An RFID Separation Communication Device

Abstract

The present invention discloses an RFID split communication device, which includes a host computer, a receiver, a transponder and a tag. The host computer is connected to the receiver. The receiver and the transponder communicate through custom commands. The transponder forwards signals to the tag, and the tag sends the tag reflection signal to the receiver. The custom commands include RQ link establishment and ID allocation commands. In the RFID system of the present invention, a transponder is added to forward the information sent by the receiver to the tag, expanding the communication distance between the reader and the tag. By adding multiple transponders, the communication range between the receiver and the tag is expanded. The adjustable filtering module maintains a fixed oversampling multiple for different backscattering rates, and a bit hard decision method based on edge detection is adopted. At the same time, frequency hopping is realized by using DDS technology in the baseband circuit, alleviating the recognition blind area caused by multipath effects and other factors in the system, and improving the inventory success rate of the system.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency identification, and particularly to an RFID split communication device. Background Art

[0002] RFID (Radio Frequency Identification) technology uses the spatial transmission and coupling characteristics of radio frequency signals to achieve non-contact automatic identification of objects, and is typically applied in fields such as the apparel retail industry and vehicle management; however, due to the limitations of the communication distance, communication range, and identification accuracy of traditional UHF RFID systems, it is not currently widely applied in fields such as logistics and warehousing management. Summary of the Invention

[0003] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide an RFID split communication device to improve the communication distance, communication range, and identification accuracy of the reader.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] An RFID split communication device includes a host computer, a receiver, a transponder, and a tag. The host computer is connected to the receiver. The receiver and the transponder communicate through custom commands. The transponder forwards the signal to the tag, and the tag sends the tag reflection signal to the receiver. The custom commands include an RQ link establishment command and an ID assignment command.

[0006] Further, the frame formats of the RQ link establishment command and the ID assignment command include a single-tone sine wave, a frame preamble, the device ID number of the receiver, the device ID number of the transponder, the frequency channel number used by the transponder's sending end, the frequency channel number used for communication between the receiver and the transponder, the transmission antenna number used by the transponder, the transmission power attenuation value used by the transponder, and the unique ID number carried by each transponder itself.

[0007] Further, the communication sampling rule between the receiver and the transponder adopts a two-way handshake mechanism and FM0 coding.

[0008] Further, the digital baseband system of the receiver includes a sending end and a receiving end;

[0009] The sending end includes:

[0010] A CRC generation module: used to generate a check code that meets the protocol requirements;

[0011] An inverse coding module: includes an inverse preamble coding module and an inverse PIE coding module, and is used to encode a high level as a low level and a low level as a high level;

[0012] FM0 Encoding Module: Used for FM0 encoding and communicating with the transponder;

[0013] Fixed-Point Modulation Module: Used for fixing the output bits of the PIE Encoding Module or FM0 Encoding Module and performing corresponding modulation on the fixed-point data;

[0014] Shaping Filter Module: Used for shaping filtering and restricting the transmission bandwidth;

[0015] Upsampling Module: Upsamples the data to make it equal to the sampling frequency of the ADC;

[0016] Frequency Translation Module: Uses direct digital frequency synthesizer technology for frequency translation, performs frequency translation on the baseband according to the transmission frequency point set by the host computer, I = i * cosω + q * sinω; Q = q * cosω - i * sinω; ω is the frequency point set by the host computer;

[0017] The receiving end includes:

[0018] Frequency Translation Module: Uses direct digital frequency synthesizer technology for frequency translation, used to shift the baseband signal near zero frequency according to the receiving frequency point set by the host computer, I = i * cosω + q * sinω; Q = q * cosω - i * sinω; ω is the frequency point set by the host computer;

[0019] Tunable Filter Module: Used to filter out out-of-band noise and maintain a fixed oversampling rate for different backscattering rates;

[0020] Power Statistics Module: Used for power statistics;

[0021] DC Removal Module: Used to remove the DC component from the data after power statistics;

[0022] Bit Hard Decision Module: Used to perform bit hard decision based on edge detection on the signal after DC removal;

[0023] Preamble Detection Module: Performs corresponding preamble detection according to whether the preamble is enabled and whether the reverse signal uses FM0 encoding or Miller2 / 4 / 8 encoding;

[0024] Baseband Processing Module: Decodes the bit data after detecting the preamble.

