CN115112964B - Method and device for recognizing characteristic current code bits after noise addition - Google Patents
Method and device for recognizing characteristic current code bits after noise addition Download PDFInfo
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Abstract
The invention relates to a recognition method and a device for characteristic current code bits after noise addition, which can recognize the code bits of characteristic current added with Gaussian white noise, impulse noise, user power consumption and other noises, the characteristic current after noise addition is processed through the flow steps of cross correlation operation, operation simplification processing, amplification smoothing processing, code bit identification and the like, so that the peak in a new signal is identified, and the code bit of the characteristic current after noise addition is identified. The cross-correlation operation is to perform cross-correlation operation on the noise-added signal and the locally recorded sequence to obtain a new signal, so that code bit identification of the characteristic current can be realized without adopting a digital filter. Compared with the recognition method in the prior art, the code bit recognition method provided by the invention can recognize the code bit of the characteristic current after noise addition without using a digital filter, and reduces the calculation amount required by an algorithm.
Description
Technical Field
The invention relates to the technical field of identification of a topological structure of a transformer area circuit, in particular to a method and a device for identifying characteristic current code bits after noise addition.
Background
At present, the line topology structure of the identification station area mainly has two large directions, one is a scheme capable of directly identifying and judging by directly utilizing a power grid acquisition system without hardware, and the other is a scheme capable of assisting in completing line topology identification by adding new hardware equipment. Regarding the hardware direction, there are various schemes for identifying the topology of the trunking line, one of which is to identify the topology of the trunking line based on the characteristic current, see patent application CN110646690a, in which the implementation of the hardware scheme and the system architecture for the topology identification of the trunking line is described.
For identifying the circuit topology based on the characteristic current, two methods are generally adopted for identifying the characteristic current after noise addition, one method is to convert a time domain signal into a frequency domain by using DFT or FFT, and the information conveyed by the characteristic current is judged through the frequency domain signal and the amplitude value on the characteristic frequency domain. The other is to use a digital filter to retain the frequency of the characteristic current and then use the autocorrelation or cross correlation of the signals to judge the information conveyed by the identification characteristic current. In the technical scheme in the prior art, as the digital filter is required to identify the characteristic code bits, the calculation amount of the algorithm is large, the complexity is high, and the code bit identification speed is influenced.
Disclosure of Invention
Based on the above situation in the prior art, the present invention aims to provide a method and a device for identifying a characteristic current code bit after noise addition, which can identify the code bit of the characteristic current after noise addition without using a digital filter compared with the identification method in the prior art, thereby reducing the calculation amount required by an algorithm.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for identifying a characteristic current code bit after noise addition, comprising the steps of:
performing cross correlation operation on the characteristic current after noise addition to obtain a sequence C;
performing operation simplification processing on the sequence C to obtain a sequence D;
amplifying and smoothing the sequence D to obtain a sequence F;
And carrying out code bit identification on the sequence F to obtain a code bit identification result.
Further, the cross correlation operation on the characteristic current after noise addition includes:
sampling the characteristic current with the time length t after noise adding at a sampling frequency f to obtain a sequence A;
sampling the characteristic current with a period of T and a code bit of 1 according to the same sampling frequency f to obtain a sequence a;
And performing cross-correlation operation on the sequences A and a according to the following formula to obtain a sequence C:
Wherein C (i) is an element of the sequence C, n a is the number of sampling points of the sequence a, and n a =t×f.
Further, the operation simplification processing for the sequence C includes:
for the sequence C, starting from the 1 st point, selecting the largest point from every n s points as an element of the sequence D, so as to form the sequence D;
Where n s is the number of points occupied by a 50Hz sine wave in each sampling period, n s = f/50.
Further, the amplifying and smoothing process for the sequence D includes:
Constructing a sequence e, wherein the sequence e comprises T x f elements, each element is 1, and the number of the sequence e is n e;
performing cross-correlation operation on the sequence D and the sequence e according to the following formula to obtain a sequence F:
Wherein F (i) is an element in the sequence F, and the number of the sequence F is n F＝nD-ne.
