CN111800359B

CN111800359B - Method, device, equipment and medium for identifying communication signal modulation mode

Info

Publication number: CN111800359B
Application number: CN202010928516.8A
Authority: CN
Inventors: 熊俊; 魏急波; 赵肖迪; 赵海涛; 周宣含; 李芳�; 周力; 张晓瀛; 辜方林
Original assignee: National University of Defense Technology
Current assignee: National University of Defense Technology
Priority date: 2020-09-07
Filing date: 2020-09-07
Publication date: 2020-12-04
Anticipated expiration: 2040-09-07
Also published as: CN111800359A

Abstract

The invention discloses a method for identifying a communication signal modulation mode, which comprises the following steps: acquiring characteristic values of the signals, wherein the characteristic values are a plurality of characteristic values extracted from the signals respectively from a statistical characteristic angle and a high-order cumulant angle; acquiring a judgment threshold corresponding to each characteristic value; and comparing the plurality of characteristic values of the signal by using the judgment threshold value, and identifying the modulation mode of the signal according to the comparison result. Therefore, when the modulation mode of the communication signal is identified, the feature values need to be respectively extracted from two angles of the statistical feature and the high-order cumulant, the extracted feature values are compared with the correspondingly set judgment threshold, the modulation mode of the signal can be identified according to the comparison result, and through the method, the identification rate is improved, and the identifiable modulation type is increased. The invention also discloses a device, equipment and a storage medium for identifying the communication signal modulation mode, and the technical effects can be realized.

Description

Method, device, equipment and medium for identifying communication signal modulation mode

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method, an apparatus, a device, and a medium for identifying a modulation scheme of a communication signal.

Background

At present, modulation signal identification is an important step between signal detection and signal demodulation, and aims to determine a modulation mode of a signal and estimate corresponding modulation parameters by processing a received signal without other prior knowledge. It finds application mainly in two areas: on one hand, the software radio system ensures the intercommunication and interconnection among communication systems of different systems; and the electronic warfare system provides a basis for intercepting information and selecting the optimal interference pattern. Modulation is an important feature for distinguishing between communication signals of different nature. For correctly demodulating, analyzing or interfering a received signal, the modulation scheme of the signal must be correctly identified, and then a corresponding demodulation method or interference method is adopted, so that the identification of the modulation scheme of the communication signal is important.

In the past years, many of the recognition algorithms for analog and digital signals can be summarized as follows: nandi and Azzouz propose three modulation identification algorithms, mainly aiming at amplitude modulation AM, frequency modulation FM, double sideband modulation DSB, lower sideband modulation LSB, upper sideband modulation USB, vestigial sideband modulation VSB, combined (AM-FM), binary amplitude keying 2ASK, quaternary amplitude keying 4ASK, binary phase shift keying 2PSK, quaternary phase shift keying 4PSK, binary digital frequency modulation 2FSK and quaternary digital frequency modulation 4FSK, when the signal-to-noise ratio is 15dB, the average identification probability reaches 94%; some scholars such as Sun adopt a deep learning method based on a VGG convolutional neural network model (VGG convolutional neural network model) to realize 6 common digital modulation signal identifications, and the identification rate reaches 98% under the condition that the signal-to-noise ratio is-2 dB; talieh adopts four features as input of a support vector machine, provides a fuzzy multi-class classification method for identifying 3 different types of digital modulation signals, achieves the identification precision of 77% when the signal-to-noise ratio is 10dB, and is unsatisfactory in performance.

Therefore, how to increase the recognition accuracy of the modulation scheme is a problem to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to provide a method, a device, equipment and a medium for identifying a communication signal modulation mode, so as to improve the identification accuracy of a debugging mode and increase the identifiable modulation mode.

In order to achieve the above object, a method for identifying a modulation scheme of a communication signal according to the present invention includes:

acquiring characteristic values of a signal, wherein the characteristic values are a plurality of characteristic values extracted from the signal respectively from a statistical characteristic angle and a high-order cumulant angle, and the characteristic values comprise the following steps: the method comprises the following steps of (1) obtaining a first standard deviation, a second standard deviation, a symmetry parameter value, an instantaneous amplitude spectrum density maximum value, an average value of instantaneous amplitude absolute values, a compactness parameter value of instantaneous frequency and a high-order cumulant parameter value; the first standard deviation is the standard deviation after the nonlinear phase centering of the zero-center non-weak signal segment is adopted; the second standard deviation is the standard deviation of the absolute value of the nonlinear instantaneous phase of the non-weak signal with a zero center;

acquiring a judgment threshold corresponding to each characteristic value;

comparing the plurality of characteristic values of the signal by using the judgment threshold value, and identifying the modulation mode of the signal according to the comparison result;

the method for acquiring the compactness parameter value of the instantaneous frequency comprises the following steps:

calculating an instantaneous frequency average value of the signal according to each instantaneous frequency in the signal, and obtaining an instantaneous frequency absolute value of each instantaneous frequency and the instantaneous frequency average value;

acquiring first length information of the signal and second length information of which the absolute value of the instantaneous frequency in the signal is greater than half of the code element rate;

and determining a compactness parameter value of the instantaneous frequency by using the ratio of the second length information to the first length information.