[0025] Furthermore, the Bit Hard Decision Module is specifically:

[0026] Perform a sliding window summation of N points on the signal after removing the DC component; S(n) = Dc(n) + Dc(n - 1) … + Dc(n - N + 1); Count the number m of samples before the sign bit transition of S. When the sign bit of S changes from positive to negative and N1 ≤ m ≤ N2, output 1 bit of 1; when N2 < m ≤ N3, output 2 bits of 1; when N3 ≤ N4, output 3 bits of 1; when m is greater than N4 and S has not yet transitioned, output 3 bits of 1 and initialize m, then re - count; Similarly, when the sign bit of S changes from negative to positive, output the corresponding number of bits of 0; where N1, N2, N3, and N4 vary according to the actual situation.

[0027] Furthermore, the digital baseband system of the transponder includes a transmitting end and a receiving end;

[0028] The transmitting end includes:

[0029] FM0 encoding module: used for FM0 encoding and communicating with the receiver;

[0030] Fixed - point module: used for fixing the output bits of the FM0 encoding module or the output bits of the bit hard - decision module at the receiving end;

[0031] Shaping filter module: used for shaping filtering and restricting the transmission bandwidth;

[0032] Upsampling module: upsamples the data to be equal to the sampling frequency of the ADC;

[0033] Frequency translation module: uses direct digital frequency synthesis technology for frequency translation. According to the TX_CH in the link - establishment command sent by the receiver R, perform frequency translation in the baseband, I = i * cosω+q * sinω; Q = q * cosω - i * sinω; ω is the frequency point set by TX_CH;

[0034] The receiving end includes:

[0035] Frequency translation module: uses direct digital frequency synthesis technology for frequency translation. According to the RX_CH in the link - establishment command sent by the receiver R, shift the baseband signal near zero frequency, I = i * cosω+q * sinω; Q = q * cosω - i * sinω; ω is the frequency point set by RX_CH;

[0036] Half - band filter bank module: used for filtering out of - band noise and downsampling;

[0037] Signal detection module: used to detect whether the receiver has a transmitted signal and give two decision thresholds for the bit hard - decision module to perform hard - decision;

[0038] Bit Hard Decision Module: Perform bit hard decision according to the decision threshold given by the signal detection module, including the RQ Link Establishment Bit Hard Decision Module and the RT Inventory Hard Decision Module. The RQ Link Establishment Bit Hard Decision Module sends the decision result to the preamble detection module for preamble detection; after the RQ link is established, the RT Inventory Hard Decision Module sends the decision result to the fixed-point module at the sending end for forwarding;

[0039] Preamble Detection Module: Used to detect the preamble of the RQ link establishment;

[0040] Baseband Processing Module: Perform FM0 decoding on the bit data after detecting the RQ link establishment preamble.

[0041] Furthermore, the signal detection module of the transponder is used to detect the start bit of the link establishment command and the decision threshold of the RT Bit Hard Decision Module; when S2(n)>N*S1(n), it is considered that this bit is the start bit of the link establishment command; where S1(n)=d(n)+d(n - 1)…+d(n - M); S2(n)=d(n - M - 1)+d(n - M - 2)…+d(n - 2*M - 1); d(n) is the input signal; M is the oversampling multiple; N can be confirmed according to the system's requirement for the sensitivity of the RQ link establishment; update the RT decision threshold, Thr1 = MAX(S1(n)) / 2; when the RQ link is successfully established, update the RT decision threshold Thr2 = MAX(S1(n)) / 2.

[0042] Furthermore, the RT Inventory Hard Decision Module of the transponder is specifically:

[0043] Perform N-point sliding window summation on the data of the oversampling signal detection module, S(n)=d(n)+d(n - 1)…+d(n - N + 1), when S(n)>Thr2, output bit 1, otherwise output bit 0; where N is the oversampling multiple.

