Acoustic Sensor Query

Abstract

The present invention relates to an interrogation device for interrogating an acoustic wave sensor, comprising a transmitting antenna, which transmits an interrogation radio frequency signal to the acoustic wave sensor; a receiving antenna, which receives a response radio frequency signal from the acoustic wave sensor; and a processing unit, which determines an in-phase component and an orthogonal component of a response radio frequency signal in each of N consecutive frames of the response radio frequency signal, N is an integer greater than 1, and each of the N frames includes X sampling points; determines a modulus of each pair of the in-phase component and the orthogonal component; determines a first norm based on the modulus; determines a first weighting function based on the first norm and the modulus; determines an in-phase component and an orthogonal component of an N+1th frame of the response radio frequency signal, the N+1th frame includes X sampling points of the response radio frequency signal; determines a modulus of each pair of the in-phase component and the orthogonal component of the N+1th frame; and applies the first weighting function to the modulus of the response radio frequency signal in the N+1th frame to obtain a weighted modulus of the response radio frequency signal for the N+1th frame.

Description

Technical Field

[0001] The present invention relates to acoustic wave type passive sensors, and in particular to interrogation of passive surface acoustic wave or bulk acoustic wave sensors. Background Art

[0002] Sensors are increasingly important and becoming more common in everyday life. Microelectromechanical systems (MEMS) are an attractive option to meet the demand for increased sensor performance and reduced size and cost. Surface acoustic wave (SAW) sensors, and to a lesser extent bulk acoustic wave (BAW) sensors or Lamb or Love wave acoustic sensors, offer a particularly advantageous option due to the wide variety of measurable environmental parameters including, for example, temperature, pressure, strain and torque.

[0003] Acoustic wave sensors use the piezoelectric effect to convert electrical signals into mechanical / acoustic waves. SAW-based sensors are built on single-crystal piezoelectric materials such as quartz (SiO2), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lanthanum gallium silicate (LGS) or on polycrystalline piezoelectric materials such as aluminum nitride (AlN) or zinc oxide (ZnO), especially deposited on silicon, or even deposited on piezoelectric on insulator (POI) composite materials including a piezoelectric material layer, specifically a single-crystal material such as lithium tantalate or lithium niobate, which is bonded to a supporting substrate such as silicon, if necessary with the help of a bonding layer such as a silicon oxide layer (usually, any combination of single-crystal piezoelectric materials and non-piezoelectric substrates, which are used due to their specific properties such as thermal stability or acoustic quality). The transducer, in the case of a surface acoustic wave sensor, an interdigitated transducer (IDT), converts the electrical energy of the electrical signal into acoustic wave energy. The acoustic waves propagate through the surface (or body) of the device substrate via a so-called delay line to another transducer, in particular an IDT, which converts the acoustic waves back into an electrical signal that can be detected. In some arrangements, mechanical absorbers and / or reflectors are provided to prevent interference patterns and reduce insertion losses. In some arrangements, the other (output) IDT is replaced by a reflector, which reflects the generated acoustic waves back to the (input) IDT, which can be coupled to an antenna for remote interrogation of the sensor device. Advantageously, the measurement can be performed completely passively, i.e. the sensor does not need to be powered by a power supply.

[0004] A specific class of acoustic sensors comprises resonators that exhibit a resonance frequency that varies according to changing environmental conditions. For example, a conventional surface wave resonator comprises an electroacoustic transducer having an interdigitated comb arranged between Bragg reflectors. At the resonance frequency, the synchronization condition between the reflectors is satisfied, so that a coherent superposition of the different reflections occurring under the reflectors can be obtained. A maximum of the acoustic energy is then observed in the resonance cavity, and from an electrical point of view, a maximum of the amplitude of the current received by the transducer is observed. A differential acoustic wave sensor may comprise two or more resonators that exhibit different resonance frequencies or resonators that operate in multimode (multiple resonance frequencies), wherein the difference in the measured frequencies reflects changes in environmental parameters, such as temperature or strain.

[0005] However, despite recent engineering processes, the entire interrogation process, in which the interrogator sends an appropriate radio frequency signal, which is received by the acoustic wave sensor via a receiving antenna and converted by the transducer into a surface acoustic wave (or a bulk wave, in the case of a device of the bulk acoustic wave sensor type) propagating along a delay line, is converted into a radio frequency signal, which is retransmitted via a transmitting antenna and received and analyzed by the interrogator. In particular, the radio frequency noise present in the commonly used ISM (Industrial, Scientific and Medical) bands, for example in bands with a center frequency of 434 MHz or 2.45 GHz, leads to reading / interpretation errors, which affect the quality of the generation and analysis of the response spectrum provided by the sensor device. Summary of the invention

[0006] It is therefore an object of the present invention to provide an apparatus and method for interrogating an acoustic wave sensor having an increased signal-to-noise ratio compared to the prior art.

