Wireless passive temperature measurement system based on MEMS resonator and temperature measurement method thereof

Abstract

The invention provides a wireless passive temperature measurement system based on an MEMS resonator and a temperature measurement method thereof, and the system comprises an MEMS oscillator which is composed of the MEMS resonator and a corresponding interface circuit and is used for generating a reference frequency signal; the phase-locked loop is used for generating a high-frequency signal; the passive frequency multiplier is used for carrying out frequency multiplication on the high frequency output by the phase-locked loop; the coupler is used for dividing the frequency-doubled high-frequency signal into two paths of harmonic signals; the adjustable filter is used for selecting a target harmonic signal; the dual-polarized antenna is used for sending the target harmonic signal to a terminal and receiving an electromagnetic wave signal transmitted by the terminal; the rectifier module is used for converting the electromagnetic wave signal and the harmonic signal reflected by the coupler into direct current; and the energy management module is used for carrying out storage and voltage stabilization output on the direct current so as to supply energy to the MEMS oscillator and the phase-locked loop. According to the invention, long-distance transmission of passive wireless temperature detection can be realized, and the measurement precision and resolution are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature monitoring, and in particular relates to a wireless passive temperature measurement system based on a MEMS resonator. Background Art

[0002] With the development of industrial automation and intelligence, real-time monitoring of equipment operating status has become particularly important. As one of the important indicators of equipment operating status, accurate measurement of temperature is of great significance for preventing equipment failure and ensuring production safety. Although traditional temperature measurement methods, such as thermocouples and thermistors, are widely used, their application is limited in some special environments, such as high temperature, high pressure, corrosive environments, or for equipment that is difficult to access.

[0003] In recent years, wireless passive temperature measurement technology has gradually become a research hotspot in the field of temperature monitoring due to its advantages such as easy installation, low maintenance cost, and no environmental restrictions. Wireless passive temperature measurement technology uses wireless signals to transmit temperature information and does not require external power supply. It is suitable for a variety of application scenarios, such as manufacturing, logistics and warehousing, and power systems.

[0004] As a new type of sensor technology, MEMS (micro-electromechanical system) resonator has great application potential in wireless passive temperature measurement systems due to its advantages of small size, light weight, high integration and low cost. MEMS resonator senses temperature changes by detecting changes in resonant frequency and has the characteristics of wide temperature coverage, high Q value, high sensitivity, high linearity and high resolution.

[0005] However, the existing wireless passive temperature measurement system based on MEMS resonators still has some technical problems: the traditional circuit design based on MEMS resonators consumes a lot of power and is difficult to achieve long-distance wireless transmission, which limits its application in the field of remote monitoring; in passive systems, it is difficult to effectively isolate energy collection and energy transmission circuits to avoid mutual interference. Under low power consumption conditions, it is difficult to achieve long-distance transmission of passive wireless temperature detection while ensuring measurement accuracy and resolution. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a wireless passive temperature measurement system based on a MEMS resonator and a temperature measurement method thereof.

[0007] In a first aspect, the present invention provides a wireless passive temperature measurement system based on a MEMS resonator, including a MEMS oscillator formed with a MEMS resonator and a corresponding interface circuit, for generating a reference frequency signal;

[0008] A phase-locked loop, electrically connected to an output end of the MEMS oscillator, for generating a high-frequency signal;

[0009] A passive frequency multiplier, electrically connected to the output end of the phase-locked loop, for multiplying the high frequency output by the phase-locked loop;

[0010] A coupler, electrically connected to the output end of the passive frequency multiplier, for dividing the frequency-multiplied high-frequency signal into two harmonic signals;

[0011] an adjustable filter, electrically connected to the output end of the coupler, for selecting a target harmonic signal;

[0012] A dual-polarized antenna, electrically connected to an output end of the tunable filter, for sending a target harmonic signal to a terminal and receiving an electromagnetic wave signal emitted by the terminal;

[0013] A rectifier module, electrically connected to the dual-polarized antenna and the coupler, respectively, for converting the electromagnetic wave signal and the harmonic signal reflected by the coupler into direct current;

[0014] The energy management module is electrically connected to the phase-locked loop and the MEMS resonator, and is used for storing and outputting DC power in a regulated voltage, so as to supply energy to the MEMS oscillator and the phase-locked loop.

