QPSK and 8PSK identification and demodulation method and system

Abstract

The invention discloses a QPSK (Quadrature Phase Shift Keying) and 8PSK (8 Phase Shift Keying) identification and demodulation method and system, which comprises the following steps of: identifying a modulation type of an input signal, performing M-power calculation on the input signal according to the modulation type, and calculating an index corresponding to a maximum amplitude spectrum power value; calculating a roughly estimated frequency offset frequency point corresponding to the index and a compensation signal corresponding to the roughly estimated frequency offset frequency point, calculating a frequency point value corresponding to the maximum value of the phase difference value of the compensation signal, and performing frequency compensation on the input signal by using the frequency point value to obtain a frequency offset-free signal; calculating corresponding positions of the frequency-offset-free signal on each point on the constellation diagram on a standard constellation diagram without phase offset to obtain a standard signal without phase offset; and correcting the phase offset of the standard signal without phase offset and the signal without frequency offset, averaging the corrected phase offset to obtain the phase offset to be compensated, and performing phase offset compensation on the signal without frequency offset to obtain the signal without phase offset. The modulation type identification of the input signal is automatically completed in the frequency offset estimation process, and the process steps of frequency offset estimation and phase offset estimation are fewer and the flow is simpler.

Description

Technical Field

[0001] The present invention relates to the technical field of digital communication, and in particular to a method and system for QPSK and 8PSK identification and demodulation. Background Art

[0002] Phase Shift Keying (PSK) is a digital modulation method and a form of phase modulation. 8PSK corresponds to 8-state PSK and QPSK corresponds to 4-state PSK. 8PSK is not as resistant to noise as QPSK, but has higher data throughput. These two signals are widely used in the field of communications. Since QPSK and 8PSK have strong similarities, many algorithms cannot correctly identify and demodulate them. Therefore, the identification, frequency offset estimation and phase offset estimation of these two signals are of great significance in communications. At present, for the identification and demodulation methods of QPSK and 8PSK, more is to identify first and then demodulate. The instantaneous characteristic parameters of the signal are combined with the digital modulation signal recognition algorithm to identify the signal and then demodulate it. The commonly used method is coherent demodulation, which uses many modules, resulting in many calculation steps and a long process. Summary of the invention

[0003] The object of the present invention is to provide a method and system for QPSK and 8PSK identification and demodulation, which automatically completes the modulation type identification of the input signal during the frequency offset estimation process, and the process steps of frequency offset estimation and phase offset estimation are fewer and the process is simpler.

[0004] To achieve the above objectives, this application provides the following solutions: On the one hand, the present application provides a method for QPSK and 8PSK identification and demodulation, comprising the following steps: S1, obtain the input signal after clock synchronization, and identify the modulation type of the input signal, which includes 8PSK and QPSK; S2. Perform M-th power calculation on the input signal according to the modulation type, where the value of M corresponds to the modulation type, and calculate the index MaxIdx corresponding to the maximum value of the amplitude spectrum power of the input signal after the M-th power calculation; S3, calculating the roughly estimated frequency offset frequency point corresponding to the index MaxIdx, calculating the compensation signal corresponding to the roughly estimated frequency offset frequency point, calculating the frequency point value corresponding to the maximum phase difference value of the compensation signal, and using the frequency point value to perform frequency compensation on the input signal to obtain a signal without frequency offset; S4, calculating the position of the frequency-free signal on the standard constellation diagram without phase deviation corresponding to each point on the constellation diagram, and obtaining the standard signal without phase deviation; S5. Calculate the phase deviation between the standard signal without phase deviation and the signal without frequency deviation, correct the phase deviation, take the average of the corrected phase deviation to obtain the phase deviation to be compensated, and perform phase deviation compensation on the signal without frequency deviation according to the phase deviation to be compensated to obtain a signal without phase deviation.

[0005] In some specific implementation schemes, the specific process of identifying the modulation type of the input signal in step S1 is: S11, calculating a power of the input signal, where the exponent of the power is a first preset value, to obtain a first input signal; S12, calculating the amplitude spectrum power of the first input signal to obtain an amplitude data set, and calculating the maximum value, the index corresponding to the maximum value, and the average value in the amplitude data set; S13, comparing the N-times average value with the maximum value, if the N-times average value is less than the maximum value, then determining that the modulation type of the input signal is QPSK, if the N-times average value is greater than or equal to the maximum value, then determining that the modulation type of the input signal is 8PSK; S14. When the modulation type of the input signal is QPSK, M is 4; when the modulation type of the input signal is 8PSK, M is 8.

