Blind demodulation analysis method of signal, chip, remote control device and storage medium

Abstract

The application provides a blind demodulation analysis method of a signal, a chip, a remote control device and a storage medium. The method comprises the following steps: determining the center frequency of a target signal through a bandwidth scanning strategy; performing mixing processing and analog-to-digital conversion on the target signal to obtain an I-path intermediate frequency digital signal and a Q-path intermediate frequency digital signal, so as to determine the amplitude of the target signal; determining the modulation mode of the target signal according to the change of the amplitude of the target signal within a preset time length; if it is determined that the modulation mode is OOK, determining the amplitude mean value of the target signal, and demodulating the target signal according to the size relationship between the amplitude of the target signal and the amplitude mean value to obtain a baseband signal; if it is determined that the modulation mode is 2FSK, determining the frequency offset estimation mean value and the frequency offset of the target signal, and demodulating the target signal according to the size relationship among the frequency of the target signal, the center frequency of the target signal and the frequency offset estimation mean value to obtain the baseband signal; and performing frequency measurement on the baseband signal to determine the symbol rate.

Description

Technical Field

[0001] This application relates to the field of signal processing technology, and in particular to a blind demodulation and analysis method for signals, a chip, a remote control device, and a storage medium. Background Technology

[0002] FSK (Frequency-shift keying) modulates the frequency of a carrier wave using digital signals. A common type is the dual-frequency FSK system (2FSK), which uses two frequencies to carry binary 1s and 0s. For example, a higher frequency represents logic 1, and a lower frequency represents logic 0. OOK (On-Off keying) modulates the amplitude of a carrier wave using digital signals; that is, one amplitude is set to 0, and the other is set to a non-zero value. Therefore, it is also known as binary amplitude shift keying (2ASK). Both of these modulation methods are widely used in the field of communications, such as in remote control systems.

[0003] In non-cooperative communication, the receiver cannot know the sender's modulation characteristics in advance. Therefore, upon receiving the signal, it needs to demodulate the signal using a blind processing strategy to obtain the main modulation characteristics (such as modulation scheme, carrier frequency, frequency offset, symbol rate, etc.) before data demodulation. Non-cooperative communication is widespread in daily life; for example, in key copying scenarios, a third party typically cannot know the original key's modulation characteristics in advance. Therefore, it is necessary to demodulate the signal using a blind processing strategy before copying the data. Thus, in non-cooperative communication systems, demodulation of FSK / OOK signals without prior knowledge is crucial.

[0004] In the prior art, Chinese patent application with publication number CN116032709A proposes a blind demodulation method, but this method is only for FSK signals and cannot achieve blind demodulation of OOK signals; moreover, this method requires time-frequency domain conversion, which is too computationally intensive. If this method is implemented on a patented integrated chip (such as ASIC), it will result in an excessively large chip area and increase the mass production cost of the chip. Summary of the Invention

[0005] Based on this, this application provides a blind demodulation and analysis method, chip, remote control device and storage medium for signals, so as to realize blind demodulation and analysis of 2FSK / OOK signals, and the computational load during demodulation and analysis is smaller.

[0006] Firstly, this application provides a blind demodulation and analysis method for signals, comprising:

[0007] The center frequency of the target signal is determined by a preset bandwidth scanning strategy;

[0008] The target signal is subjected to frequency mixing and analog-to-digital conversion to obtain I-channel intermediate frequency digital signal and Q-channel intermediate frequency digital signal;

[0009] The amplitude of the target signal is determined based on the I-channel intermediate frequency digital signal and the Q-channel intermediate frequency digital signal;

[0010] Based on the change in the amplitude of the target signal within a preset time period, the modulation method used by the target signal is determined;

[0011] If the modulation method is determined to be OOK, then the average amplitude of the target signal is determined, and the target signal is demodulated to obtain the baseband signal based on the relationship between the amplitude of the target signal and the average amplitude.

[0012] If the modulation method is determined to be 2FSK, then the estimated mean frequency offset and frequency offset of the target signal are determined, and the target signal is demodulated to obtain the baseband signal according to the relationship between the frequency of the target signal, the center frequency of the target signal and the estimated mean frequency offset.

[0013] Frequency measurement is performed on the baseband signal to determine the symbol rate.

[0014] Secondly, this application provides a dedicated integrated chip for enabling a device equipped with the dedicated integrated chip to perform the method described in the first aspect.

[0015] Thirdly, this application provides a remote control device comprising: a memory storing a computer program; and a processor that executes the computer program to implement the method described in the first aspect.