[0015] Optionally, the temperature resolution △T after frequency doubling is:

[0016]

[0017] Among them, △f is the frequency measurement resolution; N is the frequency multiplication factor; f1 is the reference frequency of the MEMS resonator; TCF is the temperature coefficient of the MEMS resonator.

[0018] Optionally, the antenna of the terminal is a dual-polarized antenna, and the dual-polarized antenna on the terminal side and the dual-polarized antenna on the MEMS resonator side are in a ±45° polarization form.

[0019] Optionally, the operating bandwidth of the dual-polarized antenna satisfies the frequency offset within a temperature variation range, and the operating bandwidth of the dual-polarized antenna is greater than or equal to the frequency offset after frequency multiplication.

[0020] Optionally, the frequency offset f3 after frequency multiplication is calculated according to the following formula:

[0021] f3 = N × f1 × TCF × (T2 - T1);

[0022] Wherein, N is the frequency multiplication factor; f1 is the reference frequency of the MEMS resonator; TCF is the temperature coefficient of the MEMS resonator; T1 is the minimum value of the measured temperature; and T2 is the maximum value of the measured temperature.

[0023] Optionally, the terminal includes a bandpass filter, a low-noise amplifier and a spectrum detection circuit; the transmission signal of the dual-polarized antenna on the MEMS resonator side is received by the dual-polarized antenna on the terminal side, and is transmitted to the spectrum detection circuit via the bandpass filter and the low-noise amplifier. The spectrum detection circuit detects the maximum power value and the corresponding frequency of the spectrum under the current working bandwidth, and determines the current test temperature based on the correlation between frequency and temperature.

[0024] Optionally, the output of the passive frequency multiplier includes multiple harmonics, and the adjustable filter is used to select harmonic components of the target output power to characterize the temperature information.

[0025] In a second aspect, the present invention provides a temperature measurement method of a wireless passive temperature measurement system based on a MEMS resonator as described in the first aspect, comprising:

[0026] Using a dual-polarized antenna to receive electromagnetic wave signals transmitted by the terminal;

[0027] The rectifier module is used to convert the received electromagnetic wave signal into direct current to supply power to the MEMS oscillator and phase-locked loop;

[0028] A reference frequency signal is generated by using a MEMS oscillator, and the frequency is multiplied by a phase-locked loop and a passive frequency multiplier;

[0029] The target harmonic signal in the frequency-multiplied high-frequency signal is selected by using an adjustable filter, and is sent to the terminal through a dual-polarized antenna;

[0030] The target harmonic signal is received by the terminal, and the current test temperature is determined according to the correlation between the frequency corresponding to the target harmonic signal and the temperature.

[0031] The invention provides a wireless passive temperature measurement system based on a MEMS resonator and a temperature measurement method thereof, wherein the system comprises a MEMS oscillator formed with a MEMS resonator and a corresponding interface circuit, and is used to generate a reference frequency signal; a phase-locked loop, electrically connected to the output end of the MEMS oscillator, and is used to generate a high-frequency signal; a passive frequency multiplier, electrically connected to the output end of the phase-locked loop, and is used to multiply the high-frequency frequency output by the phase-locked loop; a coupler, electrically connected to the output end of the passive frequency multiplier, and is used to divide the multiplied high-frequency signal into two harmonic signals; an adjustable filter, electrically connected to the output end of the coupler, and is used to select a target harmonic signal; a dual-polarized antenna, electrically connected to the output end of the adjustable filter, and is used to send the target harmonic signal to a terminal and receive an electromagnetic wave signal emitted by the terminal; a rectifier module, electrically connected to the dual-polarized antenna and the coupler, respectively, and is used to convert the electromagnetic wave signal and the harmonic signal reflected by the coupler into direct current; and an energy management module, electrically connected to the phase-locked loop and the MEMS resonator, respectively, and is used to store and output the direct current in a regulated voltage, so as to supply energy to the MEMS oscillator and the phase-locked loop. The present invention can realize long-distance wireless transmission and effectively isolate energy collection and energy transmission circuits to avoid mutual interference. Under the condition of low power consumption, the long-distance transmission of passive wireless temperature detection is realized while ensuring the measurement accuracy and resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 A schematic diagram of the structure of a wireless passive temperature measurement system based on a MEMS resonator provided in an embodiment of the present invention;