[0006] In some specific implementation schemes, the specific process of step S3 is: S31. Calculate the rough estimated frequency offset point corresponding to the index MaxIdx according to the index MaxIdx corresponding to the maximum value. , L represents the data length of the input signal; S32, calculate the compensation signal corresponding to the rough estimated frequency offset point EF , calculate the maximum phase difference value corresponding to the rough estimated frequency offset point EF according to the compensation signal P 0; S33, setting the search step value, finding the left and right frequency points on both sides of the rough estimated frequency deviation point according to the search step value, respectively calculating the compensation signal and the maximum phase difference value of the left and right frequency points, and obtaining the compensation signal corresponding to the left frequency point S l The maximum value of the phase difference P l , the compensation signal corresponding to the right frequency point S r The maximum value of the phase difference P r ; S34, from the maximum value of the phase difference P 0. Maximum phase difference value P l The maximum value of the phase difference P r Select the largest value as Pmax , update the frequency value of the rough estimated frequency offset point EF to P max The corresponding frequency value; S35, update the search step value, repeat steps S33-S34, until the search step value reaches the preset threshold, and output the compensation frequency corresponding to the rough estimated frequency offset point EF F est ; S36, according to the compensation frequency F est The compensated frequency deviation is calculated and used to compensate the input signal to obtain a signal without frequency deviation.

[0007] In some specific implementation schemes, the initial setting value of the search step value step is step=1 / L, and each time the search step value is updated, the updated search step value is set to half of the current search step value.

[0008] In some specific implementation schemes, when the modulation type of the input signal is QPSK, the specific process of step S4 is: S41, calculating the maximum phase value corresponding to the frequency deviation-free signal, and calculating the absolute value of the difference between the maximum phase value and π; S42, determining whether the absolute value of the difference is less than a second threshold value, and if the absolute value of the difference is less than or equal to the second threshold value, rotating the frequency deviation-free signal by π / 8 to obtain a frequency deviation-free correction signal; S43, for the frequency deviation-free correction signal, repeat steps S41-S42 until the absolute value of the difference is greater than a second threshold value, and then output a final frequency deviation-free signal; S44, numbering the final frequency-offset-free signal on the constellation diagram, calculating the position of the final frequency-offset-free signal on the standard constellation diagram without phase deviation, and obtaining a standard signal without phase deviation.

[0009] In some embodiments, the non-biased standard signal is calculated The specific calculation process is: calculate , Sig1(n) represents a signal without frequency deviation; Round Sig2(n) to get the number z of the frequency-free signal on the constellation diagram ( n ): According to z( n ), get the standard signal without phase deviation : ; Wherein, j represents an imaginary unit, M represents a corresponding value determined according to the modulation type of the input signal, and round represents rounding to the nearest integer.

[0010] In some specific embodiments, according to z( n ) Calculate the standard signal without phase deviation The front also includes z ( n ) is corrected by: n ) plus M for every number less than 0.

[0011] In some specific implementation schemes, the specific process of correcting the phase deviation in step S5 is: Determine whether there is a value greater than π in the phase deviation α , α If it exists, correct the value to α- 2π.

[0012] In a second aspect, the present application provides a system for QPSK and 8PSK identification and demodulation, comprising: The frequency offset estimation and compensation module specifically includes: A signal identification module is used to obtain the input signal that completes clock synchronization and identify the modulation type of the input signal, which modulation types include 8PSK and QPSK; The input signal is calculated to the Mth power according to the modulation type, the value of M corresponds to its modulation type, and the index MaxIdx corresponding to the maximum value of the amplitude spectrum power of the input signal after the Mth power calculation is calculated; A frequency offset rough estimation module is used to calculate the rough estimated frequency offset frequency point corresponding to the index MaxIdx; The frequency deviation precise estimation module is used to calculate the compensation signal corresponding to the frequency point of the roughly estimated frequency deviation, and calculate the frequency point value corresponding to the maximum phase difference value of the compensation signal; The frequency deviation compensation module is used to perform frequency compensation on the input signal using the frequency point value to obtain a signal without frequency deviation; Phase deviation estimation and compensation module, specifically including: The constellation diagram numbering and standard signal calculation module is used to calculate the position of the frequency-free signal on the standard constellation diagram without phase deviation corresponding to each point on the constellation diagram, so as to obtain the standard signal without phase deviation; The phase deviation estimation and compensation module is used to calculate the phase deviation between the standard signal without phase deviation and the signal without frequency deviation, correct the phase deviation, take the average value of the corrected phase deviation to obtain the phase deviation to be compensated, and perform phase deviation compensation on the signal without frequency deviation according to the phase deviation to be compensated to obtain a signal without phase deviation.

