation signals) in one RFID band is different from the transceiver antenna that can transmit and receive signals in another RFID band. For example, an antenna for the 13.57 MHz band may be a loop antenna designed to be primarily responsible for the RF magnetic field, and an antenna for the 2.4 GHz band may be a dipole antenna designed to respond to an electric field. As such, between searching or reading from one RFID band to another, it may be desirable to switch the transceiver antenna by providing, for example, a select output from the processor 101 to the select input of the antenna select switch 105. In some embodiments, a single transceiver antenna having a baseband covering one of a plurality of RFID bands and one or more harmonics covering one or more remaining RFID bands can be used in place of the antenna set shown in FIG. 103, or used in conjunction with one or more other antennas.

As previously indicated, when processor 101 detects the presence of an RFID tag of a given bandwidth (e.g., 125 kHz), processor 101 attempts to read the RFID tag by transmitting a query signal or an excitation signal. An example of performing a read operation by the RFID device 100 will now be described. The processor 101 outputs a signal to the local oscillator 113 indicating the target frequency (e.g., the frequency at which the detected tag is present). The local oscillator 113 is configured to respond to signals from the processor 101 by generating an oscillating carrier signal by one of the frequencies associated with the multi-type RFID tag that the device 100 is configured to process. In several embodiments, local oscillator 113 is a phase locked loop (PLL) synthesizer that can generate multiple output frequencies as a multiple of a single reference frequency. In such embodiments, the signal indicative of the target frequency provided by processor 101 may include information indicative of the multiplication factor of the PLL synthesizer. In other embodiments, the local oscillator 113 can be a voltage controlled oscillator (VCO).

The processor 101 also generates a digitally modulated signal based on a modulation scheme associated with the selected RFID tag type. Modulation schemes may involve amplitude modulation, frequency modulation, or a combination of both. The modulated signal is fed to a DAC 114, which converts the digitally modulated signal into an analog modulated signal. The analog modulation signal is also referred to as a "low frequency" signal or a "baseband" signal because the signal changes at a frequency that is typically lower than the carrier signal frequency.

The carrier signal generated by the local oscillator 113 (oscillated at the target frequency) and the analog modulated signal generated by the DAC 114 are fed to the modulator 115, which is mixed in the analog domain by an analog mixer (not shown). The signal is amplified by the output amplifier 117 and transmitted through the antenna 103 to produce a modulated "query" or "excitation" signal to be transmitted to the RFID tag. The inquiry signal includes a carrier signal modulated by a variable signal. In some embodiments, the carrier signal is amplitude modulated by a modulated signal. In other embodiments, the carrier signal is frequency modulated by a modulated signal. Antenna 103 may be a loop antenna (having a single loop or multiple loops) that has broadband characteristics to cover the frequency range associated with different types of RFID tags that multi-mode RFID reading device 100 is designed to handle.

The so-called transmitted interrogation signal forms an electromagnetic (EM) field that induces an AC current in the passive RFID tag, such as the antenna of the RFID tag 131, in the field shown in the figures. This AC current is rectified and the resulting DC current charges the capacitor within the tag 131. When the voltage signal on the capacitor is sufficient, the active electronics in the tag circuit (not shown) are energized. Once activated, the electronic device in the tag shorts the tag antenna in a short sequence of sequences that are encoded to contain certain tag information, typically the tag's unique ID (eg, an identifier string). In addition to the unique ID, the tag information may include additional non-electrical information associated with the item to which the tag is attached, such as price, quantity, or manufacturing materials. When the tag antenna is shorted, an additional load is formed on the antenna 103 of the RFID reader 100 that senses the voltage drop across the antenna 103. Such a reaction or "reflection" signal changes or induces a voltage signal at the antenna 103.

The foregoing description of RFID tags applies to passive RFID tags that do not contain their own power source and that reflect the incoming query signal in the manner previously described. Active RFID tags, on the other hand, contain their own power source and can actively generate a response signal. In view of the disclosure herein, those skilled in the art will be aware of the systems and methods disclosed herein, keeping in mind that active RFID tags can receive such interrogated signals and actively generate response signals, rather than just the passive RFID tags described previously. The way the query signal is reflected. The actively generated response signal will be processed by the RFID device 100 in much the same manner as described above.

Referring back to Figure 1, the voltage signal induced by the response signal is fed to the input amplifier 121 and then fed to the demodulator 123 along with the carrier signal oscillating at the target frequency output by the local oscillator 113. The output signal of the demodulator 123 is an intermediate frequency (IF) response signal. The IF response signal is then fed to ADC 125, which converts the IF response signal into a digital response signal. The processor 101 receives the digital response signal and performs a digital signal processing operation including digitally filtering the digital response signal and decoding the tag information based on a decoding deduction rule associated with the selected RFID tag type. The processor 101 then determines which tag(s) are within the field of the reading device 100 and reports this information and any other additional information contained in the response signal to the inventory application or end user. The processor 101 can be programmed to specifically implement a multi-mode RFID reading device by controlling the local oscillator 113 (e.g., a PLL synthesizer) to switch frequencies, and repeating the processing of the new RF target frequency.

