Orthogonal demodulation method, system and device and storage medium

Abstract

The invention discloses a quadrature demodulation method, system, device and medium, and relates to the technical field of decoding, and the quadrature demodulation method comprises the following steps: processing a sinusoidal signal and a cosine signal through a quadrature DSM modulator, and carrying out down-conversion processing on a signal output by the quadrature DSM modulator to obtain an intermediate frequency signal; obtaining an orthogonal tracking signal, and calculating an intermediate frequency conjugate signal corresponding to the intermediate frequency signal and an orthogonal conjugate signal corresponding to the orthogonal tracking signal; determining a first product of the intermediate frequency signal and the orthogonal conjugate signal, and determining a second product of the orthogonal tracking signal and the intermediate frequency conjugate signal; and taking the difference between the first product and the second product as an orthogonal demodulation result. The technical scheme of the invention aims to solve the technical problem of low signal-to-noise ratio of useful signals in the existing demodulation technology.

Description

Technical Field

[0001] The present application relates to the technical field of decoding, and particularly to a quadrature demodulation method, system, device and storage medium. Background Art

[0002] RDC (Resolver-to-Digital Converter) demodulation technology is mainly used to convert the output signal of a resolver into a digital signal to provide motor shaft position or speed feedback information.

[0003] Currently, RDC demodulation technology usually takes the sine signal and cosine signal output by the resolver as the input of the RDC, and then converts the sine signal and cosine signal into discrete signals through a DSM ADC (Delta Sigma Modulator). However, in the DSM ADC, noise is introduced during the process of converting the sine signal and cosine signal from continuous signals to discrete signals. Furthermore, when processing the discrete signals, the noise will be aliased into the signals used to calculate the motor shaft position or speed feedback information, resulting in a low signal-to-noise ratio of the useful signals. Summary of the Invention

[0004] The main objective of the present application is to provide a quadrature demodulation method, system, device and storage medium, aiming to solve the technical problem of low signal-to-noise ratio of useful signals in the existing demodulation technology.

[0005] To achieve the above objective, the present application proposes a quadrature demodulation method, and the method includes:

[0006] Process the sine signal and cosine signal through a quadrature DSM modulator, and perform down-conversion processing on the signal output by the quadrature DSM modulator to obtain an intermediate-frequency signal;

[0007] Obtain a quadrature tracking signal, and calculate the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and the quadrature conjugate signal corresponding to the quadrature tracking signal;

[0008] Determine the first product of the intermediate-frequency signal and the quadrature conjugate signal, and determine the second product of the quadrature tracking signal and the intermediate-frequency conjugate signal;

[0009] Take the difference between the first product and the second product as the quadrature demodulation result.

[0010] In one embodiment, after the step of taking the difference between the first product and the second product as the quadrature demodulation result, the method further includes:

[0011] Perform low-pass filtering on the quadrature demodulation result to obtain a low-frequency DC signal;

[0012] Decode according to the low-frequency DC signal to obtain a decoding result, where the decoding result includes the angular position and rotational speed of the motor shaft.

[0013] In one embodiment, the step of performing low-pass filtering on the quadrature demodulation result to obtain a low-frequency DC signal includes:

[0014] Obtain the frequency of the harmonic component to be eliminated, and configure a filter based on the frequency of the harmonic component to be eliminated. The filter includes a notch filter or a comb filter;

[0015] Input the quadrature demodulation result into the filter to obtain a primary filtered signal, and input the primary filtered signal into a preset low-pass filter to obtain a low-frequency DC signal.

[0016] In one embodiment, the step of performing low-pass filtering on the quadrature demodulation result to obtain a low-frequency DC signal includes:

[0017] Obtain the frequency of the harmonic component to be eliminated, and configure a half-band notch filter based on the frequency of the harmonic component to be eliminated;

[0018] Input the quadrature demodulation result into a preset cascaded integrator comb filter to obtain a cascaded filtered signal, and input the cascaded filtered signal into the half-band notch filter to obtain a low-frequency DC signal.

[0019] In one embodiment, the step of determining the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal includes:

[0020] Extract the low-frequency signal from the intermediate-frequency signal, and use the conjugate signal corresponding to the low-frequency signal as the intermediate-frequency conjugate signal.

[0021] In one embodiment, the step of obtaining the quadrature tracking signal includes:

[0022] Based on the output angle of the resolver, determine the sine value and cosine value corresponding to the output angle;

[0023] Combine the sine value and the cosine value based on Euler's formula to obtain a quadrature tracking signal.

[0024] In one embodiment, the step of determining the sine value and cosine value corresponding to the output angle includes:

[0025] In a preset mapping relation table, look up the preset sine value and cosine value corresponding to the output angle;

[0026] Calculate the sine value and cosine value corresponding to the output angle by the coordinate rotation digital computation method.

[0027] In addition, to achieve the above object, an orthogonal demodulation system, the system includes:

[0028] An acquisition module, configured to process a sine signal and a cosine signal through an orthogonal DSM modulator, and perform down-conversion processing on the signal output by the orthogonal DSM modulator to obtain an intermediate-frequency signal;

[0029] A conjugate module, configured to obtain an orthogonal tracking signal, and calculate an intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and an orthogonal conjugate signal corresponding to the orthogonal tracking signal;

[0030] A product module, configured to determine a first product of the intermediate-frequency signal and the orthogonal conjugate signal, and determine a second product of the orthogonal tracking signal and the intermediate-frequency conjugate signal;

[0031] A difference module, configured to use the difference between the first product and the second product as the orthogonal demodulation result.

[0032] In addition, to achieve the above object, the present application also provides a terminal device, the device includes: a memory, a processor, and a computer program stored on the memory and executable on the processor, the computer program is configured to implement the steps of the orthogonal demodulation method as described above.