Further, the code bit recognition on the sequence F includes:
obtaining the median of the sequence F, and recording as peak_threshold;
Let m be the index of the sequence F, find the index where F (m+1) -F (m) <0 occurs first, and F (m) -F (m-1) >0, and F (m) > peak_threshold, noted as m=a; wherein m=1, 2,3 … … … n F;
Finding m when the F (i) value is maximum from the indexes m=a to m=a+one_cycle_num, and marking the index as m=begin_index; wherein, one_cycle_num =t/0.02;
acquiring the total code number all_num of the sequence F; wherein all_num=t/T;
let j be the value of 1,
When begin_index+ (j-1) one_cycle_num is equal to or less than n F,
F (begin_index+ (j-1) one_cycle_num) > peak_ thershold, the code bit of sequence F (i) at this point is 1, otherwise is 0;
When begin _ index + (j-1) one _ cycle _ num > n F,
F (n F) > peak_ thershold, the code bit of the sequence F (i) at this point is 1, otherwise is 0;
if j < all+num, j=j+1, repeating the above steps; otherwise, ending.
According to another aspect of the present invention, there is provided an apparatus for recognizing a code bit of a noisy characteristic current, including a cross correlation operation module, an operation simplification processing module, an amplification smoothing processing module, and a code bit recognition module; wherein,
The cross-correlation operation module performs cross-correlation operation on the characteristic current after noise addition to obtain a sequence C;
The operation simplification processing module performs operation simplification processing on the sequence C to obtain a sequence D;
The amplifying and smoothing processing module is used for amplifying and smoothing the sequence D to obtain a sequence F;
And the code bit recognition module is used for carrying out code bit recognition on the sequence F to obtain a code bit recognition result.
Further, the cross-correlation operation module performs cross-correlation operation on the characteristic current after noise addition, and includes:
sampling the characteristic current with the time length t after noise adding at a sampling frequency f to obtain a sequence A;
sampling the characteristic current with a period of T and a code bit of 1 according to the same sampling frequency f to obtain a sequence a;
And performing cross-correlation operation on the sequences A and a according to the following formula to obtain a sequence C:
Wherein C (i) is an element of the sequence C, n a is the number of sampling points of the sequence a, and n a =t×f.
Further, the operation simplification processing module performs operation simplification processing on the sequence C, including:
for the sequence C, starting from the 1 st point, selecting the largest point from every n s points as an element of the sequence D, so as to form the sequence D;
Where n s is the number of points occupied by a 50Hz sine wave in each sampling period, n s = f/50.
Further, the amplifying and smoothing processing module performs amplifying and smoothing processing on the sequence D, including:
Constructing a sequence e, wherein the sequence e comprises T x f elements, each element is 1, and the number of the sequence e is n e;
performing cross-correlation operation on the sequence D and the sequence e according to the following formula to obtain a sequence F:
Wherein F (i) is an element in the sequence F, and the number n F＝nD-ne of F (i) in the sequence F.
Further, the code bit recognition module performs code bit recognition on the sequence F, and includes:
obtaining the median of the sequence F, and recording as peak_threshold;
Let i be the index of the sequence F, find the index where F (i+1) -F (i) <0 occurs first, and F (i) -F (i-1) >0, and F (i) > peak_threshold, noted as i=a; wherein i=1, 2,3 … … … n F;
Finding i when the F (i) value is maximum from the indexes i=a to i=a+one_cycle_num, and marking the index as i=begin_index; wherein, one_cycle_num =t/0.02;
acquiring the total code number all_num of the sequence F; wherein all_num=t/T;
let j be the value of 1,
When begin_index+ (j-1) one_cycle_num is equal to or less than n F,
F (begin_index+ (j-1) one_cycle_num) > peak_ thershold, the code bit of sequence F (i) at this point is 1, otherwise is 0;
When begin _ index + (j-1) one _ cycle _ num > n F,
F (n F) > peak_ thershold, the code bit of the sequence F (i) at this point is 1, otherwise is 0;
if j < all+num, j=j+1, repeating the above steps; otherwise, ending.
In summary, the present invention provides a method and an apparatus for recognizing a code bit of a characteristic current after noise addition, which can recognize the code bit of the characteristic current after noise addition such as white gaussian noise, impulse noise, and user power consumption. The cross-correlation operation is to perform cross-correlation operation on the noise-added signal and the locally recorded sequence to obtain a new signal, so that code bit identification of the characteristic current can be realized without adopting a digital filter. Compared with the recognition method in the prior art, the code bit recognition method provided by the invention can recognize the code bit of the characteristic current after noise addition without using a digital filter, reduces the calculation amount required by the algorithm, reduces the complexity of the method because the algorithm does not need a filter, and can still use the algorithm under the condition of non-ideal digital filtering, so that the algorithm is simpler to use and wider in application range.
