CN105547203A - SAW sensor multipath asynchronous reflection signal reading method - Google Patents

Abstract

The invention discloses an SAW sensor multipath asynchronous reflection signal reading method and can efficiently read plenty of multipath SAW sensor asynchronous reflection signals. The method comprises steps that (10), asynchronous reflection superposition signals of multiple time prolongation orthogonal frequency coding (OFC) SAW sensor labels in a determined distance scope are received, sampling and recording are carried out after down conversion ; (20), basic length time windows are respectively selected from different chip time scopes of the received asynchronous reflection superposition signals; (30), amplitude and phase of same center frequency chip signals in different time windows after superposition are measured; (40), through solving an equation set, amplitude and time delay of each reflection signal are calculated; (50), through comparing an amplitude calculation value of each reflection signal with the set threshold, whether an SAW sensor of the corresponding code is in a reading scope is determined; and (60), according to the relationship of the reflection signal parameters of each sensor label and the sensitive information, the sensitive information is extracted.

Description

SAW sensor multi-channel asynchronous reflection signal reading method

Technical Field

The invention belongs to the technical field of surface acoustic wave application, and particularly relates to a method for reading multiple paths of asynchronous reflected signals of an SAW (surface acoustic wave) sensor, which can efficiently and massively simultaneously read multiple paths of asynchronous reflected signals of the SAW sensor.

Background

A SAW (surface acoustic wave) sensor, i.e., a surface acoustic wave sensor, is a strain sensor based on the surface acoustic wave technology, and is an ideal choice for monitoring the operation conditions of weapons and industrial equipment in a severe environment due to a series of advantages of passive wireless operation, good stability, high sensitivity, small volume, light weight, and capability of operating in a severe environment, and has been widely studied since the last eighties, and various methods for realizing sensors by using SAW devices have been reported in published technical documents and patents. The SAW sensor converts an interrogation radio frequency pulse of a reader into SAW, sensitive information is sensed when the SAW is transmitted on a sensor substrate, the SAW is finally converted into an electromagnetic signal to be reflected back to the reader, and the reader extracts the sensitive information from the reflected signal.

Because SAW sensors operate completely passively, in a multi-sensor environment the reader receives an asynchronous superposition of reflected signals from all SAW sensor tags within the interrogation zone, which makes reading of information from each SAW sensor tag very difficult. Currently, the practically available multiple SAW sensor reading methods include Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), and Space Division Multiple Access (SDMA), but due to the limitation of the substrate length of the SAW sensor tags and the allowable bandwidth of the system, the TDM and FDM methods have a limited number of SAW sensor tags that can be read simultaneously, while the SDMA method can only be applied in a special environment with a plurality of independent electromagnetic isolation spaces, and still other methods must be adopted for multiple reading of SAW sensors in each independent space. The existing multi-path reading method cannot meet the requirement of practical application of the SAW sensor system.

Orthogonal Frequency Coding (OFC) technology proposed by the department of computer science 2004 at the university of florida in the united states simultaneously utilizes time and frequency diversity to provide SAW sensors with rich coded signals in limited time and bandwidth, but OFC-based SAW sensor systems still use TDM to achieve multiple reads.

Therefore, the prior art has the problems that: in a multi-sensor environment, the asynchronous nature of the SAW sensor tag reflected signals received by the reader creates difficulties in reading information from each SAW sensor tag, and the number of SAW sensor tags that can be read simultaneously is limited.

Disclosure of Invention

The invention aims to provide a method for reading multiple asynchronous reflected signals of a SAW sensor, which can efficiently and massively read the asynchronous reflected signals of the multiple SAW sensors at the same time.

