Battery-free ultra-low power consumption radio frequency energy taking common antenna label end device

Abstract

The invention discloses a battery-free ultra-low power consumption radio frequency energy taking common antenna tag device, and belongs to a low power consumption Internet of Things communication technology. The initial state of a tag end device is defaulted to be a to-be-awakened state; when the tag end device works in a to-be-awakened state, the control unit controls the switching unit to connect the antenna and the awakening unit; when the label end device works in a receiving state, the control unit controls the switching unit to connect the antenna and the downlink signal demodulation unit; when the label end device works in a backscattering state, the control unit controls the switching unit to connect the antenna and the backscattering signal modulation unit, and the control unit processes the collected information from the sensor into a modulation signal. The backscattering signal modulation unit receives the carrier wave from the antenna and the modulation signal from the control unit, modulates the carrier wave and the modulation signal to generate a modulated signal, and outputs the modulated signal to the antenna to complete backscattering. According to the invention, a radio frequency energy taking and communication transceiver common antenna mode is adopted, and a low-power-consumption battery-free design is realized.

Description

Technical Field

[0001] The present invention belongs to wireless communication technology, and in particular to low-power Internet of Things communication technology. Background Art

[0002] With the development of Internet of Things technology, sensor nodes of large-scale, low-cost wireless sensor networks have become a research hotspot. Most existing wireless sensor networks are battery-powered and communicate over short distances wirelessly. However, in many application scenarios, it is difficult and costly for maintenance personnel to regularly replace batteries at the nodes. The problems of powering these large numbers of miniaturized devices, daily maintenance, and wireless communication are becoming increasingly difficult.

[0003] Wireless communication systems based on backscatter technology have also received widespread attention. One of the benefits of this communication system is that it can realize passive tags, which is one of the important technologies of the future smart Internet of Things. The backscatter wireless communication system includes a reader and a tag. The tag can be used to transmit the device ID stored locally to the reader and the tag through a radio frequency signal, and can also transmit environmental information collected by local sensors.

[0004] The tag uses different reflection coefficients when the antenna is connected to different loads to achieve signal modulation. This is achieved by changing the impedance of the antenna. When the antenna is connected to different impedances, the reflected signal strength and phase will change. This change can be used to achieve signal modulation and realize signal transmission and reception on the same antenna. Backscatter communication is often based on binary amplitude keying modulation 2ASK, which transmits binary data by changing the amplitude of the carrier. The amplitude of the carrier changes with the change of the binary signal.

[0005] Using the tag based on backscatter as a sensor node can eliminate the need for batteries. It is a solution for sensor nodes in wireless sensor networks that is easy to maintain and has good environmental compatibility. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a low-power, shared-antenna and battery-free tag-end device suitable for being used as a sensor node and based on backscatter.

[0007] The technical solution adopted by the present invention to solve the above technical problems is to include an antenna, a power splitter, an energy acquisition unit, an energy management unit, a switching unit, a wake-up unit, a sensor, a communication unit and a control unit; the communication unit includes a backscatter signal modulation unit and a downlink signal demodulation unit;

[0008] The antenna is connected to the input end of the energy acquisition unit and the switching unit through a power divider; the switching unit is used to switch the connection between the input end of the wake-up unit, the backscatter signal modulation unit and the input end of the downlink signal demodulation unit; the control unit is respectively connected to the output end of the wake-up unit, the output end of the sensor, the modulation signal input end of the backscatter signal modulation unit of the communication unit and the output end of the downlink signal demodulation unit; the energy management unit supplies power to the communication unit, the wake-up unit, the sensor and the control unit;

[0009] The initial state of the tag end device defaults to the waiting state; when the tag end device works in the waiting state, the energy management unit only supplies power to the wake-up unit and the control unit, the control unit controls the switching unit to connect the antenna and the wake-up unit, and the control unit is in a dormant state; when the wake-up unit receives a wake-up signal from the antenna, the wake-up unit sends a pulse signal to the control unit, and the control unit controls the tag end device to enter a receiving state;

