CN210691334U - Ultrahigh frequency RFID reader-writer based on zero intermediate frequency receiving technology - Google Patents
Ultrahigh frequency RFID reader-writer based on zero intermediate frequency receiving technology Download PDFInfo
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- CN210691334U CN210691334U CN201922273296.5U CN201922273296U CN210691334U CN 210691334 U CN210691334 U CN 210691334U CN 201922273296 U CN201922273296 U CN 201922273296U CN 210691334 U CN210691334 U CN 210691334U
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Abstract
The utility model discloses an hyperfrequency RFID read write line based on zero intermediate frequency receiving technology, read write line adopt pi type wave filter, and suitable with the interfering signal filtering, the mode of rethread one-level amplification and second grade amplifier circuit isolation, will faint label return signal enlarge to enough high level, send into the comparator and obtain demodulation signal, supply MCU discernment. The envelope detector comprises two zero-bias Schottky diodes and an RC voltage-multiplying circuit, the output voltage sensitivity is improved, the amplifying circuit comprises two stages of differential signal amplifying circuits, millivolt-level label input signals can be amplified to 3-4V, IQ signals are obtained from the output ends of two paths of differential amplifiers, the two paths of envelope detectors are spaced by a quarter wavelength, the amplified signal phases are in an orthogonal state, and good digital signals can be obtained after the amplified signal phases pass through a comparator. The problem that the extracted label return signal is still very weak after the received signal passes through envelope detection is solved.
Description
Technical Field
The utility model belongs to the technical field of the hyperfrequency RFID read write line, concretely relates to hyperfrequency RFID read write line based on zero intermediate frequency receiving technology.
Background
The hardware of the ultrahigh frequency RFID reader is generally divided into a scheme of carrying a part of peripheral circuits on an integrated chip and a scheme of integrating a separating device, the former has high integration level and small volume and has the defect of high price, and the latter needs more components and parts, a radio frequency signal generating circuit, a signal modulating circuit, a radio frequency amplifying circuit, a receiving and demodulating circuit, a receiving and filtering circuit and the like are respectively designed, so that the ultrahigh frequency RFID reader has the advantages of complex structure, poor integration level and relatively low price, and is suitable for occasions with higher cost requirements and large-scale application. An existing RFID reader/writer mounted on a separate device generally includes a radio frequency generator, a power amplifier, a modem, a mixer, an antenna, a filter, a zero intermediate frequency receiver or a superheterodyne receiver, and the like. At present, most separating devices carry an RFID reader-writer, because microstrip antennas are adopted, directional couplers or circulators are not adopted, and input and output signals are not isolated, the signals of a receiving part are greatly interfered by the output signals, and because the received label return signals are very weak, the transmitted signals are very strong, and the identification and separation effects of the signals are often poor.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a: because most of prior separating devices carry RFID reader-writers, because microstrip antennas are adopted, directional couplers or circulators are not adopted, and input and output signals are not isolated, the signals of a receiving part are greatly interfered by the output signals, and because the received label return signals are very weak, the transmitted signals are very strong, and the identification and separation effects of the signals are often not good, the ultrahigh frequency RFID reader-writer based on the zero intermediate frequency receiving technology is provided.
The utility model adopts the technical scheme as follows:
an ultrahigh frequency RFID reader based on zero intermediate frequency receiving technology comprises a signal transmitting part and a signal receiving part, wherein the signal transmitting part comprises an MCU and a signal generating, modulating and amplifying circuit connected with the MCU, the signal generating, modulating and amplifying circuit is connected with an antenna through a microstrip line, the signal receiving part comprises 2 envelope detectors respectively connected with the strip line, 2 pi-type filters respectively connected with the output ends of the 2 envelope detectors, 2 amplifying circuits respectively connected with the output ends of the 2 pi-type filters, and a comparison circuit commonly connected with the output ends of the 2 amplifying circuits, and a signal demodulation circuit connected with the output end of the comparison circuit, the output end of the signal demodulation circuit is connected with the MCU, the distance between the 2 envelope detectors is lambda/4, the envelope detectors comprise two zero-biased Schottky diodes and an RC voltage-multiplying circuit, and the amplifying circuit comprises a two-stage differential signal amplifying circuit.
Further, as mentioned above, the signal generating, modulating and amplifying circuit includes a radio frequency signal generating module connected to the MCU, a modulating circuit connected to the MCU, a power amplifying module connected to the MCU, and a microstrip antenna connected to the power amplifying module.
Further, as mentioned above, the MCU is further connected to the LED and the buzzer.
Further, as for the ultrahigh frequency RFID reader based on the zero intermediate frequency receiving technology, the microstrip line is a 50 ohm microstrip line.
Further, as mentioned above, the antenna is a ceramic antenna for the ultrahigh frequency RFID reader based on the zero intermediate frequency receiving technology.
Further, as mentioned above, in the ultrahigh frequency RFID reader based on the zero intermediate frequency receiving technology, the MCU employs a 32-bit embedded single chip.