[0007] The present invention solves the above-mentioned object by providing an interrogation device for interrogating an acoustic wave sensor, the interrogation device comprising: a transmitting antenna, the transmitting antenna being configured to transmit an interrogation radio frequency signal to the acoustic wave sensor; a receiving antenna, the receiving antenna being configured to receive a response radio frequency signal from the acoustic wave sensor; and a processing unit, the processing unit being used to process / analyze the response radio frequency signal to determine an environmental parameter to be sensed. For example, the environmental parameter may be a temperature, pressure or strain level of a certain target sample to be monitored.

[0008] The processing unit (which may include a standard CPU, a microprocessor or a microcontroller, for example) is configured to determine the in-phase component I of the received response radio frequency signal in each of N consecutive frames (the first frame, the second frame ..., the Nth frame) of the response radio frequency signal. and the quadrature component Q N is an integer greater than 1, wherein each of the N frames comprises X sampling points (sampling points are, for example, points at which the real and imaginary parts of the signal are measured at a given frequency). According to an alternative, 1) the moduli (absolute amplitudes) of each pair of the determined in-phase component I and quadrature component Q are further processed by means of norms and weighting functions, or 2) the determined in-phase component I and quadrature component Q are further processed by means of I-norms and Q-norms and I-weighting functions and Q-weighting functions, respectively. It should also be noted that the processing according to these two alternatives can generally be performed at least partially in the time domain or the frequency domain.

[0009] According to a first alternative, for X sampling points of each of the N frames, the modulus is calculated by the processing unit:

[0010] [Formula 1]

[0011]

[0012] A first norm is calculated based on the calculated modulus. A first weighting function W is determined based on the determined first norm M and the determined modulus |Y|. An in-phase component I and a quadrature component Q of the received response RF signal of the N+1th frame (e.g., directly following the Nth frame) are determined, the N+1th frame including X sampling points of the received response RF signal. The modulus |Y| of each pair of the determined in-phase component I and the quadrature component Q of the N+1th frame is determined, and the first weighting function W is applied to the modulus |Y| of the received response RF signal in the determined N+1th frame to obtain a weighted modulus |Y|w of the received response RF signal for the N+1th frame. For example, a resonant frequency can be determined based on the weighted modulus, thereby determining an environmental parameter.

[0013] Therefore, according to the first alternative, an interrogation device for interrogating an acoustic wave sensor is provided, the interrogation device comprising a transmitting antenna, the transmitting antenna being configured to transmit an interrogation radio frequency signal to the acoustic wave sensor; a receiving antenna, the receiving antenna being configured to receive a response radio frequency signal from the acoustic wave sensor; a processing unit, the processing unit being configured to determine an in-phase component I and an orthogonal component Q of the received response radio frequency signal in each of N consecutive frames of the response radio frequency signal, N being an integer greater than 1, wherein each of the N frames comprises X sampling points; determining a modulus |Y| of each pair of the determined in-phase component I and the orthogonal component Q; based on Determine a first norm M based on the determined modulus |Y|; determine a first weighting function Wi based on the determined first norm M and the determined modulus |Y|; determine an in-phase component I and a quadrature component Q of the received response RF signal of the N+1th frame, the N+1th frame including X sampling points of the received response RF signal; determine the modulus |Y| of each pair of the determined in-phase component I and the quadrature component Q of the N+1th frame; and apply the first weighting function W to the determined modulus |Y| of the received response RF signal in the N+1th frame to obtain a weighted modulus |Y|w of the received response RF signal for the N+1th frame.

[0014] According to the second alternative, an interrogation device for interrogating an acoustic wave sensor is provided, the interrogation device comprising a transmitting antenna, the transmitting antenna being configured to transmit an interrogation radio frequency signal to the acoustic wave sensor; a receiving antenna, the receiving antenna being configured to receive a response radio frequency signal from the acoustic wave sensor; a processing unit, the processing unit being configured to determine an in-phase component I and an orthogonal component Q of the received response radio frequency signal in each of N consecutive frames of the response radio frequency signal, N being an integer greater than 1, wherein each of the N frames comprises X sampling points; determining a first I-norm MI based on the determined in-phase component I; determining a first Q-norm MQ based on the determined orthogonal component Q; determining a first I-norm MI based on the determined first I-norm MI and the determined in-phase component I; an I weighting function WI; determining a first Q weighting function WQ based on the determined first Q norm MQ and the determined orthogonal component Q; determining an in-phase component I and an orthogonal component Q of the received response RF signal of the N+1th frame, wherein the N+1th frame includes X sampling points of the received response RF signal; applying the first I weighting function WI to the in-phase component I of the received response RF signal in the determined N+1th frame to obtain a weighted in-phase component Iw of the received response RF signal for the above-mentioned N+1th frame; and applying the first Q weighting function WQ to the orthogonal component Q of the received response RF signal in the determined N+1th frame to obtain a weighted orthogonal component Qw of the received response RF signal for the N+1th frame.