[0033] In addition, to achieve the above object, the present application also provides a storage medium, the storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium, and when the computer program is executed by a processor, it implements the steps of the orthogonal demodulation method as described above.

[0034] In addition, to achieve the above object, the present application also provides a computer program product, the computer program product includes a computer program, and when the computer program is executed by a processor, it implements the steps of the orthogonal demodulation method as described above.

[0035] This application processes sine and cosine signals through an orthogonal DSM modulator, and performs down-conversion processing on the signals output by the orthogonal DSM modulator to obtain intermediate-frequency signals. The orthogonal DSM modulator can make the stopband of quantization noise fall only in the positive frequency or only in the negative frequency, reducing the noise power within the signal bandwidth, improving the signal-to-noise ratio. Additionally, through down-conversion, the effective signal in the output of the orthogonal DSM modulator is extracted, avoiding the reduction of the signal-to-noise ratio by useless signals. Then, an orthogonal tracking signal is obtained, and the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and the orthogonal conjugate signal corresponding to the orthogonal tracking signal are calculated. Then, the first product of the intermediate-frequency signal and the orthogonal conjugate signal is determined, and the second product of the orthogonal tracking signal and the intermediate-frequency conjugate signal is determined. Furthermore, by using the difference between the first product and the second product as the orthogonal demodulation result, orthogonal demodulation can be performed using a signal with lower noise, resulting in a very low noise in the obtained orthogonal demodulation result, thereby improving the signal-to-noise ratio in the orthogonal demodulation result, that is, improving the signal-to-noise ratio of the useful signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0037] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0038] Figure 1 It is a schematic diagram of a demodulation algorithm in the prior art;

[0039] Figure 2 It is a schematic diagram of signal modulation, DSM modulation quantization noise, and demodulation noise aliasing in the prior art;

[0040] Figure 3 It is a schematic flowchart provided by Embodiment 1 of the orthogonal demodulation method of the present application;

[0041] Figure 4 It is a schematic diagram of a complex filter architecture in the prior art;

[0042] Figure 5 It is a schematic diagram of the complex output of a complex DSM passing through a complex demodulator in an embodiment of the orthogonal demodulation method of the present application;

[0043] Figure 6 It is a spectral analysis diagram of excitation down-conversion in an embodiment of the orthogonal demodulation method of the present application;

[0044] Figure 7Schematic diagram of the system structure of the quadrature demodulation method of the present application;

[0045] Figure 8 Specific embodiment 1 of the quadrature demodulation method of the present application;

[0046] Figure 9 Specific embodiment 2 of the quadrature demodulation method of the present application;

[0047] Figure 10 Spectrum analysis diagram of the down-conversion of the complex-domain rotation signal in an embodiment of the quadrature demodulation method of the present application;

[0048] Figure 11 Embodiment 1 of the filter in Embodiment 2 of the present application;

[0049] Figure 12 Embodiment 2 of the filter in Embodiment 2 of the present application;

[0050] Figure 13 Schematic diagram of the module structure of the quadrature demodulation system in an embodiment of the present application;

[0051] Figure 14 Schematic diagram of the device structure of the hardware operating environment involved in the quadrature demodulation method in an embodiment of the present application.

[0052] The realization of the purpose, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0053] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0054] For a better understanding of the technical solutions of the present application, the following will be described in detail with reference to the accompanying drawings of the specification and specific embodiments.

[0055] The main solution of the embodiment of the present application is: processing a sine signal and a cosine signal through a quadrature DSM modulator, and performing down-conversion processing on the signal output by the quadrature DSM modulator to obtain an intermediate-frequency signal; acquiring a quadrature tracking signal, and calculating the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and the quadrature conjugate signal corresponding to the quadrature tracking signal; determining the first product of the intermediate-frequency signal and the quadrature conjugate signal, and determining the second product of the quadrature tracking signal and the intermediate-frequency conjugate signal; taking the difference between the first product and the second product as the quadrature demodulation result.

[0056] Due to the RDC demodulation technology in the prior art, the following method is usually adopted: the output of the resolver is used as the input of the RDC, that is, the sine signal and the cosine signal (these two signals are continuous signals) are used as the input, and then the two paths will be sent to the DSM ADC and converted into discrete signals. In the DSM ADC, during the process of converting the two signals from continuous signals to discrete signals, noise will be introduced, and after a series of subsequent processes, this noise will be aliased into the useful signal, resulting in a low final signal-to-noise ratio SNR of the noise.

[0057] Specifically, the resolver uses a sine wave reference signal sinω to excite the primary winding, and it will generate two electromagnetic induction differential output signals on the secondary winding, namely the sine signal sinω·sinθ and the cosine signal sinω·cosθ (these two signals are continuous signals). The Rotary Digital Converter (RDC) realizes the interface between the resolver and the system microprocessor, and decodes the angular position and rotational speed of the motor shaft using these sine and cosine signals.

[0058] Please refer to Figure 1 , the RDC synchronously samples the sine signal and the cosine signal (both are continuous signals), and sends them to the DSM ADC respectively. At this time, the DSM will convert the continuous input signal into a discrete output signal, that is, the signals 1 and 2 in Figure 1 are obtained. Since signals 1 and 2 undergo noise shaping by the DSM ADC, the noise components at high frequencies are relatively large.

[0059] In addition, Figure 1 the sinω in

[0060] is generated by the internal clock module, and its frequency is known. The output angle φ in sinφ and cosφ is generated by the internal second-order tracking rotation loop and is used to track the input shaft angle θ. And sin(θ - φ) in signals 5 and 7 is used to represent the error amount between the output angle φ and the input shaft angle θ. If the output angle φ is equal to the input shaft angle θ, at this time sin(θ - φ) = 0, that is, the signal amounts of signals 5 and 7 are both 0. Therefore, during the process of signal processing such as frequency analysis, a certain error is made to exist between the output angle φ and the input shaft angle θ, and at this time, signals 5 and 7 can be used to analyze the error between the two angles. When there is a 90° error between the output angle φ and the input shaft angle θ. Since the input signals 1 and 2 are the outputs of the DSM ADC, there is relatively large high-frequency noise, and thus all subsequent demodulation operations related to signals 1 and 2 have noise components.