[0044] Furthermore, when performing a service command, the receiver uses the reverse coding module to send data, the transponder flips the received and demodulated signal through the RT Inventory Hard Decision Module, and finally forwards it to the tag through the transmission link, and the tag then scatters the modulated information to the receiver through backscattering.

[0045] Furthermore, there are multiple transponders, and the receiver communicates with multiple transponders respectively.

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] (1) The present invention adds a transponder in the RFID system to forward the information sent by the receiver to the tag, expanding the communication distance between the reader and the tag, and expanding the communication range between the receiver and the tag by adding multiple transponders;

[0048] (2) The present invention adopts a reverse coding module at the receiver R, reducing the power consumption of the receiver R;

[0049] (3) For different backscattering rates of the tag, the present invention uses half-band filters with different orders for filtering, ensuring a fixed oversampling multiple for different backscattering rates. By counting the number m of symbols before the S symbol jumps and outputting the corresponding number of bits for different m, it ensures that there are no error codes even when there is a frequency offset in the reflected signal;

[0050] (4) The present invention combines quadrature demodulation for hard bit decision, does not require strict same frequency and same phase, has strong anti-carrier frequency adaptation ability, and improves the sensitivity of the reader-writer.

[0051] (5) The present invention realizes frequency hopping of the system through the frequency shift module in the baseband, alleviates the recognition blind area caused by multipath effects, and improves the recognition efficiency of the system.

[0052] (6) The present invention sends a long CW wave signal before establishing the RQ link, ensuring that the transponder can accurately detect the start bit of the signal and improving the success rate of link establishment of the system. Description of the Drawings

[0053] Figure 1 is the structural diagram of the RFID separation type communication device of the present invention;

[0054] Figure 2 is the schematic diagram of the custom command frame format for RQ link establishment of the present invention;

[0055] Figure 3 is the structural diagram of the digital baseband system of the receiver of the present invention;

[0056] Figure 4 is the structural diagram of the digital baseband system of the transponder of the present invention;

[0057] Figure 5 is the schematic diagram of the reverse coding of the receiver and the RT hard bit decision result of the transponder of the present invention. Detailed Embodiments

[0058] The following further describes the present invention in detail with reference to embodiments, but the embodiments of the present invention are not limited thereto.

[0059] Such as Figure 1As shown in the figure, this embodiment provides an RFID split communication device, including a host computer, a receiver R, a transponder Q, and a tag. Among them, in this embodiment, the transmission frequency band of the receiver is 840 - 845 MHz, and the reception frequency band is 920 - 925 MHz; the transmission frequency band of the transponder Q is 920 - 925 MHz, and the reception frequency band is 840 - 845 MHz; the receiver R and the transponder Q communicate through a custom command, adopting a two-way handshake mechanism and FM0 encoding.

[0060] Furthermore, multiple transponders can be included, and the receiver communicates with multiple transponders respectively, and each transponder is independent.

[0061] Furthermore, the custom command includes an RQ link establishment command and an ID assignment command. The frame formats of the RQ link establishment command and the ID assignment command are as Figure 2 shown, where CW is a single-tone sine wave. A section of CW wave is sent before sending the frame command to ensure that the transponder can accurately detect the start bit of the signal, improving the link establishment success rate of the system; PREMBLE is the preamble of the frame, CMD is the command, which distinguishes whether the command is an ID assignment command or a link establishment command; RID represents the device ID number of the receiver R, QID represents the device ID number of the transponder Q, TX_CH represents the frequency channel number used by the sending end of the transponder Q, RX_CH represents the frequency channel number used for communication between the receiver R and the transponder Q, ANT_ID represents the transmission antenna number used by the transponder Q, where 0 means not using any transmission antenna, that is, not forwarding the signal, TX_POWER represents the transmission power attenuation value used by the transponder Q, RSV is the reserved bit, and the SN number is the unique ID number carried by each transponder Q itself.