FIG. 2 is a block diagram illustrating another example of a multi-mode RFID reading device 200 in accordance with several embodiments. The device 200 includes a processor 201, an antenna set 203, an antenna selection switch 205, a local oscillator 213, an output amplifier 217, an antenna 203, an input amplifier 221, a demodulator 223, and an analog to digital position. Converter (ADC) 225.

Again, in several embodiments, the description of the search operation of the RFID device 200 (eg, transmitting a series of search signals to detect the presence of RFID tags in different RFID bands) is substantially the same as the RFID provided for FIG. 1 above. The description of the search signal example of device 100 is the same and will not be repeated here. Instead, the reading operation example of the RFID reading device 200 will now be described while emphasizing the difference from the reading operation of the RFID reading device 100.

In the present device configuration, processor 201 controls a local oscillator (e.g., a PLL synthesizer) that generates an RF carrier signal as previously described. The RF carrier signal is fed into an output amplifier 217 having a control input (eg, an on-off input). The control input is configured to receive the digital modulated signal from processor 201 to amplitude modulate the carrier signal. In some embodiments, the output signal of amplifier 217 is a digitally modulated interrogation signal, a simple example being an on-off keying (OOK) signal. In these digitally modulated query signals, the signal power is maintained large to indicate a binary "1", and is maintained as small or zero to indicate a binary "0". In addition, the digitally modulated query signals can be generated by an amplifier in conjunction with an analog switch of digital control. The output of amplifier 217 is coupled to antenna 203, which transmits a modulated interrogation signal.

At the receiving end, a response signal carrying one of the tag information induces a voltage signal at the antenna 203, and the voltage signal is fed to the input amplifier 221 and then demodulated by the carrier signal by the demodulator 223. The demodulated response signal is fed to an ADC 225 which converts the demodulated response signal into a digital representation of the response signal, or more simply a "digital response signal." The digital response signal is then fed to the processor 201, wherein the digital response signal is digitally filtered and decoded to obtain the tag information encoded therein. This device configuration eliminates the need for D/A converters and modulators. As previously described, the processor 201 can be programmed to implement a multi-mode RFID reading device by controlling the local oscillator 213 (eg, a PLL synthesizer) to switch frequencies, and repeating the processing procedure for the new RF frequency.

FIG. 3 is a block diagram illustrating another example of a multi-mode RFID reading device 300 in accordance with several embodiments. The device 300 includes a processor 301, an antenna set 303, an antenna selection switch 305, a digital to analog converter (DAC) 314, an output amplifier 317, an antenna 303, an input amplifier 321, and an analog to digital conversion. (ADC) 325.

Again, in several embodiments, the description of the search operation of the RFID device 300 (eg, transmitting a series of search signals to detect the presence of RFID tags in different RFID bands) is substantially as provided for the RFID for Figure 1 above. The description of the search signal example of device 100 is the same and will not be repeated here. Instead, the reading operation example of the RFID reading device 300 will now be described, and the difference from the reading operation of the RFID reading devices 100 and 200 will be emphasized.

In the present device configuration, the processor 301 has a high enough speed and capability to directly generate a digital representation of the modulated query signal. In this configuration, the processor 301 can programmatically perform modulation in the digital domain relative to the analog domain, as in the device configuration described above with respect to FIGS. 1 and 2. In addition, the device 300 can also include a memory (not shown) that is in communication with the processor 301 and is configured to store a set of digital representations of the various modulated query signals for different types of RFID tags. The processor 301 can then retrieve from the memory or through the processor 301 a particular set of ones of the digit representations corresponding to the selected one of the selected RFID tag type and the digital representation to be fed to the DAC 314. The digital representation is converted to an analog modulation query signal via DAC 314. The query signal can be frequency modulated or amplitude modulated depending on the particular modulation scheme employed. The modulated query signal is then amplified and fed to antenna 303 and transmitted.

At the receiving end, the voltage signal induced by the response signal of the RFID tag is fed to the input amplifier 321 and fed to the ADC 325, and then directly fed to the processor 301. The processor 301 then digitally demodulates, filters, and decodes the signal to obtain tag information. The carrier frequency of the modulated query signal is easily changed because it is directly controlled by the processor 301. In terms of the number of hardware components, this embodiment is less than the hardware components of the specific embodiments of Figures 1 and 2, but requires higher bandwidth components and higher performance processors to handle the additional functions performed in the digital domain. . Such high performance processors may include a model TMS320DM6431 digital media processor manufactured by Texas Instruments and having a processing speed of 2400 MIPS. However, such a digital signal processor is for illustrative purposes only.

Those skilled in the art will appreciate that the examples of multimode RFID readers shown in Figures 1 through 3 are for illustrative purposes only and are not limiting. For example, several feature structures in the illustrated example can be mixed and matched. For example, in other embodiments, the modulation can be performed in a digital domain, while demodulation can be performed in an analog domain, or vice versa.