Wherein the comparing the plurality of characteristic values of the signal with the decision threshold and identifying the modulation mode of the signal according to the comparison result comprises:

if the first standard deviation is larger than a first standard deviation judgment threshold value, judging whether the second standard deviation is larger than a third standard deviation judgment threshold value; if not, the modulation mode of the signal is determined as follows: a DSB;

if so, judging whether the symmetry parameter value is greater than or equal to a first symmetry judgment threshold value;

if yes, the modulation mode of the signal is determined as follows: LSB; if not, the modulation mode of the signal is determined as follows: and (7) USB.

if the first standard deviation is not larger than a first standard deviation judgment threshold value and the symmetry parameter value is smaller than or equal to a second symmetry judgment threshold value, judging whether the compactness parameter value of the instantaneous frequency is larger than a compactness judgment threshold value or not;

if so, judging whether the maximum value of the instantaneous amplitude spectrum density is larger than an instantaneous amplitude spectrum density judgment threshold value; if yes, the modulation mode of the signal is determined as follows: AM; if not, the modulation mode of the signal is determined as follows: FM;

if not, judging whether the first standard deviation is larger than a second standard deviation judgment threshold value; if yes, the modulation mode of the signal is determined as follows: 2 FSK; if not, the modulation mode of the signal is determined as follows: 4 FSK.

if the first standard deviation is not larger than a first standard deviation judgment threshold value, and the symmetry parameter value is larger than a second symmetry judgment threshold value and smaller than a third symmetry judgment threshold value, judging whether a sixth-order cumulant parameter value is larger than a first-order cumulant judgment threshold value;

if yes, the modulation mode of the signal is determined as follows: BPSK; if not, judging whether the fourth-order cumulant parameter value is larger than a second high-order cumulant judgment threshold value;

if the second high-order cumulant is larger than the second high-order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: QPSK; if the second high-order cumulant is not larger than the second high-order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: 8 PSK.

if the first standard deviation is not larger than a first standard deviation judgment threshold value and the symmetry parameter value is larger than or equal to a third symmetry judgment threshold value, judging whether the average value of the instantaneous amplitude absolute values is larger than the instantaneous amplitude absolute value judgment threshold value or not;

if yes, the modulation mode of the signal is determined as follows: pi/4-DQPSK; if not, judging whether the sixth-order cumulant parameter value is larger than a third high-order cumulant judgment threshold value;

if the second order cumulant is larger than the second order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: 2 ASK; if the signal is not larger than the third high-order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: 4 ASK.

In order to achieve the above object, the present invention further provides an apparatus for identifying a modulation scheme of a communication signal, comprising:

the characteristic value obtaining module is used for obtaining a characteristic value of the signal, wherein the characteristic value is a plurality of characteristic values extracted from the signal from a statistical characteristic angle and a high-order cumulant angle respectively, and the characteristic value obtaining module comprises the following steps: the method comprises the following steps of (1) obtaining a first standard deviation, a second standard deviation, a symmetry parameter value, an instantaneous amplitude spectrum density maximum value, an average value of instantaneous amplitude absolute values, a compactness parameter value of instantaneous frequency and a high-order cumulant parameter value; the first standard deviation is: adopting a standard deviation after the non-linear phase centralization of a zero-center non-weak signal segment; the second standard deviation is: using the standard deviation of the non-linear instantaneous phase absolute value of the zero center non-weak signal;

a decision threshold acquisition module for acquiring a decision threshold corresponding to each feature value;

the characteristic value comparison module is used for comparing a plurality of characteristic values of the signal by using the judgment threshold value and identifying the modulation mode of the signal according to the comparison result;

the compactness parameter value acquisition module is used for calculating an instantaneous frequency average value of the signal according to each instantaneous frequency in the signal and acquiring an instantaneous frequency absolute value of each instantaneous frequency and the instantaneous frequency average value; acquiring first length information of the signal and second length information of which the absolute value of the instantaneous frequency in the signal is greater than half of the code element rate; and determining a compactness parameter value of the instantaneous frequency by using the ratio of the second length information to the first length information.

Wherein the characteristic value comparison module comprises:

a first judgment unit configured to judge whether or not the second standard deviation is greater than a third standard deviation determination threshold value if the first standard deviation is greater than a first standard deviation determination threshold value; if not, the modulation mode of the signal is determined as follows: a DSB; if yes, triggering a second judgment unit;

the second judging unit is used for judging whether the symmetry parameter value is greater than or equal to a first symmetry judging threshold value; if yes, the modulation mode of the signal is determined as follows: LSB; if not, the modulation mode of the signal is determined as follows: and (7) USB.

Wherein the characteristic value comparison module comprises:

a third determination unit configured to determine whether or not the value of the degree of compactness parameter of the instantaneous frequency is greater than a degree of compactness determination threshold value when the first standard deviation is not greater than a first standard deviation determination threshold value and the value of the symmetry parameter is not greater than a second symmetry determination threshold value; if yes, triggering a fourth judging unit, and if not, triggering a fifth judging unit;

the fourth judging unit is used for judging whether the maximum value of the instantaneous amplitude spectrum density is larger than the instantaneous amplitude spectrum density judging threshold value or not; if yes, the modulation mode of the signal is determined as follows: AM; if not, the modulation mode of the signal is determined as follows: FM;

the fifth judging unit is used for judging whether the first standard deviation is larger than a second standard deviation judging threshold value or not; if yes, the modulation mode of the signal is determined as follows: 2 FSK; if not, the modulation mode of the signal is determined as follows: 4 FSK.