[0010] When the tag-end device is working in the receiving state, the energy management unit supplies power to the control unit and the downlink signal demodulation unit, the control unit controls the switching unit to connect the antenna and the downlink signal demodulation unit, and the control unit works in a low-power operation state; the downlink signal demodulation unit demodulates the radio frequency signal from the antenna and outputs the demodulated signal to the control unit for decoding; after the control unit completes decoding, the control unit controls the tag-end device to enter the backscattering state;

[0011] When the tag-end device works in the backscattering state, the energy management unit supplies power to the control unit, the sensor and the backscattering signal modulation unit, the control unit controls the switching unit to connect the antenna and the backscattering signal modulation unit, the sensor transmits the collected information to the control unit, the control unit processes the collected information into a modulation signal and outputs it to the modulation signal input end of the backscattering signal modulation unit, the backscattering signal modulation unit receives the carrier from the antenna and the modulation signal from the control unit, generates a modulated signal after modulation, and outputs it to the antenna to complete backscattering; after the backscattering is completed, the control unit controls the tag-end device to enter the wake-up state.

[0012] Today's low-power sensor technology effectively reduces the power consumption of sensor nodes in short-distance wireless communications, making it feasible to collect environmental energy around sensor nodes and convert it into electrical energy to power the nodes. Passive wireless communication systems use RF signals in the environment as energy sources and use environmental backscatter technology to achieve wireless communication between passive devices, getting rid of the sensor nodes' dependence on batteries. This power solution that does not require external power input effectively reduces the operating and maintenance costs of sensors and extends the life of sensor nodes.

[0013] Furthermore, for the tag end device of the 2ASK modulation signal, in order to improve the high sensitivity reception of the tag end device and avoid the backscattering self-interference problem, the present invention also provides an active frequency shifting backscattering 2ASK modulation unit as a backscattering signal modulation unit.

[0014] In addition to outputting the 2ASK modulation signal, the control unit is also used to output a frequency shift signal. The control unit includes a first control signal output terminal and a second control signal output terminal; the control unit outputs the 2ASK modulation signal through the first control signal output terminal and outputs the frequency shift signal through the second control signal output terminal.

[0015] The specific structure of the backscatter signal modulation unit is as follows: it includes a signal directional transmission isolation module and a switch amplification modulation circuit; the antenna is connected to the signal directional transmission isolation module through a power divider; the switch amplification modulation circuit includes a circuit switching unit, a carrier signal input terminal, a modulation signal input terminal, a modulated signal input terminal, a frequency shift signal input terminal, a non-output reflection signal terminal, a filtering amplification unit and a backscatter signal output terminal;

[0016] The 2ASK modulation signal is output to the modulation signal input terminal of the line switching unit through the first control signal output terminal of the control unit, and the frequency shift signal is output to the frequency shift signal input terminal of the line switching unit through the second control signal output terminal of the control unit;

[0017] The antenna is connected to the carrier signal input terminal and the backscatter signal output terminal through the signal directional transmission isolation module, the modulation signal input terminal is connected to the modulated signal input terminal, the frequency shift signal input terminal is connected to the input terminal of the filter amplifier unit, and the output terminal of the filter amplifier unit is connected to the backscatter signal output terminal; the line switching unit controls the carrier signal input terminal to be connected to the modulation signal input terminal or to the non-output reflection signal terminal, and controls the modulated signal input terminal to be connected to the frequency shift signal input terminal or to the non-output reflection signal terminal.

[0018] The working principle of the backscatter signal modulation unit is:

[0019] When the 2ASK modulation signal is 1, the line switching unit controls the carrier signal input terminal to be connected to the modulation signal input terminal, controls the modulated signal input terminal to be connected to the frequency shift signal input terminal, and the carrier from the antenna and the 2ASK modulation signal from the control unit are modulated to generate a 2ASK modulated signal to the modulated signal input terminal. The 2ASK modulated signal is frequency shifted by the frequency shift signal from the control unit, and then passes through the filtering and amplifying unit to form a frequency shifted backscattered 2ASK modulated signal to the backscattered signal output terminal, and finally radiates to space through the antenna;

[0020] When the 2ASK modulation signal is 0, the line switching unit controls the carrier signal input terminal and the modulated signal input terminal to be connected to the no-output reflected signal terminal.