Drawings
FIG. 1 is a flow chart of a method for identifying characteristic current code bits after noise addition according to the invention;
FIG. 2a is a waveform diagram of a characteristic current, and FIG. 2b is a code bitmap of the characteristic current;
FIG. 3 is a waveform diagram of a characteristic current after noise addition;
FIG. 4 is a flowchart of an enlarged smoothing process;
FIG. 5 is a cross-correlation and amplification smoothing comparison;
FIG. 6 is a flow chart of a code bit identification process;
Fig. 7 is a block diagram showing the constitution of the recognition device of characteristic current code bits after noise addition according to the present invention.
Detailed Description
The objects, technical solutions and advantages of the present invention will become more apparent by the following detailed description of the present invention with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the invention. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present invention.
The following describes the technical scheme of the present invention in detail with reference to the accompanying drawings. According to one embodiment of the invention, a method for identifying the code bits of the characteristic current after noise addition is provided, and the method identifies the peaks in the obtained new signals by performing flow steps such as cross correlation operation, operation simplification processing, amplification smoothing processing, code bit identification and the like on the characteristic current after noise addition, so as to identify the code bits of the characteristic current after noise addition. The flowchart of the identification method in this embodiment is shown in fig. 1, and includes the steps of:
performing cross correlation operation on the characteristic current after noise addition to obtain a sequence C;
performing operation simplification processing on the sequence C to obtain a sequence D;
amplifying and smoothing the sequence D to obtain a sequence F;
And carrying out code bit identification on the sequence F to obtain a code bit identification result.
The above steps of the method are specifically described below. The identification method is used for identifying the code bits of the characteristic current after noise adding, wherein the noise adding comprises Gaussian white noise, impulse noise, noise generated by household user electricity and the like.
Firstly, performing cross correlation operation on the characteristic current after noise addition to obtain a sequence C. The cross-correlation operation is to perform cross-correlation operation on the noise-added signal and the locally recorded sequence to obtain a new signal. When the receiver receives the current sequence, the cross correlation operation is performed on the current sequence, the waveform in fig. 2a is a waveform diagram of the characteristic current, fig. 2b is a code bitmap of the characteristic current, and the sliding point multiplication is performed on the denoised signal by using the signal with one period of the code bit of 1 in fig. 2b, so as to obtain a new signal. The step of cross-correlation operation may be performed as follows:
sampling the characteristic current with the time length t after noise adding at a sampling frequency f to obtain a sequence A;
sampling the characteristic current with a period of T and a code bit of 1 according to the same sampling frequency f to obtain a sequence a;
And performing cross-correlation operation on the sequences A and a according to the following formula to obtain a sequence C:
Wherein C (i) is the i-th element of the sequence C, n a is the number of sampling points of the sequence a, and n a =t×f. i represents the i-th element of the sequence C, the total number of which is related to the number of elements of the sequence a, n C＝nA–na, where n C is the number of elements of the sequence C, n A is the number of elements of the sequence a, n A＝t*f,na = T f, and T is the time period required to transmit one code bit.
The waveform in fig. 2a is a waveform diagram of the characteristic current, which is formed on the ac of the grid at a switching frequency of 833.3 Hz; FIG. 2b is a code bit map of the signature current, when the code bit is 0, the switch is turned off; when the code bit is 1, the characteristic current waveform in fig. 2a is formed, and the period of the code is 0.6s.
Fig. 3 shows the characteristic current representing the code bits plus gaussian white noise, impulse noise and user current noise, the signal shown in fig. 3 being the current sequence sampled by the receiver, with a sampling frequency of 5kHz.
Because of the electricity consumption of multiple users, the current amplitude is relatively large, and the maximum amplitude is about 250A, so that the signal of 0.06A of the characteristic current is totally submerged in noise. At this time, the common practice is to filter out 50Hz household electricity and then to perform autocorrelation or cross correlation operation, and the invention provides a new method, the core thought of which is to filter out the influence of 50Hz household electricity without a filter, and when the code bit of the characteristic current is 1, the change trend of the code bit information of the sampling current after noise addition is not obvious due to the influence of noise, but the trend is still contained in the current curve. When the characteristic current code bit is 1, from the single sampling point, the influence of noise is larger, and the integral change trend of a plurality of sampling points with the current code bit of 1 is more accurate than that of the single sampling point, so that the characteristic current code bit can be represented, the amplitude is 1, the number of the sequence points is equal to the number of the current code bit sampled points, and the sequence is subjected to cross correlation operation with the original sequence, thereby amplifying the change trend and resisting the interference of noise. The method is specifically described below:
And carrying out cross-correlation operation on the unfiltered signal to obtain a new signal, and carrying out amplification smoothing treatment on the signal. Before this processing is performed, a simple operation simplification processing can be performed. The operation is simplified, namely, the maximum electricity is selected from each sine wave period to represent the characteristic of each sine wave period, and the sequence D is obtained after the processing.
