CN-122021690-A - Surface acoustic wave tag structure and phase defuzzification algorithm adopting reflective grating spacing mutual quality

CN122021690ACN 122021690 ACN122021690 ACN 122021690ACN-122021690-A

Abstract

The invention discloses a surface acoustic wave tag structure adopting reflective grating spacing mutual quality and a phase disambiguation algorithm. The tag comprises three reflecting grids, the two phase difference changes detected by the reader theoretically have a staggered phenomenon according to the fact that the ratio of the distances between the adjacent reflecting grids is prime, and therefore the non-fuzzy period of the phase difference changes can be expanded, and the measuring range is greatly enlarged. The algorithm firstly presents the theoretical value without phase error in an offline diagram, then leads the phase detection result into the offline diagram in a coordinate form, adopts a geometric drawing mode to restore the theoretical value, and finally adopts a table look-up-like method to restore the non-fuzzy phase difference, thereby not only being simple and convenient, having good robustness and strong visual characteristics, but also determining the requirement of the normal operation of the algorithm on the phase detection precision of the reader through drawing. Aiming at the scene that a plurality of labels are simultaneously applied in a multi-node mode, the space between the reflecting grids adopts a special mutual mass ratio and changes alternately, so that the number of available nodes is greatly improved.

Inventors

CHEN ZHIJUN
LIU QINGRUI
XIAO LIJUN
GUO JIE
Su Piqiang
LIU XIANGYU
ZHU WEIJUN

Assignees

南京航空航天大学
中国航发四川燃气涡轮研究院
中电科技德清华莹电子有限公司

Dates

Publication Date: 20260512
Application Date: 20251230

Claims (3)