[0021] The beneficial effects of the present invention are that a battery-free design is realized, and the radio frequency power acquisition and communication share the same antenna, and ultra-low power consumption operation of the device is achieved through a high-sensitivity wake-up unit. It has the advantages of easy maintenance, good environmental compatibility, long service life, and stability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a block diagram of the module composition of the tag device of the embodiment;

[0023] Figure 2 It is a flowchart of the energy management unit working process of the embodiment;

[0024] Figure 3 The wake-up unit of the embodiment receives a signal waveform;

[0025] Figure 4 The signal waveform after envelope detection of the wake-up unit in the embodiment;

[0026] Figure 5 A pulse signal generated by the wake-up device of the embodiment;

[0027] Figure 6 Schematic diagram of an active frequency shifting Backscatter 2ASK modulation unit according to an embodiment;

[0028] Figure 7 The backscatter modulation signal waveform of the communication unit of the embodiment;

[0029] Figure 8 The figure is a spectrum diagram of the backscattered modulation signal of the communication unit according to the embodiment. Specific implementation methods

[0031] The ultra-low power consumption radio frequency energy acquisition tag device described in the embodiment is shown in the figure, including 1 antenna, 1 energy acquisition unit, 1 switching unit, 1 energy management unit, 1 wake-up unit, 1 sensor, 1 communication unit, and 1 control unit. The communication unit includes a backscatter signal modulation unit and a downlink signal demodulation unit.

[0032] The switching unit is used to switch the connection between the input end of the wake-up unit, the backscatter signal modulation unit, and the input end of the downlink signal demodulation unit. The switching unit consists of a single-pole double-throw switch 1 and a single-pole double-throw switch 2. The single-pole double-throw switch 1 consists of three ports, namely, a fixed end RFc1 and two movable ports RFs11 and RFs12; the single-pole double-throw switch 2 consists of three ports, namely, a movable end RFc2 and two fixed ends RFs21 and RFs22.

[0033] The antenna is connected to the RFc1 end of the single-pole double-throw switch 1 through a power divider, the RFs12 end is connected to the backscatter signal modulation unit of the communication unit, and the RFs11 end is connected to the RFc2 end of the single-pole double-throw switch 2; among the two fixed ports of the single-pole double-throw switch 2, the RFs22 end is connected to the input end of the downlink signal demodulation unit, and the RFs21 end is connected to the input end of the wake-up unit.

[0034] The control unit is respectively connected to the output end of the wake-up unit, the output end of the sensor, the modulation signal input end of the backscatter signal modulation unit of the communication unit, and the output end of the downlink signal demodulation unit; the energy management unit supplies power to the communication unit, the wake-up unit, the sensor and the control unit.

[0035] The energy acquisition unit includes a matching network and a rectifier-boost circuit. When the rectifier-boost circuit matches the antenna, the reflection of the incident power of the antenna RF signal will be reduced, thereby reducing losses and making better use of RF energy. The rectifier-boost circuit can convert AC RF signals into DC power and increase the voltage. Since the RF energy collection module collects very limited energy from environmental electromagnetic waves, it is generally impossible to make ordinary diodes conduct. Therefore, a Schottky diode with a lower voltage threshold and lower junction capacitance than a PN diode is selected in the rectifier circuit of the device. This allows the rectifier circuit to have a larger frequency operating range and can operate effectively at low power.