4 is a flow chart illustrating an example of a processing procedure for a search and read operation of a multi-mode RFID reading device in accordance with several embodiments. The method 400 begins at state 410 and proceeds to state 420 where the device is designed to read a search signal for a first RFID band (e.g., 125 kHz) in a set of RFID bands (e.g., 125 kHz, 13.56 MHz, and 915 MHz bands). In some embodiments, transmitting a search signal for a particular RFID frequency band includes transmitting a relatively wideband signal having a spectrum that substantially covers the entire bandwidth of the frequency band (e.g., from about 900 MHz to about 928 MHz for the 915 MHz band). In other embodiments, transmitting the search signal includes sweeping a frequency (e.g., transmitting a series of narrowband signals or "cut slices") substantially across the entire bandwidth of the frequency band. The selection of the frequency band or one or more frequency band portions, and thus the selection of the search signal, may depend on the type of RFID tag being searched. For example, if the RFID tag of interest is known to be supported only by a portion of the spectrum of a particular RFID band, the search signal can be assembled to sweep only or only the portion of the spectrum rather than the entire bandwidth.

The method 400 proceeds to a decision state 420 where an inquiry is made as to whether a tag presence indication is detected in response to the transmitted search signal. Taking a passive RFID tag as an example, the indication may include a decrease in the intensity of the reflected search signal. Taking an active RFID tag as an example, the indication may include a "beep" signal transmitted by the active RFID tag at the same or different frequencies. If the answer to the query in decision state 430 is no (no indication of the presence of the tag is detected), then method 400 proceeds to another decision state 470 in which the query is in the set of RFID bands to be read by the RFID reader. One wants to search for a frequency band. If the query in decision state 430 is yes (detected tag presence indication), then method 400 proceeds to state 440A, B where an attempt is made to read a possible RFID tag. The reading procedure will be described later on the fifth and sixth figures. After attempting to read, method 400 proceeds to decision state 450 where the query read is successful. If the query response in decision state 450 is yes (read successful), then method 400 proceeds to decision state 460 where a tag output signal (e.g., the ID of the RFID tag) is provided, for example, to a display or library. Method 400 proceeds to decision state 470 after the tag output signal is provided. On the other hand, if the query answer in decision state 450 is no (reading is unsuccessful), then method 400 proceeds to decision state 470 where no tag output signal is provided.

If the query response in decision state 470 is yes (to search for another frequency band), then method 400 proceeds to state 480 where the search signal for the next RFID band (eg, 13.56 MHz) is transmitted, and after the search or listening tag presence indication Advance to decision state 430. On the other hand, if the query response in decision state 470 is no (no other frequency bands to search for), for example, because all of the frequency bands in the set have been searched, method 400 loop returns to state 420 where the first frequency band is again transmitted (eg, 125 kHz) ) the search signal, and repeat the aforementioned remaining states.

FIG. 5 is a flow diagram illustrating an example of a method 440A for generating and transmitting an inquiry signal to read an RFID tag in accordance with some embodiments. Method 440A begins at state 510 and proceeds to state 520, where a carrier signal (eg, an RF signal) that oscillates at a target frequency (eg, the frequency at which the detected tag presence is indicated) is generated. The generation of the carrier signal can be performed by a local oscillator, which receives an indication signal of the target frequency (e.g., information indicative of the multiplication factor of the PLL synthesizer) as described above with respect to Figures 1 and 2.

Method 440A proceeds to state 530 where a modulated signal is generated. The modulated signal can be an analog modulated signal that is generated by a digital-to-analog converter (DAC) conversion as described above with respect to Figure 1, and is represented by a digital representation of one of the modulated signals provided by the processor. In addition, the modulated signal may be a digital modulated signal output by the processor as described above with respect to FIG. 2, which may be used to digitally modulate the carrier signal.

Method 440A proceeds to state 540 where a modulated query signal is generated. In some embodiments, an analog modulator, such as the modulator 115 shown in FIG. 1, can be implemented, as described above with respect to FIG. 1, which mixes the carrier signal with the analog modulation signal. In other embodiments, as previously described with respect to FIG. 2, this may be achieved by an amplifier having a switch control input or an amplifier that combines digital control analog switches. In yet another embodiment, as described above with respect to FIG. 3, the modulated query signal can be generated directly by digital to analog conversion of the digital representation. In such embodiments, the programs executed in states 520 and 530 may not be needed. Method 440A proceeds to state 550, wherein the modulated query signal is transmitted through an antenna, such as a transceiver antenna in the set of antennas 103 shown in FIG. 1, after amplification. Method 440A ends in state 590.