1. A surface acoustic wave label structure adopting mutual quality of reflecting grating spacing is composed of a piezoelectric substrate, an interdigital transducer, a 1 st reflecting grating, a2 nd reflecting grating and a 3 rd reflecting grating, wherein the 1 st reflecting grating is nearest to the interdigital transducer, the 2 nd reflecting grating is farthest from the interdigital transducer, and the 3 rd reflecting grating is farthest from the interdigital transducer.
2. The surface acoustic wave tag structure using reflection grating spacing mutual quality according to claim 1, wherein when n surface acoustic wave tags are required to be simultaneously applied in the form of n nodes to form a surface acoustic wave tag group, not only are each surface acoustic wave tag of the surface acoustic wave tag group and only three reflection gratings, but also the ratio of the distances between adjacent reflection gratings of each surface acoustic wave tag is a prime number and is x (2x+1); According to the distance between the 1 st reflecting grating and the interdigital transducer on n surface acoustic wave labels, the n surface acoustic wave labels are sequenced from the near to the far and marked as 1 st, 2 nd and k, the number of the surface acoustic wave labels is the number of the surface acoustic wave labels, (n-1) and n surface acoustic wave labels, the ratio d 12 :d 23 = x (2x+1) of the distances between the adjacent reflecting gratings of all the odd surface acoustic wave labels, the ratio d 23 :d 12 = x (2x+1) of the distances between the adjacent reflecting gratings of all the even surface acoustic wave labels, if the distance between the 1 st reflecting grating of any even surface acoustic wave label and the interdigital transducer is d 1 , the distance between the 2 nd reflecting grating of the odd surface acoustic wave label and the interdigital transducer which are arranged immediately before the 1 st reflecting grating is d 2 , the distance between the 3 rd reflecting grating and the interdigital transducer is d 3 , and the ratio of the distances between the adjacent reflecting gratings of the odd surface acoustic wave labels and the even surface acoustic wave labels is x (2x+1) through the structure of (d 1 -d 2 ):(d 3 -d 1 ) =x (x+1), and the sequential reflection grating spacing ratio between the adjacent reflecting gratings of the odd surface acoustic wave labels and the even surface acoustic wave labels is x (2x+1); The distances between all 3n reflecting grids and the interdigital transducers on the n surface acoustic wave labels are different, the 3n reflecting grids are sequenced from the near to the far according to the distances between all 3n reflecting grids and the interdigital transducers, and the ratio of the distances between the reflecting grids which are sequentially adjacent is x, x (x+1) x, x and x are circularly generated.
3. A phase disambiguation algorithm employing surface acoustic wave tag structures with reflective grating spacing interstitiality as claimed in claim 1 or 2, wherein: the method comprises the following steps, wherein step A, B, C is an offline stage: Step A, according to the ratio d 12 :d 23 =a:b of the distances between adjacent reflection grids on the surface acoustic wave label, when an object to be measured changes, the phase difference between echoes corresponding to the reflection grids also changes, the ratio delta phi 12 of the non-fuzzy phase difference change delta phi 23 between echoes corresponding to the 1 st reflection grid and the 2 nd reflection grid and the ratio delta phi 12 :Δψ 23 =a:b of the non-fuzzy phase difference change delta phi 23 between echoes corresponding to the 2 nd reflection grid and the 3 rd reflection grid also mutually becomes prime numbers, if the change of d 12 <d 23 ,Δψ 23 is more frequent than delta phi 12 , if the change of d 12 >d 23 ,Δψ 12 is more frequent than delta phi 23 , the change of delta phi 12 、Δψ 23 is in a proportional relation, and when delta phi 12 changes a by 360 degrees, delta phi 23 just changes b by 360 degrees; Step B, because of the fuzzy problem of phase detection, the phase difference change delta phi 12 between the echoes corresponding to the 1 st reflecting grating and the 2 nd reflecting grating detected by the reader through the orthogonal demodulation scheme and the phase difference change delta phi 23 between the echoes corresponding to the 2 nd reflecting grating and the 3 rd reflecting grating are changed only between 0 degrees and 360 degrees, and the whole period number of 360 degrees in delta phi 12 、Δψ 23 is not included; since Δψ 12 :Δψ 23 =a:b are prime numbers, Δφ 12 and Δφ 23 are staggered, when one of the phase difference changes is affected by ambiguity to generate a discontinuous phenomenon, i.e. when the phase difference changes are stepped down from 360 ° to 0 °, the value of the other phase difference change is continuous nearby, so that even if the phase difference change between echoes corresponding to nearest adjacent reflection grids exceeds 360 °, the whole period number of 360 ° in Δψ 12 、Δψ 23 can be recovered by Δφ 12 、Δφ 23 as long as the phase difference change does not exceed a×360 (a < B) or b×360 (a > B); Step C, on the basis of the step A and the step B, drawing an offline two-dimensional line graph with a delta phi 12 as a horizontal axis and a delta phi 23 as a vertical axis, wherein the line graph consists of (a+b-1) oblique lines which are parallel to each other, and the slopes of all the oblique lines are The distance between adjacent oblique lines is The corresponding blur-free phase difference change Δψ 12 、Δψ 23 of each point on all the diagonal lines is a known determined value; Step D, when the object to be detected is not loaded or is a reference value, measuring an initial phase difference phi ́ 12 between echoes corresponding to the 1 st reflecting grating and the 2 nd reflecting grating and an initial phase difference phi ́ 23 between echoes corresponding to the 2 nd reflecting grating and the 3rd reflecting grating by a reader; Step E, when the object to be measured is loaded or changed, measuring a phase difference phi 12 between echoes corresponding to the 1 st reflecting grating and the 2 nd reflecting grating and a phase difference phi 23 between echoes corresponding to the 2 nd reflecting grating and the 3 rd reflecting grating through a reader, making a difference between the phase difference and the corresponding initial phase difference, and obtaining a phase difference change delta phi 12 、Δφ 23 caused by the object to be measured after taking a model for 360 degrees; Step F, the measured value coordinate point (delta phi 12 、Δφ 23 ) obtained in the step E is imported into the two-dimensional line graph drawn in the step C, and the distance between the measured value coordinate point and each oblique line is calculated in a numerical combination mode Where k is the slope of all the slopes and c m is the intercept of the mth slope on the vertical axis; step G, the measured value coordinate point (delta phi 12 、Δφ 23 ) is drawn along the oblique line on the line graph, the vertical foot coordinate point (delta phi ́ 12 、Δφ´ 23 ) on the oblique line closest to the measured value coordinate point is the measurement result with the phase detection error eliminated, and the calculation can be performed by a digital combination mode 、 Wherein k is the slope of the oblique line, c is the intercept of the oblique line with the vertical coordinate point (delta phi ́ 12 、Δφ´ 23 ) on the vertical axis, and the maximum phase error allowed when the oblique line is not misjudged can be calculated by a digital combination mode I.e. the phase detection error of the reader needs to be smaller than ; Step H, obtaining a blur-free phase difference change delta phi 12 、Δψ 23 according to the foot coordinate point (delta phi ́ 12 、Δφ´ 23 ) obtained in the step G, and further obtaining delta phi 13 =Δψ 12 +Δψ 23 ; Step I, obtaining an object value to be measured according to the delta phi 13 obtained by the phase ambiguity resolution algorithm; And J, aiming at the surface acoustic wave label group formed by simultaneously applying n surface acoustic wave labels in the form of n nodes, as the distances between all 3n reflecting grids and interdigital transducers are different, the echoes corresponding to the three reflecting grids on each surface acoustic wave label can be selected from all 3n echoes, and then the steps A-I are repeated n times, so that the object values to be measured at the n nodes are obtained.