After the sequence C is obtained through cross-correlation operation, the sequence C is subjected to operation simplification processing to obtain a sequence D, and the operation simplification processing is to extract a part of signals to be processed according to a rule to form new signals, and the operation simplification processing can be performed by adopting the following steps:
for the sequence C, starting from the 1 st point, selecting the largest point from every n s points as an element of the sequence D, so as to form the sequence D;
Where n s is the number of points occupied by a 50Hz sine wave in each sampling period, n s = f/50.
And amplifying and smoothing the sequence D to obtain a sequence F. The amplification smoothing process is to amplify some rules hidden in the signal and smooth the compared jitter signal to obtain a new signal, so as to facilitate the next recognition step. In fig. 4, a flowchart of an amplifying smoothing process is shown, which mainly has two steps, the first step is to construct a new sequence e, the number of points of the sequence is the same as the number of samples with 1 code bit, and each value of the sequence is 1; and secondly, taking sliding point multiplication by using the new sequence e and the new sequence D, thereby obtaining a new sequence F. The amplifying and smoothing step aims to mine code bit information which cannot be reflected from the cross-correlation sequence, so that hidden information is amplified and can be normally identified. A comparison of cross-correlation and amplification smoothing is shown in fig. 5. The specific steps of the amplification smoothing process may be as follows:
Constructing a sequence e, wherein the sequence e comprises T x f elements, each element is 1, and the number of the sequence e is n e;
performing cross-correlation operation on the sequence D and the sequence e according to the following formula to obtain a sequence F:
Wherein F (i) is an element in the sequence F, and the number n F＝nD-ne,nD of F (i) in the sequence F represents the number of elements in the sequence D, n D may be calculated in some ways:
Every n s sampling points (n s =f/50) from the sequence C, the largest point is selected from among them to form a new sequence D, n D＝nC/ns.
After the sequence F of the recognizable peaks is obtained through the amplification and smoothing process, the code bit recognition can be performed on the sequence F, and the code bit judgment flow shown in fig. 6 can be referred to. Firstly, solving some characteristic thresholds in a sequence F, then roughly positioning a sequence index from which a code bit 1 starts, then finding a point with the largest amplitude in a next code bit period according to the index, taking the point as a middle point of the code bit 1, finally, according to the point, presuming the middle point of each code bit after the sequence, and judging the condition of the code bit by utilizing the threshold. The code bit identification can be specifically performed by the following steps:
obtaining the median of the sequence F, and recording as peak_threshold;
Let m be the index of the sequence F, find the index where F (m+1) -F (m) <0 occurs first, and F (m) -F (m-1) >0, and F (m) > peak_threshold, record the corresponding index m as m=a; wherein m=1, 2,3 … … … n F;
Finding out an index value m corresponding to the maximum value of F (m) from the indexes m=a to m=a+one_cycle_num, and marking the index as m=begin_index; wherein, one_cycle_num =t/0.02;
acquiring the total code number all_num of the sequence F; wherein all_num=t/T;
let j be the value of 1,
When begin_index+ (j-1) one_cycle_num is equal to or less than n F,
F (begin_index+ (j-1) one_cycle_num) > peak_ thershold, the code bit of sequence F (m) at this point is 1, otherwise is 0;
When begin _ index + (j-1) one _ cycle _ num > n F,
F (n F) > peak_ thershold, the code bit of the sequence F (m) is 1 at this point, otherwise is 0;
If j < all+num, j=j+1, repeating the above steps to search again; otherwise, the code bit identification process is ended.
According to another embodiment of the present invention, a device for recognizing a code bit of a characteristic current after noise addition is provided, and a block diagram of the device is shown in fig. 7, and the device includes a cross correlation operation module, an operation simplification processing module, an amplification smoothing processing module, and a code bit recognition module. The modules are connected with each other in sequence to recognize the code bits of the characteristic current after noise addition. The functions of the respective modules are explained below.