[0013] The present invention has the beneficial effects: Compared with the prior art which first identifies and then demodulates QPSK and 8PSK, the signal is identified by combining the instantaneous characteristic parameters of the signal with a digital modulation signal recognition algorithm, and then demodulated. The commonly used method is coherent demodulation, and the calculation process is complicated.

[0014] In the present application, the recognition and demodulation of QPSK and 8PSK can automatically complete two types of recognition in the process of frequency offset estimation, and the process steps of frequency offset estimation and phase offset estimation are fewer and simpler, which reduces the computational complexity of recognition, frequency offset estimation and phase offset estimation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart of a QPSK and 8PSK identification and demodulation method provided in an embodiment of the present invention; Figure 2 A flow chart of a method for identifying a modulation type of an input signal provided by an embodiment of the present invention; Figure 3 A flow chart of a method for frequency offset estimation and compensation provided by an embodiment of the present invention; Figure 4 A block diagram of the QPSK and 8PSK identification and demodulation system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] The relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0018] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0019] Additionally, descriptions of well-known structures, functions, and configurations may be omitted for clarity and conciseness.One of ordinary skill in the art will recognize that various changes and modifications may be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0020] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0021] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0022] Before introducing the specific implementation methods of this application, the concepts involved are first explained: Example 1 like Figure 1 As shown, this embodiment provides a method for QPSK and 8PSK identification and demodulation, including the following steps: S1, obtain the input signal after clock synchronization, and identify the modulation type of the input signal, which includes 8PSK and QPSK; Specifically, Figure 2 As shown, the specific process of identifying the modulation type of the input signal in step S1 is: S11, calculating a power of the input signal, where the exponent of the power is a first preset value, to obtain a first input signal; S12, calculating the amplitude spectrum power of the first input signal to obtain an amplitude data set, and calculating the maximum value, the index corresponding to the maximum value, and the average value in the amplitude data set; S13, comparing the N-times average value with the maximum value, if the N-times average value is less than the maximum value, then determining that the modulation type of the input signal is QPSK, if the N-times average value is greater than or equal to the maximum value, then determining that the modulation type of the input signal is 8PSK; S14. When the modulation type of the input signal is QPSK, M is 4; when the modulation type of the input signal is 8PSK, M is 8.

[0023] S2. Perform M-th power calculation on the input signal according to the modulation type, where the value of M corresponds to the modulation type, and calculate the index MaxIdx corresponding to the maximum value of the amplitude spectrum power of the input signal after the M-th power calculation; The first preset value is set to 4. When the modulation type of the input signal is QPSK, step S2 directly calls the maximum value, the index corresponding to the maximum value, and the average value calculated by step S12. When the modulation type of the input signal is 8PSK, step S2 corrects the value of M to 8, and repeats steps S11-S12 to calculate the maximum value corresponding to 8PSK, the index corresponding to the maximum value, and the average value.

[0024] S3, calculating the roughly estimated frequency offset frequency point corresponding to the index MaxIdx, calculating the compensation signal corresponding to the roughly estimated frequency offset frequency point, calculating the frequency point value corresponding to the maximum phase difference value of the compensation signal, and using the frequency point value to perform frequency compensation on the input signal to obtain a signal without frequency offset; Specifically, Figure 3 As shown, the specific process of step S3 is: S31. Calculate the rough estimated frequency offset point corresponding to the index MaxIdx according to the index MaxIdx corresponding to the maximum value. , L represents the data length of the input signal; S32, calculate the compensation signal corresponding to the rough estimated frequency offset point EF , calculate the maximum phase difference value corresponding to the rough estimated frequency offset point EF according to the compensation signal P 0; S33, setting the search step value, finding the left and right frequency points on both sides of the rough estimated frequency deviation point according to the search step value, respectively calculating the compensation signal and the maximum phase difference value of the left and right frequency points, and obtaining the compensation signal corresponding to the left frequency point S l The maximum value of the phase difference P l , the compensation signal corresponding to the right frequency point S r The maximum value of the phase difference P r ; S34, from the maximum value of the phase difference P 0. Maximum phase difference value P l The maximum value of the phase difference P r Select the largest value as P max , update the frequency value of the rough estimated frequency offset point EF to P max The corresponding frequency value; S35, update the search step value, repeat steps S33-S34, until the search step value reaches the preset threshold, and output the compensation frequency corresponding to the rough estimated frequency offset point EF F est ; S36, according to the compensation frequency F est The compensated frequency deviation is calculated and used to compensate the input signal to obtain a signal without frequency deviation.