[0061] Please refer to Figure 2 , analyze Figure 2It can be known that: due to the shifting of the signal spectrum, the noise will also be shifted. Therefore, with the demodulation operation, the noise component at low frequencies will increase as the spectrum is shifted. And, if the frequency is higher, the spectrum shift is greater, so the noise shift is also greater. Therefore, the higher-frequency noise (i.e., greater noise) will aliase with the signal components at low frequencies, resulting in a worse final signal-to-noise ratio.

[0062] In addition, the noise of sinw·sinθ·cosφ at the 1 / 4 signal component is basically equal to the noise at the signal component where signal 1 is at a higher frequency (affected by noise shifting). The same applies to sinw·cosθ·sinφ, which is affected by the noise of signal 2. And signal 5 is obtained by subtracting the two signals sinw·sinθ·cosφ and sinw·cosθ·sinφ. This operation will perform a subtraction operation on the signal. However, since the noise is non-correlated and cannot be directly added or subtracted, it can only be in the relationship of the sum of squares. Therefore, it can be seen that the signal components in signal 5 perform a subtraction operation, but the noise components perform a sum-of-squares addition operation, so the noise floor is higher. In addition, Figure 1 the noise of signal 7 at DC is basically equal to the noise at the signal component where signal 5 is (affected by noise shifting).

[0063] Therefore, from Figure 1 and Figure 2 it can be known that affected by the noise shaping of the DSM ADC, signals 1 and 2 are the output signals of the DSM ADC. Therefore, the high-frequency noise components of signals 1 and 2 are large. And as the subsequent demodulation progresses, the frequency will be shifted and the noise will also be shifted. Therefore, the noise of signals 1 and 2 at the 1 / 4 signal component will be shifted to the low-frequency signal of the final result, resulting in aliasing between the signal at low frequencies and the noise at high frequencies, thus resulting in a worse final signal-to-noise ratio. To solve the problem of the low signal-to-noise ratio of the final signal (useful signal), this application proposes a solution that uses an orthogonal DSM modulator to modulate the signal and then obtains the useful signal through orthogonal demodulation technology to improve the signal-to-noise ratio of the useful signal.

[0064] Based on this, an embodiment of this application provides an orthogonal demodulation method. Referring to Figure 3 , Figure 3 is a schematic flowchart of the first embodiment of the orthogonal demodulation method of this application.

[0065] In this embodiment, the orthogonal demodulation method includes steps S10 to S40:

[0066] Step S10, process the sine signal and the cosine signal through an orthogonal DSM modulator, and perform down-conversion processing on the signal output by the orthogonal DSM modulator to obtain an intermediate-frequency signal;

[0067] It should be noted that an orthogonal DSM modulator refers to a device that incorporates the high-resolution quantization characteristics of Delta Sigma Modulation (Δ-Σ modulation). The working principle of Delta Sigma Modulation is as follows:

[0068] Input signal separation: First, the multiple signals to be transmitted or a single broadband signal are decomposed into two orthogonal components (I and Q), so that two independent pieces of information can be transmitted within the same time and the same frequency band by utilizing the orthogonality in space.

[0069] Δ-Σ modulation: The two signals are respectively modulated by Delta Sigma Modulators. In this process, the signals are highly quantized, and through oversampling technology and digital noise shaping, most of the quantization noise can be shifted to the high-frequency region far from the signal frequency band.

[0070] Orthogonal synthesis: The I and Q signals after Δ-Σ modulation are then synthesized by digital or analog means to form a composite modulated signal. This composite signal contains all the information of the original signal and has good anti-interference ability and high resolution due to the characteristics of Δ-Σ modulation.

[0071] Filtering and recovery: At the receiving end, the received composite signal needs to pass through a low-pass filter to remove the high-frequency noise introduced during the Δ-Σ modulation process, and then the original I and Q signals are recovered through the demodulation process. Finally, they are combined into the original information, thus obtaining the signal output by the orthogonal DSM modulator.

[0072] In addition, regarding orthogonality, it should also be noted that, for reference, Figure 4 , an orthogonal filter can also be used to filter the orthogonal tracking signal (i.e., a complex signal). The transfer function H of the orthogonal filter can be expressed by the following equation:

[0073] H = H x +jH y Equation 1;

[0074] where H x and H y are real transfer functions; if the input signal is an orthogonal tracking signal U, its expression is as follows:

[0075] U = U x +jU y Equation 2;

[0077] Thus, the output of the orthogonal filter is:

[0078] V = U·H = (U x +jUy )·(H x +jH y )

[0079] =(U x ·H x -U y ·H y )+j(U y ·H x +U x ·H y )=V x +jV y Equation 3;

[0080] The implementation process of the above formula 3 can be implemented with the block diagram of Figure 4 .

[0081] In addition, it should be noted that down-conversion processing refers to converting a high-frequency signal into a lower-frequency signal, and the intermediate-frequency signal refers to the signal obtained after down-conversion processing.

[0082] In this embodiment, the RDC synchronously acquires the sine signal and the cosine signal (both are continuous signals), transmits them to the quadrature DSM modulator QDSM respectively, and then performs down-conversion processing on the output V of the quadrature DSM modulator (QDSM). The operation process is as follows Figure 5 shown. As can be seen from the above formula, the output V of the in-phase channel (I channel) of the QDSM x , the output V of the quadrature channel (Q channel) y , and the total output, that is, the complex output V, are respectively:

[0083] I: V x =sinω·cosθ - sinω·sinθ Equation 4;

[0084] Q: V y =sinω·cosθ + sinω·sinθ Equation 5;

[0085] V=(sinω·cosθ - sinω·sinθ)+j(sinω·cosθ + sinω·sinθ) Equation 6;

[0086] Among them, after the resolver input signal is modulated by the QDSM, its final output signal V is a digital orthogonal output including the required signal plus shaped quantization noise. Figure 5 The frequency analysis of the operation process is as follows Figure 6 shown.