To achieve the above object, the present invention further provides an electronic device comprising:

a memory for storing a computer program;

and a processor for implementing the steps of the method for identifying a modulation scheme of a communication signal when executing the computer program.

To achieve the above object, the present invention further provides a computer-readable storage medium, which stores a computer program, and the computer program, when executed by a processor, implements the steps of the method for identifying a modulation scheme of a communication signal.

According to the above scheme, the method for identifying the modulation mode of the communication signal provided by the embodiment of the invention comprises the following steps: acquiring characteristic values of a signal, wherein the characteristic values are a plurality of characteristic values extracted from the signal respectively from a statistical characteristic angle and a high-order cumulant angle, and the characteristic values comprise the following steps: the method comprises the following steps of (1) obtaining a first standard deviation, a second standard deviation, a symmetry parameter value, an instantaneous amplitude spectrum density maximum value, an average value of instantaneous amplitude absolute values, a compactness parameter value of instantaneous frequency and a high-order cumulant parameter value; the first standard deviation is the standard deviation after the nonlinear phase centering of the zero-center non-weak signal segment is adopted; the second standard deviation is the standard deviation of the absolute value of the nonlinear instantaneous phase of the non-weak signal with a zero center; acquiring a judgment threshold corresponding to each characteristic value; comparing the plurality of characteristic values of the signal by using the judgment threshold value, and identifying the modulation mode of the signal according to the comparison result; the method for acquiring the compactness parameter value of the instantaneous frequency comprises the following steps: calculating an instantaneous frequency average value of the signal according to each instantaneous frequency in the signal, and obtaining an instantaneous frequency absolute value of each instantaneous frequency and the instantaneous frequency average value; acquiring first length information of the signal and second length information of which the absolute value of the instantaneous frequency in the signal is greater than half of the code element rate; and determining a compactness parameter value of the instantaneous frequency by using the ratio of the second length information to the first length information.

Therefore, when the modulation mode of the communication signal is identified, the characteristic values need to be respectively extracted from two angles of the statistical characteristic and the high-order cumulant, the extracted characteristic values are compared with the correspondingly set judgment threshold value, the modulation mode of the signal can be identified according to the comparison result, and through the mode, the identification rate is improved, and the identifiable modulation type is increased; in addition, the application also provides a compactness characteristic parameter, and the parameter overcomes the condition that the signals are under higher signal-to-noise ratio or the identification number is less in the prior art, and realizes the modulation identification of various signals under low signal-to-noise ratio. The invention also discloses a device, equipment and a storage medium for identifying the communication signal modulation mode, and the technical effects can be realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic flow chart of a method for identifying a modulation scheme of a communication signal according to an embodiment of the present invention;

fig. 2 is a schematic flow chart of a specific modulation scheme identification method according to an embodiment of the present invention;

FIG. 3a is a schematic diagram of a classification based on a first standard deviation according to an embodiment of the present invention;

FIG. 3b is a schematic diagram of another classification based on the first standard deviation according to the embodiment of the present invention;

FIG. 4 is a diagram illustrating a classification based on a second standard deviation according to an embodiment of the present invention;

FIG. 5a is a schematic diagram of a classification based on symmetry parameter values according to an embodiment of the present invention;

FIG. 5b is a schematic diagram of another symmetry-based parameter value classification according to the embodiment of the present invention;

FIG. 6 is a schematic diagram of a classification based on the maximum value of the instantaneous amplitude spectrum density according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of classification based on the average of absolute values of instantaneous amplitudes according to an embodiment of the present invention;

FIG. 8 is a schematic diagram illustrating classification of an average value of a compactness parameter based on instantaneous frequency according to an embodiment of the present invention;

FIG. 9a is a schematic diagram illustrating a classification based on a high-order cumulant parameter value according to an embodiment of the present invention;

FIG. 9b is a schematic diagram illustrating another classification based on high-order cumulant parameter values according to an embodiment of the present invention;

FIG. 9c is a schematic diagram of another classification based on high-order cumulant parameter values according to the disclosure of the present invention;

FIG. 10 is a diagram illustrating modulation recognition probabilities of respective signals according to variations between SNR according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of an apparatus for identifying a modulation scheme of a communication signal according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of an electronic device according to an embodiment of the disclosure.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention discloses a method, a device, equipment and a medium for identifying a communication signal modulation mode, which aim to improve the identification accuracy of a debugging mode and increase the identifiable modulation mode.

Referring to fig. 1, a method for identifying a modulation scheme of a communication signal according to an embodiment of the present invention includes:

s101, obtaining characteristic values of the signals, wherein the characteristic values are a plurality of characteristic values extracted from the signals respectively from a statistical characteristic angle and a high-order cumulant angle;

it should be noted that, when identifying the modulation mode, the present application specifically identifies the modulation mode by combining two-dimensional features, i.e., the statistical features and the high-order cumulant, and can identify the modulation modes of a plurality of analog and digital signals under the condition of a low signal-to-noise ratio, and has strong robustness to gaussian noise.