[0036] The energy management unit includes a power management chip and a supercapacitor. The electric energy from the energy acquisition unit is boosted and output by the power management chip. When the voltage reaches the set value, it is input into the supercapacitor for energy storage. When the device is working in different states, the energy management unit supplies different power to different parts of the device. Figure 2 It is a flowchart of the working process of the energy management unit; the initial state of the device defaults to the waiting state, at which time the energy management unit only supplies power to the wake-up unit and the control unit MCU, and the MCU is in the sleep state; when the device wake-up unit receives the wake-up signal from the antenna, the wake-up unit sends a pulse signal to the MCU, and the MCU enters the low-power operation state, and the MCU controls the switching of the single-pole double-throw switch. At this time, the device enters the receiving state, and the energy management unit supplies power to the MCU and the downlink signal receiving channel of the communication unit; when the device receives the broadcast signal, the MCU controls the switching of the single-pole double-throw switch, and the device enters the backscattering state, and the energy management unit supplies power to the sensor, MCU and the backscattering channel of the communication unit.

[0037] The wake-up unit includes envelope detection and wake-up device. The wake-up device selected by the device works in monitoring mode. Only the amplifier and clock generator are working inside. When a low-frequency carrier signal with a frequency of 15-150kHz is detected, a pulse signal is output and sent to the control unit MCU for wake-up. Because the required wake-up signal frequency is low, the wake-up device has nW-level ultra-low power consumption. However, due to the common antenna design, the antenna is applicable to a higher frequency band and cannot receive low-frequency carrier signals. Therefore, envelope detection is added before the wake-up device in the wake-up unit. When the antenna receives the ASK signal, the signal is detected by envelope detection to obtain a low-frequency carrier to wake up the wake-up device.

[0038] The communication unit includes a backscatter modulation signal transmission channel and a downlink signal receiving channel. The MCU of the control unit sends the sensor information outward through the backscatter modulation signal transmission channel and the antenna; the downlink signal receiving channel includes an amplifier, matching, envelope detection and comparator, which is used to receive instructions from other devices to this device.

[0039] The RF signal passes through the antenna and then the power divider, and then enters the energy acquisition unit. After passing through the matching network, it enters the rectifier and boost circuit, and is converted into usable DC power before entering the energy management unit, thereby completing the RF energy acquisition and supplying power to each active device in the device.

[0040] The control unit provides control signals to the single-pole double-throw switch 1 and the single-pole double-throw switch 2 at the same time, thereby switching the working state of the device.

[0041] The initial state of the tag end device defaults to the waiting state; when the tag end device works in the waiting state, the energy management unit only supplies power to the wake-up unit and the control unit, the control unit controls the switching unit to connect the antenna and the wake-up unit, and the control unit is in a dormant state; when the wake-up unit receives a wake-up signal from the antenna, the wake-up unit sends a pulse signal to the control unit, and the control unit controls the tag end device to enter a receiving state;

[0042] When the tag-end device is working in the receiving state, the energy management unit supplies power to the control unit and the downlink signal demodulation unit, the control unit controls the switching unit to connect the antenna and the downlink signal demodulation unit, that is, the antenna is connected to the receiving channel, and the control unit works in a low-power operation state; the downlink signal demodulation unit demodulates the radio frequency signal from the antenna, and outputs the demodulated signal to the control unit for decoding; after the control unit completes decoding, the control unit controls the tag-end device to enter the backscattering state;

[0043] When the tag-end device works in the backscattering state, the energy management unit supplies power to the control unit, the sensor and the backscattering signal modulation unit. The control unit controls the switching unit to connect the antenna and the backscattering signal modulation unit, that is, the antenna is connected to the reverse dispersion transmission channel. The sensor transmits the collected information to the control unit. The control unit processes the collected information into a modulation signal and outputs it to the modulation signal input end of the backscattering signal modulation unit. The backscattering signal modulation unit receives the carrier from the antenna and the modulation signal from the control unit, modulates them, generates a modulated signal, and outputs it to the antenna to complete backscattering. After the backscattering is completed, the control unit controls the tag-end device to enter the wake-up state.

[0044] The specific steps of using the present invention to communicate are described below:

[0045] Step 1

[0046] The antenna continuously receives radio frequency signals in the environment. The signal passes through the power divider and enters the energy acquisition unit for radio frequency energy acquisition. After the signal is rectified into direct current, it is boosted by the power management chip and stored in the capacitor to power the device.