[0087] From Figure 6From the spectrum analysis, it can be seen that a significant feature of the quadrature DSM modulator (QDSM) is that the stopband of its quantization noise only needs to exist in the positive (or negative) frequency. In this embodiment, the stopband of the quantization noise is made to fall in the positive frequency, that is, the zeros of the noise transfer function NTF are at positive frequencies. In addition, since the energy of the QDSM is concentrated in the single-sided spectrum, its signal components will be higher than those of the DSM (the energy is distributed in the double-sided spectrum), which is beneficial to improving the SNR.

[0088] In Figure 6 the result of the first down-conversion of the QDSM output in 1 is the S 1 signal. From the spectrum of the S

[0089] Step S20, obtain a quadrature tracking signal, and calculate the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and, the quadrature conjugate signal corresponding to the quadrature tracking signal;

[0090] It should be noted that the quadrature tracking signal is a signal used to calculate the error between the resolver output angle (the angle information represented by the electrical signal output according to the position change of its rotor relative to the stator when the resolver is working) and the rotation input shaft angle. In a feasible implementation manner, the conjugate signals corresponding to the intermediate-frequency signal and the quadrature information can be calculated through conjugate operations, so as to obtain the intermediate-frequency conjugate signal and the quadrature conjugate signal.

[0091] In addition, in a feasible implementation manner, the above step S20 further includes:

[0092] Step S201, based on the output angle of the resolver, determine the sine value and cosine value corresponding to the output angle;

[0093] Step S202, combine the sine value and the cosine value based on Euler's formula to obtain a quadrature tracking signal.

[0094] It should be noted that since the sinω component in the resolver input signal is generated by the internal clock module and its frequency is known. While the rotation input shaft angle θ is determined by the external resolver and is unknown. Therefore, the rotation digital converter RDC generates an output angle φ through the internal second-order tracking rotation loop, and the output angle φ is used to track the rotation input shaft angle θ. If the output angle φ is equal to the input shaft angle θ, then sin(θ - φ) = 0 at this time. Therefore, the error between the output angle φ and the rotation input shaft angle θ can be judged by sin(θ - φ). Therefore, a signal quantity related to e j(θ-φ) used in the down-conversion can be constructed, so as to extract sin(θ - φ), and further obtain the error between the resolver output angle and the rotation input shaft angle. And Figure 6The useful signal in it, that is, the signal at the frequency where the noise is the lowest, and the signal component at this place can be expressed as:

[0095]

[0096] Thus, e can be constructed jφ (that is, the orthogonal tracking signal), and then based on e jφ and the above S 2 expression, sin(θ - φ) is extracted, so that the error between the output angle φ and the rotation input shaft angle θ can be judged by sin(θ - φ).

[0097] In addition, it can be known from Euler's formula that:

[0098] e jφ = cosφ + j·sinφ Equation 8;

[0099] Therefore, the orthogonal tracking signal e can be constructed through sinφ and cosφ jφ . Among them, the output angle φ is generated by the internal second-order tracking rotation loop.

[0100] In this embodiment, in order to obtain the value of sin(θ - φ), the present application starts from the S 2 expression obtained by down-conversion, constructs e jφ , and then through Euler's formula, obtains the corresponding expression of e jφ , so that e can be constructed based on Euler's formula jφ . That is, the output angle can be obtained first, the sine value and cosine value corresponding to the output angle are calculated, and then the sine value and cosine value are substituted into Euler's formula, so as to obtain the orthogonal tracking signal e jφ . Thus, after obtaining the quadrature demodulation result, decoding can be performed based on the quantity related to sin(θ - <) in the quadrature demodulation result.

[0101] In a feasible implementation manner, the above step S201 further includes:

[0102] Step S2011, in the preset mapping relation table, look up the preset sine value and cosine value corresponding to the output angle;

[0103] Step S2012, calculate the sine value and cosine value corresponding to the output angle by the coordinate rotation digital calculation method.

[0104] It is understandable that the mapping relation table refers to a table storing the corresponding relations between angular values and sine values and cosine values. The coordinate rotation digital calculation method, i.e., the CORDIC algorithm, has a core idea of decomposing complex trigonometric function calculations into a series of simple displacement and accumulation operations. Through continuous rotation and scaling, the target vector is gradually transformed into a vector parallel to the x-axis, and then the required trigonometric function values are calculated.

[0105] Exemplarily, a pre-set mapping relation table can be obtained, and then the sine value and cosine value can be obtained by looking up the table.

[0106] As another example, the steps for calculating the sine value and cosine value by the coordinate rotation digital calculation method can be as follows:

[0107] 1) Initialization:

[0108] Initialize the angular value as the angle (θ) to be calculated.

[0109] Initialize the vector (x, y) as (1, 0), which represents the starting point on the unit circle (during the CORDIC iteration process, this point will gradually approach the end point of the target angle).

[0110] Initialize the rotation factor K (Ki) as 1, and this factor is used to record the cumulative effect of all rotations.

[0111] 2) Iterative calculation:

[0112] The iterative loop starts, and a series of displacement and accumulation operations are performed according to a predetermined precision or the number of iterations.

[0113] In each iteration:

[0114] Judge the relationship between the Y component (y) of the target vector and 0 to determine the rotation direction (positive rotation or reverse rotation).