[0062] The working process of this device is as follows:

[0063] Before performing a service command, the receiver R first sends an ID allocation command to determine the transmission and reception frequency point numbers. When the receiver R still does not receive a reply command from the transponder Q after waiting for a period of time, it changes the transmission and reception frequency point numbers and continues to send the ID allocation command until it receives the reply command from the transponder Q. When the transponder Q receives the ID allocation command and the SN number matches its own, it responds to the command and configures information such as RID, QID, transmission and reception frequency points, transmission antenna ID number, transmission power, etc.; after the ID allocation command is completed, the transmission and reception frequency points, transmission antenna ID number, transmission power, etc. can be modified through the RQ link establishment command later; after the RQ link establishment or ID allocation command is completed, the service command can be performed. When performing the service command, the receiver R uses the reverse coding module to send data, and the transponder Q will receive the information sent by R, reverse the received bit information and forward it to the tag through the transmission link, and the tag will then scatter the modulated information to the receiver R through backscattering; after the service command is completed, the host computer issues a de-link establishment command. At this time, ANT_ID is 0. After receiving this command, the transponder Q replies with an ACK signal and no longer forwards the received signal;

[0064] Specifically, the digital baseband system of the receiver R is as Figure 3 shown. The sending end includes

[0065] CRC generation module: used to generate a check code that meets the protocol requirements;

[0066] Reverse coding module: includes a reverse preamble coding module and a reverse PIE coding module, used to encode high level as low level and low level as high level;

[0067] Among them, the reverse preamble coding module includes the preamble of the service command and the CW wave used to activate the tag. As Figure 5 shown, after the RQ link establishment is completed, the signal is flipped through the RT bit hard decision module at the transponder end to save the power consumption of the receiver;

[0068] FM0 coding module: used to perform FM0 coding and communicate with the transponder; 1]

[0069] Fixed-point modulation module: used to perform fixed-point on the output bits of the PIE coding module or the FM0 coding module, and perform corresponding modulation on the fixed-point data, including ASK modulation, PSK modulation, PR-ASK modulation;

[0070] Shaping filter module: used to perform shaping filtering, limit the transmission bandwidth, and avoid inter-symbol interference;

[0071] Upsampling module: upsamples the data to make it equal to the sampling frequency of the ADC.

[0072] Frequency translation module: It uses direct digital frequency synthesizer technology for frequency translation. According to the transmission frequency point set by the host computer, it performs a certain frequency translation on the baseband. I = i * cosω + q * sinω; Q = q * cosω - i * sinω; ω is the frequency point set by the host computer.

[0073] Receiver:

[0074] It includes a frequency translation module: It uses direct digital frequency synthesizer technology for frequency translation, which is used to shift the baseband signal near zero frequency according to the received frequency point set by the host computer. I = i * cosω + q * sinω; Q = q * cosω - i * sinω; ω is the frequency point set by the host computer.

[0075] Adjustable filtering module: It is used to filter out of-band noise and maintain a fixed oversampling rate for different backscattering rates. Specifically, when the backscattering rate of the tag is 640 Kbit / s, it passes through 3 half-band filters for downsampling and filtering out of-band noise; when the backscattering rate of the tag is 320 Kbit / s, it passes through 4 half-band filters for downsampling and filtering out of-band noise, so that the system can maintain a fixed oversampling multiple for different backscattering rates of the tag.

[0076] Power statistics module: It is used to perform power statistics. P(n) = I^2(n) + Q^2(n);

[0077] DC removal module: It is used to remove the DC component from the data after power statistics.

[0078] Bit hard decision module: It is used to perform bit hard decision based on edge detection on the signal after DC removal. Specifically, it performs a sliding window summation of N points on the signal after DC removal. S(n) = Dc(n) + Dc(n - )… + Dc(n - N + 1); It counts the number m of samples before the sign change of S. When the sign of S changes from positive to negative and N1 ≤ m ≤ N2, it outputs 1 bit of 1; when N2 < m ≤ N3, it outputs 2 bits of 1; when N3 ≤ N4, it outputs 3 bits of 1; when m is greater than N4 and S has not changed yet, it outputs 3 bits of 1 and initializes m, and re-counts; Similarly, when the sign of S changes from negative to positive, it outputs the corresponding number of bits of 0; where N1, N2, N3, N4 can be changed according to the actual situation.