The technical solution for realizing the purpose of the invention is as follows: a method for reading multiple asynchronous reflected signals of a SAW sensor comprises the following steps:

(10) signal receiving: receiving a plurality of time delay OFC signals within a determined distance range, and performing sampling recording after down-conversion, wherein the time delay OFC signals are asynchronous reflection superposition signals of the SAW sensor tag;

(20) selecting a basic length time window: respectively selecting time windows with basic lengths in different chip time ranges of the received asynchronous reflection superposition signals;

(30) and (3) amplitude and phase measurement: measuring the amplitude and the phase of the superposed chip signals with the same central frequency in different time windows;

(40) amplitude delay calculation: calculating the amplitude and the time delay of each reflected signal by solving an equation set reflecting the relationship between the superposed signal measurement value and the reflected signal of each SAW sensor tag;

(50) code identification: determining whether the SAW sensor with the corresponding code is in a reading range or not by comparing the amplitude calculation value of each reflected signal with a set threshold value;

(60) sensitive information extraction: and extracting the sensitive information according to the relation between the reflected signal parameter of each sensor label and the sensitive information.

Compared with the prior art, the invention has the following remarkable advantages:

1. the reading efficiency is high: according to the invention, the central frequency is unchanged after the sine waves with the same central frequency are asynchronously superposed, and the sine waves with different central frequencies keep orthogonal characteristics in a time window with an integer period length, so that the asynchronous superposed signals with different central frequencies are respectively measured, and the reading of the tag information of the SAW sensor is converted into a solution equation set, thereby improving the multi-path reading efficiency of the SAW sensor;

2. the reading quantity is large: the number of the SAW sensor tags which can be read simultaneously by the method is proportional to the square of the selectable center frequency of the reflecting grating of the SAW sensor tags, and the number is obviously increased compared with the number obtained by the conventional method.

The invention is described in further detail below with reference to the figures and the detailed description.

Drawings

FIG. 1 is a flow chart of a method for reading multiple asynchronous reflected signals of a SAW sensor according to the present invention.

Fig. 2 is a schematic diagram of the time-delayed OFC signal of the present invention.

Fig. 3 is a schematic diagram of a multiple SAW sensor environment.

Fig. 4 is a schematic diagram of asynchronous reflection signals of a plurality of time-delayed OFCSAW sensor tags.

Fig. 5 is a graph illustrating the amplitude-frequency curve and the phase-frequency curve of the superimposed signal with the same center frequency in the time window shown in fig. 4.

FIG. 6 is a flow chart of a computer simulation test of a method for reading an asynchronous reflected signal of a multiple SAW sensor according to the present invention.

FIG. 7 is a schematic diagram of an asynchronous superimposed signal received by a reader and a time window selection position in a computer simulation test according to the present invention.

Fig. 8 is a schematic diagram of randomly selected tags (8a) in a computer simulation test and the amplitude (8b) and delay (8c) of the reflected signal of each tag calculated by the reader.

FIG. 9 is a block diagram of a multiple asynchronous reflected signal reading system for a SAW sensor according to the method of the present invention.

Detailed Description

As shown in fig. 1, the SAW sensor multi-channel asynchronous reflected signal reading method of the present invention includes the following steps:

(10) signal receiving: receiving a plurality of time extension OFC signals (OFC, orthogonal frequency coding) in a determined distance range, performing sampling recording after down-conversion, wherein the time extension OFC signals are asynchronous reflection superposition signals of the SAW sensor tag;

in the signal receiving step (10), the time-delay OFC signal is composed of N-1 chip signals with different center frequencies, and a time domain mathematical model of the time-delay OFC signal is as follows:

$h\left(t\right)=\underset{k=1}{\overset{N-1}{\Σ}}{a}_k\·rect\left(\frac{t-{\mathrm{\τ}}_{pk}}{{\mathrm{\τ}}_{chip}}-\frac{1}{2}\right)\·cos\[2{\mathrm{\πf}}_{chipk}(t-{\mathrm{\τ}}_{pk})\]$

wherein,

wherein N represents the number of chip selectable center frequencies, an OFC signal can be uniquely determined by arranging N-1 frequencies, and the code capacity is N! (ii) a

a_kRepresents the amplitude of the k-th chip signal, k ∈ {1,2, …, N-1 };

τ_pkrepresenting the delay difference of the kth chip compared with the 1 st chip of each coded signal;

f_chipkrepresents the center frequency of the k-th chip;

center frequency f of each chip_chipk＝n·f₀Where N is an integer, and N ∈ {1,2, …, N }, f₀Referred to as the fundamental frequency. If the k chip center frequency of an OFC signal is n_k·f₀Then the code of the OFC signal is n_1,n_2,…,n_(N-1)；