[0115] Perform a displacement operation, that is, rotate the target vector according to the rotation direction and the rotation angle (arctan(1 / (2^i)), where i is the number of iterations).

[0116] According to the rotation direction and the rotation angle, perform an accumulation operation to update the values of x and y (i.e., perform coordinate rotation).

[0117] Update the angle θ, subtracting the rotated angle (d*atan(2^(-i)), where d is the rotation direction, 1 represents positive rotation, and -1 represents reverse rotation).

[0118] 3) Output result:

[0119] When the predetermined precision or the number of iterations is reached, stop the iteration.

[0120] The x and y coordinates at this time are the sine and cosine values of the required angle (sin(θ) and cos(θ)).

[0121] Output the final x and y values (i.e., the results of sin and cos).

[0122] Compared with the above method of obtaining sine and cosine values according to the mapping relationship table, the method of obtaining sine and cosine values through the coordinate rotation digital calculation method can automatically calculate the values of each angle, and has higher efficiency compared with the table lookup method.

[0123] In a feasible implementation manner, the above step S20 further includes:

[0124] Step S203, extract the low-frequency signal from the intermediate-frequency signal, and use the conjugate signal corresponding to the low-frequency signal as the intermediate-frequency conjugate signal.

[0125] It can be understood that in a feasible implementation manner, since the useful signal in the S 1 signal is the low-frequency signal, to reduce the amount of data processing, the low-frequency signal in the intermediate-frequency signal can also be extracted, and the conjugate signal corresponding to the low-frequency signal is used as the intermediate-frequency conjugate signal.

[0126] Step S30, determine the first product of the intermediate-frequency signal and the quadrature conjugate signal, and determine the second product of the quadrature tracking signal and the intermediate-frequency conjugate signal;

[0127] Step S40, use the difference between the first product and the second product as the quadrature demodulation result.

[0128] It should be noted that both the first product and the second product are signals, and the quadrature demodulation result is also a signal. In this embodiment, the quadrature demodulation result is the useful signal.

[0129] Exemplarily, please refer to Figure 7 and Figure 8 , where Figure 7 is the system structure diagram of the present application, Figure 8 is the schematic diagram of a specific embodiment. Figure 7 The function modules such as the excitation signal complex demodulation, rotation signal complex demodulation, and quadrature oscillator in Figure 8 can be implemented in the way of Figure 8 , or can be implemented in other ways. In

[0130] Step 1, use the sine signal and cosine signal output by the resolver as the input signals of the RDC, and send these two input signals to the QDSM ADC, and the signals in equation (6) will be obtained.

[0131] Step 2, the signal of equation (6) is down-converted for the first time to obtain the S 1 signal. In the following formula derivation process, the useless signal components at its high frequency are temporarily not considered, and only the useful signal components at its low frequency are considered, that is, the S 2 signal.

[0132] In addition, the orthogonal tracking signal e jφ is constructed by sinφ and cosφ, that is, the signal S 4 . Among them, the output angle φ is generated by the internal second-order tracking loop. And sinφ and cosφ can be obtained by the method of LUT (looking up the table) / CORDIC through the output angle φ.

[0133] Step 3, the signal S 1 (considering the useful signal component S 2 at its low frequency in the formula derivation) performs a conjugate operation to obtain the signal S 3 ;

[0134] In addition, the signal S 4 performs a conjugate operation to obtain the signal S 5 .

[0135] Step 4, the signal S 3 and the signal S 4 perform a multiplication operation to obtain the signal S 6 ;

[0136] In addition, the signal S 1 (considering the useful signal component S 2 at its low frequency in the formula derivation) and the signal S 5 perform a multiplication operation to obtain the signal S 7 .

[0137] Step 5, the signal S 6 subtracts the signal S 7 to obtain the signal S 8 , that is, the quadrature demodulation result is obtained.

[0138] Figure 8 The expressions of each signal in

[0139]

[0140] S 4 = e jφ Equation 10;

[0141] S 5 = e -jφ Equation 11;

[0143]

[0144] It can be known from Euler's formula that:

[0145] e j(θ-φ) -e -j(θ-φ) = 2·j·sin(θ - φ), Equation 16;

[0147] e j(θ-φ) +e -j(θ-φ) = 2·cos(θ - φ), Equation 17;

[0148] Therefore, Equation (15) can be simplified to:

[0149] S 8 = j·(cos(θ - φ) - sin(θ - φ)), Equation 18;

[0150] It can be understood that Figure 8 the final demodulation result contains the useful signal at DC and the useless signal at twice the excitation frequency. Therefore, it is necessary to filter the quadrature demodulation result of Figure 8 , and the filtering process is as shown in Figure 9 .

[0151] In this embodiment, the present application processes the sine signal and the cosine signal through a quadrature DSM modulator, and performs down-conversion processing on the signal output by the quadrature DSM modulator to obtain an intermediate-frequency signal. The stopband of the quantization noise can be made to fall only on the positive frequency or only on the negative frequency through the quadrature DSM modulator, reducing the noise power within the signal bandwidth and improving the signal-to-noise ratio. Also, through the down-conversion method, the effective signal in the signal output by the quadrature DSM modulator is extracted to avoid the useless signal from reducing the signal-to-noise ratio; then the quadrature tracking signal is obtained, and the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and the quadrature conjugate signal corresponding to the quadrature tracking signal are calculated; then the first product of the intermediate-frequency signal and the intermediate-frequency conjugate signal is determined, and the second product of the quadrature tracking signal and the intermediate-frequency conjugate signal is determined; further, the difference between the first product and the second product is used as the quadrature demodulation result, so that a signal with lower noise can be used for quadrature demodulation, making the noise in the obtained quadrature demodulation result very low, thereby improving the signal-to-noise ratio in the quadrature demodulation result, that is, improving the signal-to-noise ratio of the useful signal.