[0079] Preamble detection module: It performs corresponding preamble detection according to whether the preamble is enabled and whether the reverse signal uses FM0 coding or Miller2 / 4 / 8 coding.

[0080] Baseband processing module: It decodes the bit data after detecting the preamble, including performing FM0 decoding and Miller2 / 4 / 8 decoding.

[0081] The digital baseband system of repeater Q is as follows Figure 4 as shown

[0082] The transmitting end includes:

[0083] FM0 encoding module: used for FM0 encoding and communicating with receiver R;

[0084] Fixed-point module: used for fixing the output bits of the FM0 encoding module or the output bits of the bit hard decision module at the receiving end;

[0085] Shaping filter module: used for shaping filtering, restricting the transmission bandwidth, and avoiding inter-symbol interference;

[0086] Upsampling module: upsamples the data to make it equal to the sampling frequency of the ADC;

[0087] Frequency translation module: uses direct digital frequency synthesizer technology for frequency translation, performs frequency translation in the baseband according to TX_CH in the link establishment command sent by receiver R, I = i*cosω + q*sinω; Q = q*cosω - i*sinω; ω is the frequency point set by TX_CH.

[0088] The receiving end includes:

[0089] Frequency translation module: uses direct digital frequency synthesizer technology for frequency translation, shifts the baseband signal to near zero frequency according to RX_CH in the link establishment command sent by receiver R, I = i*cosω + q*sinω; Q = q*cosω - i*sinω; ω is the frequency point set by RX_CH.

[0090] Half-band filter bank module: used for filtering out-of-band noise and downsampling;

[0091] Signal detection module: used for detecting the start bit of the link establishment command and the decision threshold of the RT bit hard decision module; when S2(n) > N*S1(n), it is considered that this bit is the start bit of the link establishment command; where S1(n) = d(n) + d(n - 1)… + d(n - M); S2(n) = d(n - M - 1) + d(n - M - 2)… + d(n - 2*M - 1); d(n) is the input signal; M is the oversampling multiple; N can be confirmed according to the system's requirement for the RQ link establishment sensitivity; update the RT decision threshold, Thr1 = MAX(S1(n)) / 2; when the RQ link establishment is successful, update the RT decision threshold Thr2 = MAX(S1(n)) / 2;

[0092] Bit hard decision module: can be divided into the RQ link establishment bit hard decision module and the RT point hard decision module; for the RQ link establishment bit hard decision module, its basic working principle is the same as that of the bit hard decision module in the receiver.

[0093] Perform hard bit decision according to the decision threshold Thr1 given by the signal detection module. When S(n) > Thr1, output bit 1; otherwise, output bit 0. Count the number m of consecutive bit 1s and the number n of consecutive bit 0s. When 10 < m < 16, hard-decide it as 1 bit 1; when m > 16, hard-decide it as 2 bit 1s. When 10 < n < 16, hard-decide it as 1 bit 0; when m > 16, hard-decide it as 2 bit 0s. 10 and 16 are specific reference values provided in this embodiment and can be adjusted according to the oversampling multiple of the system architecture, etc. For the RT inventory hard decision module, after successful link establishment, perform hard bit decision according to the decision threshold Thr2 given by the signal detection module. When S(n) > Thr2, output bit 0; otherwise, output bit 1, and send the decision result to the fixed-point module at the sending end for forwarding. Where S(n) = d(n) + d(n - 1)… + d(n - M); M is the oversampling multiple.

[0094] Preamble detection module: used to detect the preamble of the RQ link establishment.

[0095] Baseband processing module: perform FM0 decoding on the bit data after detecting the RQ link establishment preamble.

[0096] The control module in the attached figure has the following functions. One is to control the receiver to send commands such as link establishment or inventory according to the commands of the upper computer. The other is to control its transmitting and receiving links according to the state machine of the receiver itself.

