Evaluation method for rotor wing shielding resistance condition of helicopter

Abstract

The invention provides a helicopter anti-rotor shielding condition evaluation method, which comprises the following steps: acquiring a third signal which is output by a transmission channel, and the input of the transmission channel is a second signal, the second signal is obtained after a satellite communication system corresponding to the helicopter performs binary phase keying modulation and Walsh-Hadamard coding on the first signal; carrying out Walsh-Hadamard decoding on the third signal to obtain a fourth signal; performing dry demodulation on the fourth signal to obtain a fifth signal; and evaluating the anti-rotor wing shielding condition of the helicopter based on the fifth signal to obtain an evaluation result. According to the method provided by the invention, the anti-rotor wing shielding condition of the helicopter can be accurately evaluated.

Description

Technical Field

[0001] The present application relates to the field of helicopter communication technology, and in particular to a method for evaluating a helicopter's anti-rotor shielding condition. Background Art

[0002] With the continuous development of science and technology, helicopters are widely used in military and civilian fields. They have become an important support force in special occasions such as disaster relief, forest fire prevention, material transportation, major security and disaster reconnaissance and detection. Due to the complexity of the environment in which helicopters perform missions, high-quality communications must be guaranteed during flight. With the continuous development of satellite communication technology, using satellites for communication is one of the important ways for helicopters. Usually, airborne communication equipment is installed on the fuselage near the tail of the helicopter under the rotor rod. Therefore, during the flight of the helicopter, the rotor rod will periodically block the communication equipment, thereby affecting the communication quality. In related technologies, the evaluation method for the helicopter's anti-rotor shielding situation has a high error rate.

[0003] Therefore, how to accurately evaluate the anti-rotor shading situation of a helicopter has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] Based on the above problems, the present application provides a method for evaluating the anti-rotor shading situation of a helicopter, so as to accurately evaluate the anti-rotor shading situation of a helicopter.

[0005] The present application provides a method for evaluating the anti-rotor shielding condition of a helicopter, the method comprising the following steps:

[0006] Acquire a third signal, wherein the third signal is output by a transmission channel, the input of the transmission channel is a second signal, and the second signal is obtained after the satellite communication system corresponding to the helicopter performs binary phase keying modulation and Walsh-Hadamard encoding on the first signal;

[0007] Performing Walsh-Hadamard decoding on the third signal to obtain a fourth signal;

[0008] Performing interference demodulation on the fourth signal to obtain a fifth signal;

[0009] The anti-rotor shading condition of the helicopter is evaluated based on the fifth signal to obtain an evaluation result.

[0010] In a possible implementation manner, the second signal is obtained in the following manner:

[0011] The first signal is subjected to binary phase keying modulation to obtain a first intermediate signal, wherein the binary phase keying modulation is performed according to the following formula:

[0012]

[0013] Among them, b i represents the first intermediate signal, a i Indicates the first signal, E b represents the signal energy of the first signal per bit;

[0014] Walsh-Hadamard encoding is performed on the first intermediate signal to obtain a second signal, wherein the Walsh-Hadamard encoding is performed using the following formula:

[0015]

[0016] Among them, s i represents the second signal, N represents the multiplexing factor, N is a real number not greater than i, H N represents the Walsh-Hadamard matrix, B0 and B1 are obtained through the first intermediate signal, and B0 is expressed as [b1b2…b N / 2 ] T , B1 is expressed as [b N / 2+1 b N / 2+2 …b N ] T .

[0017] In a possible implementation, the method further includes:

[0018] The Walsh-Hadamard matrix is ​​expressed as:

[0019]

[0020] The Walsh-Hadamard encoding is performed by the following formula:

[0021]

[0022] When B0 and B1 are real numbers, s i With s i The time diversity signal is equal when i is greater than or equal to 1 and less than or equal to N / 2. The formula is expressed as in Yes i time diversity signal.

[0023] In a possible implementation manner, the relationship between the second signal and the third signal can be expressed by the following formula:

[0024] r i =h i s i +z i ;

[0025] Among them, r i Indicates the third signal, si represents the second signal, h i represents the interference caused by the helicopter rotor, z i represents white noise generated when the second signal is transmitted through the transmission channel;

[0026] In a possible implementation manner, performing Walsh-Hadamard decoding on the third signal to obtain the fourth signal includes:

[0027] The fourth signal is extracted from the third signal based on Walsh-Hadamard decoding, and the fourth signal is expressed by the following formula:

[0028]

[0029] in, Indicates the fourth signal, r i Indicates the third signal, represents a diversity signal of the third signal, and N represents a multiplexing factor.