[0034] Figure 2 A spectrum diagram of a frequency doubling circuit constructed based on a MEMS resonator provided in an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of an electromagnetic energy collection circuit provided by an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of signal link isolation based on dual-polarization transceiver provided in an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of a signal link of a frequency multiplication circuit using specific devices provided in an embodiment of the present invention;

[0038] Figure 6A test spectrum diagram of an oscillator provided in an embodiment of the present invention;

[0039] Figure 7 A test spectrum diagram of a phase-locked loop provided in an embodiment of the present invention;

[0040] Figure 8 A test spectrum diagram of a passive frequency multiplier provided by an embodiment of the present invention;

[0041] Fig. 9 A schematic flow chart of a temperature measurement method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] like Figure 1 As shown, this embodiment provides a wireless passive temperature measurement system based on a MEMS resonator, comprising:

[0045] A MEMS oscillator formed with a MEMS resonator and a corresponding interface circuit is used to generate a reference frequency signal;

[0046] A phase-locked loop, electrically connected to an output end of the MEMS oscillator, for generating a high-frequency signal;

[0047] A passive frequency multiplier, electrically connected to the output end of the phase-locked loop, for multiplying the high frequency output by the phase-locked loop;

[0048] A coupler, electrically connected to the output end of the passive frequency multiplier, for dividing the frequency-multiplied high-frequency signal into two harmonic signals;

[0049] an adjustable filter, electrically connected to the output end of the coupler, for selecting a target harmonic signal;

[0050] A dual-polarized antenna, electrically connected to an output end of the tunable filter, for sending a target harmonic signal to a terminal and receiving an electromagnetic wave signal emitted by the terminal;

[0051] A rectifier module, electrically connected to the dual-polarized antenna and the coupler, respectively, for converting the electromagnetic wave signal and the harmonic signal reflected by the coupler into direct current;

[0052] The energy management module is electrically connected to the phase-locked loop and the MEMS resonator, and is used for storing and outputting DC power in a regulated voltage, so as to supply energy to the MEMS oscillator and the phase-locked loop.

[0053] For a temperature sensor based on a MEMS resonator, its resolution can be calculated by the temperature coefficient of frequency (TCF, in ppm / °C) of the resonator.

[0054] In order to effectively improve the resolution of temperature measurement, the reference frequency can be multiplied to a high frequency through devices such as a phase-locked loop and a passive frequency multiplier. The temperature resolution △T after multiplication can be expressed as:

[0055]

[0056] Among them, △f is the frequency measurement resolution; N is the frequency multiplication factor; f1 is the reference frequency of the MEMS resonator; TCF is the temperature coefficient of the MEMS resonator.

[0057] like Figure 1 As shown, the oscillator is formed by combining the MEMS resonator with the interface circuit to generate a signal with a reference frequency of f1, and a high-frequency signal (M×N×f2, M is the multiplication number of the multiplier, and N is the multiplication coefficient of the multiplier) is generated by combining the phase-locked loop (output frequency is f2) with the passive frequency multiplier. Through the adjustable filter, only a certain harmonic can pass through the filter and be sent to the terminal through the antenna. Other harmonics are reflected to the rectifier module through the coupler for further energy conversion.

[0058] In this embodiment, two fixed-multiple phase-locked loops and a passive frequency multiplier are used to achieve a higher frequency multiplication number. Through testing, it is found that the harmonic power of the passive frequency multiplier is also high, so harmonics are selected to further increase the frequency multiplication number, thereby improving the temperature resolution.