[0152] Based on the first embodiment of the present application, the second embodiment of the present application is proposed. In the second embodiment of the present application, the content that is the same as or similar to the above-mentioned Embodiment 1 can be referred to the above introduction and will not be elaborated hereinafter. In this embodiment, after step S40, the quadrature demodulation method further includes steps S50 to S60:

[0153] Step S50: perform low-pass filtering on the quadrature demodulation result to obtain a low-frequency DC signal;

[0154] It should be noted that the low-frequency DC signal is the signal after low-pass filtering.

[0155] Step S60: decode according to the low-frequency DC signal to obtain a decoding result, where the decoding result includes the angular position and rotational speed of the motor shaft.

[0156] It should be noted that, as can be seen from equation (15), sin(θ - φ) can be extracted from S 8 , and its amplitude is -j, only including one direction. If the amplitude vector includes both real and imaginary components, an angle will be formed, and the extraction difficulty will be greater than that of the method of the present application. Therefore, the present application also reduces the extraction difficulty. In addition, when the output angle φ tracks the rotation input shaft angle θ, that is, θ - φ = 0, S 8 = j, that is, at this time, the amplitude vector obtained at DC is j, which is contributed by cos(θ - φ). In the above first embodiment, only the useful signal S 1 at low frequencies in the signal is considered, and its high-frequency components are ignored. However, its final result (quadrature demodulation result) includes high-frequency components. Therefore, in actual operation, in addition to considering the useful signal at low frequencies in the S 2 signal, its high-frequency components also need to be considered. In a feasible implementation manner, considering the full amount of the S 1 signal, the obtained spectrum analysis diagram can refer to 1 . Figure 10 .

[0157] Through Figure 10 it can be seen that: the final demodulation result includes the useful signal at DC and the useless signal at twice the excitation frequency. In the spectrum analysis diagram, when θ - φ = 0, the final demodulation result is obtained, that is, the S 8 signal, and the amplitude vector of the signal at the DC frequency is j, which conforms to equation (15), verifying the correctness of the present application to obtain the quadrature tracking signal through Euler's formula and then obtain the quadrature demodulation result.

[0158] In addition, from Figure 10 it can also be seen that for the final output result obtained by the quadrature demodulation method of the present application, there will be a very low noise component at DC. Therefore, a very obvious advantage of the present invention compared with other structures is that the quantization noise introduced by the DSM in the entire system is very small, which is beneficial to improving the SNR.

[0159] In this embodiment, since the signal component at the DC frequency is required for decoding, low-pass filtering can be performed. By filtering out the signal at twice the excitation frequency, the DC component at low frequencies (low-frequency DC signal) can be obtained, and thus the angular position and rotational speed of the motor shaft can be calculated by extracting sin(θ - φ).

[0160] It should be noted that since there are harmonic components at twice the excitation frequency, if only filtered by a low-pass filter, the slope between the passband and the stopband needs to be very steep, so it is very difficult and costly to implement.

[0161] In this embodiment, the present application can calculate the relatively accurate angular position and rotational speed of the motor shaft based on the quadrature demodulation result with a relatively high signal-to-noise ratio.

[0162] Please refer to Figure 11 , in a feasible implementation manner, the above step S50 further includes:

[0163] Step S501, obtaining the frequency of the harmonic component to be eliminated, and configuring a filter based on the frequency of the harmonic component to be eliminated, where the filter includes a notch filter or a comb filter;

[0164] It can be understood that the frequency of the harmonic component to be eliminated is the frequency of the harmonic component to be eliminated. In the Figure 10 shown spectrum analysis diagram, the frequency of the harmonic component to be eliminated is twice the excitation frequency.

[0165] Step S502, inputting the quadrature demodulation result into the filter to obtain a primary filtered signal, and inputting the primary filtered signal into a preset low-pass filter to obtain a low-frequency DC signal.

[0166] In this embodiment, the present application can create a notch point at twice the excitation frequency by using a low-pass filter + notch filter, or a low-pass filter + comb filter, so as to eliminate the harmonic component at twice the excitation frequency. In this way, the slope between the passband and the stopband of the low-pass filter does not need to be very steep, which can greatly reduce the requirements for the low-pass filter.

[0167] Please refer to Figure 12 , in a feasible implementation manner, the above step S50 may further include:

[0168] Step S503, obtaining the frequency of the harmonic component to be eliminated, and configuring a half-band notch filter based on the frequency of the harmonic component to be eliminated;

[0169] Step S504, inputting the quadrature demodulation result into a preset cascaded integrator comb filter to obtain a cascaded filtered signal, and inputting the cascaded filtered signal into the half-band notch filter to obtain a low-frequency DC signal.

[0170] In this embodiment, based on the above step S501, a half-band notch filter can be configured. Furthermore, by combining a cascaded integrator-comb filter and a half-band notch filter, while eliminating the harmonic components at twice the excitation frequency, a low-pass filtering function can be achieved.

[0171] The above method of using a low-pass filter + notch filter requires more computing resources or hardware complexity. Especially when the filter is required to have a steep roll-off characteristic and a narrow-band notch, even more resources are needed. However, the method of using a CIC filter + notch filter proposed in this embodiment can be implemented through a simple integration and comb structure, hardly occupying multiplication operations, and reducing hardware resources and power consumption.

[0172] In this embodiment, the present application can further reduce the resource consumption during the filtering process through the method of using a CIC filter + notch filter, thereby reducing the hardware cost.

[0173] It should be noted that the above examples are only for understanding the present application and do not constitute a limitation on the quadrature demodulation method of the present application. Based on this technical concept, more forms of simple transformations are within the protection scope of the present application.