[0030] In a possible implementation manner, performing interference demodulation on the fourth signal to obtain the fifth signal is performed by the following formula:

[0031]

[0032] in, Represents the fourth signal, β i represents a second intermediate signal;

[0033] The β i It is expressed by the following formula:

[0034]

[0035] in, represents the fourth signal, and N represents the multiplexing factor;

[0036] The cross-correlation coefficient of the desired demodulation is expressed by the following formula:

[0037]

[0038] Where C(i) represents the cross-correlation coefficient, n is an integer not greater than i, and L represents the observable length of the signal. represents the nth fourth signal, r n Indicates the nth third signal.

[0039] In a possible implementation, the evaluating the anti-rotor shielding condition of the helicopter based on the fifth signal to obtain an evaluation result includes:

[0040] Evaluating rotor occlusion channels based on cross-correlation coefficient and threshold In the case of rotor blocking channel, the blocking condition is expressed by the following formula:

[0041]

[0042] in, represents the rotor occlusion channel, Threshold is the corresponding threshold, and C(i) represents the cross-correlation coefficient;

[0043] The performance of the rotor occlusion channel is evaluated by evaluating the error rate, and the evaluation error rate is expressed by the following formula:

[0044]

[0045] Among them, EER represents the evaluation error rate, N T represents a rotor shading cycle, h i represents the disturbance caused by the helicopter rotor, Indicates that the rotor blocks the channel;

[0046] The evaluation error rate is taken as the evaluation result.

[0047] The present application also provides a device for evaluating the anti-rotor shielding condition of a helicopter, the device comprising:

[0048] an acquisition module, configured to acquire a third signal, wherein the third signal is output by a transmission channel, the input of the transmission channel is a second signal, and the second signal is obtained by performing binary phase keying modulation and Walsh-Hadamard encoding on the first signal by a satellite communication system corresponding to the helicopter;

[0049] A decoding module, configured to perform Walsh-Hadamard decoding on the third signal to obtain a fourth signal;

[0050] A demodulation module, used for performing interference demodulation on the fourth signal to obtain a fifth signal;

[0051] An evaluation module is used to evaluate the anti-rotor shading situation of the helicopter based on the fifth signal to obtain an evaluation result.

[0052] The present application also provides an electronic device, the electronic device comprising a processor and a memory:

[0053] The memory is used to store a computer program and transmit the computer program to the processor;

[0054] The processor is used to execute the steps of the above-mentioned method for evaluating the anti-rotor shading situation of the helicopter according to the instructions in the computer program.

[0055] The present application also provides a computer-readable storage medium, which is used to store a computer program. When the computer program is executed by an electronic device, the steps of the above-mentioned method for evaluating the anti-rotor shading situation of a helicopter are implemented.

[0056] Compared with the prior art, this application has the following beneficial effects:

[0057] The method provided by the present application obtains and processes the third signal, and uses Walsh-Hadamard decoding and coherent demodulation technology to efficiently decode and modulate the satellite communication signal. This method can effectively resist the signal interference caused by rotor occlusion, ensuring that a high-quality communication link can still be maintained in a complex flight environment. Compared with the traditional signal processing method, the present application can better maintain the integrity and stability of the signal when facing periodic rotor occlusion. The present invention proposes to use the signal generated by Walsh-Hadamard decoding and the received signal for cross-correlation calculation, and evaluate the channel transmission performance by defining the evaluation error rate. Walsh-Hadamard decoding is a binary orthogonal code with good autocorrelation and cross-correlation characteristics, which can well generate the required related signals. Walsh-Hadamard decoding only needs to perform real number operations, and the storage capacity is much less than the fast Fourier transform used in the relevant technology, and the operation speed is much faster. By introducing Walsh-Hadamard encoding and decoding, the present application can quickly identify and correct the signal distortion caused by rotor occlusion during signal processing. This method not only improves the efficiency of signal processing, but also reduces the bit error rate of signal transmission, ensuring the reliability of communication. Especially in highly dynamic helicopter flight missions, the efficiency of signal processing can greatly improve the success rate of mission execution. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0059] Figure 1 A flowchart of a method for evaluating a helicopter against rotor shielding provided in an embodiment of the present application;