The cross-correlation operation module is used for carrying out cross-correlation operation on the characteristic current after noise addition to obtain a sequence C: sampling the characteristic current with the time length t after noise adding at a sampling frequency f to obtain a sequence A;
sampling the characteristic current with a period of T and a code bit of 1 according to the same sampling frequency f to obtain a sequence a;
And performing cross-correlation operation on the sequences A and a according to the following formula to obtain a sequence C:
Wherein C (i) is an element of the sequence C, n a is the number of sampling points of the sequence a, and n a =t×f.
The operation simplification processing module is used for carrying out operation simplification processing on the sequence C to obtain a sequence D: for the sequence C, starting from the 1 st point, selecting the largest point from every n s points as an element of the sequence D, so as to form the sequence D;
Where n s is the number of points occupied by a 50Hz sine wave in each sampling period, n s = 50/f.
The amplifying and smoothing processing module is used for amplifying and smoothing the sequence D to obtain a sequence F: constructing a sequence e, wherein the sequence e comprises T x f elements, each element is 1, and the number of the sequence e is n e;
performing cross-correlation operation on the sequence D and the sequence e according to the following formula to obtain a sequence F:
Wherein F (i) is an element in the sequence F, and the number n F＝nD-ne of F (i) in the sequence F.
The code bit recognition module is used for carrying out code bit recognition on the sequence F to obtain a code bit recognition result:
obtaining the median of the sequence F, and recording as peak_threshold;
let m be the index of the sequence F, find the index where F (m+1) -F (m) <0 occurs first, and F (m) -F (m-1) >0, and F (m) > peak_threshold, noted as m=a; wherein m=1, 2,3 … … n F;
finding m when the F (m) value is maximum from the indexes m=a to m=a+one_cycle_num, and marking the index as m=begin_index; wherein, one_cycle_num =t/0.02;
acquiring the total code number all_num of the sequence F; wherein all_num=t/T;
let j be the value of 1,
When begin_index+ (j-1) one_cycle_num is equal to or less than n F,
F (begin_index+ (j-1) one_cycle_num) > peak_ thershold, the code bit of sequence F (i) at this point is 1, otherwise is 0;
When begin _ index + (j-1) one _ cycle _ num > n F,
F (n F) > peak_ thershold, the code bit of the sequence F (m) is 1 at this point, otherwise is 0;
if j < all+num, j=j+1, repeating the above steps; otherwise, the code bit identification process is ended.
In summary, the present invention relates to a method and an apparatus for recognizing a code bit of a characteristic current after noise addition, which can recognize the code bit of the characteristic current after noise addition such as white gaussian noise, impulse noise, and user power consumption. The cross-correlation operation is to perform cross-correlation operation on the noise-added signal and the locally recorded sequence to obtain a new signal, so that code bit identification of the characteristic current can be realized without adopting a digital filter. Compared with the recognition method in the prior art, the code bit recognition method provided by the invention can recognize the code bit of the characteristic current after noise addition without using a digital filter, and reduces the calculation amount required by an algorithm.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explanation of the principles of the present invention and are in no way limiting of the invention. Accordingly, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention should be included in the scope of the present invention. Furthermore, the appended claims are intended to cover all such changes and modifications that fall within the scope and boundary of the appended claims, or equivalents of such scope and boundary.