Specifically, the characteristic values of the signals acquired in the present application include: the method comprises the following steps of (1) obtaining a first standard deviation, a second standard deviation, a symmetry parameter value, an instantaneous amplitude spectrum density maximum value, an average value of instantaneous amplitude absolute values, a compactness parameter value of instantaneous frequency and a high-order cumulant parameter value; wherein the first standard deviation is: adopting a standard deviation after the non-linear phase centralization of a zero-center non-weak signal segment; the second standard deviation is: the standard deviation of the non-linear instantaneous phase absolute value of the zero center non-weak signal is used. Further, among the above-mentioned feature values, the first standard deviation, the second standard deviation, the symmetry parameter value, the maximum value of the instantaneous amplitude spectral density, the average value of the instantaneous amplitude absolute value, and the compactness parameter value of the instantaneous frequency are feature values extracted from a statistical feature angle, and the higher-order cumulant parameter value is a feature value extracted from a higher-order cumulant angle, and the higher-order cumulant parameter value may specifically include: a fourth order cumulant parameter value and a sixth order cumulant parameter value.

S102, acquiring a judgment threshold corresponding to each characteristic value;

in the present application, it is necessary to set a corresponding determination threshold for each eigenvalue, and to identify the modulation scheme used for the signal by comparing the eigenvalue with the determination threshold, specifically, the present application sets the following determination thresholds based on the above-described procedure for determining the eigenvalue and the modulation parameter:

1. a first standard deviation determination threshold value and a second standard deviation determination threshold value corresponding to the first standard deviation, wherein the first standard deviation determination threshold value is greater than the second standard deviation determination threshold value;

2. a third standard deviation determination threshold value corresponding to the second standard deviation;

3. a first symmetry determination threshold, a second symmetry determination threshold, and a third symmetry determination threshold corresponding to the symmetry parameter value; wherein the first symmetry decision threshold is less than the second symmetry decision threshold and less than the third symmetry decision threshold;

4. an instantaneous amplitude spectrum density determination threshold value corresponding to the maximum value of the instantaneous amplitude spectrum density;

5. an instantaneous amplitude absolute value determination threshold value corresponding to an average value of instantaneous amplitude absolute values;

6. a compactness decision threshold corresponding to a compactness parameter value of the instantaneous frequency;

7. a first high-order cumulant determination threshold, a second high-order cumulant determination threshold and a third high-order cumulant determination threshold corresponding to the high-order cumulant parameter value; wherein the first higher-order accumulation amount determination threshold value is larger than the third higher-order accumulation amount determination threshold value and larger than the second higher-order accumulation amount determination threshold value.

It can be understood that the specific value of the determination threshold set in this embodiment may be set in advance by a user, or may be adjusted according to actual conditions, or of course, the optimal value may be summarized from multiple test data. Is not particularly limited herein

S103, comparing the plurality of characteristic values of the signal by using the judgment threshold, and identifying the modulation mode of the signal according to the comparison result.

Specifically, after acquiring a plurality of eigenvalues and corresponding decision thresholds, the present application needs to match the eigenvalues with the corresponding decision thresholds, and the comparison result can classify the modulation scheme of the signal, thereby completing the identification of the modulation scheme.

In summary, the present invention extracts feature values from two angles of statistical features and high-order cumulant, and then sets corresponding decision thresholds to classify and identify communication signals, specifically, the joint multidimensional signal identification method provided by the present invention can identify the following common modulation modes of 13 signals: the method comprises the steps of amplitude modulation AM, double-sideband modulation DSB, lower sideband modulation LSB, upper sideband modulation USB, frequency modulation FM, binary amplitude keying 2ASK, quaternary amplitude keying 4ASK, binary digital frequency modulation 2FSK, quaternary digital frequency modulation 4FSK, binary phase shift keying 2PSK, quaternary phase shift keying 4PSK, octal phase shift keying 8PSK and linear narrowband digital modulation technology pi/4-DQPSK.

The above-mentioned feature values extracted from the signals respectively from the statistical feature angle and the higher-order accumulation amount angle may be extracted by any currently existing acquisition method, and the following steps are only used to describe the acquisition method of each feature value, but the present invention is not limited thereto.

First, in order to obtain the above-mentioned characteristic value, the present application needs to obtain an instantaneous characteristic value of the signal, such as an instantaneous amplitude value

Instantaneous phase

And instantaneous frequency

And so on. In particular, modulated signals

Obtaining orthogonal baseband signals after conversion

And

then the instantaneous amplitude of the signal is calculated through Kardy transformation

Instantaneous phase

And instantaneous frequency

When the characteristic parameters are equal, Kardy transformation is shown as the following formula, and then each characteristic value is obtained in turn through the following steps.

Step 1: obtaining a first standard deviation of a zero-center non-weak signal segment after nonlinear phase centralization

Definition of

(ii) a Wherein the content of the first and second substances,

in order to be the instantaneous amplitude value,

is an amplitude decision threshold for judging weak signal, C represents in all samples

The number of non-weak signals is,

is the nonlinear component of the instantaneous phase after zero-centering,

，

represents the calculated i-th phase position,

is the average of the instantaneous phase and,

wherein, in the step (A),

is a serial number of the discrete signal,

s in (a) is the modulated signal represented. The signals can be divided into two categories of { DSB, USB and LSB } and { AM, FM, 2ASK, 4ASK, 2FSK, 4FSK, 2PSK, 4PSK, 8PSK and pi/4-DQPSK } through the first standard deviation and a preset first standard deviation determination threshold, and identification in MFSK categories, such as identification of 2FSK and 4FSK, can be well distinguished through the first standard deviation and the second standard deviation determination threshold.