FIG. 6 is a flow diagram illustrating an example of a method 440B for receiving and processing a response signal to read an RFID tag in accordance with several embodiments. Method 440B begins at state 610 and proceeds to state 620 where the response signal from the RFID tag is received by the antenna at the multimode RFID reader. The response signal can be a signal reflected from a passive RFID tag or a signal generated by an active RFID tag. Method 440B proceeds to state 630 where the voltage signal induced by the response signal at the antenna is amplified. Method 440B then proceeds to decision state 640 where the query response signal is to be demodulated in the analog domain, for example, by a dedicated hardware demodulator as shown in Figures 1 and 2; or to demodulate in a digital domain, such as Processor demodulation as shown in Figure 3. Such decision states are provided by way of illustration of two types (analog and digital) demodulation, it being understood that particular instances of multimode RFID reading devices typically do not make such queries. The reason is that such a device may be pre-assembled for analog or digital modulation operations.

If the answer to the query in decision state 640 is "analog" (analog demodulation embodiment), then method 440B enters the analog demodulation branch and proceeds to state 651, where the amplified response signal is demodulated in the analog domain, such as by a special analogy solution The modulator is demodulated, such as the demodulator 123, 223 shown in Figures 1 and 2. At the analog demodulation branch, method 440B proceeds further to state 661, where a digital response signal (eg, a digit of the demodulation response signal) is generated, for example, by analog to digital converter (ADC), such as ADCs 125, 225 shown in FIGS. 1 and 2. Representation type).

On the other hand, if the answer to the query in decision state 640 is "digital" (digital demodulation embodiment), then method 440B enters the digital demodulation branch and proceeds to state 653, where the amplified response signal is passed to the ADC, such as Figure 3. The ADC 325 is shown converted to a digital response signal (eg, a digital representation of the response signal). At the digital demodulation branch, method 440B proceeds to state 663 where the digital response signal is digitally demodulated by the processor as previously described with respect to FIG.

For the analog and demodulation embodiment, method 440B converges in state 670, where the digital response signal (now demodulated) is subjected to digital filtering by the processor. The type of digital filtering applied depends on the type of RFID tag being read and its associated frequency and coding scheme. Method 440B proceeds to state 680 where the processor decodes the demodulated and filtered digital response signal to obtain the tag information encoded therein. Method 440B ends in state 690.

Those skilled in the art will appreciate that the examples of the methods illustrated in Figures 4 through 6 are for illustrative purposes only and are not to be construed as limiting. For example, referring to FIG. 5, generating a modulated signal at state 530 is typically performed concurrently with generating a carrier signal at state 520. In several embodiments similar to the illustrations of FIG. 3, states 520 and 530 may be deleted. Referring to Figure 6, the digital demodulation at state 663 can be performed after or at the same time as digital filtering, for example, state 670.

FIG. 7 is a block diagram illustrating an example of a computer system 700 that can embody certain embodiments disclosed herein. The computer system 700 includes a bus 702 or other communication mechanism for communicating information, and a processor 704 coupled to the bus 702 for processing information. Computer system 700 also includes a memory 706, such as a random access memory (RAM) or other dynamic storage device, for storing information and instructions to be executed by processor 704. Memory 706 can also be used to store temporal variables or other intermediate information during execution of instructions by processor 704. The computer system 700 further includes a data storage device 710, such as a magnetic disk or a compact disk, coupled to the busbar 702 for storing information and instructions.

The computer system 700 can be coupled to a display device (not shown) through an I/O module 708, such as a cathode ray tube (CRT) or a liquid crystal display (LCD) for displaying information to a computer user. An input device, such as a keyboard or mouse, can also be coupled to computer system 700 via I/O module 708 for communicating information and instructions to processor 704.

According to several embodiments, the plurality of facets, such as the modulated query signal and the response signal from the RFID tag, are generated by the computer system 700 in response to the processor 704 executing one of the one or more sequences contained in the memory 706. Executed with multiple instructions. Processor 704 can be a microprocessor, a microcontroller, and a digital signal processor (DSP) that can execute computer instructions. Such instructions may be read into memory 706 from another machine readable medium, such as data storage device 710. Execution of the sequence of instructions contained in main memory 706 causes processor 704 to perform the method steps described herein. One or more processors in a multi-processing configuration may also be employed to execute the sequence of instructions contained in main memory 706. In other embodiments, wired circuitry may be used in place of or in combination with software instructions to implement various embodiments. As such, embodiments are not limited to any specific combination of hardware circuitry and software.

The term "machine readable medium" as used herein refers to any medium that participates in providing instructions to a processor for execution. Such media may take many forms, including but not limited to non-electrical media, power-based media, and transmitting media. The non-electrical medium includes, for example, a compact disc or a magnetic disk, such as a data storage device 710. The power-dependent media includes dynamic memory such as memory 706. The transmission medium includes a coaxial cable, a copper wire, and an optical fiber, and includes a wire including a bus bar 702 connecting the processor and the memory segment. The transmitting medium can also be in the form of sound waves or light waves, such as those generated during radio frequency communication or infrared data communication. Common forms of machine readable media include, for example, floppy disks, flexible disks, hard disks, magnetic tape, any other magnetic media, CD-ROM, DVD, any other optical media, punched cards, paper tape, any other holes. A style of physical media, RAM, PROM, EPROM, FLASH EPROM, any other memory chip or cartridge, carrier, or any other medium from which a computer can read.