[0015] The weighted modulus may be calculated from the obtained weighted in-phase component Iw of the received response RF signal for the N+1th frame and the weighted quadrature component Iw of the received response RF signal for the N+1th frame.

[0016] By applying the norm and weighting function in both alternatives, an increased signal-to-noise ratio can be achieved compared to the prior art. The above operation is recursively applied to subsequent frames, especially in this case, where for each subsequent frame (N+2 frame, N+3 frame...), when determining the norm and weighting function, the corresponding 1st frame is ignored (i.e., when processing the N+2 frame, the 1st frame is ignored, when processing the N+3 frame, the 2nd frame (and the 1st frame) is ignored, etc.). Thus, an effective adaptive weighting process is provided that takes into account the most recent environmental conditions.

[0017] Thus, the processing unit may be configured to (according to a first alternative) determine the in-phase component I and the quadrature component Q of the received response RF signal in the N+2th frame of the response RF signal (e.g., directly following the N+1th frame), the N+2th frame comprising X sampling points of the received response RF signal; determine the modulus |Y| of each pair of the determined in-phase component I and the quadrature component Q of the N+2th frame; and determine the modulus |Y| of the second to the N+1th frames without using the determined modulus |Y|. The invention relates to a method for determining a second norm M based on the modulus |Y| of the first frame of the N frames; determining a second weighting function W based on the determined second norm M and the determined moduli |Y| of the second to N+1 frames without using the determined modulus |Y| of the first frame of the N frames; and applying the second weighting function W to the determined modulus |Y| of the received response RF signal in the N+2 frame to obtain a weighted modulus |Y|w of the received response RF signal for the N+2 frame.

[0018] According to a second alternative, the processing unit may be configured to determine an in-phase component I and a quadrature component Q of the received response RF signal in the N+2th frame of the response RF signal, the N+2th frame including X sampling points of the received response RF signal; determine a second I norm MI based on the determined in-phase component I of the 2nd to N+2th frames without using the determined in-phase component I of the 1st frame of the N frames; determine a second Q norm MQ based on the determined quadrature component Q of the 2nd to N+2th frames without using the determined quadrature component Q of the 1st frame of the N frames; determine a second I norm MI based on the determined second I norm MI and A second I weighting function WI is determined based on the determined in-phase component I of the 2nd to N+2th frames without using the determined in-phase component I of the 1st frame of the N frames; a second Q weighting function WQ is determined based on the determined second Q norm MQ and the determined orthogonal component Q of the 2nd to N+2th frames without using the determined orthogonal component Q of the 1st frame of the N frames; and the second Q weighting function WQ is applied to the orthogonal component Q of the received response RF signal in the determined N+2th frame to obtain a weighted orthogonal component Qw of the received response RF signal for the N+2th frame.

[0019] As already stated, these processes may be performed recursively on subsequent frames N+3, N+4, etc.

[0020] In the following, specific non-limiting examples for calculating the norm and the weighting function are given. According to the first alternative (calculating the first norm and the first weighting function based on the determined modulus of the N frames), the processing unit can be configured to determine the first norm M according to the following formula:

[0021] [Formula 2]

[0022]

[0023] where |Y n (ω x )| represents the modulus of the in-phase component I and the orthogonal component Q for the x-th sampling point and the n-th frame.

[0024] In this case, the processing unit may be configured to determine the first weighting function according to the following formula:

[0025] [Formula 3]

[0026]

[0027] It includes the modulus Y for each sampling point x (x = 1, ..., x) over N frames n (ω n )

[0028] [Formula 4]

[0029]

[0030] The processing unit may also be configured to apply a Gaussian density function to the obtained weighted modulus |Y|w to further increase the signal-to-noise ratio.

[0031] According to a second alternative (further processing the determined in-phase component I and quadrature component Q by means of an I-norm and a Q-norm and an I-weighting function and a Q-weighting function, respectively), the processing unit may be configured to determine a first I-norm MI according to the following formula:

[0032] [Formula 5]

[0033]

[0034] Among them, I n (ω x ) represents the in-phase component for the x-th sampling point and the n-th frame, and the first Q norm MQ is determined according to the following formula:

[0035] [Formula 6]

[0036]

[0037] Where Q n (ω x ) represents the orthogonal component for the x-th sampling point and the n-th frame.