[0025] S4, calculating the position of the frequency-free signal on the standard constellation diagram without phase deviation corresponding to each point on the constellation diagram, and obtaining the standard signal without phase deviation; Specifically, calculate the phase-biased standard signal The specific calculation process is: calculate , Sig1(n) represents a signal without frequency deviation; Round Sig2(n) to get the number z of the frequency-free signal on the constellation diagram ( n ): For z( n ) is corrected by: n ) plus M for every number less than 0.

[0026] According to the corrected z( n ), get the standard signal without phase deviation : ; Wherein, j represents an imaginary unit, M represents a corresponding value determined according to the modulation type of the input signal, and round represents rounding to the nearest integer.

[0027] When the modulation type of the input signal is QPSK (with phase deviation at this time), if there are points on the constellation diagram of the input QPSK (with phase deviation at this time) that are located above the X or Y axis, it will affect the subsequent phase deviation estimation result, so the input QPSK is rotated until no point on the constellation diagram is located above the X or Y axis. Therefore, when the modulation type of the input signal is QPSK, the specific process of step S4 is: S41, calculating the maximum phase value corresponding to the frequency deviation-free signal, and calculating the absolute value of the difference between the maximum phase value and π; S42, determining whether the absolute value of the difference is less than a second threshold value, and if the absolute value of the difference is less than or equal to the second threshold value, rotating the frequency deviation-free signal by π / 8 to obtain a frequency deviation-free correction signal; S43, for the frequency deviation-free correction signal, repeat steps S41-S42 until the absolute value of the difference is greater than a second threshold value, and then output a final frequency deviation-free signal; S44, numbering the final frequency-offset-free signal on the constellation diagram, calculating the position of the final frequency-offset-free signal on the standard constellation diagram without phase deviation, and obtaining a standard signal without phase deviation.

[0028] S5. Calculate the phase deviation between the standard signal without phase deviation and the signal without frequency deviation, and correct the phase deviation. The specific process of correcting the phase deviation is as follows: Determine whether there is a large π value in the phase deviation α , α If it exists, correct the value toα- 2π.

[0029] An average value of the corrected phase deviation is taken to obtain the phase deviation to be compensated, and phase deviation compensation is performed on the frequency-free signal according to the phase deviation to be compensated to obtain a signal without phase deviation.

[0030] Input signal For example, the specific process includes: 1. Frequency offset estimation and compensation Step 1-1: Input signal Sig ( n ) is the baseband IQ signal that has completed clock synchronization, and the data length is L, where n =1,2,… …,L.

[0031] right Sig ( n ) to the Mth power, because we don’t know Sig ( n ) is QPSK or 8PSK, first uniformly set the first preset value to M = 4, that is, the first input signal for the next step is .

[0032] Step 1-2: Calculation The amplitude spectrum power of After performing a fast Fourier transform and calculating the amplitude, we get Find out The maximum value MaxAbs and the index MaxIdx corresponding to the maximum value are calculated at the same time The average .

[0033] Step 1-3: 10 times Compared with MaxAbs, if , then the input signal is QPSK, otherwise, , the input signal is 8PSK, modify M=8, and recalculate The index MaxIdx corresponding to the maximum value of the amplitude spectrum power.

[0034] Step 1-4: Calculate the frequency corresponding to MaxIdx At this time, EF is also a rough estimate of the frequency deviation.