[0047] Step 2

[0048] Assume that the control signal of the control unit

[0049]

[0050] The default control signal c(t)=00, at this time, the default working state of the device is the waiting state, at this time, the RFc1 port of the single-pole double-throw switch 1 is connected to the RFc2 port of the single-pole double-throw switch 2, and the RFc2 port of the single-pole double-throw switch 2 is connected to the RFs21 port, which is connected to the input end of the wake-up unit. At this time, the energy management unit only supplies power to the wake-up unit and the control unit MCU.

[0051] Step 3

[0052] When the antenna receives the ASK signal, the signal enters the wake-up unit through the other path of the power divider. Figure 3 The wake-up unit of the present invention receives a signal waveform, Figure 4 The low-frequency sine wave with a frequency of 30kHz is obtained by envelope detection of the wake-up unit. The low-frequency sine wave enters the input end of the wake-up device, and the wake-up device will generate the following Figure 5 The pulse signal shown is sent to the MCU, waking the MCU from the sleep state and entering the low-power operation state.

[0053] To ensure that the wake-up unit of the device has a large dynamic range, the receiving sensitivity of the wake-up unit is tested. The receiving sensitivity refers to the minimum input power of the receiver under the minimum signal-to-noise ratio required by the demodulator front end of a given receiver. The calculation formula is as follows, where NF is the noise factor, B is the signal bandwidth, and SNR is out,min The minimum signal-to-noise ratio required by the demodulator front end.

[0054] P in,min (dBm)=-174(dBm / Hz)+NF(dB)+10logB+SNR out,min (dB)

[0055] When measuring the sensitivity of the wake-up unit, reduce the signal power input to the antenna port until the wake-up device can no longer send a wake-up signal to the MCU. At this time, the input signal to the antenna port is the sensitivity of the wake-up unit. After testing, the receiving sensitivity of the wake-up unit of the device is -54dBm.

[0056] Step 4

[0057] After the MCU enters the low-power operation state, the control signal c(t) = 01, controlling the RFc2 port of the single-pole double-throw switch 2 to be connected to the RFs22 port. At this time, the antenna is connected to the downlink signal receiving channel of the communication unit, the device enters the receiving state, and the energy management unit supplies power to the MCU and the downlink signal receiving channel of the communication unit.

[0058] When the antenna receives the ASK modulated broadcast signal, the signal is amplified, matched, envelope detected and compared in the receiving channel, and then demodulated to obtain a low-frequency square wave that enters the MCU for decoding.

[0059] Test the sensitivity of the device's downlink signal receiving channel. When measuring the sensitivity of the communication unit's receiving channel, reduce the signal power input to the antenna port until the MCU cannot demodulate the received broadcast signal. At this time, the input signal to the antenna port is the sensitivity of the communication unit's downlink signal receiving channel; after testing, the receiving sensitivity of the device's communication unit's receiving channel is -44dBm.

[0060] Step 4

[0061] After decoding is completed, the control signal c(t) = 1x, the MCU controls the RFc1 port of the single-pole double-throw switch 1 to be connected to the RFs12 port, and then connected to the backscattering output end of the communication unit. At this time, the device enters the backscattering state, and the energy management unit supplies power to the sensor, MCU and the backscattering channel of the communication unit.

[0062] The sensor starts working and transmits the collected information to the MCU through the I2C protocol. The MCU encodes the sensor information and sends it to the communication unit. At this time, the device receives the carrier. The MCU controls the two RF switches on the backscatter channel to modulate the sensor information to obtain the ASK signal, and sends it to the antenna to backscatter the sensor information outward.

[0063] In order to overcome the backscatter self-interference problem, a backscatter 2ASK modulation unit is provided as a backscatter modulation unit for realizing high-sensitivity reception of a common antenna by frequency shifting. Figure 6 shown.