τ_chipRepresents the time length of each chip;

length of time per chip τ_chipFrom a basic length τ_chip0And continuation length tau_MComposition i.e. tau_chip＝τ_chip0+τ_MWherein the basic length τ_chip0＝f₀ ^-1Extension length τ_MAccording to the maximum distance d between the measured sensor label and the reader_MAnd period determination after down-conversion of different center frequency signals to make tau_MIs greater than the time delay of the reflected signal of each measured sensor label to reach the reader and the time delay tau after the down-conversion of the signal_MThe resulting phase change is less than 2 pi.

The code capacity for encoding with the random permutation of N different center frequency chips is the same as the code capacity for encoding with the random permutation of N-1 of N different center frequency chips, i.e., N! Therefore, the time-extended OFC signal proposed by the present invention is composed of N-1 chips.

When the reflected signals of the SAW sensor tags adopting the OFC asynchronously reach a reader, the reflected signals of different tags mutually interfere, and each reflected signal is very difficult to extract.

However, the uncertainty distortion of the reflected signal caused by the asynchronous nature of the signal generally occurs at both ends of each chip signal, similar to the intersymbol interference caused by multipath in wireless communications. And the signal in the nondeterminacy distortion time period is formed by the superposition of reflection signals of the same reflection grating position of different SAW sensor tags, which is called as deterministic distortion. Therefore, the OFC signal is improved, namely the time delay OFC signal provided by the invention enables that after SAW sensor tag reflected signals within a certain range from a reader are asynchronously superposed, a deterministic distortion signal can still be utilized by ignoring an uncertain distortion time period. Because the center frequency of the superposed sinusoidal signals with the same center frequency is unchanged, the sinusoidal waves with different center frequencies in the time window with the integral cycle length are kept orthogonal, and the superposed signal parameters with the same center frequency in deterministic distortion can be extracted by utilizing the property. It is thus ensured in the design that the deterministic distortion time period is greater than or equal to the period of the different center frequency signals. In practical engineering implementation, it should be ensured that the deterministic distortion time period of the asynchronous superimposed signal after down-conversion is greater than or equal to the period of the chip signals with different center frequencies. The time-lapse OFC signal is schematically shown in fig. 2, the encoding of which is 1432.

In the step (10) of receiving the signal, a time domain mathematical model after down-conversion of the asynchronous reflection superposition signal is as follows:

$h_M\left(t\right)=\underset{k=1}{\overset{N-1}{\Σ}}\underset{m=1}{\overset{N_t}{\Σ}}{a}_{mk}\·rect\left(\frac{t-{\mathrm{\τ}}_{pk}-{\mathrm{\τ}}_{OFCm}}{{\mathrm{\τ}}_{chip}}-\frac{1}{2}\right)\·\cos \[2{\mathrm{\πf}}_{chipmk}\left(t-{\mathrm{\τ}}_{pk}-{\mathrm{\τ}}_{OFCm}\right)\]$

in the formula, N_tRepresenting the number of SAW sensor tags within range of the reader;

a_mkthe amplitude of the kth chip of the mth tag reflection signal reaching the reader is represented, and the chip is obtained by reflecting an interrogation signal by the kth reflection grating of the mth tag;

τ_OFCmthe delay of the m-th tag reflected signal reaching the reader is represented;

f_chipmkthe center frequency of the k chip of the m-th tag reflection signal is represented; center frequency f of each chip_chipmk＝n·f₀Wherein N is an integer, and N ∈ {1,2, …, N };

if the k chip center frequency of the m time-delay OFCSAW sensor tag reflected signal (or the k reflection grid matching frequency of the tag) is n_k·f₀K ∈ {1,2, …, N-1}, then the m-th tag is encoded as N_1,n_2,…,n_(N-1)。

Multiple SAW sensor Environment schematic As shown in FIG. 3, all sensor tags are less than d from the reader_MThe reflected signal arrives asynchronously at the reader as schematically shown in figure 4.