[0035] Step 1-5: Calculate the compensation signal corresponding to EF ,in k =0, 1, 2, ... ..., L-1. Calculate the corresponding maximum phase difference value , where angle, sort, diff and max are commonly used descriptions in matlab software. angle means returning the phase angle in the interval [-π, π] for each element of the complex array, sort means sorting the elements of the array in ascending order, diff means finding the difference, and max means finding the maximum value of the array. Calculate the search step step = 1 / L, calculate the compensation signal and the maximum phase difference value of the left and right frequency points of EF according to the step step, and obtain the compensation signal corresponding to the left frequency point (EF-step) respectively S l Compensation signal corresponding to the right frequency point (EF+step) S r And its corresponding maximum phase difference value P l and P r , and find out P 0. P l and P r The maximum value in P max Update the frequency value of EF to P max Corresponding frequency value and update search step , repeat this process until , terminate the loop.

[0036] It should be noted that is the termination condition, where 0.0001 can be adjusted to other values ​​according to requirements: the smaller the value, the more calculation times, the slower the calculation speed, and the higher the accuracy of the estimated frequency deviation value.

[0037] Step 1-6: At this point, we get the final P max The corresponding compensation frequency F est , calculate the compensation frequency deviation ,right Compensation is performed to obtain the compensated frequency deviation-free signal Sig1(n), that is, .

[0038] 2. Phase bias estimation and compensation Step 2-1: Calculate the phase .

[0039] Step 2-2: When the signal is QPSK and M=4, calculate The absolute value of the difference between the maximum value in and π, that is, calculate ,contrast With a size of 0.001, if , rotate Sig1(n) by π / 8, and update ,renew , calculate the new ,contrast Repeat this process with a size of 0.001 until > 0.001, terminate the loop, and transfer the latest Assign to As a frequency-free signal.

[0040] Step 2-3: Calculation , , , round is a common description in matlab software, which means rounding to the nearest integer. Then z(n) is corrected: add M to every number less than 0 in z(n).

[0041] If the input signal is QPSK, the numbers in z(n) are 0, 1, 2, 3; if the input signal is 8PSK, the numbers in z(n) are 0, 1, 2, 3, 4, 5, 6, 7.

[0042] Step 2-4: Calculation And calculate the phase-free standard signal .

[0043] Step 2-5: Calculation ,like There are values ​​greater than π α , then the value is corrected to α- 2π, after the correction of the completed value The average value is the phase deviation β to be compensated. After phase deviation compensation, we get , that is, a signal without phase deviation is obtained.

[0044] Example 2 like Figure 4 As shown, this embodiment provides a system for QPSK and 8PSK identification and demodulation, including: 1. Frequency offset estimation and compensation module, specifically including: 1.1 Signal recognition module: 1.1.1 signal processing module, used for performing M-th power calculation on the input signal that has completed clock synchronization to obtain a first input signal M, and the first preset value can be set to 4 to facilitate subsequent signal recognition and frequency deviation estimation; 1.1.2 Amplitude power spectrum calculation module, used to calculate the amplitude of the first input signal, as well as the average value, maximum value and index corresponding to the maximum value of the amplitude, in preparation for the next step of identification.