[0038] In this case, the processing unit may be configured to determine the first I weighting function WI according to the following formula:

[0039] [Formula 7]

[0040]

[0041] And the first Q weighting function WQ is determined according to the following formula:

[0042] [Formula 8]

[0043]

[0044] As in the first alternative, the signal-to-noise ratio can be further enhanced by applying a Gaussian density function. Therefore, the processing unit can also be configured to calculate the weighted modulus |Y|w for the weighted in-phase component Iw of the received response RF signal of the obtained N+1th frame and the weighted orthogonal component Qw of the received response RF signal of the obtained N+1th frame and apply the Gaussian density function to the calculated weighted modulus |Y|w. As in the first alternative, the Gaussian density function can be applied to subsequent frames N+2, N+3, etc. in the above recursive process.

[0045] By ignoring defective frames, the efficiency and reliability of the operation of the above-mentioned embodiments can be further improved. Therefore, the interrogation device according to any of the above-mentioned embodiments can also include a filtering unit (which can be a part of the processing unit), which is configured to filter the received response RF signal before determining the first norm M or the first I norm MI and the first Q norm MQ to eliminate the frames in the N frames that present the variance or standard deviation of the in-phase component I and the orthogonal component Q exceeding the predetermined variance threshold or standard deviation threshold over the corresponding entire frame. It should be understood that when the optional filtering is performed to eliminate defective frames, the above-mentioned Nth frame, N+1th frame and N+2th frame represent defect-free frames and corresponding subsequent defect-free frames, respectively.

[0046] The variance or standard deviation threshold value can be implemented as follows according to the embodiment. The variance or standard deviation of the in-phase component I and the orthogonal component Q on a specific entire frame (e.g., the first frame) of N frames is calculated and represents the initial threshold value. For subsequent frames, again, the variance or standard deviation of the in-phase component I and the orthogonal component Q on the corresponding entire frame is calculated. If the variance or standard deviation of the subsequent frame is decreasing, the threshold value will be updated by the variance or standard deviation of the subsequent frame. When the variance or standard deviation of the subsequent frame is greater than the variance or standard deviation of the previous frame, the variance or standard deviation of the previous frame is used as the threshold value.

[0047] In addition, a system for monitoring / measuring environmental parameters (e.g., temperature, strain level, pressure, or torque level of a rotating shaft) is provided, the system comprising an interrogation device according to one of the above-mentioned embodiments and an acoustic wave sensor device communicatively coupled to the interrogation device, wherein the acoustic wave sensor device is, for example, a passive surface acoustic wave sensor device.

[0048] Furthermore, a method of interrogating an acoustic wave sensor is provided herein, wherein the above-mentioned processing steps are performed. Furthermore, a computer program product is provided herein, comprising instructions for causing a processing unit (when run on the processing unit) to perform the above-mentioned processing steps.

[0049] As mentioned above, processing may be performed at least partially in the time domain or the frequency domain.All of the above equations can be directly converted into corresponding expressions in the frequency domain, and it will be appreciated that the claimed invention encompasses appropriate representations of norms and weighting functions in the time domain. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Other features and advantages of the present invention will be described with reference to the accompanying drawings. In the specification, reference is made to the accompanying drawings for illustrating preferred embodiments of the present invention. It should be understood that these embodiments do not represent the full scope of the present invention.

[0051] Figure 1A system including an acoustic wave sensor and a query device capable of implementing the embodiment of the present invention is shown.

[0052] Figure 2 is a flow chart illustrating a process of receiving a response radio frequency signal according to an embodiment of the present invention.

[0053] Figure 3 FIG. 4 shows the influence of the processing of the received response radio frequency signal on the signal quality of the obtained signal according to the embodiment of the present invention. DETAILED DESCRIPTION

[0054] The present invention provides a technique for remote interrogation of a passive acoustic wave sensor, in particular a SAW sensor, wherein the technique is characterized by a high signal-to-noise ratio. The technique can be applied to any interrogator configured to determine a response spectrum from an interrogated acoustic wave sensor. The interrogating acoustic wave sensor can be, for example, a resonator device, such as a differential SAW sensor. Figure 1 An exemplary relatively simple system (i.e., a resonator exhibiting multiple modes satisfying the cavity resonance condition) is illustrated in which the present invention according to the embodiments can be implemented. It goes without saying that the present invention can be implemented in any device employing an acoustic wave sensor or a dielectric resonator, an RLC circuit, etc. The interrogation device used can include, for example, any reader operating with an IQ detector in a network analyzer signal acquisition / processing mode.