[0060] Figure 2 A schematic diagram of a signal transmission process provided in an embodiment of the present application;

[0061] Figure 3 A schematic diagram of periodic shielding of a rotor provided in an embodiment of the present application;

[0062] Figure 4 An EER and an Schematic diagram of the proportion

[0063] Figure 5 A schematic diagram of an evaluation result provided in an embodiment of the present application;

[0064] Figure 6 A schematic diagram of the structure of a device for evaluating the anti-rotor shading condition of a helicopter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0065] As described above, helicopters are widely used in military and civilian fields. They have become an important support force for special occasions such as disaster relief, forest fire prevention, material transportation, major security and disaster reconnaissance and detection. Due to the complexity of the environment in which helicopters perform missions, high-quality communications must be guaranteed during flight. With the continuous development of satellite communication technology, using satellites for communication is one of the important ways for helicopters. Usually, airborne communication equipment is installed on the fuselage near the tail of the helicopter under the rotor rod. Therefore, during the flight of the helicopter, the rotor rod will periodically block the communication equipment, thereby affecting the communication quality.

[0066] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0067] It is understandable that the method provided in the present application can be applied to a processing device, which is a processing device that can obtain a third signal, such as a terminal device or a server that can obtain a third signal. The method provided in the present application can be executed independently by a terminal device or a server, or can be applied to a network scenario in which a terminal device and a server communicate, and is executed by the cooperation of a terminal device and a server. Among them, the terminal device can be a computer, a mobile phone and other devices. The server can be understood as an application server or a Web server. In actual deployment, the server can be a stand-alone server or a cluster server.

[0068] Figure 1 A flowchart of a method for evaluating a helicopter against rotor shielding provided in the present application, the method comprising the following steps:

[0069] S101: Acquire a third signal.

[0070] The processing device obtains a third signal, which is output by a transmission channel. The input of the transmission channel is a second signal, which is obtained by performing binary phase keying modulation and Walsh-Hadamard encoding on the first signal by a satellite communication system corresponding to the helicopter.

[0071] Figure 2 A schematic diagram of a signal transmission process provided in an embodiment of the present application, in Figure 2 In, a i represents the first signal, s i represents the second signal, r i Indicates the third signal, Indicates the fourth signal, Indicates the fifth signal. i represents the first intermediate signal. The BPSK modulator is a binary phase shift keying modulator (BPSK).

[0072] In a possible implementation, the second signal may be obtained in the following manner:

[0073] The first signal is subjected to binary phase keying modulation to obtain a first intermediate signal, and the binary phase keying modulation is performed according to the following formula:

[0074]

[0075] Among them, b i represents the first intermediate signal, a i Indicates the first signal, E b represents the signal energy of the first signal per bit;

[0076] Walsh-Hadamard encoding is performed on the first intermediate signal to obtain a second signal. The Walsh-Hadamard encoding is performed using the following formula:

[0077]

[0078] Among them, s i represents the second signal, N represents the multiplexing factor, N is a real number not greater than i, H N represents the Walsh-Hadamard matrix, B0 and B1 are obtained through the first intermediate signal, and B0 is expressed as [b1b2…b N / 2 ] T , B1 is expressed as [b N / 2+1 b N / 2+2 …b N ] T .

[0079] Specifically, the Walsh-Hadamard matrix can be expressed as:

[0080]

[0081] When the Walsh-Hadamard matrix is ​​expressed as the above matrix, Walsh-Hadamard encoding can be performed by the following formula:

[0082]

[0083] When B0 and B1 are real numbers, s i With s i The time diversity signal is equal when i is greater than or equal to 1 and less than or equal to N / 2. The formula is expressed as in Yes i time diversity signal.

[0084] In actual use, the signal will inevitably generate white noise and rotor shielding interference when it is transmitted in the transmission channel. The relationship between the second signal and the third signal can be expressed by the following formula:

[0085] r i =h i s i +z i ;

[0086] Among them, r i Indicates the third signal, s i represents the second signal, h i represents the interference caused by the helicopter rotor, z i Represents white noise generated when the second signal is transmitted in the transmission channel.