[0059] In this embodiment, electromagnetic waves are actively emitted by the terminal, and the wireless passive temperature sensor receives electromagnetic wave signals, which are converted into direct current through the rectifier module and then stabilized to drive the MEMS resonator and the phase-locked loop. The rectifier module contains two types of RF signals, one is the electromagnetic wave signal actively emitted by the outside (terminal), and the other is the fundamental and harmonic signals of the frequency multiplier. The introduction of two RF signal streams improves the efficiency of the rectifier module, reduces the charging time, and improves the response speed of the temperature sensor. The rectifier module needs to perform RF-DC conversion in multiple frequency bands according to the externally emitted RF signal and the signal reflected by the coupler to achieve high-efficiency rectification.

[0060] In this embodiment, the terminal antenna and the temperature sensor antenna both use dual-polarized antennas, such as ±45 degree polarization. If the terminal uses +45° polarization to send to the temperature sensing node, the temperature sensing node uses -45° polarization to send to the terminal. Using different polarization forms can effectively avoid electromagnetic coupling between sending and receiving, and achieve effective isolation from the perspective of polarization orthogonality. The terminal and the temperature sensor can send and receive each other uninterruptedly, and a temperature measurement system with uninterrupted temperature detection or configurable refresh rate can be realized.

[0061] like Figure 2 As shown in the figure, it is a spectrum diagram of the frequency multiplication circuit built based on the MEMS resonator. The purpose is to increase the frequency multiplication factor as much as possible on the basis of considering the system power consumption, and finally improve the resolution of temperature measurement. The output frequency f1 of the MEMS resonator itself has a linear relationship with the temperature and has a certain TCF. The signal of the MEMS resonator is multiplied to f2 through the phase-locked loop. Furthermore, the frequency multiplication factor is increased by the passive frequency multiplier, and the output of the passive frequency multiplier contains multiple harmonics (M×N×f2). Through the coupler and the bandpass filter, the high-order harmonics can be reasonably selected and wirelessly sent to the terminal through the antenna, but it is necessary to consider whether the output power of the harmonic meets the wireless coverage distance of the temperature sensing node. The other filtered harmonics are reflected to the rectifier module through the coupler to achieve more efficient energy collection.

[0062] like Figure 3 The figure shows a schematic diagram of the electromagnetic energy collection circuit. The RF signal sources of the rectifier module include two types: one is the external actively transmitted RF signal, which is received by one end of the dual-polarized antenna to the rectifier circuit, and the other is the harmonic signal reflected after filtering by the reflective filter, which is transmitted to the rectifier circuit through the other end of the coupler to achieve multi-band RF-DC conversion and more efficient energy collection. After the rectifier circuit, the DC-DC conversion, storage and voltage regulated output are realized through the energy management circuit, and finally the energy supply to the MEMS oscillator and phase-locked loop is realized.

[0063] like Figure 4As shown in the figure, it is a transceiver link isolation scheme based on dual-polarized antenna. The terminal can generate a fixed frequency signal through the RF signal source and radiate it after amplification by the amplifier. The polarization of the radiated electromagnetic wave is +45° linear polarization. The polarized electromagnetic wave is received by the dual-polarized antenna of the temperature sensor node and transmitted to the rectifier circuit for rectification. It should be noted that in order to meet the national standard on transmission power, the designed terminal transmission frequency is in the RFID frequency band, and the corresponding transmission power + transmission antenna gain ≤36dBm, that is, EIRP (Effective Isotropic Radiated Power) ≤36dBm. The output signal of the frequency multiplier is wirelessly transmitted through the dual-polarized antenna, and the polarization of the transmitted electromagnetic wave is -45° polarization. The transmission signal is received by the dual-polarized antenna of the terminal (the terminal includes a bandpass filter, a low-noise amplifier and a spectrum detection circuit), and is transmitted to the spectrum detection circuit through the bandpass filter and the low-noise amplifier (LNA). The detection circuit detects the maximum power and corresponding frequency of the spectrum under the current bandwidth, and determines the current test temperature through the correlation between frequency and temperature. In this solution, there is a high degree of isolation between the transmitting link and the receiving link of the terminal, and there is also a high degree of isolation between the transmitting link and the receiving link in the sensor node. Based on this, the transmission of external electromagnetic energy can work continuously or intermittently to achieve uninterrupted or periodic wireless passive temperature measurement with a high degree of freedom. In this embodiment, the working bandwidth of the dual-polarized antenna needs to meet the frequency offset under the temperature variation range. In the current TCF of the MEMS resonator, the measurement temperature range (T1~T2℃) is considered to determine the frequency offset after frequency doubling. The working bandwidth of the dual-polarized antenna needs to be greater than or equal to this frequency offset; wherein, the frequency offset f3 after frequency doubling is calculated according to the following formula:

[0064] f3 = N × f1 × TCF × (T2 - T1);

[0065] Wherein, N is the frequency multiplication factor; f1 is the reference frequency of the MEMS resonator; TCF is the temperature coefficient of the MEMS resonator; T1 is the minimum value of the measured temperature; and T2 is the maximum value of the measured temperature.

[0066] It should be pointed out that Figure 1 In the circuit, any MEMS resonator with stable TCF can be used to realize high-precision temperature detection function. Taking the MEMS oscillator model LTC1799 as an example, the following is built: Figure 5In the frequency multiplication circuit shown, the MEMS oscillator generates a reference signal of ~10MHz, which is multiplied by two phase-locked loops. The frequency multiplication coefficients of the two phase-locked loops are 3.33 and 6 respectively. The final output frequency of the phase-locked loop is ~200MHz, and the signal power is about 17dBm. Furthermore, after the passive frequency multiplier MK-5-14, the output signal frequency is increased to ~1GHz, and its power is -5dBm. Higher frequency harmonic signals (such as 1.2GHz, 1.4GHz and other harmonics) can also be selected to characterize temperature information, but it is necessary to consider that the output power of higher harmonic signals is lower, making it difficult to achieve long-distance coverage. The total frequency multiplication coefficient of this scheme is 99.8, which verifies Figure 1 The feasibility of the circuit architecture shown in the figure can achieve effective frequency multiplication on the basis of considering the system power consumption through the frequency multiplication scheme, and further improve the resolution of temperature sensing.

[0067] like Figure 6 , Figure 7 and Figure 8 As shown in the figure, the test spectrum diagrams of the oscillator, phase-locked loop and passive frequency multiplication circuit are shown respectively. From the test results, it can be seen that the phase noise of the MEMS oscillator and the phase-locked loop is ~-61dBc / Hz@1kHz. This phase noise is subject to the selected MEMS oscillator model. In the future, a MEMS oscillator with a higher Q value can be selected to reduce the system phase noise and achieve higher-precision temperature measurement. From the output spectrum of the passive frequency multiplier, it can be seen that although it is calibrated to a fixed frequency multiplication factor, the output spectrum of the frequency multiplier has harmonic characteristics, which can be used to characterize temperature information by selecting harmonic components with higher output power and higher frequency.

[0068] In summary, this embodiment provides a wireless passive temperature measurement system based on a MEMS resonator, which can realize long-distance wireless transmission and effectively isolate the energy collection and energy transmission circuits to avoid mutual interference. It can realize long-distance transmission of passive wireless temperature detection under low power consumption conditions while ensuring the measurement accuracy and resolution.

[0069] Example 2

[0070] like Fig. 9 As shown, this embodiment provides a temperature measurement method of a wireless passive temperature measurement system based on a MEMS resonator as described in Embodiment 1, comprising:

[0071] Step 101: Receive an electromagnetic wave signal transmitted by a terminal using a dual-polarized antenna.

[0072] Step 102: Use a rectifier module to convert the received electromagnetic wave signal into direct current to supply power to the MEMS oscillator and the phase-locked loop.

[0073] Step 103, using a MEMS oscillator to generate a reference frequency signal, and multiplying the frequency through a phase-locked loop and a passive frequency multiplier.

[0074] Step 104: Use an adjustable filter to select a target harmonic signal in the frequency-multiplied high-frequency signal, and send the target harmonic signal to the terminal through a dual-polarized antenna.

[0075] Step 105: Utilize a terminal to receive a target harmonic signal, and determine a current test temperature based on a correlation between a frequency corresponding to the target harmonic signal and temperature.