[0174] The present application also provides a quadrature demodulation system. Please refer to Figure 13 , the quadrature demodulation system includes:

[0175] An acquisition module 10, configured to process a sine signal and a cosine signal through a quadrature DSM modulator, and perform down-conversion processing on the signal output by the quadrature DSM modulator to obtain an intermediate-frequency signal;

[0176] A conjugate module 20, configured to obtain a quadrature tracking signal, and calculate the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and the quadrature conjugate signal corresponding to the quadrature tracking signal;

[0177] A product module 30, configured to determine a first product of the intermediate-frequency signal and the quadrature conjugate signal, and determine a second product of the quadrature tracking signal and the intermediate-frequency conjugate signal;

[0178] A difference module 40, configured to use the difference between the first product and the second product as the quadrature demodulation result.

[0179] In one embodiment, the quadrature demodulation system includes:

[0180] A filtering module, configured to perform low-pass filtering processing on the quadrature demodulation result to obtain a low-frequency DC signal;

[0181] A decoding module for decoding according to the low-frequency DC signal to obtain a decoding result, where the decoding result includes the angular position and rotational speed of the motor shaft.

[0182] In one embodiment, the filtering module is further configured to:

[0183] Obtain the frequency of the harmonic component to be eliminated, and configure a filter based on the frequency of the harmonic component to be eliminated, where the filter includes: a notch filter and a comb filter;

[0184] Input the quadrature demodulation result into the filter to obtain a primary filtered signal, and input the primary filtered signal into a preset low-pass filter to obtain a low-frequency DC signal.

[0185] In one embodiment, the filtering module is further configured to:

[0186] Obtain the frequency of the harmonic component to be eliminated, and configure a half-band notch filter based on the frequency of the harmonic component to be eliminated;

[0187] Input the quadrature demodulation result into a preset cascaded integrator comb filter to obtain a cascaded filtered signal, and input the cascaded filtered signal into the half-band notch filter to obtain a low-frequency DC signal.

[0188] In one embodiment, the conjugate module 20 is further configured to:

[0189] Extract the low-frequency signal from the intermediate-frequency signal, and use the conjugate signal corresponding to the low-frequency signal as the intermediate-frequency conjugate signal.

[0190] In one embodiment, the acquisition module 10 is further configured to:

[0191] Based on the output angle of the resolver, determine the sine value and cosine value corresponding to the output angle;

[0192] Combine the sine value and the cosine value based on Euler's formula to obtain a quadrature tracking signal.

[0193] In one embodiment, the acquisition module 10 is further configured to:

[0194] In a preset mapping relation table, look up the preset sine value and cosine value corresponding to the output angle;

[0195] Calculate the sine value and cosine value corresponding to the output angle through a coordinate rotation digital calculation method.

[0196] The quadrature demodulation system provided by this application adopts the quadrature demodulation method in the above embodiments, and can solve the technical problem of low signal-to-noise ratio of the useful signal in the existing demodulation technology. Compared with the prior art, the beneficial effects of the quadrature demodulation system provided by this application are the same as those of the quadrature demodulation method provided by the above embodiments, and other technical features in the quadrature demodulation system are the same as the features disclosed in the method of the above embodiments, which will not be elaborated here.

[0197] This application provides a terminal device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the quadrature demodulation method in Embodiment 1 above.

[0198] Reference is made below to Figure 14 , which shows a schematic structural diagram of a terminal device suitable for implementing the embodiments of this application. Figure 14 The terminal device shown is only an example and should not impose any limitation on the functions and usage scope of the embodiments of this application.

[0199] As Figure 14 shown, the terminal device may include a processing device 1001 (such as a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to the program stored in a read-only memory (ROM: Read Only Memory) 1002 or the program loaded from a storage device 1003 into a random access memory (RAM: Random Access Memory) 1004. In the RAM 1004, various programs and data required for the operation of the terminal device are also stored. The processing device 1001, the ROM 1002, and the RAM 1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems may be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touchpad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: LiquidCrystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the terminal device to communicate with other devices wirelessly or wiredly to exchange data. Although the figure shows a terminal device having various systems, it should be understood that it is not required to implement or include all the systems shown. More or fewer systems may be alternatively implemented or included.

[0200] In particular, according to the embodiments disclosed in the present application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, the embodiments disclosed in the present application include a computer program product that includes a computer program carried on a computer-readable medium, and the computer program includes program code for performing the methods shown in the flowcharts. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by a processing device 1001, the above-mentioned functions defined in the methods of the embodiments disclosed in the present application are executed.

[0201] The terminal device provided by the present application adopts the quadrature demodulation method in the above-mentioned embodiment, and can solve the technical problem of low signal-to-noise ratio of the useful signal in the existing demodulation technology. Compared with the prior art, the beneficial effects of the terminal device provided by the present application are the same as those of the quadrature demodulation method provided in the above-mentioned embodiment, and other technical features in the terminal device are the same as those disclosed in the method of the previous embodiment, and will not be elaborated here.

[0202] It should be understood that each part disclosed in the present application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0203] As mentioned above, the above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present application, and all should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0204] The present application provides a computer-readable storage medium having computer-readable program instructions (i.e., computer programs) stored thereon, and the computer-readable program instructions are used to execute the quadrature demodulation method in the above-mentioned embodiment.

[0205] The computer-readable storage medium provided by the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or components, or any combination of the above. More specific examples of the computer-readable storage medium may include, but are not limited to: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM) or flash memory, optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium that contains or stores a program, and the program can be used by or in conjunction with an instruction execution system, device, or component. The program code contained on the computer-readable storage medium can be transmitted by any appropriate medium, including but not limited to: wires, optical cables, RF (radio frequency), etc., or any suitable combination of the above.

[0206] The above computer-readable storage medium may be included in the terminal device; or it may exist separately without being assembled into the terminal device.