[0055] Figure 1 The system shown comprises a resonator 1, an acoustic wave (SAW) sensor device 10 comprising an antenna 11 for receiving an interrogation radio frequency signal and transmitting a response radio frequency signal, a comb transducer 12 connected to the antenna 11 and comprising interdigitated electrodes, and a SAW resonant cavity 13 comprising two reflector series. The sensor device 10 may comprise a SAW-based sensor constructed on a single crystal piezoelectric material such as quartz (SiO2), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lanthanum gallium silicate (LGS) or a polycrystalline piezoelectric material such as aluminum nitride (AlN) or zinc oxide (ZnO), in particular deposited on silicon, or even deposited on a piezoelectric on insulator (POI) composite material comprising a piezoelectric material layer, in particular a single crystal material such as lithium tantalate or lithium niobate, bonded to a supporting substrate such as silicon, if necessary by means of a bonding layer such as a silicon oxide layer. The transducer 12 converts the interrogation RF signal received by the antenna 11 into an acoustic wave, which is reflected by the reflector of the resonant cavity 13 and converted back into an RF signal, which is transmitted by the antenna 11 as a response RF signal in the process.

[0056] The system also includes an interrogation device 20, which includes a transmitting antenna 21 for transmitting an interrogation radio frequency signal to the acoustic wave (SAW) sensor device 10 and a receiving antenna 22 for receiving a response radio frequency signal from the acoustic wave (SAW) sensor device 10. The interrogation radio frequency signal transmitted by the transmitting antenna 21 is generated by a signal generator 23, which may include an radio frequency synthesizer or oscillator and optionally some signal shaping modules that provide appropriate frequency conversion and / or amplification of the signal to be transmitted by the transmitting antenna 21. The interrogation radio frequency signal generated by the signal generator 23 may be a pulse or burst signal having a frequency selected according to the resonant frequency of the acoustic sensor device 10.

[0057] Furthermore, the interrogation device 20 comprises a processing unit 24 connected to the receiving antenna 22. The processing unit 24 may comprise filtering and / or amplifying means and is configured to analyse the response radio frequency signal received by the receiving antenna 22. For example, the sensor device 10 operates at a resonant frequency of 434 MHz or 2.45 GHz. The interrogation device 20 may transmit long radio frequency pulses and, after the transmission has ceased, the resonant cavity 13 discharges at its resonant eigenfrequency with a time constant τ equal to Qf / πF, where F is the centre frequency and Qf is the quality factor Qf corresponding to the ratio between the centre frequency and the half-width of the passband used during the interrogation. The spectral analysis performed by the processing unit 24 of the interrogation device 20 allows the resonator frequency to be calculated and thus allows the environmental parameters to be sensed. The received response radio frequency signal may be mixed with the interrogation radio frequency signal by the processing unit according to the so-called IQ protocol known in the art to extract the real and imaginary parts (in-phase I and quadrature Q), from which the modulus and phase may then be derived.

[0058] According to the present invention, the received response radio frequency signal is processed by a norm and a weighting function to increase the signal-to-noise ratio. In principle, the processing can be performed at least partially in the time domain or the frequency (spectrum) domain. For exemplary purposes, the following processing in the spectral domain will be considered. Figure 2 A flowchart illustrating a process according to an embodiment of the present invention is shown, for example, Figure 1 The processing unit 24 of the challenge device 20 shown in FIG.

[0059] In the first step of the process, a query device (e.g. Figure 1 The interrogation device 20 shown in FIG. 1 is used to send an acoustic wave sensor device (eg Figure 1 The acoustic wave sensor device 10) shown in FIG. 1 sends 101 an interrogation radio frequency signal. The interrogation device receives 102 a response radio frequency signal. The received response radio frequency signal is processed / analyzed by the interrogation device, for example, by Figure 1 The processing unit 24 of the challenge device 20 is shown.

[0060] In particular, the in-phase component I and the orthogonal component Q of the received response RF signal are determined in each of N consecutive frames of the response RF signal (N consecutive frames (1, ..., N) of the response RF signal, N is an integer greater than 1, wherein each of the N frames includes X sampling (frequency) points. For example, X can be in the range of 100 to 1000, and N can be in the range of 20 to 100.

[0061] Based on the determined in-phase component I and quadrature component Q, a norm is determined 104. According to a particular embodiment, the modulus of the determined pair of in-phase component I and quadrature component Q for N frames of the received response radio frequency signal is calculated:

[0062] [Formula 9]

[0063]

[0064] Calculate the 104 first norm according to the following formula:

[0065] [Formula 10]

[0066]

[0067] where |Y n (ω x )| represents the modulus of the in-phase component I and the orthogonal component Q for the x-th sampling point and the n-th frame.

[0068] Based on the first norm, a first weighting function is calculated 105:

[0069] [Formula 11]

[0070]

[0071] The weighting function is applied to the received response radio frequency signal (also including X sampling points) at 106, the N+1st frame may directly follow the Nth frame (for understanding, the function means that there is no unique or single value applied to the data series of the N+1st frame, but the weight depends on the signal recorded at each sampling point, whereby the weighting operation is achieved by multiplying the weight at each sampling point by the value of the sampling point in the N+1th frame). The in-phase component I and the orthogonal component Q of the received response radio frequency signal of the N+1th frame are determined, and the modulus |Y| of each pair of the determined in-phase component I and orthogonal component Q of the N+1th frame is determined. The weighting function is applied to the modulus to obtain a weighted modulus exhibiting a good signal-to-noise ratio. By fitting the data to an appropriate fitting function, in particular a Gaussian fit as described in more detail below, the resonant frequency can be determined from the weighted modulus, and based on the determined resonant frequency, the environmental parameter can be monitored.