Claims (2)
1. The method for identifying the characteristic current code bits after noise addition is characterized by comprising the following steps:
performing cross correlation operation on the denoised characteristic current to obtain a sequence C, wherein the cross correlation operation comprises the following steps:
sampling the characteristic current with the time length t after noise adding at a sampling frequency f to obtain a sequence A;
sampling the characteristic current with a period of T and a code bit of 1 according to the same sampling frequency f to obtain a sequence a;
And performing cross-correlation operation on the sequences A and a according to the following formula to obtain a sequence C:
Wherein C (i) is the i-th element of the sequence C, n a is the number of sampling points of the sequence a, n a =t×f;
performing operation simplification processing on the sequence C to obtain a sequence D, wherein the operation simplification processing comprises the following steps:
for the sequence C, starting from the 1 st point, selecting the largest point from every n s points as an element of the sequence D, so as to form the sequence D;
Wherein n s is the number of sampling points occupied by the 50Hz sine wave in each period, and n s =f/50;
amplifying and smoothing the sequence D to obtain a sequence F, wherein the amplifying and smoothing comprises the following steps:
Constructing a sequence e, wherein the sequence e comprises T x f elements, each element is 1, and the number of the elements of the sequence e is n e;
performing cross-correlation operation on the sequence D and the sequence e according to the following formula to obtain a sequence F:
Wherein F (i) is an element in the sequence F, and the number n F＝nD-ne,nD of F (i) in the sequence F is the number of elements in the sequence D;
performing code bit recognition on the sequence F to obtain a code bit recognition result, wherein the code bit recognition result comprises the following steps:
obtaining the median of the sequence F, and recording as peak_threshold;
Let m be the index of the sequence F, find the index where F (m+1) -F (m) <0 occurs first, and F (m) -F (m-1) >0, and F (m) > peak_threshold, noted as m=k; wherein m=1, 2,3 … … … n F;
Finding m when the value of F (m) is maximum from the indexes m=k to m=k+one_cycle_num, and marking the index as m=begin_index; wherein, one_cycle_num =t/0.02;
acquiring the total code number all_num of the sequence F; wherein all_num=t/T;
let j be the value of 1,
Step (1), when begin_index+ (j-1) one_cycle_num is less than or equal to n F,
F (begin_index+ (j-1) one_cycle_num) > peak_ thershold, the code bit of sequence F (m) at this point is 1, otherwise is 0;
step (2), when begin_index+ (j-1) one_cycle_num > n F,
F (n F) > peak_ thershold, the code bit of the sequence F (m) is 1 at this point, otherwise is 0;
Step (3), if j < all+num, j=j+1, repeating steps (1) - (3); otherwise, ending.
2. The recognition device of the characteristic current code bits after noise addition is characterized by comprising a cross correlation operation module, an operation simplification processing module, an amplification smoothing processing module and a code bit recognition module; wherein,
The cross-correlation operation module performs cross-correlation operation on the denoised characteristic current to obtain a sequence C, and the cross-correlation operation module comprises:
sampling the characteristic current with the time length t after noise adding at a sampling frequency f to obtain a sequence A;
sampling the characteristic current with a period of T and a code bit of 1 according to the same sampling frequency f to obtain a sequence a;
And performing cross-correlation operation on the sequences A and a according to the following formula to obtain a sequence C:
Wherein C (i) is an element of the sequence C, n a is the number of sampling points of the sequence a, and n a =t×f;
the operation simplifying processing module performs operation simplifying processing on the sequence C to obtain a sequence D, and the operation simplifying processing module comprises the following steps:
for the sequence C, starting from the 1 st point, selecting the largest point from every n s points as an element of the sequence D, so as to form the sequence D;
wherein n s is the number of points occupied by a 50Hz sine wave in each sampling period, n s =f/50;
the amplifying and smoothing processing module is used for amplifying and smoothing the sequence D to obtain a sequence F, and the amplifying and smoothing processing module comprises the following steps:
Constructing a sequence e, wherein the sequence e comprises T x f elements, each element is 1, and the number of the sequence e is n e;
performing cross-correlation operation on the sequence D and the sequence e according to the following formula to obtain a sequence F:
Wherein F (i) is an element in a sequence F, and the number n F＝nD-ne of F (i) in the sequence F;
The code bit recognition module performs code bit recognition on the sequence F to obtain a code bit recognition result, and the code bit recognition module comprises:
obtaining the median of the sequence F, and recording as peak_threshold;
Let m be the index of the sequence F, find the index where F (m+1) -F (m) <0 occurs first, and F (m) -F (m-1) >0, and F (m) > peak_threshold, noted as m=k; wherein m=1, 2,3 … … … n F;
Finding m when the value of F (m) is maximum from the indexes m=k to m=k+one_cycle_num, and marking the index as m=begin_index; wherein, one_cycle_num =t/0.02;
acquiring the total code number all_num of the sequence F; wherein all_num=t/T;
let j be the value of 1,
Step (1), when begin_index+ (j-1) one_cycle_num is less than or equal to n F,
F (begin_index+ (j-1) one_cycle_num) > peak_ thershold, the code bit of sequence F (m) at this point is 1, otherwise is 0;
step (2), when begin_index+ (j-1) one_cycle_num > n F,
F (n F) > peak_ thershold, the code bit of the sequence F (m) is 1 at this point, otherwise is 0;
Step (3), if j < all+num, j=j+1, repeating steps (1) - (3); otherwise, ending.
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