The foregoing description is intended to enable a person skilled in the art to practice the various embodiments described herein. While the foregoing embodiments have been described with reference to the embodiments of the invention

There are many other ways in which the invention can be embodied. Without departing from the scope of the invention, the various functions and elements described herein may differ from those of the present invention. Various modifications to these embodiments are apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Thus, various modifications and changes may be made to the present invention without departing from the spirit and scope of the invention.

Unless specifically stated otherwise, the singular elements are not intended to mean "one and only", but rather "one or more." The term "a number" means one or more. The underlined and/or italicized headings and subheadings are for convenience only and are not intended to limit the invention, but are interpreted in conjunction with the description of the invention. All of the structural and functional equivalents of the various embodiments of the present invention, which are known to those skilled in the art, which are known to those skilled in the art, are hereby incorporated by reference. Moreover, the disclosure herein is not intended to be disclosed to the public unless specifically recited in the foregoing description.

All of the elements, parts and steps described herein are preferably included. As will be apparent to those skilled in the art, it is to be understood that any of these elements, components, and steps may be substituted or otherwise deleted.

Broadly speaking, the description herein discloses apparatus and methods for reading multi-type RFID tags having different frequencies and/or coding schemes. The transmission covers one or more search signals of multiple RFID bands. An indication of the presence of the RFID tag in one of the plurality of RFID bands is detected. Transmitting a query signal having a carrier frequency set to one of the frequencies at which the presence indication is detected. A tag response signal containing one of tag information associated with the RFID tag is received. The digital response signal based on one of the tag response signals is processed by digital signal to obtain the tag information.

Conception

This specification has disclosed at least the following concepts.

Concept 1. A method of reading a radio frequency identification (RFID) tag, the method comprising: transmitting a search signal covering one of a plurality of RFID frequency bands; detecting an presence indication of one of the RFID tags in one of the plurality of RFID frequency bands ; and read the RFID tag.

Concept 2. The method of Concept 1, wherein the search signal includes a search signal set for one of the plurality of RFID frequency bands.

Concept 3. The method of Concept 2, wherein transmitting the search signal for one of a particular RFID frequency band comprises sweeping a frequency substantially one of a full bandwidth of the RFID frequency band.

Concept 4. The method of Concept 2, wherein transmitting a search signal for one of a particular RFID frequency band comprises transmitting a single search signal having a spectrum that substantially covers one of the full bandwidths of the particular RFID frequency band.

Concept 5. The method of Concept 1, wherein the presence indication comprises a decrease in the intensity of a reflected signal.

Concept 6. The method of Concept 1, wherein reading the RFID tag comprises: generating a modulation query signal having a carrier frequency set to detect a target frequency of the tag presence indication; receiving one from an RFID tag a tag response signal, the tag response signal includes tag information associated with the RFID tag; generating a digital response signal based on the tag response signal; and performing digital signal processing on the digital response signal to obtain the tag information, wherein the digital information Signal processing includes at least one of digital modulation, digital filtering, and digital decoding.

Concept 7. The method of Concept 6, wherein generating the modulated query signal comprises modulating a carrier signal of the target frequency oscillation with a modulated signal that is less than a frequency change of the target frequency.

Concept 8. The method of Concept 7, wherein modulating the carrier signal is performed in a digital domain.

Concept 9. The method of Concept 7, wherein modulating the carrier signal is performed in an analog domain.

Concept 10. The method of Concept 6, further comprising demodulating the target response signal or the digital response signal by one of the carrier signals oscillating at the target frequency.

Concept 11. The method of Concept 10, wherein the demodulation is performed in a digital domain.

Concept 12. The method of Concept 10, wherein the demodulation is performed in an analog domain.

Concept 13. A method of reading a multi-type RFID tag, the method comprising: transmitting one or more search signals covering a plurality of RFID frequency bands; detecting an presence indication of one of the RFID tags in one of the plurality of RFID frequency bands Transmitting an inquiry signal having a carrier frequency set to detect a frequency of the presence indication; receiving a tag response signal from the RFID tag, the tag response signal including tag information associated with the RFID tag And performing digital signal processing on the digital response signal based on the tag response signal to obtain the tag information.

Concept 14. A radio frequency identification (RFID) device comprising: an antenna; and a processor configured to cause the antenna to transmit a search signal covering one of a plurality of RFID bands; detecting the plurality of RFIDs An indication of one of the RFID tags within one of the frequency bands is present, and the RFID tag is read based on a tag response signal containing one of the tag information associated with the RFID tag.

Concept 15. The apparatus of concept 14 further comprising an analog to digital converter configured to generate a digital response signal based on the tag response signal; wherein: the processor is further configured to The digital response signal is processed by digital signal to obtain the tag information, and the digital signal processing includes at least one of digital modulation, digital filtering, and digital decoding.