(20) Selecting a basic length time window: respectively selecting time windows with basic lengths in different chip time ranges of the received asynchronous reflection superposition signals;

in the step of (20) selecting the basic length time window, the range of the basic length time window selected in different chip ranges is as follows:

[τ_pk+τ_M,τ_pk+τ_chip]，k∈{1,2,…,N-1}。

the basic time window is selected to ensure that the window only contains deterministic distortion signals, and the length of the time window contains integral multiple of the period of different center frequency signals. The basic time window of the invention is schematically selected as shown in fig. 4.

(30) And (3) amplitude and phase measurement: measuring the amplitude and the phase of the superposed chip signals with the same central frequency in different time windows;

the (30) amplitude phase measuring step specifically comprises:

$\frac{2}{{\mathrm{\τ}}_{chip0}}{\∫}_{{\mathrm{\τ}}_M+{\mathrm{\τ}}_{pk}}^{{\mathrm{\τ}}_{pk}+{\mathrm{\τ}}_{chip}}{h}_M\left(t\right)\·cos\[{\mathrm{n\ω}}_0(t-{\mathrm{\τ}}_{pk})\]dt={\mathrm{\α}}_{kn}cos\left({\mathrm{n\ω}}_0{\mathrm{\τ}}_{Fkn}\right),$

$\frac{2}{{\mathrm{\τ}}_{chip0}}{\∫}_{{\mathrm{\τ}}_M+{\mathrm{\τ}}_{p_k}}^{{\mathrm{\τ}}_{p_k}+{\mathrm{\τ}}_{chip}}{h}_M\left(t\right)\·\sin \[{\mathrm{n\ω}}_0(t-{\mathrm{\τ}}_{pk})\]dt={\mathrm{\α}}_{kn}\sin \left({\mathrm{n\ω}}_0{\mathrm{\τ}}_{Fkn}\right),$

y_kn＝α_kncos(nω₀τ_Fkn)-j·α_knsin(nω₀τ_Fkn)

wherein, ω is₀＝2πf₀，α_kn、τ_FknRespectively representing the k-th chip position with a center frequency of n · f₀The amplitude and the pseudo-delay of the asynchronously superimposed chip signal α_kn＝|y_knThe false delay is caused by asynchronous superposition of the same center frequency signal. y is_knRespectively indicates that the k-th chip position has a center frequency of n · f₀The amplitude and phase of the asynchronously superimposed chip signals.

Measured value y_knIs recorded in a column vector Y_NThe (k-1) th × N + N elements.

Because the signals with different center frequencies in the basic time window are kept orthogonal, the amplitude and the phase of the superposed signal with the same center frequency in the basic time window can be respectively extracted.

The amplitude-frequency and phase-frequency curves of the superimposed signals with the same central frequency in the time window shown in fig. 4 are shown in fig. 5, and it can be seen from fig. 5(a) that at the position of the maximum value of the amplitude in the frequency domain of a certain central frequency superimposed signal, the amplitudes of the superimposed signals with other central frequencies are exactly 0, which indicates that the signals with different central frequencies keep orthogonal, and the amplitude values and the phase values of the superimposed signals at these frequency points are the values we want to measure.

(40) Amplitude delay calculation: calculating the amplitude and the time delay of each reflected signal by solving an equation set reflecting the relationship between the superposed signal measurement value and the reflected signal of each SAW sensor tag;

the amplitudes of different chip signals reflected by different reflecting grids of the OFCSAW sensor label at the same time are in a fixed proportional relation. Under the assumption that the reflected signal amplitudes of different reflective gratings of the same sensor tag are equal, namely a_m1＝a_m2＝…＝a_m(N-1)Let the m-th label be coded as n_1,n_2,…,n_(N-1)，h_{n1,n2,…,n(N-1)}、τ_{n1,n2,…,n(N-1)}Respectively represent codes as n_1,n_2,…,n_(N-1)The amplitude and the time delay of the reflected signal of the SAW sensor tag reflect the relationship equation of the reflected signal of the OFCSAW sensor tag of each time delay and the measurement value of the superposed signal with the same central frequency in the basic time window as follows:

B_eN·H_N＝Y_N

wherein,

H_N＝(h_1,2,...,N-1h_1,2,...,N...h_N,N-1,...,2)^T，

Y_N＝(y₁₁y₁₂...y_1Ny₂₁y₂₂...y_2N......y_(N-1)1y_(N-1)2...y_(N-1)N)^T，

the amplitude and delay calculation of each reflection signal of the (40) is specifically to solve the equation system, namely to obtain an unknown quantity h_{n1,n2,…,n(N-1)}And τ_{n1,n2,…,n(N-1)}. Matrix B_eNFor a total of (N-1) × N columns, N | columns, the mth column corresponds to a particular OFC and is encoded as the column unknown τ_{n1,n2,…,n(N-1)}Or column vector H_NUnknown quantity h of m row_{n1,n2,…,n(N-1)}Subscript n of (1)_1,n_2,…,n_(N-1)M ∈ {1,2, …, N! } line (k-1) × N + N corresponds to the k chip position centered at n.f₀Of the signal of (1). If the (k-1) · N + N elements in a certain column are not zero, it means that the k-th chip center frequency of the reflected signal of the tag is N · f₀。

In engineering practice, the proportional relation of different chip signal amplitudes of OFCSAW sensor tags is extended according to each time, and the proportional relation is set in the matrix B_eNThe respective scaling factors are multiplied in different rows of the respective columns.

The set of equations may be equivalent to (N-1) N complex equations with the number of unknowns being 2N! The solid solution is not unique. So we need to first run from N! And selecting a tag set which can be identified at the same time from the coded SAW sensor tags, so that a unique solution is provided for a relational equation set which adopts the reflected signals of the selected time-extension OFCSAW sensor tags and the measurement values of the superposed signals with the same central frequency in a basic time window.

(50) Code identification: determining whether the SAW sensor with the corresponding code is in a reading range or not by comparing the amplitude calculation value of each reflected signal with a set threshold value;

the (50) code identification is specifically: calculating the amplitude of the reflected signal of each coded label, h_{n1,n2,…,n(N-1)}And comparing with a set threshold value to determine whether the coded label is in a reading range, wherein the selection of the threshold value is specifically determined according to the signal-to-noise ratio of the received signal.

(60) Sensitive information extraction: and extracting the sensitive information according to the relation between the reflected signal parameter of each sensor label and the sensitive information.

Based on the above description, the SAW sensor tag multipath asynchronous reflected signal reading method provided by the invention is subjected to computer simulation verification. The parameters we used in the simulation are shown in table 1, and the chosen simultaneous identifiable time-prolongation OFCSAW tagset encoding is shown in table 2.

TABLE 1SAW sensor multipath asynchronous reflected signal reading method simulation verification parameters

TABLE 2 selected simulation-identifiable time-lapse OFCSAW tag encodings

As shown in fig. 6, firstly, randomly selecting a plurality of tags from a tag set capable of being identified simultaneously and generating a time-delayed OFC asynchronous reflection superimposed signal by simulation, where the asynchronous superimposed signal generated by simulation is shown in fig. 7. Secondly, the amplitude and phase of the asynchronously superimposed signal with the same center frequency in different time windows are measured, and the position of the selected time window is shown in fig. 7. Finally, the amplitude and the time delay of each reflected signal are calculated, and the randomly selected label and the simulation calculation result are shown in fig. 8.

As can be seen from fig. 8, the tag numbers with amplitude much greater than 0 in (b) are the same as the randomly selected tag numbers in (a); and the tag number with amplitude equal to 0 in (b) is the same as the tag number which is not selected in (a). The simulation result shows that the SAW sensor multi-channel asynchronous reflected signal reading method provided by the invention can simultaneously read the information of a plurality of time-delayed OFCSAW sensor tags in a certain range.