[0097] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. An RFID separable communication device, characterized in that It includes a host computer, a receiver, a repeater, and a tag. The host computer is connected to the receiver. The receiver and the repeater communicate via custom commands. There are multiple repeaters, and the receiver communicates with each of the multiple repeaters respectively. The repeater is connected to the tag, and the tag sends a tag reflection signal to the receiver. The signal flow direction of the receiver, the repeater, and the tag is that the receiver sends a signal to the repeater, the repeater forwards the signal to the tag, and the tag backscatters the signal to the receiver. The custom commands include an RQ link establishment command and an ID assignment command; The frame formats of the RQ link establishment command and the ID assignment command include a single-tone sine wave, a frame preamble, the device ID number of the receiver, the device ID number of the repeater, the frequency channel number TX_CH used by the sending end of the repeater, the frequency channel number RX_CH used for communication between the receiver and the repeater, the transmitting antenna number used by the repeater, the transmit power attenuation value used by the repeater, and the unique ID number carried by each repeater itself; The digital baseband system of the receiver includes a sending end and a receiving end; The sending end of the digital baseband system of the receiver includes: CRC generation module: used to generate a check code that meets the protocol requirements; Inverse coding module: includes an inverse preamble coding module and an inverse PIE coding module, used to encode high level as low level and low level as high level; FM0 coding module: used to perform FM0 coding for communication with the repeater; Fixed-point modulation module: used to fix the output bits of the inverse PIE coding module or the FM0 coding module at the sending end of the digital baseband system of the receiver, and perform corresponding modulation on the fixed-point data; Shaping filter module: used to perform shaping filtering to limit the transmission bandwidth; Upsampling module: used to upsample the data to make it equal to the sampling frequency of the ADC; Frequency shifting module: uses direct digital frequency synthesizer technology for frequency shifting, and performs frequency shifting on the baseband according to the sending frequency point set by the host computer; Among them, the signal flow direction of each module is that the CRC generation module outputs a signal to the inverse coding module and the FM0 coding module, the inverse coding module and the FM0 coding module output a signal to the fixed-point modulation module, the fixed-point modulation module outputs a signal to the shaping filter module, the shaping filter module outputs a signal to the upsampling module, and the upsampling module outputs a signal to the frequency shifting module; The receiving end of the digital baseband system of the receiver includes: Frequency shifting module: uses direct digital frequency synthesizer technology for frequency shifting, used to shift the baseband signal to near zero frequency according to the receiving frequency point set by the host computer; Adjustable filter module: used to filter out out-of-band noise and maintain a fixed oversampling rate for different backscattering rates; Power statistics module: used to perform power statistics; DC removal module: used to remove DC from the data after power statistics; Bit hard decision module: used to perform bit hard decision based on edge detection on the signal after DC removal; Preamble detection module: performs corresponding preamble detection according to whether the preamble is enabled and whether the backscattered signal uses FM0 coding or Miller2 / 4 / 8 coding; Baseband processing module: Decodes the bit data after the preamble is detected; Among them, the signal flow of each module is that the frequency translation module outputs a signal to the adjustable filter module, the adjustable filter module outputs a signal to the power statistics module, the power statistics module outputs a signal to the DC removal module, the DC removal module outputs a signal to the bit hard decision module, the bit hard decision module outputs a signal to the preamble detection module, and the preamble detection module outputs a signal to the baseband processing module; The digital baseband system of the transponder includes a transmitting end and a receiving end; The transmitting end of the digital baseband system of the transponder includes: FM0 encoding module: Used for FM0 encoding and communicating with the receiver; Fixed-point module: Used to perform fixed-point processing on the output bits of the FM0 encoding module at the transmitting end of the digital baseband system of the transponder or the output bits of the bit hard decision module at the receiving end of the digital baseband system of the transponder; Shaping filter module: Used for shaping filtering and restricting the transmission bandwidth; Upsampling module: Upsamples the data to make it equal to the sampling frequency of the ADC; Frequency translation module: Performs frequency translation using direct digital frequency synthesizer technology, and performs frequency translation on the baseband according to TX_CH in the RQ link establishment command sent by the receiver; Among them, the signal flow of each module is that the FM0 encoding module outputs a signal to the fixed-point module, the fixed-point module outputs a signal to the shaping filter module, the shaping filter module outputs a signal to the upsampling module, and the upsampling module outputs a signal to the frequency translation module; The receiving end of the digital baseband system of the transponder includes: Frequency translation module: Performs frequency translation using direct digital frequency synthesizer technology, and shifts the baseband signal to near zero frequency according to RX_CH in the RQ link establishment command sent by the receiver; Half-band filter bank module: Used to filter out out-of-band noise and downsample; Signal detection module: Used to detect whether the receiver has a transmitted signal and gives two decision thresholds for the bit hard decision module at the receiving end of the digital baseband system of the transponder to perform hard decision; Bit hard decision module: Performs bit hard decision according to the decision thresholds given by the signal detection module, including the RQ link establishment bit hard decision module and the RT inventory hard decision module. The RQ link establishment bit hard decision module sends the decision result to the preamble detection module for preamble detection; After the RQ link establishment command is completed, the RT inventory hard decision module sends the decision result to the fixed-point module at the transmitting end of the digital baseband system of the transponder for forwarding; Preamble detection module: Used to detect the preamble of the RQ link establishment command; Baseband processing module: Performs FM0 decoding on the bit data after the preamble of the RQ link establishment command is detected; Among them, the signal flow of each module is that the frequency translation module outputs a signal to the half-band filter bank module, the half-band filter bank module outputs a signal to the signal detection module, the signal detection module outputs a signal to the bit hard decision module, the bit hard decision module outputs a signal to the preamble detection module, and the preamble detection module outputs a signal to the baseband processing module.