[0072] The above process according to the present embodiment is recursively performed for subsequent frames N+2, N+3, etc., wherein in each recursive loop the norm (and hence the weighting function) is calculated ignoring the first frame used in the previous loop. Thus, in the next loop 107, the first (oldest) frame 1 is removed from consideration and the second (updated) norm is calculated by using frames 2 to N+1:

[0073] [Formula 12]

[0074]

[0075] Therefore, in the next loop 107, the (second) weighting function is given by

[0076] [Formula 13]

[0077]

[0078] And is applied to the N+2th frame, and so on.

[0079] Figure 3 The effect of this processing on enhancing the signal-to-noise ratio is illustrated. Figure 3 The raw data of the I component and the Q component and the modulus obtained for the raw data (curve a) are shown. In contrast, Figure 3 Curve b in FIG. 1 shows the weighted modulus obtained by the above process. Figure 3 It can be clearly seen that in this example the signal-to-noise ratio can be increased by an order of magnitude.

[0080] However, in the above embodiment, the norm and weighting function are determined and applied to the modulus of the I component and the Q component, alternatively, the norm and weighting function may be determined for the I component and the Q component respectively, and the weighting function thus obtained may be applied to the I component and the Q component of the corresponding subsequent frame. According to this alternative, the first I norm MI is calculated according to the following formula:

[0081] [Formula 14]

[0082]

[0083] Among them, I n (ω x ) represents the in-phase component for the x-th sampling point and the n-th frame, and the first Q-norm MQ is calculated according to the following formula:

[0084] [Formula 15]

[0085]

[0086] Among them, Q n (ωx ) represents the orthogonal component for the x-th sampling point and the n-th frame.

[0087] Therefore, the first I weighting function WI is calculated according to the following formula:

[0088] [Formula 16]

[0089]

[0090] The first Q-weighting function WQ is determined according to the following formula:

[0091] [Formula 17]

[0092]

[0093] Then the first I weighting function WI is applied to the I component of the N+1th frame, and the first Q weighting function WQ is applied to the Q component of the N+1th frame. Accordingly, the second I norm MI and the second Q norm MQ are calculated:

[0094] [Formula 18]

[0095]

[0096] To determine the second I weighting function WI and the second Q weighting function WQ:

[0097] [Formula 19]

[0098]

[0099] The second I weighting function WI and the second Q weighting function WQ will be applied to the I component and Q component of the N+1th frame respectively to obtain the weighted I component and Q component. The weighted modulus can be easily calculated based on the weighted I component and Q component. Additional recursive loops (for the N+2th frame, the N+3th frame, etc.) follow in a direct manner (each loop ignores the corresponding first frame of the previous loop).

[0100] According to a specific embodiment, Figure 2Step 104 of the flowchart is preceded by a pre-filtering step to eliminate defective frames. In fact, frames in which the variance of the in-phase component I and the orthogonal component Q on the corresponding entire frame exceeds a predetermined variance threshold can be eliminated. Thresholding can be adaptive. For example, the variance threshold can be dynamically determined by the following process: the initial threshold is set to the variance of the in-phase component I and the orthogonal component Q in a specific frame among the N frames, and if the variance of the in-phase component I and the orthogonal component Q in the frame directly following the specific frame is less than the variance in the specific frame, the variance of the in-phase component I and the orthogonal component Q in the frame directly following the specific frame is determined as the threshold, or otherwise the initial threshold. The process can be recursively performed on subsequent frames, that is, for subsequent frames, the variance of the in-phase component I and the orthogonal component Q on the corresponding entire frame is calculated again, and if the variance of the subsequent frame decreases, the threshold is updated with the variance of the subsequent frame. In the case where the variance of the subsequent frame is greater than the variance of the previous frame, the variance of the previous frame is used as the threshold.

[0101] Furthermore, in both alternatives, the Gaussian density function exp(-0,5(|bx| / c)2) can be applied to the resulting weighted modulus, where x represents the time or frequency variable, c represents the variance, and b represents the maximum value of x. Thus, for example, Figure 1 The resonant frequency of the resonant device shown. Fitting the processed signal with such a density function directly yields the resonant frequency corresponding to the variable b.

[0102] Due to the high signal-to-noise ratio obtained, any smoothing of the data is no longer necessary in the case of some post-processing required in the art. In particular, any signal component exhibiting an amplitude close to the noise level can be reliably minimized or even eliminated.