Concept 16. The apparatus of concept 15, wherein the processor is further configured to output a signal indicative of a target frequency associated with detecting a target frequency of the presence indication, and a digital modulation signal, The apparatus further includes: a local oscillator configured to receive a signal indicative of the target frequency, and a carrier signal generated from the target frequency oscillation; a digital to analog converter configured to receive the digital tone Varying the signal, and generating an analog modulation signal, the analog modulation signal is changed at a lower frequency than the target frequency; and an analog modulator is configured to receive the carrier signal and the analog modulation signal, And generating a modulated query signal by mixing the carrier signal and the analog modulation signal.

Concept 17. The device of Concept 16, wherein the local oscillator comprises a phase locked loop (PLL) synthesizer.

Concept 18. The apparatus of Concept 16, wherein the analog modulated signal is an orthogonally encoded signal.

Concept 19. The device of Concept 16, wherein the analog modulation signal provides frequency modulation of the carrier signal.

Concept 20. The device of Concept 16, wherein the analog modulation signal provides amplitude modulation of the carrier signal.

Concept 21. The apparatus of Concept 16 further comprising an analogy demodulator configured to receive the response signal and to demodulate the received response signal with the carrier signal to generate an intermediate frequency (IF) a response signal, wherein the IF response signal is converted to a digital response signal by the analog to digital converter.

Concept 22. The device of Concept 15, wherein the processor is configured to output a signal indicative of detecting the target frequency of the presence indication, and a digitally modulated signal, the apparatus further comprising: a local oscillator The device is configured to receive a signal indicative of the target frequency and a carrier signal generated from the target frequency oscillation; and one or more electronic components are configured to receive the carrier signal and the digital modulation signal, and A modulated query signal is generated by amplitude-modulating the carrier signal with the digital modulated signal.

Concept 23. The device of Concept 22, wherein the one or more electronic components comprise an output amplifier having a digital on/off control input that is configured to receive the digital modulated signal.

Concept 24. The device of concept 22, wherein the one or more electronic components comprise an output amplifier, and an analog switch coupled to the output amplifier and having a digital on/off control input is coupled The digital modulation signal is received.

Concept 25. The apparatus of concept 22, further comprising an analogy demodulator configured to receive the response signal and to demodulate the signal with the carrier signal to generate an intermediate frequency (IF) response signal, The IF response signal is converted into a digital response signal by the analog to digital converter.

Concept 26. The apparatus of concept 15, wherein the processor is further configured to output a digital query signal, the apparatus further comprising a digital to analog (D/A) converter configured to receive the digital query The signal, and an analog modulation query signal, having a carrier frequency set to detect the presence frequency of one of the target frequencies.

Concept 27. The apparatus of Concept 26, further comprising an output amplifier configured to amplify the analog modulated query signal prior to being wirelessly transmitted.

Concept 28. The apparatus of concept 26, further comprising an input amplifier configured to receive the response signal and amplify the signal, wherein the amplified response signal is converted to a digital bit by the analog to digital converter Response signal.

Concept 29. The device of Concept 14, wherein the processor is configured to initially plan to read a set of multi-type RFID tags, and then to re-plan and read a new RFID tag.

Concept 30. The device of Concept 29, wherein the multi-type RFID tags comprise RFID tags based on different coding schemes.

Concept 31. The device of Concept 29, wherein the multi-type RFID tags comprise RFID tags having different RFID bands.

Concept 32. The device of concept 31, wherein the RFID bands comprise the 125 kHz, 13.56 MHz, 915 MHz, and 2.4 GHz bands.

Concept 33. The device of Concept 14, wherein the tag response signal comprises a signal reflected from a passive RFID tag.

Concept 34. The device of Concept 14, wherein the tag response signal comprises reflecting a signal from an active RFID tag.

Concept 35. The device of concept 14, wherein the antenna comprises a set of transceiver antennas, each of the transceiver antennas being configured to transmit and receive signals in one of the different RFID bands.

Concept 36. The device of concept 14, wherein the antenna comprises a single transceiver antenna having a fundamental frequency covering one of the plurality of RFID frequency bands and covering one or more of the one or more remaining RFID frequency bands frequency.

100, 200, 300. . . Multi-mode radio frequency identification (RFID) reading device

101, 201, 301. . . processor

103, 203, 303. . . Antenna set, antenna

105, 205, 305. . . Antenna selection switch

113, 213. . . Local oscillator

114, 314. . . Digital to analog converter (DAC)

115. . . Modulator

117, 217, 317. . . Output amplifier

121, 221, 321. . . Input amplifier

123, 223. . . Demodulator

125, 225, 325. . . Analog to digital converter (ADC)

131. . . RFID tag

400. . . method

410-480, 440A-B, 510-590, 610-690. . . status

700. . . computer system

702. . . Busbar

704. . . processor

706. . . Memory

708. . . I/O module

710. . . Data storage device

1 is a block diagram showing an example of a multimode RFID reading device in accordance with several embodiments;

2 is a block diagram showing another example of a multimode RFID reading device in accordance with several embodiments;

3 is a block diagram showing still another example of a multimode RFID reading device in accordance with several embodiments;

4 is a flow chart showing an example of a method for searching and reading an RFID tag in a multi-RFID frequency band, in accordance with some embodiments;

5 is a flow chart showing an example of a method for generating and transmitting a modulated query signal to an RFID tag in accordance with some embodiments;

6 is a flow chart showing an example of a method for receiving and processing a response signal from an RFID tag in accordance with some embodiments;

Figure 7 is a block diagram showing a computer system in which several embodiments may be embodied.