[0064] like Figure 6 As shown, the active Backscatter 2ASK modulation device includes a common antenna for transmission and reception, a three-port circulator as a signal directional transmission isolation module, and a switch amplification modulation line; the switch amplification modulation line includes a circuit switching unit composed of a single-pole double-throw switch a and a single-pole double-throw switch b, a non-output reflection signal terminal, and a filter amplification unit composed of a low-power amplifier 1, a filter and a low-power amplifier 2 connected in sequence. The non-output reflection signal terminal is two matching loads. The switch amplification modulation line also includes a carrier signal input terminal, a modulation signal input terminal, a modulated signal input terminal, a frequency shift signal input terminal, and a backscatter signal output terminal. The circuit switching unit receives two different control signals from the control module to realize the separate control of the single-pole double-throw switch a and the single-pole double-throw switch b, thereby realizing the modulation and frequency shift of the signal.

[0065] The control module generates two control signals and outputs them to the backscatter modulation unit, control signal 1 and control signal 2. Control signal 1 is a user modulation signal, i.e., a 2ASK modulation signal, which is used to control single-pole double-throw switch a to realize the ASK modulation function. Control signal 2 is a square wave signal of a certain frequency, i.e., a frequency shift signal, which is used to control single-pole double-throw switch b to realize frequency shifting. The control signal 1 output terminal of the control module is output to the modulation signal input terminal of the line switching unit, and the control signal output terminal 2 is output to the frequency shift signal input terminal of the line switching unit. The switch amplification modulation circuit is used to receive the control signal provided by the control module to modulate the carrier, shift the frequency, and then perform power amplification.

[0066] The antenna is connected to the antenna through port 1 of a three-port circulator, port 2 of the circulator is connected to the carrier signal input end of the switch amplification modulation circuit, and port 3 of the circulator is connected to the backscatter signal output end.

[0067] The single-pole double-throw switch a and b are composed of three ports, namely, a fixed port and two movable ports, and the two ports are respectively a first movable port and a second movable port. The fixed port of the single-pole double-throw switch a is a carrier signal input port, the first movable port of the single-pole double-throw switch a is a modulation signal input port, the second movable port is connected to a non-output reflection signal terminal, and the single-pole double-throw switch a controls the carrier signal input port to be connected to the modulation signal input port or to the non-output reflection signal terminal; the first movable port of the single-pole double-throw switch a is connected to the fixed port of the single-pole double-throw switch b; the fixed port of the single-pole double-throw switch b is a modulated signal input port, the first movable port of the single-pole double-throw switch b is a frequency shift signal input port, the second movable port is connected to a non-output reflection signal terminal, and the single-pole double-throw switch b controls the modulated signal input port to be connected to the frequency shift signal input port or to the non-output reflection signal terminal. The second moving end of the single-pole double-throw switch b is connected to the input end of the low-power amplifier 1, the output end of the low-power amplifier 1 is connected to the input end of the filter, the output end of the filter is connected to the input end of the low-power amplifier 2, and the output end of the low-power amplifier 2 is connected to the backscatter signal output end.

[0068] When the 2ASK modulation signal is 1, the fixed end of the single-pole double-throw switch a is connected to the first moving end, and the fixed port of the single-pole double-throw switch b is connected to its first moving end. The carrier from the antenna and the 2ASK modulation signal from the control module are modulated to generate a 2ASK modulated signal to the modulated signal input end. The 2ASK modulated signal is frequency shifted by the frequency shift signal from the control module, and then filtered and amplified by two low-power amplifiers and filters in the on state to form a frequency-shifted backscattered 2ASK modulated signal to the backscattered signal output end, and finally radiated into space through the antenna.

[0069] When the 2ASK modulation signal is 0, the fixed end of the single-pole double-throw switch a is connected to its second moving end, the fixed end of the single-pole double-throw switch b is connected to its second moving end, the second moving ends of the single-pole double-throw switches a and b are respectively connected to matching loads, the low-power amplifier is in the disconnected state, the carrier signal received by the antenna is absorbed by the matching load, and the antenna has no signal output.