Step 2: obtaining a second standard deviation of the absolute value of the nonlinear instantaneous phase of the zero-center non-weak signal

Is defined as

. The { LSB, USB } and { DSB } can be well distinguished by the second standard deviation and the third standard deviation decision threshold.

And step 3: obtaining the symmetry P of the frequency spectrum amplitude of the band-pass signal at two sides of the carrier frequency, wherein the symmetry P represents the symmetry degree of the signals at two sides of the carrier frequency signal and is defined as

Wherein, in the step (A),

the power value of the left-hand signal is calculated,

the power value of the right half is calculated. Wherein the content of the first and second substances,

，

，

，

is the number of samples and is related to the carrier frequency rate,

defined as the discrete fourier transform of the communication information,

in order to be able to sample the frequency,

the carrier frequency is indicated. USB and LSB can be distinguished through the symmetry parameter value and the first symmetry judgment threshold value, and the whole signal can be divided into 3 types of signals which are { pi/4-DQPSK, 2ASK, 4ASK }, {2PSK, 4PSK, 8PSK } and { AM, FM, 2FSK, 4FSK }, respectively, through the symmetry parameter value and the first symmetry judgment threshold value and the second symmetry judgment threshold value and the third symmetry judgment threshold value.

And 4, step 4: obtaining the maximum value of zero-center normalized instantaneous amplitude spectrum density

Is defined as

Wherein, in the step (A),

in order to count the number of sampling points,

normalized instantaneous amplitude for zero center, calculated by:

，

，

(ii) a Wherein the content of the first and second substances,

is the instantaneous amplitude of the signal and,

is the average of the instantaneous amplitude values,

the amplitude after zero center. The AM and FM signals can be identified through the maximum value of the instantaneous amplitude spectrum density and the judgment threshold value of the instantaneous amplitude spectrum density.

And 5: obtaining an average of the absolute values of the recursive zero-center normalized instantaneous amplitudes

Is defined as

，

Wherein A isRecursively calculating a zero-centered normalized instantaneous amplitude once on the basis of the calculated zero-centered normalized instantaneous amplitude, i.e. repeating pairs of the generated zero-centered normalized instantaneous amplitudes

Once again, mean represents the mean calculated, and mean | a | represents the mean calculated and then the absolute value of a. The identification of the MASK and pi/4-DQPSK signals can be realized through the average value of the instantaneous amplitude absolute value and the instantaneous amplitude absolute value judgment threshold value.

Step 6: obtaining a zero-center normalized instantaneous frequency compactness parameter

. The identification performance under a low signal-to-noise ratio can be improved through the compactness parameter of the instantaneous frequency, and specifically, the method for acquiring the compactness parameter value of the instantaneous frequency comprises the following steps:

calculating an instantaneous frequency average value of the signal according to each instantaneous frequency in the signal, and obtaining an instantaneous frequency absolute value of each instantaneous frequency and the instantaneous frequency average value; acquiring first length information of the signal and second length information of which the absolute value of the instantaneous frequency in the signal is greater than half of the code element rate; and determining a compactness parameter value of the instantaneous frequency by using the ratio of the second length information to the first length information.

In particular, in the present embodiment

Representing the ith instantaneous frequency in the signal, according to

Calculating each instantaneous frequency in the signal

Average value of (2)

，

The representation is an average of instantaneous frequencies; the absolute value of the instantaneous frequency of the difference of each instantaneous frequency from the mean is then calculated:

(ii) a Obtaining first length information of a signal

The first length information refers to the length of the whole signal, and then the instantaneous frequency absolute value is searched according to the calculated instantaneous frequency absolute value

As second length information

Then, the ratio of the second length information to the first length information is used as a compactness parameter value for normalizing the instantaneous frequency from the zero center

Namely:

. Wherein the content of the first and second substances,

the symbol rate is half, and MFSK signals can be well distinguished from AM signals and FM signals through a compactness parameter of instantaneous frequency and a compactness judgment threshold value.

And 7: acquiring high-order cumulant after down conversion, wherein the second-order cumulant, the fourth-order cumulant and the sixth-order cumulant are respectively defined as:

；

；

，

，

，

，

wherein the content of the first and second substances,

refers to a signal obtained by down-converting a received signal,

is the cumulative quantity of the order 2,

is the cumulative quantity of the 4 th order,

is to the down-conversion signal

The power value is calculated and then passes through E [, ]]The average value of the signal is calculated,

is a complex random process

Is/are as follows

The order mixing moment, expressed as:

。

、

is based on

Calculated, the sum of p + q being equal to the order, e.g.

， p =4,q =0,p+q =4；

、

Is the cumulative quantity of the 4 th order,

is the cumulative quantity of the order of 6,

representing signals

Conjugation of (1). The modulation identification of five digital signals of 2ASK, 4ASK, BPSK, QPSK and 8PSK can be realized through the fourth-order cumulant parameter value, the sixth-order cumulant parameter value, the first high-order cumulant judgment threshold value, the second high-order cumulant judgment threshold value and the third high-order cumulant judgment threshold value.