[0087] Figure 3 A schematic diagram of periodic shielding of a rotor provided in an embodiment of the present application, in Figure 3 In, h t A function that represents the change of a signal over time. Usually, helicopter rotors will cause periodic occlusion of the signal, which can be divided into three stages: no occlusion, partial occlusion, and full occlusion. The occlusion rate is expressed as δ = T0 / T.

[0088] S102: Perform Walsh-Hadamard decoding on the third signal to obtain a fourth signal.

[0089] The processing device performs Walsh-Hadamard decoding on the third signal to obtain a fourth signal.

[0090] Specifically, the processing device may extract the fourth signal from the third signal based on Walsh-Hadamard decoding, and the fourth signal may be expressed by the following formula:

[0091]

[0092] in, Indicates the fourth signal, r i Indicates the third signal, represents a diversity signal of the third signal, and N represents a multiplexing factor.

[0093] S103: Perform interferometric demodulation on the fourth signal to obtain a fifth signal.

[0094] The processing device performs interference demodulation on the fourth signal to obtain a fifth signal.

[0095] Specifically, performing interferometric demodulation on the fourth signal to obtain the fifth signal may be performed by the following formula:

[0096]

[0097] in, Represents the fourth signal, β i represents a second intermediate signal;

[0098] β i It is expressed by the following formula:

[0099]

[0100] in, represents the fourth signal, and N represents the multiplexing factor;

[0101] The cross-correlation coefficient of the desired demodulation is expressed by the following formula:

[0102]

[0103] Where C(i) represents the cross-correlation coefficient, n is an integer not greater than i, and L represents the observable length of the signal. represents the nth fourth signal, r n Indicates the nth third signal.

[0104] S104: Evaluate the anti-rotor shielding condition of the helicopter based on the fifth signal to obtain an evaluation result.

[0105] The processing device evaluates the anti-rotor shading situation of the helicopter based on the fifth signal to obtain an evaluation result.

[0106] Specifically, the processing device can evaluate the rotor occlusion channel based on the cross-correlation coefficient and the threshold In the case of rotor blocking channel, the blocking condition is expressed by the following formula:

[0107]

[0108] in, represents the rotor occlusion channel, Threshold is the corresponding threshold, and C(i) represents the cross-correlation coefficient. The threshold Threshold may be the occlusion rate δ recorded in S101. When it is greater than or equal to 1, there is no occlusion. When it is less than 1, it is occlusion (including full occlusion and partial occlusion).

[0109] The processing device can evaluate the performance of the rotor occlusion channel by evaluating the error rate, and the error rate can be expressed by the following formula:

[0110]

[0111] Among them, EER represents the evaluation error rate, N T represents a rotor shading cycle, h i represents the disturbance caused by the helicopter rotor, Indicates that the rotor blocks the channel;

[0112] The evaluation error rate is used as the evaluation result. In order to better evaluate the rotor occlusion situation, the signal observable length L should be less than the standardized occlusion period Then reducing the L value can reduce the signal-to-noise ratio of C(i), that is, the EER of the system can be optimized by finding the optimal value L.

[0113] The method provided by the present application obtains and processes the third signal, and uses Walsh-Hadamard decoding and coherent demodulation technology to efficiently decode and modulate the satellite communication signal. This method can effectively resist the signal interference caused by rotor occlusion, ensuring that a high-quality communication link can still be maintained in a complex flight environment. Compared with the traditional signal processing method, the present application can better maintain the integrity and stability of the signal when facing periodic rotor occlusion. The present invention proposes to use the signal generated by Walsh-Hadamard decoding and the received signal for cross-correlation calculation, and evaluate the channel transmission performance by defining the evaluation error rate. Walsh-Hadamard decoding is a binary orthogonal code with good autocorrelation and cross-correlation characteristics, which can well generate the required related signals. Walsh-Hadamard decoding only needs to perform real number operations, and the storage capacity is much less than the fast Fourier transform used in the relevant technology, and the operation speed is much faster. By introducing Walsh-Hadamard encoding and decoding, the present application can quickly identify and correct the signal distortion caused by rotor occlusion during signal processing. This method not only improves the efficiency of signal processing, but also reduces the bit error rate of signal transmission, ensuring the reliability of communication. Especially in highly dynamic helicopter flight missions, the efficiency of signal processing can greatly improve the success rate of mission execution.