A SAW sensor multiple asynchronous reflected signal reading system using the method of the present invention is shown in fig. 9. In this embodiment, the step of simultaneously reading the OFCSAW sensor tags by the reader for time extension within a certain distance range is as follows:

(1) the reader transmits an electromagnetic inquiry signal to trigger the sensor label to reflect time to prolong the OFC signal;

(2) the reader receives a plurality of time delay OFC asynchronous superposed signals, and sampling recording is carried out after down-conversion;

(3) respectively selecting time windows with basic lengths in different chip time ranges of the received asynchronous reflection superposition signals;

(4) measuring the amplitude and the phase of the superposed chip signals with the same central frequency in different time windows;

(5) by solving the system of equations B_eN×H_N＝Y_NAnd calculating the amplitude and the time delay of each reflected signal.

(6) By comparing each reflected signal amplitude calculation value with a set threshold value, whether the corresponding coded SAW sensor is in a reading range is determined.

(7) And extracting the sensitive information according to the relation between the parameters of the reflected signals of each sensor and the sensitive information.

Claims (7)

1. A method for reading a multi-channel asynchronous reflection signal of a SAW sensor is characterized by comprising the following steps:

(10) signal receiving: receiving a plurality of time delay OFC signals within a determined distance range, and performing sampling recording after down-conversion, wherein the time delay OFC signals are asynchronous reflection superposition signals of the SAW sensor tag;

(20) selecting a basic length time window: respectively selecting time windows with basic lengths in different chip time ranges of the received asynchronous reflection superposition signals;

(30) and (3) amplitude and phase measurement: measuring the amplitude and the phase of the superposed chip signals with the same central frequency in different time windows;

(40) amplitude delay calculation: calculating the amplitude and the time delay of each reflected signal by solving an equation set reflecting the relationship between the superposed signal measurement value and the reflected signal of each SAW sensor tag;

(50) code identification: determining whether the SAW sensor with the corresponding code is in a reading range or not by comparing the amplitude calculation value of each reflected signal with a set threshold value;

(60) sensitive information extraction: and extracting the sensitive information according to the relation between the reflected signal parameter of each sensor label and the sensitive information.

2. The signal reading method according to claim 1, wherein in the (10) signal receiving step, the time-delayed OFC signal is composed of N-1 chip signals with different center frequencies, and the time-domain mathematical model is:

$h\left(t\right)=\underset{k=1}{\overset{N-1}{\Σ}}{a}_k\·rect(\frac{t-{\mathrm{\τ}}_{pk}}{{\mathrm{\τ}}_{chip}}-\frac{1}{2})\·cos\[2{\mathrm{\πf}}_{chipk}(t-{\mathrm{\τ}}_{pk})\]$

wherein,

wherein N represents the number of chip selectable center frequencies, an OFC signal is uniquely determined by N-1 frequency arrangements, and the code capacity is N! (ii) a

a_kRepresents the amplitude of the k-th chip signal, k ∈ {1,2, …, N-1 };

τ_pkrepresenting the delay difference of the kth chip compared with the 1 st chip of each coded signal;

f_chipkrepresents the center frequency of the k-th chip;

center frequency f of each chip_chipk＝n·f₀Where N is an integer, and N ∈ {1,2, …, N }, f₀As fundamental frequency, if the k-th chip center frequency of an OFC signal is n_k·f₀Then the code of the OFC signal is n₁,n₂,…,n_(N-1)；

τ_chipRepresents the time length of each chip;

length of time per chip τ_chipFrom a basic length τ_chip0And continuation length tau_MComposition i.e. tau_chip＝τ_chip0+τ_MWherein the basic length τ_chip0＝f₀ ^-1Extension length τ_MAccording to the maximum distance between the measured sensor tag and the readerd_MAnd period determination after down-conversion of different center frequency signals to make tau_MIs greater than the time delay of the reflected signal of each measured sensor label to reach the reader and the time delay tau after the down-conversion of the signal_MThe resulting phase change is less than 2 pi.