100. . . Multi-model RFID reading device

101. . . processor

103. . . Antenna collection

105. . . Antenna selection switch

113. . . Local oscillator

114. . . Digital to analog converter (DAC)

115. . . Modulator

117. . . Output amplifier

121. . . Input amplifier

123. . . Demodulator

125. . . Analog to digital converter (ADC)

131. . . RFID tag

Claims (25)

A method of reading a radio frequency identification (RFID) tag, the method comprising the steps of: transmitting a search signal covering one of a plurality of RFID bands, the search signal comprising one of a wideband signal or a swept signal; detecting more One of the RFID tags has an indication of one of the RFID tags; the presence of the target frequency is selected based on the presence indication of the RFID tag; and a carrier signal comprising a baseband signal and one of the carrier signals at the target frequency is generated in a processor ???a digital representation of the inquiry signal; broadcasting the inquiry signal with an antenna; detecting a response from the RFID tag by measuring a change in voltage on the antenna; and reading the RFID tag. The method of claim 1, further comprising the step of converting the digital representation of the interrogation signal into an analog signal in a digital to analog converter (DAC). The method of claim 2, wherein the step of broadcasting the inquiry signal comprises providing the analog signal to the antenna. The method of claim 1, further comprising converting the change in the voltage measured on the antenna to a digital signal in a analog to digital converter (ADC). The method of claim 1, wherein the target frequency is associated with a nominal frequency of 125 kHz, 13.56 MHz, 915 MHz, and 2.4 GHz. Selected in the RFID band. The method of claim 4, wherein the step of reading the RFID tag comprises: receiving the digital signal by the processor; demodulating the digital signal using the carrier frequency by the processor; and decoding the demodulated digit signal. A radio frequency identification (RFID) device comprising: an antenna configured to transmit a search signal covering a plurality of RFID frequency bands, the search signal comprising one of a broadband signal or a frequency sweep signal; having a connection to An output of the antenna and a digit-to-analog converter (DAC) of an input; an analog-to-digital converter (ADC) having an input coupled to the antenna and an output; and having a connection to the DAC An output of the input end and a processor coupled to an input of the output of the ADC, the processor being configured to: detect an presence indication of an RFID tag in one of the plurality of RFID bands; based on the RFID The presence of the label indicates that a target frequency is selected; and a digital signal including a modulated query signal is provided at the output to represent a first digital signal, the query signal including a carrier frequency signal modulated by a baseband signal, Where the carrier frequency signal is the target a frequency; receiving a second digit signal at the input; demodulating the second digit signal to remove the carrier frequency signal; and decoding the demodulated second digit signal. The device of claim 7, wherein: the processor comprises a memory that is configured to store a plurality of digit representations of the modulated interrogation signal; and the processor is further configured to retrieve the And modulating one of a plurality of digit representations of the modulated query signal and providing the one of the plurality of digit representations of the modulated query signals as the first digit signal. A radio frequency identification (RFID) device comprising: an antenna configured to transmit a search signal covering a plurality of RFID frequency bands, the search signal comprising one of a wideband signal or a frequency sweep signal; having an output And a modulator of the first and second input terminals, wherein the output terminal is connected to the antenna; and has a first input end and a second input end and an output end demodulator, wherein the first input An end connected to the antenna; a local oscillator having a first input coupled to the modulator and an output coupled to the second input of the demodulator, the oscillator being assembled to provide a target a class of carrier signals of a frequency selected from the presence of an indication of one of the RFID tags in one of the plurality of RFID bands; a digital-to-analog converter (DAC) having an output and an input, wherein the output is coupled to the second input of the modulator; and has an analog input to an analog converter An ADC), wherein the input is coupled to an output of the demodulator; and a first output coupled to the input of the oscillator, a second output coupled to the input of the DAC, and coupled to the a processor at an input of the output of the ADC, the processor being configured to: provide the signal indicative of the target frequency at the first output; provide a baseband signal at the second output; A digital signal is received at the input; and the digital signal is decoded. The device of claim 9, wherein the local oscillator comprises a phase locked loop (PLL) synthesizer. The apparatus of claim 9, wherein the modulator provides an analog modulation signal at its output, which is an orthogonally encoded signal. The apparatus of claim 9, wherein the modulator provides an analog modulation signal at its output that includes one of the carrier signals for frequency modulation. The device of claim 9, wherein the modulator provides an analog modulation signal at its output comprising amplitude modulation of one of the carrier signals. For example, the device of claim 9 of the patent scope, wherein the target frequency is from The RFID bands associated with the nominal frequencies of 125 kHz, 13.56 MHz, 915 MHz, and 2.4 GHz are selected. The device of claim 7, wherein the target frequency is selected from the RFID bands associated with nominal frequencies of 125 kHz, 13.56 MHz, 915 MHz, and 2.4 GHz. The device