[0070] The control unit of the tag device of the embodiment outputs a control signal 1 to change the state of the single-pole double-throw switch a in the backscatter modulation unit, thereby effectively realizing the modulation of the 2ASK signal; the control unit outputs a control signal 2 to change the state of the single-pole double-throw switch b in the device, thereby effectively realizing the frequency shift of the 2ASK signal, and filtering out some of the other useless frequency components introduced when the single-pole double-throw switches a and b are switched through a filter, thereby ensuring that the frequency output by the switch amplification modulation module is clean; a low-power amplifier module is added, on the one hand, to compensate for the loss introduced by the switch switching modulation process and the filter, and on the other hand, to isolate the signal transmitted in the reverse direction of the circulator to prevent it from entering the switch to participate in the modulation and introducing other useless frequency components.

[0071] Assume that the carrier signal (taking a single tone as an example) received by the antenna is A0cos(2πf c t+θ). The frequency shift signal is of frequency f c2 The square wave transmitted by the antenna s(t) can be expressed as:

[0072] s(t)=A·c1(t)·cos(2π(f c t±f c2 )t+θ+ξ)

[0073] Where A is the amplitude of the transmitted signal, which is related to the amplitude of the control signal, the circulator loss and other actual circuit losses, and ξ is the phase change caused by reflection and circuit transmission. From the expression, it can be seen that the transmitted signal is a 2ASK signal modulated by the control signal, and the envelope characteristics of the modulated signal are consistent with the modulation waveform input by the control module.

[0074] The time domain waveform of the backscattered modulation signal of the communication unit is as follows: Figure 7 shown. Figure 8 This is the spectrum diagram of the backscatter modulation signal, where the 468MHz signal is the carrier and the 473MHz signal is the backscatter signal generated by the device.

[0075] The device described in the present invention has high sensitivity and can work without batteries, realizes radio frequency power acquisition and communication through a common antenna, and gets rid of the dependence of sensor nodes on batteries.

Claims

1. A battery-free ultra-low power consumption RF energy-taking shared antenna tag end device, characterized in that: It includes an antenna, a power splitter, an energy acquisition unit, an energy management unit, a switching unit, a wake-up unit, a sensor, a communication unit and a control unit; the communication unit includes a backscatter signal modulation unit and a downlink signal demodulation unit; The antenna is connected to the input end of the energy acquisition unit and the switching unit through a power divider; the switching unit is used to switch the connection between the input end of the wake-up unit, the backscatter signal modulation unit and the input end of the downlink signal demodulation unit; the control unit is respectively connected to the output end of the wake-up unit, the output end of the sensor, the modulation signal input end of the backscatter signal modulation unit of the communication unit and the output end of the downlink signal demodulation unit; the energy management unit is used to power the communication unit, the wake-up unit, the sensor and the control unit; The initial state of the tag end device is the waiting state for awakening; when the tag end device is working in the waiting state for awakening, the energy management unit only supplies power to the awakening unit and the control unit, the control unit controls the switching unit to connect the antenna and the awakening unit, and the control unit is in a dormant state; when the awakening unit receives the awakening signal from the antenna, the awakening unit sends a pulse signal to the control unit, and the control unit controls the tag end device to enter the receiving state; When the tag-end device is working in the receiving state, the energy management unit supplies power to the control unit and the downlink signal demodulation unit, the control unit controls the switching unit to connect the antenna and the downlink signal demodulation unit, and the control unit works in a low-power operation state; the downlink signal demodulation unit demodulates the radio frequency signal from the antenna and outputs the demodulated signal to the control unit for decoding; After the control unit completes decoding, the control unit controls the tag end device to enter a backscattering state; When the tag-end device works in the backscattering state, the energy management unit supplies power to the control unit, the sensor and the backscattering signal modulation unit, the control unit controls the switching unit to connect the antenna and the backscattering signal modulation unit, the sensor transmits the collected information to the control unit, the control unit processes the collected information into a modulation signal and outputs it to the modulation signal input end of the backscattering signal modulation unit, the backscattering signal modulation unit receives the carrier from the antenna and the modulation signal from the control unit, modulates them, generates a modulated signal, and outputs it to the antenna to complete backscattering; After the backscattering is completed, the control unit controls the tag end device to enter the wake-up state.

2. The label end device according to claim 1, characterized in that: The wake-up signal is a 2ASK signal; the modulation signal output by the control unit is a 2ASK modulation signal.