To sum up, owing to adopted above-mentioned technical scheme, the beneficial effects of the utility model are that:
1. the utility model discloses in, the read write line adopts pi type filter, and is suitable with the interfering signal filtering, then through two-stage amplifier circuit, the mode that one-level enlargies and second grade amplifier circuit keeps apart is enlarged enough high level with weak label return signal, sends into the comparator and obtains demodulation signal, supplies MCU discernment. The envelope detector comprises two zero-bias Schottky diodes and an RC voltage-multiplying circuit, the output voltage sensitivity is improved, the amplifying circuit comprises two stages of differential signal amplifying circuits, millivolt-level label input signals can be amplified to 3-4V, IQ signals are obtained from the output ends of two paths of differential amplifiers, the two paths of envelope detectors are spaced by a quarter wavelength, the amplified signals are enabled to have phase difference of 90 degrees and to be in an orthogonal state, and good binary digital signals can be obtained after passing through a comparator. The problem that the extracted label return signal is still very weak after the received signal passes through envelope detection is solved.
2. The utility model discloses in, MCU controls the work of other modules as the brain of whole read write line, and MCU adopts 32 embedded singlechip chips, and it is fast to have a computational rate, and the performance is strong, characteristics that the consumption is low.
3. The utility model discloses in, peripheral circuit includes bee calling organ, LED lamp etc. and bee calling organ and LED lamp are controlled by MCU, play effects such as suggestion, report an emergency and ask for help or increased vigilance.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic diagram of the ultrahigh frequency RFID reader/writer of the present invention;
FIG. 2 is a schematic diagram of the signal generating, modulating and amplifying circuit of the present invention;
fig. 3 is a schematic diagram of the signal receiving and demodulating circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention, i.e., the described embodiments are merely some, but not all, embodiments of the invention. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiment of the present invention, all other embodiments obtained by the person skilled in the art without creative work belong to the protection scope of the present invention.
It is noted that relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The features and properties of the present invention are described in further detail below with reference to examples.
An ultrahigh frequency RFID reader based on zero intermediate frequency receiving technology comprises a signal transmitting part and a signal receiving part, wherein the signal transmitting part comprises an MCU and a signal generating, modulating and amplifying circuit connected with the MCU, the signal generating, modulating and amplifying circuit is connected with an antenna through a microstrip line, the signal receiving part comprises 2 envelope detectors respectively connected with the strip line, 2 pi-type filters respectively connected with the output ends of the 2 envelope detectors, 2 amplifying circuits respectively connected with the output ends of the 2 pi-type filters, a comparison circuit commonly connected with the output ends of the 2 amplifying circuits, and a signal demodulating circuit connected with the output end of the comparison circuit, the output end of the signal demodulating circuit is connected with the MCU, the distance between the 2 envelope detectors is lambda/4, the envelope detectors comprise two zero-offset Schottky diodes and a voltage doubling circuit, the amplifying circuit comprises a two-stage differential signal amplifying circuit.
Further, as for the ultrahigh frequency RFID reader based on the zero intermediate frequency receiving technology, the microstrip line is a 50 ohm microstrip line.
Further, in a specific embodiment, the antenna is a ceramic antenna.
Further, in a specific embodiment, the MCU employs a 32-bit embedded single chip. The method has the characteristics of high calculation speed, strong performance and low power consumption.
The antenna transmits a specific coding signal meeting international standards, the electronic tag responds after receiving the signal, induces current and transmits a corresponding response signal, the response signal enters a microstrip line after being received by the ceramic antenna, the response signal is detected and analyzed by two envelope detection circuits connected to the microstrip line, the distance between the two envelope detection circuits is lambda/4, the two signals are orthogonal, after useless signals are filtered out by a filter, the two signals are sent to a two-stage differential amplifier, and finally the two signals enter a comparator and a signal demodulator, and the demodulated signals are sent to the MCU for analysis and judgment.
The reader adopts a separated device carrying mode. The RFID reader/writer carried by the separation device generally includes a radio frequency generator, a power amplifier, a modem, a mixer, an antenna, a filter, a zero intermediate frequency receiver or a superheterodyne receiver, and the like. The signal transmitting part adopts an MCU control frequency comprehensive source to generate radio frequency waves in an ultrahigh frequency band, controls a switch in a practical digital modulation mode, modulates AM modulation signals meeting the standard, and transmits the signals through a power amplifier and an antenna. The signal receiving part is the key point of the design of the reader-writer, and is different from a common superheterodyne receiver, the reader-writer adopts an easily-realized zero intermediate frequency receiver technology, a received label return signal is taken out from a microstrip antenna, an IQ signal is generated through envelope detection and a low-pass filter, and the IQ signal is amplified for the second time, sent to a comparator, restored to a demodulated signal and sent to an MCU for analysis and restoration.