[0076] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A wireless passive temperature measurement system based on MEMS resonator, characterized in that: include: A MEMS oscillator formed with a MEMS resonator and a corresponding interface circuit is used to generate a reference frequency signal; A phase-locked loop, electrically connected to an output end of the MEMS oscillator, for generating a high-frequency signal; A passive frequency multiplier, electrically connected to the output end of the phase-locked loop, for multiplying the high frequency output by the phase-locked loop; A coupler, electrically connected to the output end of the passive frequency multiplier, for dividing the frequency-multiplied high-frequency signal into two harmonic signals; an adjustable filter, electrically connected to the output end of the coupler, for selecting a target harmonic signal; A dual-polarized antenna, electrically connected to the output end of the tunable filter, for sending the target harmonic signal to the terminal and receiving the electromagnetic wave signal emitted by the terminal; A rectifier module, electrically connected to the dual-polarized antenna and the coupler, respectively, for converting the electromagnetic wave signal and the harmonic signal reflected by the coupler into direct current; The energy management module is electrically connected to the phase-locked loop and the MEMS resonator, and is used for storing and outputting DC power in a regulated voltage, so as to supply energy to the MEMS oscillator and the phase-locked loop.

2. The wireless passive temperature measurement system based on MEMS resonator according to claim 1 is characterized in that: The temperature resolution △T after frequency doubling is: Among them, △f is the frequency measurement resolution; N is the frequency multiplication factor; f1 is the reference frequency of the MEMS resonator; TCF is the temperature coefficient of the MEMS resonator.

3. The wireless passive temperature measurement system based on MEMS resonator according to claim 1 is characterized in that: The antenna of the terminal is a dual-polarized antenna, and the dual-polarized antenna on the terminal side and the dual-polarized antenna on the MEMS resonator side are in the form of ±45° polarization.

4. The wireless passive temperature measurement system based on MEMS resonator according to claim 1 is characterized in that: The working bandwidth of the dual-polarized antenna meets the frequency offset under the temperature variation range, and the working bandwidth of the dual-polarized antenna is greater than or equal to the frequency offset after frequency multiplication.

5. The wireless passive temperature measurement system based on MEMS resonator according to claim 4 is characterized in that: The frequency offset f3 after frequency multiplication is calculated according to the following formula: f3 = N × f1 × TCF × (T2 - T1); Wherein, N is the frequency multiplication factor; f1 is the reference frequency of the MEMS resonator; TCF is the temperature coefficient of the MEMS resonator; T1 is the minimum value of the measured temperature; and T2 is the maximum value of the measured temperature.

6. The wireless passive temperature measurement system based on MEMS resonator according to claim 3 is characterized in that: The terminal includes a bandpass filter, a low-noise amplifier and a spectrum detection circuit; the transmission signal of the dual-polarized antenna on the MEMS resonator side is received by the dual-polarized antenna on the terminal side, and is transmitted to the spectrum detection circuit via the bandpass filter and the low-noise amplifier. The spectrum detection circuit detects the maximum power and corresponding frequency of the spectrum under the current working bandwidth, and determines the current test temperature according to the correlation between frequency and temperature.

7. The wireless passive temperature measurement system based on MEMS resonator according to claim 1, characterized in that: The output of the passive frequency multiplier includes multiple harmonics, and the adjustable filter is used to select the harmonic components of the target output power to characterize the temperature information.

8. A temperature measurement method of a wireless passive temperature measurement system based on a MEMS resonator according to any one of claims 1 to 7, characterized in that: include: Using a dual-polarized antenna to receive electromagnetic wave signals transmitted by the terminal; The rectifier module is used to convert the received electromagnetic wave signal into direct current to supply power to the MEMS oscillator and phase-locked loop; A reference frequency signal is generated by using a MEMS oscillator, and the frequency is multiplied by a phase-locked loop and a passive frequency multiplier; The target harmonic signal in the frequency-multiplied high-frequency signal is selected by using an adjustable filter, and is sent to the terminal through a dual-polarized antenna; The target harmonic signal is received by the terminal, and the current test temperature is determined according to the correlation between the frequency corresponding to the target harmonic signal and the temperature.

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