3. The signal reading method according to claim 2, wherein in the signal receiving step (10), the time domain mathematical model after the down-conversion of the asynchronous reflection superposition signal is as follows:

$h_M\left(t\right)=\underset{k=1}{\overset{N-1}{\Σ}}\underset{m=1}{\overset{N_t}{\mathrm{\Σ}}}{a}_{mk}\·rect(\frac{t-{\mathrm{\τ}}_{pk}-{\mathrm{\τ}}_{OFCm}}{{\mathrm{\τ}}_{chip}}-\frac{1}{2})\·cos\[2{\mathrm{\πf}}_{chipmk}(t-{\mathrm{\τ}}_{pk}-{\mathrm{\τ}}_{OFCm})\]$

in the formula, N_tThe number of OFCSAW sensor tags which delay the time in the range of the reader is represented;

a_mkthe amplitude of the kth chip of the mth tag reflection signal reaching the reader is represented, and the chip is obtained by reflecting an interrogation signal by the kth reflection grating of the mth tag;

τ_OFCmthe delay of the m-th tag reflected signal reaching the reader is represented;

f_chipmkthe center frequency of the k chip of the m-th tag reflection signal is represented; center frequency f of each chip_chipmk＝n·f₀；

If the k chip center frequency of the m time-delay OFCSAW sensor label reflection signal or the matching frequency of the k reflection grid of the label is n_k·f₀K ∈ {1,2, …, N-1}, then the m-th tag is encoded as N₁,n₂,…,n_(N-1)。

4. A signal reading method according to claim 3, wherein in the step of (20) selecting the basic length time window, the range of the basic length time windows selected in different chip ranges is:

[τ_pk+τ_M,τ_pk+τ_chip]，k∈{1,2,…,N-1}。

5. method for signal reading according to claim 4, characterized in that said (30) amplitude phase measurement step is in particular:

$\frac{2}{{\mathrm{\τ}}_{chip0}}{\∫}_{{\mathrm{\τ}}_M+{\mathrm{\τ}}_{pk}}^{{\mathrm{\τ}}_{pk}+{\mathrm{\τ}}_{chip}}{h}_M\left(t\right)\·cos\[{\mathrm{n\ω}}_0(t-{\mathrm{\τ}}_{pk})\]dt={\mathrm{\α}}_{kn}cos\left({\mathrm{n\ω}}_0{\mathrm{\τ}}_{Fkn}\right),$

$\frac{2}{{\mathrm{\τ}}_{chip0}}{\∫}_{{\mathrm{\τ}}_M+{\mathrm{\τ}}_{p_k}}^{{\mathrm{\τ}}_{p_k}+{\mathrm{\τ}}_{chip}}{h}_M\left(t\right)\·sin\[{\mathrm{n\ω}}_0(t-{\mathrm{\τ}}_{pk})\]dt={\mathrm{\α}}_{kn}sin\left({\mathrm{n\ω}}_0{\mathrm{\τ}}_{Fkn}\right),$

y_kn＝α_kncos(nω₀τ_Fkn)-j·α_knsin(nω₀τ_Fkn)，

wherein, ω is₀＝2πf₀，α_kn、τ_FknRespectively representing the k-th chip position with a center frequency of n · f₀The amplitude and the pseudo-delay of the asynchronously superimposed chip signal α_kn＝|y_kn|，y_knRespectively indicates that the k-th chip position has a center frequency of n · f₀The amplitude and phase of the asynchronously superimposed chip signals.

6. The signal reading method according to claim 5, wherein said (40) amplitude delay calculating step is embodied by solving the following equation set:

B_eN·H_N＝Y_N，

wherein,

H_N＝(h_1,2,...,N-1h_1,2,...,N...h_N,N-1,...,2)^T，

Y_N＝(y₁₁y₁₂...y_1Ny₂₁y₂₂...y_2N......y_(N-1)1y_(N-1)2...y_(N-1)N)^T，

in the formula, h_{n1,n2,…,n(N-1)}、τ_{n1,n2,…,n(N-1)}Respectively represent codes as n₁,n₂,…,n_(N-1)Amplitude and delay, y, of reflected signal from SAW sensor tag_knRespectively indicates that the center frequency in the kth time window is n.f₀The amplitude and phase of the superimposed chip signal.

7. Method for reading a signal according to claim 6, characterized in that said (50) coded identification is in particular: calculating the amplitude of the reflected signal of each coded label, h_{n1,n2,…,n(N-1)}And comparing with a set threshold value to determine whether the coded label is in a reading range, wherein the selection of the threshold value is specifically determined according to the signal-to-noise ratio of the received signal.