[0114] Next, a specific example is used to illustrate that the present invention uses the information data as 32 kbps, the multiplexing factor as N=1024, and the signal-to-noise ratio as E. b The simulation experiment is carried out with the setting of / N0=2dB, occlusion period of 38.9 milliseconds, and occlusion rate of δ=0.321 as an example. Figure 4 As shown, when When , the error rate EER reaches the optimal value, Figure 4 An EER and an Schematic diagram of the scale. Figure 5 As shown, Figure 5 A schematic diagram of an evaluation result provided in an embodiment of the present application, Figure 5 It is shown that the channel estimation method proposed in this invention can still obtain accurate results even under the interference of rotor occlusion and Gaussian white noise. It can accurately evaluate the channel obstruction situation, improve the channel transmission performance and reduce the communication error rate.

[0115] This application also provides a Figure 6 The schematic diagram of the structure of the device for evaluating the anti-rotor shielding condition of a helicopter is shown, wherein the device 600 for evaluating the anti-rotor shielding condition of a helicopter comprises:

[0116] An acquisition module 601 is used to acquire a third signal, where the third signal is output by a transmission channel, the input of the transmission channel is a second signal, and the second signal is obtained by performing binary phase keying modulation and Walsh-Hadamard encoding on the first signal by a satellite communication system corresponding to the helicopter;

[0117] A decoding module 602, configured to perform Walsh-Hadamard decoding on the third signal to obtain a fourth signal;

[0118] A demodulation module 603, configured to perform interference demodulation on the fourth signal to obtain a fifth signal;

[0119] The evaluation module 604 is used to evaluate the anti-rotor shielding situation of the helicopter based on the fifth signal to obtain an evaluation result.

[0120] The device provided by the present application obtains and processes the third signal, and uses Walsh-Hadamard decoding and coherent demodulation technology to efficiently decode and modulate the satellite communication signal. This method can effectively resist the signal interference caused by rotor occlusion, ensuring that a high-quality communication link can still be maintained in a complex flight environment. Compared with the traditional signal processing method, the present application can better maintain the integrity and stability of the signal when facing periodic rotor occlusion. The present invention proposes to use the signal generated by Walsh-Hadamard decoding and the received signal for cross-correlation calculation, and evaluate the channel transmission performance by defining the evaluation error rate. Walsh-Hadamard decoding is a binary orthogonal code with good autocorrelation and cross-correlation characteristics, which can well generate the required related signals. Walsh-Hadamard decoding only needs to perform real number operations, and the storage capacity is much less than the fast Fourier transform used in the relevant technology, and the operation speed is much faster. By introducing Walsh-Hadamard encoding and decoding, the present application can quickly identify and correct the signal distortion caused by rotor occlusion during signal processing. This method not only improves the efficiency of signal processing, but also reduces the bit error rate of signal transmission, ensuring the reliability of communication. Especially in highly dynamic helicopter flight missions, the efficiency of signal processing can greatly improve the success rate of mission execution.

[0121] An embodiment of the present application also provides an evaluation device for the anti-rotor shading condition of a helicopter, wherein the device includes a memory and a processor, the memory is used to store instructions or codes, and the processor is used to execute the instructions or codes so that the device performs the steps of the method for evaluating the anti-rotor shading condition of a helicopter described in any embodiment of the present application.

[0122] In practical applications, the computer-readable storage medium may be any combination of one or more computer-readable media, which may be a computer-readable signal medium or a computer-readable storage medium.

[0123] The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, device, or device.

[0124] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0125] The program code embodied on the computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0126] Computer program code for performing the operations of the present invention may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0127] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The device embodiment described above is merely schematic, in which the unit described as a separate component may or may not be physically separated, and the component prompted as a unit may or may not be a physical unit, that is, it may be located in one place, or it may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0128] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for evaluating the anti-rotor shielding condition of a helicopter, characterized in that: include: Acquire a third signal, wherein the third signal is output by a transmission channel, the input of the transmission channel is a second signal, and the second signal is obtained after the satellite communication system corresponding to the helicopter performs binary phase keying modulation and Walsh-Hadamard encoding on the first signal; Performing Walsh-Hadamard decoding on the third signal to obtain a fourth signal; Performing interference demodulation on the fourth signal to obtain a fifth signal; The anti-rotor shading condition of the helicopter is evaluated based on the fifth signal to obtain an evaluation result.