[0207] The above computer-readable storage medium carries one or more programs. When the one or more programs are executed by the terminal device, the terminal device: processes the sine signal and the cosine signal through an orthogonal DSM modulator, and performs down-conversion processing on the signal output by the orthogonal DSM modulator to obtain an intermediate-frequency signal; obtains an orthogonal tracking signal, and calculates the intermediate-frequency conjugate signal corresponding to the intermediate-frequency signal, and the orthogonal conjugate signal corresponding to the orthogonal tracking signal; determines the first product of the intermediate-frequency signal and the orthogonal conjugate signal, and determines the second product of the orthogonal tracking signal and the intermediate-frequency conjugate signal; and uses the difference between the first product and the second product as the orthogonal demodulation result.

[0208] Computer program code for performing the operations of this application can be written in one or more programming languages or combinations thereof. The above-mentioned programming languages include object-oriented programming languages such as Java, Smalltalk, C++, and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, executed as an independent 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 can 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 it can be connected to an external computer (for example, by using an Internet service provider to connect through the Internet).

[0209] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutively represented blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, as well as the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0210] The modules involved in the embodiments described in this application can be implemented in software or in hardware. Among them, the name of the module does not constitute a limitation on the unit itself in some cases.

[0211] The readable storage medium provided in this application is a computer-readable storage medium. The computer-readable storage medium stores computer-readable program instructions (i.e., computer programs) for performing the above-mentioned quadrature demodulation method, and can solve the technical problem of low signal-to-noise ratio of useful signals in the existing demodulation technology. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the quadrature demodulation method provided in the above embodiments, and will not be elaborated here.

[0212] The present application also provides a computer program product, including a computer program which, when executed by a processor, implements the steps of the orthogonal demodulation method as described above.

[0213] The computer program product provided by the present application can solve the technical problem of low signal-to-noise ratio of useful signals in the existing demodulation technology. Compared with the prior art, the beneficial effects of the computer program product provided by the present application are the same as those of the orthogonal demodulation method provided in the above embodiments, and will not be elaborated herein.

[0214] The above are only partial embodiments of the present application, and thus do not limit the patent scope of the present application. Any equivalent structural transformation made under the technical concept of the present application by using the content of the specification and drawings of the present application, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present application.

Claims

1. A quadrature demodulation method, characterized in that: The method includes: Processing the sine signal and the cosine signal by an orthogonal DSM modulator, and performing down-conversion processing on the signal output by the orthogonal DSM modulator to obtain an intermediate frequency signal; Acquire an orthogonal tracking signal, and calculate an intermediate frequency conjugate signal corresponding to the intermediate frequency signal, and an orthogonal conjugate signal corresponding to the orthogonal tracking signal; Determine a first product of the intermediate frequency signal and the orthogonal conjugate signal, and determine a second product of the orthogonal tracking signal and the intermediate frequency conjugate signal; The difference between the first product and the second product is used as an orthogonal demodulation result.

2. The method according to claim 1, characterized in that After the step of taking the difference between the first product and the second product as the orthogonal demodulation result, the method further comprises: Performing low-pass filtering on the orthogonal demodulation result to obtain a low-frequency DC signal; Decoding is performed according to the low-frequency DC signal to obtain a decoding result, wherein the decoding result includes the angular position and rotation speed of the motor shaft.

3. The method according to claim 2, characterized in that The step of performing low-pass filtering on the orthogonal demodulation result to obtain a low-frequency DC signal comprises: Acquire the frequency of the harmonic component to be eliminated, and configure a filter based on the frequency of the harmonic component to be eliminated, wherein the filter includes a notch filter or a comb filter; The orthogonal demodulation result is input into the filter to obtain a primary filter signal, and the primary filter signal is input into a preset low-pass filter to obtain a low-frequency DC signal.

4. The method according to claim 2, characterized in that The step of performing low-pass filtering on the orthogonal demodulation result to obtain a low-frequency DC signal comprises: Acquire the frequency of the harmonic component to be eliminated, and configure a half-band notch filter based on the frequency of the harmonic component to be eliminated; The orthogonal demodulation result is input into a preset cascaded integral comb filter to obtain a cascaded filtered signal, and the cascaded filtered signal is input into the half-band notch filter to obtain a low-frequency DC signal.

5. The method according to claim 1, characterized in that The step of determining the intermediate frequency conjugate signal corresponding to the intermediate frequency signal comprises: A low-frequency signal is extracted from the intermediate-frequency signal, and a conjugate signal corresponding to the low-frequency signal is used as an intermediate-frequency conjugate signal.

6. The method according to claim 1, characterized in that The step of obtaining the orthogonal tracking signal comprises: Based on the output angle of the resolver, determining a sine value and a cosine value corresponding to the output angle; The sine value and the cosine value are combined based on the Euler formula to obtain an orthogonal tracking signal.

7. The method according to claim 6, characterized in that The step of determining the sine value and cosine value corresponding to the output angle comprises: In a preset mapping relationship table, searching for preset sine and cosine values ​​corresponding to the output angle; The sine value and cosine value corresponding to the output angle are calculated by coordinate rotation digital calculation method.

8. An orthogonal demodulation system, characterized in that: The system comprises: An acquisition module is used to process the sine signal and the cosine signal through an orthogonal DSM modulator, and perform down-conversion processing on the signal output by the orthogonal DSM modulator to obtain an intermediate frequency signal; A conjugation module, used for acquiring an orthogonal tracking signal, and calculating an intermediate frequency conjugate signal corresponding to the intermediate frequency signal, and an orthogonal conjugate signal corresponding to the orthogonal tracking signal; A product module, used to determine a first product of the intermediate frequency signal and the orthogonal conjugate signal, and to determine a second product of the orthogonal tracking signal and the intermediate frequency conjugate signal; A difference module is used to take the difference between the first product and the second product as an orthogonal demodulation result.

9. A terminal device, characterized in that: The terminal device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the orthogonal demodulation method according to any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the orthogonal demodulation method according to any one of claims 1 to 7 are implemented.

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