[0103] By the techniques disclosed herein, an acoustic wave sensor device and an interrogation device for interrogating the acoustic wave sensor can be used to sense environmental parameters, wherein by using norms and weighting functions, an enhanced signal-to-noise ratio can be achieved. In particular, the stability of the measurement of environmental parameters (such as temperature, strain, pressure or torque of a rotating shaft) allows for robust and reliable monitoring.

[0104] All previously discussed embodiments are not intended to be limiting but rather serve as examples to illustrate the features and advantages of the present invention. It should be understood that some or all of the above features may also be combined in different ways.

Claims

1. An interrogation device (20) for interrogating an acoustic wave sensor (10), the interrogation device comprising a transmitting antenna (21), the transmitting antenna being configured to transmit (101) an interrogation radio frequency signal to the acoustic wave sensor (10); a receiving antenna (22) configured to receive a response radio frequency signal (102) from the acoustic wave sensor (10); and A processing unit (24) configured to determining (103) an in-phase component I and a quadrature component Q of the received response radio frequency signal (102) in each of N consecutive frames of the response radio frequency signal (102), N being an integer greater than 1, wherein, Each frame of the N frames includes X sampling points; Determine the modulus |Y| of each pair of the determined in-phase component I and quadrature component Q; determining (104) a first norm M based on the determined modulus |Y|; determining (105) a first weighting function W based on the determined first norm M and the determined modulus |Y|; Determine an in-phase component I and a quadrature component Q of an N+1th frame of the received response radio frequency signal, wherein the N+1th frame includes X sampling points of the received response radio frequency signal (102); Determine the modulus |Y| of each pair of the determined in-phase component I and the orthogonal component Q of the N+1th frame; as well as The first weighting function W is applied (106) to the determined modulus |Y| of the received response radio frequency signal (102) in the N+1th frame to obtain a weighted modulus |Y|w of the received response radio frequency signal (102) for the N+1th frame.

2. The interrogation device (20) according to claim 1, wherein: The processing unit (24) is further configured to: Determining an in-phase component I and a quadrature component Q of the received response radio frequency signal in an N+2th frame of the response radio frequency signal (102), wherein the N+2th frame includes X sampling points of the received response radio frequency signal (102); Determine the modulus |Y| of each pair of the determined in-phase component I and quadrature component Q of the N+2th frame; determining a second norm M based on the determined moduli |Y| of the 2nd to N+1th frames without using the determined modulus |Y| of the 1st frame of the N frames; determining a second weighting function W based on the determined second norm M and the determined moduli |Y| of the 2nd to N+1th frames without using the determined modulus |Y| of the 1st frame of the N frames; as well as The second weighting function W is applied to the determined modulus |Y| of the received response radio frequency signal (102) in the N+2th frame to obtain a weighted modulus |Y|w of the received response radio frequency signal (102) for the N+2th frame.

3. The interrogation device (20) according to claim 1, wherein: The processing unit (24) is configured to determine (104) the first norm M according to the following formula: Among them, |Y n (ω x )| represents the modulus of the in-phase component I and the orthogonal component Q for the x-th sampling point and the n-th frame.

4. The interrogation device (20) according to claim 3, wherein: The processing unit (24) is configured to determine (105) the first weighting function according to the following formula:

5. The interrogation device (20) according to any one of claims 1 to 4, wherein: The processing unit (24) is further configured to apply a Gaussian density function to the obtained weighted modulus |Y|w.

6. The interrogation device (20) according to any one of claims 1 to 4, further comprising a filtering unit, configured to filter the received response radio frequency signal (102) before determining the first norm M, so as to eliminate frames in which the variance or standard deviation of the in-phase component I and the orthogonal component Q in the N frames exceeds a predetermined variance or standard deviation threshold over the corresponding entire frame.

7. The interrogation device (20) according to claim 6, wherein: The filtering unit is configured to dynamically determine the variance or standard deviation or the corresponding threshold by the following processing: determining the initial threshold as the variance or standard deviation of the in-phase component I and the quadrature component Q in a specific frame among the N frames, and if the variance or standard deviation of the in-phase component I and the quadrature component Q in the frame directly following the specific frame is smaller than the variance or standard deviation in the specific frame, then determining the variance or standard deviation of the in-phase component I and the quadrature component Q in the frame directly following the specific frame as the threshold.