2. The RFID separable communication device according to claim 1, wherein, The communication sampling rule between the receiver and the transponder adopts a two-way handshake mechanism and FM0 encoding.

3. The RFID split communication device according to claim 1, characterized in that The bit hard decision module of the digital baseband system of the receiver is specifically: Perform a sliding window summation of N points on the signal after removing the DC component; S(n) = Dc(n) + Dc(n - 1) +... + Dc(n - N + 1); count the number m of samples before the sign bit transition of S(n). When the sign bit of S(n) changes from positive to negative and N1 ≤ m ≤ N2, output 1 bit of 1; when N2 < m ≤ N3, output 2 bits of 1; when N3 ≤ m ≤ N4, output 3 bits of 1; when m > N4 and the sign bit of S(n) has not yet changed, output 3 bits of 1 and initialize m, then re-count. Similarly, when the sign bit of S(n) changes from negative to positive, output the corresponding number of bits of 0; where Dc(n) is the signal after removing the DC component at time n, S(n) is the sum of the N signals after removing the DC component before time n, and N1, N2, N3, and N4 vary according to the actual situation.

4. The RFID split communication device according to claim 3, wherein, The signal detection module of the repeater is used to detect the start bit of the RQ link establishment command and the decision threshold of the RT bit hard decision module; when S2(n) > N * S1(n), it is considered that this bit is the start bit of the RQ link establishment command; where S1(n) = d(n) + d(n - 1) +... + d(n - M + 1); S2(n) = d(n - M) + d(n - M - 1) +... + d(n - 2 * M + 1); d(n) is the input signal; M is the oversampling ratio; N can be determined according to the system's requirement for the sensitivity of RQ link establishment; update the RT decision threshold, Thr1 = MAX(S1(n)) / 2; when the RQ link establishment is successful, update the RT decision threshold Thr2 = MAX(S1(n)) / 2.

5. The RFID split communication device according to claim 4, characterized in that, The RT inventory hard decision module of the repeater is specifically: Perform a sliding window summation of M points on the data from the signal detection module, S(n) = d(n) + d(n - 1) +... + d(n - M + 1). When S(n) > Thr2, output bit 1, otherwise output bit 0.

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