of claim 15, wherein the processor comprises a memory for assembling a plurality of sets of information respectively associated with the plurality of types of RFID tags, each group of information including a different encoding scheme and an RFID frequency band. . The device of claim 16, wherein the memory comprises first and second sets of information associated with first and second RFID tags having different RFID bands. The device of claim 17, wherein the RFID bands comprise the 125 kHz, 13.56 MHz, 915 MHz, and 2.4 GHz bands. The device of claim 7, wherein the input of the ADC receives a voltage on the antenna, wherein the change in voltage represents a signal reflected from a passive RFID tag. The device of claim 7, wherein the input of the ADC receives a voltage on the antenna, wherein the change in voltage represents a signal generated by an active RFID tag. The device of claim 7, wherein the antenna comprises a set of transceiver antennas, each of the transceiver antennas being configured to transmit and receive a signal in a different RFID frequency band. The device of claim 7, wherein the antenna comprises a single A transceiver antenna having a fundamental frequency covering one of the plurality of RFID frequency bands and covering one or more of the one or more remaining RFID frequency bands. A method of reading a radio frequency identification (RFID) tag, the method comprising the steps of: transmitting a search signal covering one of a plurality of RFID frequency bands, the search signal comprising one of a wideband signal or a frequency sweep signal; detecting multiple An indication of one of the RFID tags in one of the RFID bands; selecting a target frequency based on the presence indication of the RFID tag; generating a query including a baseband signal and a carrier signal at the target frequency in a processor a digital representation of the signal; converting the digital representation of the query signal into an analog signal in a digital to analog converter (DAC); providing the analog signal to one of the at least two antennas, the at least two The antennas are each associated with a different one of the at least two RFID bands; the selected antenna is used to broadcast the analog signal; and the response from the RFID tag is detected by measuring a change in the voltage on the antenna ; and read the RFID tag. A radio frequency identification (RFID) device comprising: at least two antennas respectively associated with at least two RFID frequency bands, the at least two RFID frequency bands being associated with first and second target frequencies, wherein the first target frequency system At least twice the frequency of the second target a digital-to-analog converter (DAC) having an output and an input; an analog-to-digital converter (ADC) having an input and an output; coupled to an output of the DAC and the ADC An input and optionally coupled to one of the at least two antennas; and an output operatively coupled to the antenna selection switch and having an input coupled to the DAC and a processor coupled to an input of an output of the ADC, the processor being configured to: assemble the antenna selection switch to select one of the at least two antennas; causing one of the at least two antennas Transmitting a search signal covering the at least two RFID frequency bands, the search signal comprising one of a broadband signal or a frequency sweep signal; detecting that one of the RFID tags is present in one of the at least two RFID frequency bands; Determining a target frequency based on the presence indication of the RFID tag; providing, at the output, a first digit signal comprising a digit representation of a modulation query signal, the query signal comprising a baseband signal The modulation of a carrier frequency signal, wherein the carrier frequency signal is selected based on the target frequency; received on the input terminal a second digital signal; demodulating the second digital signal to remove the carrier frequency signal; and decoding the demodulated second digital signal. A radio frequency identification (RFID) device comprising: at least two antennas respectively associated with at least two RFID frequency bands, the at least two RFID frequency bands being associated with first and second target frequencies, wherein the first target frequency system At least twice the frequency of the second target, the at least two antennas are configured to transmit a search signal covering the at least two RFID bands, the search signal comprising one of a wideband signal or a swept signal, and An indicator for detecting presence of one of the RFID tags of one of the at least two RFID bands; a modulator having an output and the first and second inputs; having a first a demodulator of the input end and a second input end and an output end; coupled to the output end of the modulator and the first input end of the demodulator and selectively coupled to the at least two antennas One of the antenna selection switches; and a local oscillator having an output coupled to the first input of the modulator and the second input of the demodulator, the oscillator being assembled Provided at the target frequency a type of carrier signal; a digital to analog converter (DAC) having an output and an input, wherein the output is coupled to the second input of the modulator; having an analogy of an input and an output a digital converter (ADC), wherein the input is coupled to an output of the demodulator; a processor operatively coupled to the antenna selection switch and having a first output coupled to an input of the oscillator, a second output coupled to an input of the DAC, and coupled to the ADC An input of the output, the processor being configured to: provide a signal indicative of an operating frequency at the first output; and assemble the antenna selection switch to select the plurality of antennas associated with the operating frequency An antenna; a baseband signal is provided at the second output; a digital signal is received at the input; and the digital signal is decoded.