8. An interrogation device (20) for interrogating an acoustic wave sensor (10), the interrogation device comprising: a transmitting antenna (22) configured to transmit (101) an interrogation radio frequency signal to the acoustic wave sensor (10); a receiving antenna (21) configured to receive a response radio frequency signal (102) from the acoustic wave sensor (10); and A processing unit (24) configured to Determining (103) an in-phase component I and a quadrature component Q of the received response radio frequency signal (102) in each of N consecutive frames of the response radio frequency signal (102), N being an integer greater than 1, wherein each of the N frames includes X sampling points; Determining a first I-norm MI based on the determined in-phase component I; Determining a first Q-norm MQ based on the determined orthogonal component Q; determining a first I-weighting function WI based on the determined first I-norm MI and the determined in-phase component I; determining a first Q-weighting function WQ based on the determined first Q-norm MQ and the determined orthogonal component Q; Determine an in-phase component I and a quadrature component Q of an N+1th frame of the received response radio frequency signal (102), wherein the N+1th frame includes X sampling points of the received response radio frequency signal (102); Applying a first I weighting function WI to the determined in-phase component I of the received response radio frequency signal (102) in the N+1th frame to obtain a weighted in-phase component Iw of the received response radio frequency signal (102) for the N+1th frame; and The first Q-weighting function WQ is applied to the determined quadrature component Q of the received response radio frequency signal (102) in the N+1th frame to obtain a weighted quadrature component Qw of the received response radio frequency signal (102) for the N+1th frame.

9. The interrogation device (20) according to claim 8, wherein: The processing unit (24) is further configured to: Determining an in-phase component I and a quadrature component Q of the received response radio frequency signal (102) in an N+2th frame of the response radio frequency signal (102), the N+2th frame including X sampling points of the received response radio frequency signal; Determine a second I-norm MI based on the determined in-phase components I of the 2nd to N+2th frames without using the determined in-phase component I of the 1st frame of the N frames; determining a second Q norm MQ based on the determined orthogonal components Q of the 2nd to N+2th frames without using the determined orthogonal component Q of the 1st frame of the N frames; Determine a second I weighting function WI based on the determined second I norm MI and the determined in-phase components I of the 2nd to N+2th frames without using the determined in-phase component I of the 1st frame of the N frames; determining a second Q-weighting function WQ based on the determined second Q-norm MQ and the determined orthogonal components Q of the 2nd to N+2th frames without using the determined orthogonal component Q of the 1st frame of the N frames; Applying the second I weighting function WI to the determined in-phase component I of the received response radio frequency signal (102) in the N+2th frame to obtain a weighted in-phase component Iw of the received response radio frequency signal (102) for the N+2th frame; as well as The second Q-weighting function WQ is applied to the determined quadrature component Q of the received response radio frequency signal (102) in the N+2th frame to obtain a weighted quadrature component Qw of the received response radio frequency signal (102) for the N+2th frame.

10. The interrogation device (20) according to claim 8, wherein: The processing unit (24) is configured to determine (104) the first I-norm MI according to the following formula: Among them, I n (ω x ) represents the in-phase component for the x-th sampling point and the n-th frame, and the first Q norm MQ is determined according to the following formula: Among them, Q n (ω x ) represents the orthogonal component for the x-th sampling point and the n-th frame.

11. The interrogation device (20) according to claim 10, wherein: The processing unit (24) is configured to determine the first I weighting function WI according to the following formula: And the first Q weighting function WQ is determined according to the following formula:

12. The challenge device (20) according to any one of claims 8 to 11, wherein: The processing unit (24) is also configured to The weighted modulus |Y|w of the obtained weighted in-phase component Iw of the received response radio frequency signal (102) for the N+1th frame and the obtained weighted quadrature component Qw of the received response radio frequency signal (102) for the N+1th frame is calculated, and a Gaussian density function is applied to the calculated weighted modulus |Y|w.

13. The interrogation device (20) according to any one of claims 8 to 11, further comprising a filtering unit, configured to filter the received response radio frequency signal (102) before determining the first I norm MI and the first Q norm MQ, so as to eliminate frames in which the variance or standard deviation of the in-phase component I and the orthogonal component Q in the N frames exceeds a predetermined variance or standard deviation threshold over the corresponding entire frames.

14. The interrogation device (20) according to claim 13, wherein: The filtering unit is configured to dynamically determine the variance or standard deviation or the corresponding threshold by the following processing: determining the initial threshold as the variance or standard deviation of the in-phase component I and the quadrature component Q in a specific frame among the N frames, and if the variance or standard deviation of the in-phase component I and the quadrature component Q in the frame directly following the specific frame is smaller than the variance or standard deviation in the specific frame, then determining the variance or standard deviation of the in-phase component I and the quadrature component Q in the frame directly following the specific frame as the threshold.

15. A system for monitoring an environmental parameter, the system comprising: The interrogation device (20) according to any one of claims 1 to 14; as well as An acoustic wave sensor device (10) is communicatively coupled to the interrogation device, wherein the acoustic wave sensor device (10) is particularly a passive surface acoustic wave sensor device and the environmental parameter is particularly temperature, strain, pressure or torque of a rotating shaft.

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