Referring to fig. 2, a flowchart of a specific modulation scheme identification method disclosed in the embodiment of the present invention is shown, in the embodiment, each feature value is compared with a corresponding decision threshold, so that identification of a debugging scheme can be achieved. It should be noted that each determination parameter in fig. 2 has been represented by a specific numeral, but the determination parameters are not limited thereto, and may be customized and adjusted according to actual situations. As can be seen from fig. 2, in the identification method described in this embodiment, the determination threshold values corresponding to the feature values are respectively:

a first standard deviation determination threshold value corresponding to the first standard deviation is 1.3, and a second standard deviation determination threshold value corresponding to the first standard deviation is 0.4; a third standard deviation determination threshold value corresponding to the second standard deviation is 0.54; a first symmetry decision threshold value corresponding to the symmetry parameter value is-0.5, a corresponding second symmetry decision threshold value is-0.3, and a corresponding third symmetry decision threshold value is 0.3; the instantaneous amplitude spectrum density determination threshold value corresponding to the maximum value of the instantaneous amplitude spectrum density is 10, the instantaneous amplitude absolute value determination threshold value corresponding to the average value of the instantaneous amplitude absolute values is 0.58, the compactness determination threshold value corresponding to the compactness parameter value of the instantaneous frequency is 0.2, the first higher-order cumulant determination threshold value corresponding to the higher-order cumulant parameter value is 8, the corresponding second higher-order cumulant determination threshold value is 0.5, and the corresponding third higher-order cumulant determination threshold value is 1.17.

It should be noted that the identification method described in this embodiment includes four decision branches in total, and 13 modulation methods can be identified by the four decision branches.

1. A first identification branch:

if the first standard deviation is larger than the first standard deviation judgment threshold, judging whether the second standard deviation is larger than a third standard deviation judgment threshold; if not, the modulation mode of the signal is determined as follows: a DSB;

if yes, judging whether the symmetry parameter value is larger than or equal to a first symmetry judgment threshold value; if yes, the modulation mode of the signal is determined as follows: LSB; if not, the modulation mode of the signal is determined as follows: and (7) USB.

2. A second identification branch:

if the first standard deviation is not larger than the first standard deviation judgment threshold value and the symmetry parameter value is not larger than the second symmetry judgment threshold value, judging whether the compactness parameter value of the instantaneous frequency is larger than the compactness judgment threshold value or not;

if so, judging whether the maximum value of the instantaneous amplitude spectrum density is larger than the judgment threshold value of the instantaneous amplitude spectrum density; if yes, the modulation mode of the signal is determined as follows: AM; if not, the modulation mode of the signal is determined as follows: FM;

3. A third identification branch:

if the first standard deviation is not larger than the first standard deviation judgment threshold value, and the symmetry parameter value is larger than the second symmetry judgment threshold value and smaller than the third symmetry judgment threshold value, judging whether the sixth-order cumulant parameter value is larger than the first-order cumulant judgment threshold value;

if the second high-order cumulant is larger than the second high-order cumulant judgment threshold, the modulation mode of the judgment signal is as follows: QPSK; if the second high-order cumulant is not larger than the second high-order cumulant judgment threshold, the modulation mode of the judgment signal is as follows: 8 PSK.

4. A fourth identification branch:

if the first standard deviation is not larger than the first standard deviation judgment threshold value and the symmetry parameter value is larger than or equal to the third symmetry judgment threshold value, judging whether the average value of the instantaneous amplitude absolute values is larger than the instantaneous amplitude absolute value judgment threshold value or not;

if the second order cumulant is larger than the second order cumulant judgment threshold, judging the modulation mode of the signal as follows: 2 ASK; if the second-order cumulant is not larger than the third-order cumulant judgment threshold, the modulation mode of the judgment signal is as follows: 4 ASK.

It can be seen that, as can be seen from the above-mentioned identification branch, the present application passes through various characteristic valuesAnd the corresponding decision threshold can identify 13 modulation schemes. Referring to fig. 3a, a classification diagram based on a first standard deviation is provided for the present embodiment; FIG. 3 shows the first standard deviation

Under the condition of different signal-to-noise ratios, the signals can be divided into two categories of { DSB, USB and LSB } and { AM, FM, 2ASK, 4ASK, 2FSK, 4FSK, 2PSK, 4PSK, 8PSK and pi/4-DQPSK } by setting proper threshold values, see FIG. 3b, the other classification diagram based on the first standard deviation provided by the embodiment can also realize the identification in the MFSK category by setting proper threshold values;

referring to fig. 4, a classification diagram based on the second standard deviation is provided for the present embodiment; as can be seen from FIG. 4, the second standard deviation

Under the condition of different signal-to-noise ratios, the change conditions of the communication signal values can be well distinguished from { LSB, USB } and { DSB };

referring to fig. 5a, a schematic diagram of classification based on symmetry parameter values provided for this embodiment is shown, and referring to fig. 5b, a schematic diagram of classification based on symmetry parameter values provided for this embodiment is shown; as can be seen from fig. 5a, the whole signal can be divided into 3 types of signals according to the variation of the value of the communication signal under different signal-to-noise ratios of the parameter P, which are { pi/4-DQPSK, 2ASK, 4ASK }, {2PSK, 4PSK, 8PSK }, and { AM, FM, 2FSK, 4FSK }, respectively, and referring to fig. 5b, the symmetric parameter value can also have a good discrimination for two signals, namely USB and LSB;

referring to fig. 6, a schematic classification diagram based on the maximum value of the instantaneous amplitude spectral density is provided in this embodiment; as can be seen from FIG. 6, the parameters