[0045] 1.1.3 Identification module, used to compare the average value of 10 times the amplitude with the maximum value. If the average value of 10 times the amplitude is less than the maximum value, the modulation type of the input signal is determined to be QPSK. If the N times the average value is greater than or equal to the maximum value, the modulation type of the input signal is determined to be 8PSK. 1.1.4 Output module, used to determine when the modulation type of the input signal is QPSK, and output the average value, maximum value and index corresponding to the maximum value of the amplitude currently calculated by the amplitude power spectrum calculation module as the input of the frequency deviation rough estimation module; When the modulation type of the input signal is 8PSK, the M value is corrected to 8, and the signal processing module and the amplitude power spectrum calculation module are recalculated, and then the average value, maximum value and index output corresponding to the maximum value of the amplitude are output as the input of the frequency deviation rough estimation module; 1.2 A frequency offset rough estimation module is used to calculate a rough estimated frequency offset frequency point corresponding to the index MaxIdx; 1.3 Frequency deviation precise estimation module, used to calculate the compensation signal corresponding to the coarse frequency deviation frequency point, and calculate the frequency point value corresponding to the maximum phase difference value of the compensation signal; 1.4 Frequency deviation compensation module, used to perform frequency compensation on the input signal using the frequency point value to obtain a signal without frequency deviation; 2. Phase deviation estimation and compensation module, specifically including: 2.1QPSK special processing module When the modulation type of the input signal is QPSK, this module is executed to prevent the points on the constellation diagram of the input QPSK (with phase deviation) from being located above the X or Y axis, which will affect the subsequent phase deviation estimation results. The frequency-free signal corresponding to the input QPSK is rotated until no points on the constellation diagram are located above the X or Y axis. Specifically, it includes: 2.1.1 Phase calculation module, used to calculate the phase of the signal without frequency deviation and the absolute value of the difference between the maximum phase value and π; 2.1.2QPSK rotation module, used to determine whether the absolute value of the difference is less than the second threshold. If the absolute value of the difference is less than or equal to the second threshold, the frequency-free signal is rotated by π / 8 to obtain a frequency-free correction signal, and the phase calculation module is called again until the absolute value of the difference is greater than the second threshold, and then the final frequency-free signal is output; 2.2 Constellation diagram numbering module, used to calculate the position of each point on the constellation diagram corresponding to the frequency-free signal on the standard constellation diagram without phase deviation; 2.3 standard signal calculation module, used to calculate the phase-bias-free standard signal according to the output result of the constellation diagram numbering module; 2.4 Phase deviation estimation and compensation module, used to calculate the phase deviation between the standard signal without phase deviation and the signal without frequency deviation, correct the phase deviation, take the average of the corrected phase deviation to obtain the phase deviation to be compensated, and perform phase deviation compensation on the signal without frequency deviation according to the phase deviation to be compensated to obtain a signal without phase deviation.

[0046] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for identifying and demodulating QPSK and 8PSK, characterized in that: The following steps are involved: S1, obtain the input signal after clock synchronization, and identify the modulation type of the input signal, which includes 8PSK and QPSK; S2. Calculate the input signal to the Mth power according to the modulation type, where the value of M corresponds to the modulation type, and calculate the index MaxIdx corresponding to the maximum value of the amplitude spectrum power of the input signal after the Mth power calculation; S3, calculating the roughly estimated frequency offset frequency point corresponding to the index MaxIdx, calculating the compensation signal corresponding to the roughly estimated frequency offset frequency point, calculating the frequency point value corresponding to the maximum phase difference value of the compensation signal, and using the frequency point value to perform frequency compensation on the input signal to obtain a signal without frequency offset; S4, calculating the position of the frequency-free signal corresponding to each point on the constellation diagram on the standard constellation diagram without phase deviation, and obtaining a standard signal without phase deviation; S5. Calculate the phase deviation between the standard signal without phase deviation and the signal without frequency deviation, correct the phase deviation, take the average of the corrected phase deviation to obtain the phase deviation to be compensated, and perform phase deviation compensation on the signal without frequency deviation according to the phase deviation to be compensated to obtain a signal without phase deviation.

2. The method for QPSK and 8PSK identification and demodulation according to claim 1, characterized in that: The specific process of identifying the modulation type of the input signal in step S1 is: S11, calculating a power of the input signal, where the exponent of the power is a first preset value, to obtain a first input signal; S12, calculating the amplitude spectrum power of the first input signal to obtain an amplitude data set, and calculating the maximum value, the index corresponding to the maximum value, and the average value in the amplitude data set; S13, comparing the N-times average value with the maximum value, if the N-times average value is less than the maximum value, then determining that the modulation type of the input signal is QPSK, if the N-times average value is greater than or equal to the maximum value, then determining that the modulation type of the input signal is 8PSK; S14. When the modulation type of the input signal is QPSK, M is 4; when the modulation type of the input signal is 8PSK, M is 8.

3. The method for QPSK and 8PSK identification and demodulation according to claim 2, characterized in that: The specific process of step S3 is: S31, according to the index MaxIdx corresponding to the maximum value, calculate the rough estimated frequency offset point EF corresponding to the index MaxIdx = (MaxIdx-1) / L, where L represents the data length of the input signal; S32, calculate the compensation signal corresponding to the rough estimated frequency offset point EF , calculate the maximum phase difference value corresponding to the rough estimated frequency offset point EF according to the compensation signal P 0; S33, setting the search step value, finding the left and right frequency points on both sides of the rough estimated frequency deviation point according to the search step value, respectively calculating the compensation signal and the maximum phase difference value of the left and right frequency points, and obtaining the compensation signal corresponding to the left frequency point S l The maximum value of the phase difference P l , the compensation signal corresponding to the right frequency point S r The maximum value of the phase difference P r ; S34, from the maximum value of the phase difference P 0. Maximum phase difference value P l The maximum value of the phase difference P r Select the largest value as P max , update the frequency value of the rough estimated frequency offset point EF to P max The corresponding frequency value; S35, update the search step value, repeat steps S33-S34, until the search step value reaches the preset threshold, and output the compensation frequency corresponding to the rough estimated frequency offset point EF F est ; S36, according to the compensation frequency F est The compensated frequency deviation is calculated and used to compensate the input signal to obtain a signal without frequency deviation.