3. The label end device as claimed in claim 2, characterized in that: The control unit is also used to output a frequency shift signal; the control unit includes a first control signal output terminal and a second control signal output terminal; the control unit outputs a 2ASK modulated signal through the first control signal output terminal and outputs a frequency shift signal through the second control signal output terminal; The backscatter signal modulation unit includes a signal directional transmission isolation module and a switch amplification modulation circuit; the antenna is connected to the signal directional transmission isolation module through a power divider; the switch amplification modulation circuit includes a circuit switching unit, a carrier signal input terminal, a modulation signal input terminal, a modulated signal input terminal, a frequency shift signal input terminal, a non-output reflection signal terminal, a filtering amplification unit and a backscatter signal output terminal; The first control signal output terminal of the control unit outputs a 2ASK modulation signal to the modulation signal input terminal of the line switching unit, and the second control signal output terminal outputs a frequency shift signal to the frequency shift signal input terminal of the line switching unit; The antenna is connected to the carrier signal input terminal and the backscatter signal output terminal through the signal directional transmission isolation module, the modulation signal input terminal is connected to the modulated signal input terminal, the frequency shift signal input terminal is connected to the input terminal of the filter amplifier unit, and the output terminal of the filter amplifier unit is connected to the backscatter signal output terminal; the line switching unit controls the carrier signal input terminal to be connected to the modulation signal input terminal or to the non-output reflection signal terminal, and controls the modulated signal input terminal to be connected to the frequency shift signal input terminal or to the non-output reflection signal terminal.

4. The label end device as claimed in claim 3, characterized in that: When the 2ASK modulation signal is 1, the line switching unit controls the carrier signal input terminal to be connected to the modulation signal input terminal, controls the modulated signal input terminal to be connected to the frequency shift signal input terminal, and the carrier from the antenna and the 2ASK modulation signal from the control unit are modulated to generate a 2ASK modulated signal to the modulated signal input terminal. The 2ASK modulated signal is frequency shifted by the frequency shift signal from the control unit, and then passes through the filtering and amplifying unit to form a frequency shifted backscattered 2ASK modulated signal to the backscattered signal output terminal, and finally radiates to space through the antenna; When the 2ASK modulation signal is 0, the line switching unit controls the carrier signal input terminal and the modulated signal input terminal to be connected to the no-output reflected signal terminal.

5. The label end device according to claim 1, characterized in that: The downlink signal demodulation unit completes demodulation by amplifying, matching, envelope detecting and comparing the input RF signal.

6. The label end device according to claim 1, characterized in that: The switching unit consists of a first single-pole double-throw switch and a second single-pole double-throw switch; the fixed end of the first single-pole double-throw switch is connected to the power divider, one moving end of the first single-pole double-throw switch is connected to the fixed end of the second single-pole double-throw switch, and the other moving end is connected to the modulation signal input end of the backscatter signal modulation unit; one moving end of the second single-pole double-throw switch is connected to the wake-up unit, and the other moving end is connected to the input end of the downlink signal demodulation unit.

7. The label end device according to claim 1, characterized in that: The energy acquisition unit includes a matching network and a rectifier-boost circuit; the antenna is connected to the rectifier-boost circuit through the matching network; the rectifier-boost circuit converts the radio frequency signal into direct current and increases the voltage, and a Schottky diode is selected for use in the rectifier module.

8. The label end device according to claim 1, characterized in that: The energy management unit includes a power management chip and a supercapacitor. The antenna is connected to the supercapacitor through the power management chip. The electric energy from the energy acquisition unit is boosted and output by the power management chip. When the voltage reaches the set value, it is input into the supercapacitor for energy storage.

9. The label end device according to claim 1, characterized in that: The wake-up unit includes an envelope detection module and a wake-up device; the switching unit is connected to the wake-up device through the envelope detection module; the wake-up device works in the monitoring mode, and envelope detection is added before the wake-up device; when the antenna receives the carrier signal, the carrier signal is processed into a low-frequency carrier after envelope detection and output to the wake-up device for wake-up.

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