The AM and FM signals can be identified under the condition of different signal-to-noise ratio changes of the communication signals;

with reference to figure 7 of the drawings,the classification diagram based on the average value of the absolute value of the instantaneous amplitude provided by the embodiment is shown; as can be seen from FIG. 7, the parameters

The identification of MASK and pi/4-DQPSK signals can be realized under the condition of different signal-to-noise ratios and the change condition of the value of the communication signal;

referring to fig. 8, a schematic diagram of classification of an average value of a compactness parameter value based on an instantaneous frequency is provided in this embodiment; as can be seen from FIG. 8, the parameters

The change situation of the value of the communication signal under the situation of different signal-to-noise ratios is used for distinguishing MFSK signals from AM and FM signals;

referring to fig. 9a, 9b, and 9C, for the classification diagram based on the high-order cumulant parameter values provided in this embodiment, MASK and MPSK are distinguished by setting appropriate threshold values according to the variation of the communication signal values under different signal-to-noise ratios of the parameters C40 and C60;

referring to fig. 10, a schematic diagram of a variation of modulation identification probability of each signal with a signal-to-noise ratio provided in this embodiment is shown; specifically, fig. 10 identifies different communication signals through the threshold values set in fig. 2, where the identification probability of pi/4-DQPSK, FM, DSB, AM, 4ASK, 2ASK, BPSK, LSB, and QPSK modulation signals reaches over 90% when the carrier frequency rate and symbol rate are estimated accurately and the signal-to-noise ratio is 0dB, and when the signal-to-noise ratio reaches 3dB, the identification probability among 13 modulation signals under study reaches over 90%, and the overall identification probability reaches 98.5%.

It can be seen that when the modulation mode of the communication signal is identified, the feature values are respectively extracted from two angles of the statistical feature and the high-order cumulant, the extracted feature values are compared with the correspondingly set judgment threshold value, the modulation mode of the signal can be identified according to the comparison result, and through the mode, the identification rate is improved, and the identifiable modulation type is increased. In addition, the method and the device provide a compactness characteristic parameter of zero-center normalized instantaneous frequency, overcome the condition that the conventional signal is under a higher signal-to-noise ratio or the identification number is less, and realize the modulation identification of various signals under a low signal-to-noise ratio.

In the following, the identification apparatus provided by the embodiment of the present invention is introduced, and the identification apparatus described below and the identification method described above may be referred to each other.

Referring to fig. 11, a schematic structural diagram of an apparatus for identifying a modulation scheme of a communication signal according to an embodiment of the present invention includes:

a feature value obtaining module 100, configured to obtain feature values of a signal, where the feature values are a plurality of feature values extracted from the signal from a statistical feature angle and a high-order cumulant angle, respectively;

a decision threshold acquisition module 200 configured to acquire a decision threshold corresponding to each feature value;

and a feature value comparison module 300, configured to compare the plurality of feature values of the signal with the decision threshold, and identify a modulation mode of the signal according to a comparison result.

Wherein the obtaining the characteristic value of the signal comprises:

acquiring a first standard deviation, a second standard deviation, a symmetry parameter value, an instantaneous amplitude spectrum density maximum value, an average value of instantaneous amplitude absolute values, a compactness parameter value of instantaneous frequency and a high-order cumulant parameter value of a signal; wherein the first standard deviation is: adopting a standard deviation after the non-linear phase centralization of a zero-center non-weak signal segment; the second standard deviation is: the standard deviation of the non-linear instantaneous phase absolute value of the zero center non-weak signal is used.

The device further comprises a compactness parameter value acquisition module, which is specifically used for:

calculating an average value of each instantaneous frequency in the signal and obtaining an instantaneous frequency absolute value of each instantaneous frequency and the average value; acquiring first length information of the signal and second length information of which the absolute value of the instantaneous frequency in the signal is greater than half of the code element rate; and determining a compactness parameter value of the instantaneous frequency by using the ratio of the second length information to the first length information.

Wherein the characteristic value comparison module comprises:

a sixth judgment unit configured to judge whether or not the sixth-order cumulant parameter value is greater than the first-order cumulant determination threshold when the first standard deviation is not greater than the first standard deviation determination threshold and the symmetry parameter value is greater than the second symmetry determination threshold and smaller than the third symmetry determination threshold; if yes, the modulation mode of the signal is determined as follows: BPSK; if not, triggering a seventh judging unit;

the seventh judging unit judges whether the fourth-order cumulant parameter value is larger than a second high-order cumulant judgment threshold value; if the second high-order cumulant is larger than the second high-order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: QPSK; if the second high-order cumulant is not larger than the second high-order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: 8 PSK.