Because the microstrip antenna is adopted, a directional coupler or a circulator is not adopted, and input and output signals are not isolated, the signal of the receiving part in the scheme is greatly interfered by the output signal, and because the received label return signal is very weak and the transmitting signal is very strong, the identification and separation of the receiving signal are very important. After the received signal passes through the envelope detection, the extracted tag return signal is very weak, so that the filter circuit and the signal amplification circuit are the key points in the design. The reader adopts a pi-type filter to properly filter interference signals, then amplifies weak label return signals to a high enough level by a two-stage amplifying circuit, a first-stage amplifying circuit and a second-stage amplifying circuit in an isolating mode, and sends the amplified signals to a comparator to obtain demodulated signals for MCU identification.
Further, in a specific embodiment, as shown in fig. 2, the signal generating, modulating and amplifying circuit includes a radio frequency signal generating module connected to the MCU, a modulating circuit connected to the MCU, a power amplifying module connected to the MCU, and a microstrip antenna connected to the power amplifying module. The signal generating, modulating and amplifying circuit comprises a radio frequency signal generating module, a modulating circuit, a radio frequency amplifying module, a microstrip antenna and other modules, wherein the radio frequency signal generator is used for continuously generating an ultrahigh frequency radio frequency signal under the control of an MCU (microprogrammed control Unit), the ultrahigh frequency radio frequency signal enters the signal modulator through an LC (inductance-capacitance) filtering circuit, an AM (amplitude modulation) signal is modulated under the control of the MCU, and the ultrahigh frequency radio frequency signal which meets the international standard is transmitted out through a 50 ohm microstrip line and a ceramic antenna after being amplified by the radio frequency amplifier.
Further, in a specific embodiment, the MCU is further connected with an LED and a buzzer. For example, in fig. 1, the peripheral circuit includes a buzzer, an LED lamp, a crystal oscillator, etc., the crystal oscillator provides a clock source for the MCU, and the buzzer and the LED lamp are controlled by the MCU to play roles of prompting, alarming, etc.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.
Claims (6)
1. The ultrahigh frequency RFID reader-writer based on the zero intermediate frequency receiving technology comprises a signal sending part and a signal receiving part, and is characterized in that: the signal transmitting part comprises an MCU and a signal generating, modulating and amplifying circuit connected with the MCU, the signal generating, modulating and amplifying circuit is connected with an antenna through a microstrip line, the signal receiving part comprises 2 envelope detectors respectively connected with the strip line, 2 pi-type filters respectively connected with the output ends of the 2 envelope detectors, 2 amplifying circuits respectively connected with the output ends of the 2 pi-type filters, a comparison circuit commonly connected with the output ends of the 2 amplifying circuits, and a signal demodulating circuit connected with the output end of the comparison circuit, the output end of the signal demodulating circuit is connected with the MCU, the interval between the 2 envelope detectors is lambda/4, the envelope detectors comprise two zero-offset Schottky diodes and an RC voltage-multiplying circuit, and the amplifying circuit comprises two stages of differential signal amplifying circuits.
2. The ultrahigh frequency RFID reader-writer based on the zero intermediate frequency receiving technology as claimed in claim 1, characterized in that: the signal generating, modulating and amplifying circuit comprises a radio frequency signal generating module connected with the MCU, a modulating circuit connected with the MCU, a power amplifying module connected with the MCU and a microstrip antenna connected with the power amplifying module.
3. The ultrahigh frequency RFID reader-writer based on the zero intermediate frequency receiving technology as claimed in claim 1, characterized in that: the MCU is also connected with an LED and a buzzer.
4. The ultrahigh frequency RFID reader-writer based on the zero intermediate frequency receiving technology as claimed in claim 1, characterized in that: the microstrip line adopts a 50 ohm microstrip line.
5. The ultrahigh frequency RFID reader-writer based on the zero intermediate frequency receiving technology as claimed in claim 1, characterized in that: the antenna adopts a ceramic antenna.
6. The ultrahigh frequency RFID reader-writer based on the zero intermediate frequency receiving technology as claimed in claim 1, characterized in that: the MCU adopts a 32-bit embedded single chip microcomputer chip.
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| CN201922273296.5U CN210691334U (en) | 2019-12-17 | 2019-12-17 | Ultrahigh frequency RFID reader-writer based on zero intermediate frequency receiving technology |
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| CN201922273296.5U CN210691334U (en) | 2019-12-17 | 2019-12-17 | Ultrahigh frequency RFID reader-writer based on zero intermediate frequency receiving technology |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115277328A (en) * | 2022-07-12 | 2022-11-01 | 中国科学院上海微系统与信息技术研究所 | Demodulation circuit and capacitive coupling digital isolator |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115277328A (en) * | 2022-07-12 | 2022-11-01 | 中国科学院上海微系统与信息技术研究所 | Demodulation circuit and capacitive coupling digital isolator |
| CN115277328B (en) * | 2022-07-12 | 2024-01-26 | 中国科学院上海微系统与信息技术研究所 | Demodulation circuit and capacitive coupling digital isolator |
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