Description

Surface acoustic wave tag structure and phase defuzzification algorithm adopting reflective grating spacing mutual quality Technical Field The invention relates to a surface acoustic wave label structure and a phase disambiguation algorithm adopting the fact that the ratio of the distances between adjacent reflecting grids is prime, and belongs to the field of sensors. Background The surface acoustic wave tag is composed of a piezoelectric substrate, interdigital transducers and reflection grids, and the tag coding function of the radio frequency identification system is generally realized through information such as the number of the reflection grids, the distance between the reflection grids and the like. The surface acoustic wave tag can be used for radio frequency identification and wireless sensing. The temperature, strain and torque waiting for the object to be measured all cause the change of the propagation speed of the surface acoustic wave and the change of the distance between the reflecting grids, so that the time delay between echoes corresponding to the reflecting grids is caused to change. Because the time delay change is smaller, in order to avoid the excessively high requirement on the sampling rate index of the analog-to-digital converter of the reader, in view of the essentially linear relationship between the phase and the time delay, the reader usually performs phase detection through a quadrature demodulation architecture to replace the time delay detection, but the phase detection has the problem of phase ambiguity, namely the phase takes 360 degrees as a period, the quadrature demodulation only can measure the phase between 0 degrees and 360 degrees, and the whole period number of 360 degrees cannot be measured. When the surface acoustic wave tag is used for sensing, a reflection grating is added on the basis of two reflection gratings, and on the premise that the surface acoustic wave tag is uniformly changed due to an object to be measured, the influence caused by phase ambiguity is reduced to a certain extent by combining a phase recurrence and other ambiguity resolution algorithms according to the proportional relation between the adjacent reflection gratings, but the following problems exist at present: (1) According to the proportional relation between the distances of the reflecting grids, the phase difference change between the echoes caused by the change of the object to be measured can be recursively calculated, under the premise that the phase error is not amplified to 180 degrees during recursion, the phase difference change between the echoes corresponding to the two reflecting grids which are farthest and secondarily farthest can exceed 360 degrees, but the phase difference change between the echoes corresponding to the two reflecting grids which are closest cannot exceed 360 degrees to avoid phase ambiguity, so that the measurement range is limited, and the application scene of the surface acoustic wave tag is greatly limited. Taking a YZ cut lithium niobate piezoelectric substrate commonly used for temperature sensing as an example, the time delay temperature coefficient tcd=94 ppm/°c, and when the distance between two adjacent nearest reflection grids is 120 times of wavelength, the temperature measurement range is only 44.33 ℃. (2) Although the object value to be measured is obtained through the phase difference change result between the echoes corresponding to the two reflection grids with the farthest distance, the measurement precision is much higher than that of the two reflection grids with the next-farthest and nearest distances, the phase is inevitably jitter and instability problems in the measurement process due to the unavoidable phase detection error of the reader, and the jitter and instability of the measurement result are caused. (3) In the practical application of wireless sensing, there is often a scenario where multiple sensors are simultaneously applied in the form of multiple nodes, such as using multiple nodes to simultaneously measure temperatures at multiple locations. On the premise of determining the packaging size of the surface acoustic wave labels, after one reflecting grating is added on each label, in order to avoid collision problems caused by echo aliasing when a plurality of nodes are simultaneously applied, the number of the nodes which can be simultaneously used is sharply reduced, and the application scene is limited. Disclosure of Invention Aiming at the problems existing when the surface acoustic wave tag is used for sensing, the invention provides a surface acoustic wave tag structure and a phase disambiguation algorithm, which adopt the fact that the distance ratio between adjacent reflecting grids is prime, so that the measuring range is greatly enlarged, the phase detection is more stable, and in addition, the number of available nodes is greatly improved when a plurality of nodes are simultaneously applied. The invention ado