2. The method according to claim 1, characterized in that The second signal is obtained by: The first signal is subjected to binary phase keying modulation to obtain a first intermediate signal, wherein the binary phase keying modulation is performed according to the following formula: Among them, b i represents the first intermediate signal, a i Indicates the first signal, E b represents the signal energy of the first signal per bit; Walsh-Hadamard encoding is performed on the first intermediate signal to obtain a second signal, wherein the Walsh-Hadamard encoding is performed using the following formula: Among them, s i represents the second signal, N represents the multiplexing factor, N is a real number not greater than i, H N represents the Walsh-Hadamard matrix, B0 and B1 are obtained through the first intermediate signal, and B0 is expressed as [b1 b2 … b N / 2 ] T , B1 is expressed as [b N / 2+1 b N / 2+2 …b N ] T .

3. The method according to claim 2, characterized in that The method further comprises: The Walsh-Hadamard matrix is ​​expressed as: The Walsh-Hadamard encoding is performed by the following formula: When B0 and B1 are real numbers, s i With s i The time diversity signal is equal when i is greater than or equal to 1 and less than or equal to N / 2. The formula is expressed as in Yes i time diversity signal.

4. The method according to claim 1, characterized in that: The relationship between the second signal and the third signal can be expressed by the following formula: r i =h i s i +z i ; Among them, r i Indicates the third signal, s i represents the second signal, h i represents the interference caused by the helicopter rotor, z i Represents white noise generated when the second signal is transmitted in the transmission channel.

5. The method according to claim 1, characterized in that The performing Walsh-Hadamard decoding on the third signal to obtain the fourth signal comprises: The fourth signal is extracted from the third signal based on Walsh-Hadamard decoding, and the fourth signal is expressed by the following formula: in, Indicates the fourth signal, r i Indicates the third signal, represents a diversity signal of the third signal, and N represents a multiplexing factor.

6. The method according to claim 1, characterized in that The interferential demodulation of the fourth signal to obtain the fifth signal is performed by the following formula: in, Represents the fourth signal, β i represents a second intermediate signal; The β i It is expressed by the following formula: in, represents the fourth signal, and N represents the multiplexing factor; The cross-correlation coefficient of the desired demodulation is expressed by the following formula: Where C(i) represents the cross-correlation coefficient, n is an integer not greater than i, and L represents the observable length of the signal. represents the nth fourth signal, r n Indicates the nth third signal.

7. The method according to claim 6, characterized in that The evaluation result obtained by evaluating the anti-rotor shielding condition of the helicopter based on the fifth signal includes: Evaluating rotor occlusion channels based on cross-correlation coefficient and threshold In the case of rotor blocking channel, the blocking condition is expressed by the following formula: in, represents the rotor occlusion channel, Threshold is the corresponding threshold, and C(i) represents the cross-correlation coefficient; The performance of the rotor occlusion channel is evaluated by evaluating the error rate, and the evaluation error rate is expressed by the following formula: Among them, EER represents the evaluation error rate, N T represents a rotor shading cycle, h i represents the disturbance caused by the helicopter rotor, Indicates that the rotor blocks the channel; The evaluation error rate is taken as the evaluation result.

8. A device for evaluating the anti-rotor shielding condition of a helicopter, characterized in that: include: an acquisition module, configured to acquire a third signal, wherein the third signal is output by a transmission channel, the input of the transmission channel is a second signal, and the second signal is obtained by performing binary phase keying modulation and Walsh-Hadamard encoding on the first signal by a satellite communication system corresponding to the helicopter; A decoding module, configured to perform Walsh-Hadamard decoding on the third signal to obtain a fourth signal; A demodulation module, used for performing interference demodulation on the fourth signal to obtain a fifth signal; An evaluation module is used to evaluate the anti-rotor shading situation of the helicopter based on the fifth signal to obtain an evaluation result.

9. An electronic device, characterized in that: comprising a memory and a processor, wherein: The memory is used to store the computer program; The processor is used to execute the computer program to implement the method for evaluating the anti-rotor shading situation of a helicopter as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: Used to store a computer program, wherein when the computer program is executed by a processor, the method for evaluating the anti-rotor shading situation of a helicopter as described in any one of claims 1 to 7 is implemented.

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