Wherein the characteristic value comparison module comprises:

an eighth judging unit, configured to judge whether an average value of the instantaneous amplitude absolute values is greater than an instantaneous amplitude absolute value determination threshold when the first standard deviation is not greater than a first standard deviation determination threshold and the symmetry parameter value is greater than or equal to a third symmetry determination threshold; if yes, the modulation mode of the signal is determined as follows: pi/4-DQPSK; if not, triggering a ninth judging unit;

the ninth judging unit judges whether the value of the sixth-order cumulant parameter is greater than a third-order cumulant judgment threshold; if the second order cumulant is larger than the second order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: 2 ASK; if the signal is not larger than the third high-order cumulant judgment threshold, judging that the modulation mode of the signal is as follows: 4 ASK.

Referring to fig. 12, an electronic device according to an embodiment of the present invention includes:

a memory 11 for storing a computer program;

the processor 12 is configured to implement the steps of the method for identifying a modulation scheme of a communication signal according to the above-mentioned method embodiment when executing the computer program.

In this embodiment, the device may be a PC (Personal Computer), or may be a terminal device such as a smart phone, a tablet Computer, a palmtop Computer, or a portable Computer.

The device may include a memory 11, a processor 12, and a bus 13.

The memory 11 includes at least one type of readable storage medium, which includes a flash memory, a hard disk, a multimedia card, a card type memory (e.g., SD or DX memory, etc.), a magnetic memory, a magnetic disk, an optical disk, and the like. The memory 11 may in some embodiments be an internal storage unit of the device, for example a hard disk of the device. The memory 11 may also be an external storage device of the device in other embodiments, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), etc. provided on the device. Further, the memory 11 may also include both an internal storage unit of the device and an external storage device. The memory 11 may be used not only to store application software installed in the device and various types of data such as program codes for performing the above-described recognition method, but also to temporarily store data that has been output or is to be output.

The processor 12 may be a Central Processing Unit (CPU), a controller, a microcontroller, a microprocessor or other data Processing chip in some embodiments, and is used for executing program codes stored in the memory 11 or Processing data, such as program codes for executing the above-mentioned identification method.

The bus 13 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 12, but this is not intended to represent only one bus or type of bus.

Further, the device may further include a network interface 14, and the network interface 14 may optionally include a wired interface and/or a wireless interface (e.g., WI-FI interface, bluetooth interface, etc.), which are generally used to establish a communication connection between the device and other electronic devices.

Optionally, the device may further comprise a user interface 15, the user interface 15 may comprise a Display (Display), an input unit such as a Keyboard (Keyboard), and the optional user interface 15 may further comprise a standard wired interface, a wireless interface. Alternatively, in some embodiments, the display may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch device, or the like. The display, which may also be referred to as a display screen or display unit, is suitable for displaying information processed in the device and for displaying a visualized user interface.

Fig. 12 shows only the device with the components 11-15, and it will be understood by those skilled in the art that the structure shown in fig. 12 does not constitute a limitation of the device, and may comprise fewer or more components than those shown, or some components may be combined, or a different arrangement of components.

The embodiment of the invention also discloses a computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, and when the computer program is executed by a processor, the steps of the method for identifying the communication signal modulation mode are realized.

Wherein the storage medium may include: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for identifying a modulation scheme of a communication signal, comprising:

acquiring a judgment threshold corresponding to each characteristic value;

the method for acquiring the compactness parameter value of the instantaneous frequency comprises the following steps: calculating an instantaneous frequency average value of the signal according to each instantaneous frequency in the signal, and taking an absolute value of a difference value of each instantaneous frequency and the instantaneous frequency average value as an instantaneous frequency absolute value; acquiring first length information of the signal and second length information of which the absolute value of the instantaneous frequency in the signal is greater than half of the code element rate; determining a compactness parameter value of the instantaneous frequency by using a ratio of the second length information to the first length information; the first length information is the length of the whole signal;

2. The identification method according to claim 1, wherein comparing the plurality of feature values of the signal with the decision threshold and identifying the modulation scheme of the signal based on the comparison result comprises:

3. The identification method according to claim 1, wherein comparing the plurality of feature values of the signal with the decision threshold and identifying the modulation scheme of the signal based on the comparison result comprises:

4. The identification method according to claim 1, wherein comparing the plurality of feature values of the signal with the decision threshold and identifying the modulation scheme of the signal based on the comparison result comprises:

5. An apparatus for identifying a modulation scheme of a communication signal, comprising:

the compactness parameter value acquisition module is used for calculating an instantaneous frequency average value of the signal according to each instantaneous frequency in the signal and taking an absolute value of a difference value between each instantaneous frequency and the instantaneous frequency average value as an instantaneous frequency absolute value; acquiring first length information of the signal and second length information of which the absolute value of the instantaneous frequency in the signal is greater than half of the code element rate; determining a compactness parameter value of the instantaneous frequency by using a ratio of the second length information to the first length information; the first length information is the length of the whole signal;

wherein the characteristic value comparison module comprises:

6. The apparatus of claim 5, wherein the feature value comparison module comprises:

7. An electronic device, comprising:

a memory for storing a computer program;

a processor for implementing the steps of the method for identifying a modulation scheme of a communication signal according to any one of claims 1 to 4 when executing said computer program.

8. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a computer program which, when being executed by a processor, carries out the steps of the method for identifying a modulation scheme of a communication signal according to any one of claims 1 to 4.