4. The method for QPSK and 8PSK identification and demodulation according to claim 3, characterized in that: The initial setting value of the search step value step is step=1 / L. Each time the search step value is updated, the updated search step value is set to half of the current search step value.

5. The method for QPSK and 8PSK identification and demodulation according to claim 3, characterized in that: When the modulation type of the input signal is QPSK, the specific process of step S4 is: S41, calculating the maximum phase value corresponding to the frequency deviation-free signal, and calculating the absolute value of the difference between the maximum phase value and π; S42, determining whether the absolute value of the difference is less than a second threshold value, and if the absolute value of the difference is less than or equal to the second threshold value, rotating the frequency deviation-free signal by π / 8 to obtain a frequency deviation-free correction signal; S43, for the frequency deviation-free correction signal, repeat steps S41-S42 until the absolute value of the difference is greater than a second threshold value, and then output a final frequency deviation-free signal; S44, numbering the final frequency-offset-free signal on the constellation diagram, calculating the position of the final frequency-offset-free signal on the standard constellation diagram without phase deviation, and obtaining a standard signal without phase deviation.

6. The method for QPSK and 8PSK identification and demodulation according to claim 1, characterized in that: Calculate the standard signal without phase deviation The specific calculation process is: calculate , Sig1(n) represents a signal without frequency deviation; Round Sig2(n) to get the number z(n) of the frequency-free signal on the constellation diagram: According to z(n), we get the standard signal without phase deviation. : ； Wherein, j represents an imaginary unit, M represents a corresponding value determined according to the modulation type of the input signal, and round represents rounding to the nearest integer.

7. The method for QPSK and 8PSK identification and demodulation according to claim 6, characterized in that: Calculate the phase-biased standard signal based on z(n) The previous part also includes the correction of , and the correction method is: add M to every number less than 0 in z(n).

8. The method for QPSK and 8PSK identification and demodulation according to claim 6, characterized in that: The specific process of correcting the phase deviation in step S5 is as follows: Determine whether there is a value greater than π in the phase deviation α , α If it exists, correct the value to α- 2π.

9. A system for QPSK and 8PSK identification and demodulation, characterized in that: include: The frequency offset estimation and compensation module specifically includes: A signal identification module is used to obtain the input signal that completes clock synchronization and identify the modulation type of the input signal, which modulation types include 8PSK and QPSK; The input signal is calculated to the Mth power according to the modulation type, the value of M corresponds to its modulation type, and the index MaxIdx corresponding to the maximum value of the amplitude spectrum power of the input signal after the Mth power calculation is calculated; A frequency offset rough estimation module is used to calculate the rough estimated frequency offset frequency point corresponding to the index MaxIdx; The frequency deviation precise estimation module is used to calculate the compensation signal corresponding to the frequency point of the roughly estimated frequency deviation, and calculate the frequency point value corresponding to the maximum phase difference value of the compensation signal; The frequency deviation compensation module is used to perform frequency compensation on the input signal using the frequency point value to obtain a signal without frequency deviation; Phase deviation estimation and compensation module, specifically including: The constellation diagram numbering and standard signal calculation module is used to calculate the position of the frequency-free signal on the standard constellation diagram without phase deviation corresponding to each point on the constellation diagram, so as to obtain the standard signal without phase deviation; The phase deviation estimation and compensation module is used to calculate the phase deviation between the standard signal without phase deviation and the signal without frequency deviation, correct the phase deviation, take the average value of the corrected phase deviation to obtain the phase deviation to be compensated, and perform phase deviation compensation on the signal without frequency deviation according to the phase deviation to be compensated to obtain a signal without phase deviation.

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