[0016] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect.

[0017] Based on the above technical solution, the center frequency of the target signal is first determined, and then the modulation scheme used by the target signal is determined. If the modulation scheme is determined to be OOK, the baseband signal is obtained by demodulating the target signal based on the amplitude; if the modulation scheme is determined to be 2FSK, the baseband signal is obtained by demodulating the target signal based on the frequency and the frequency offset is determined. Finally, the symbol rate is determined based on the baseband signal. Therefore, the method provided in this application can realize blind demodulation and analysis of 2FSK / OOK signals. Furthermore, the method provided in this application does not require time-frequency domain conversion during demodulation and analysis, resulting in lower computational complexity. Attached Figure Description

[0018] Figure 1 This is an exemplary scenario for applying the embodiments of this application;

[0019] Figure 2 A schematic flowchart illustrating a blind demodulation and analysis method for signals provided in an embodiment of this application;

[0020] Figure 3 This is a schematic diagram illustrating the determination of indication intensity based on amplitude in an embodiment of this application;

[0021] Figure 4 This is an exemplary structural diagram for determining the center frequency estimate in the embodiments of this application;

[0022] Figure 5 This is an exemplary structural diagram illustrating the determination of the correction frequency value in an embodiment of this application;

[0023] Figure 6 This is an exemplary structural diagram of obtaining the I-channel intermediate frequency digital signal and the Q-channel intermediate frequency digital signal in an embodiment of this application;

[0024] Figure 7 This is an exemplary schematic diagram illustrating the determination of the modulation scheme as OOK in an embodiment of this application;

[0025] Figure 8 This is an exemplary schematic diagram illustrating the determination of the modulation scheme as 2FSK in an embodiment of this application;

[0026] Figure 9 This is an exemplary schematic diagram of the demodulated target signal when the modulation mode is OOK in an embodiment of this application;

[0027] Figure 10 This is an exemplary schematic diagram of the demodulated target signal when the modulation method is 2FSK in an embodiment of this application;

[0028] Figure 11 This is an exemplary structural diagram for determining frequency offset in the embodiments of this application;

[0029] Figure 12 This is an exemplary schematic diagram showing two frequency representations of square waves in the embodiments of this application;

[0030] Figure 13 This is a schematic diagram of a remote control device provided in an embodiment of this application. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0032] The embodiments of this application can be applied, by way of example, to, such as Figure 1 The scenario is illustrated. In this scenario, the user needs to copy the original remote control, so a third-party remote control can be used for key copying. The user can control the original remote control to send a target signal to the third-party remote control (e.g., long-press the unlock button), causing the third-party remote control to demodulate and analyze the target signal using the method provided in this embodiment to determine the main modulation characteristics (e.g., modulation scheme, carrier frequency, frequency offset, symbol rate, etc.), and then perform a data copying operation to complete the key copying. It should be noted that remote control devices typically use 2FSK or OOK modulation, and the method provided in this embodiment can achieve blind demodulation and analysis of 2FSK / OOK signals, thus resulting in a high success rate for key copying, i.e., high reliability. Furthermore, the method provided in this embodiment does not require time-frequency domain conversion during demodulation and analysis, reducing computational load. Therefore, if a dedicated integrated chip is used to implement this method, the chip area can be reduced, thereby lowering the mass production cost of the chip.

[0033] This application provides a blind demodulation and parsing method for signals, which can be applied to remote control devices. For example, the method in this application can be executed by a chip installed in the remote control device. Exemplarily, the chip installed in the remote control device may include an ASIC chip.

[0034] like Figure 2 As shown, the method may include steps S10 to S70.

[0035] S10. Determine the center frequency of the target signal using a preset bandwidth scanning strategy.

[0036] As mentioned earlier, when a target device (e.g., an original remote control) sends a target signal to a remote control device, the remote control device cannot know the main modulation characteristics in advance, therefore blind demodulation analysis is required. Thus, the remote control device can determine the center frequency of the target signal using a bandwidth scanning strategy. For example, a scan search is performed within a preset bandwidth range to determine the center frequency using a blind frequency sweep method.

[0037] In one embodiment, step S10 may include sub-steps S110 to S170.

[0038] Sub-step S110: Scan multiple preset bandwidths sequentially until the target bandwidth among the multiple bandwidths is determined.

[0039] Sub-step S120: Use the frequency value corresponding to the target bandwidth as the estimated value of the center frequency of the target signal.

[0040] For example, a large bandwidth can be divided into multiple smaller bandwidths (or multiple wide bandwidths), and each smaller bandwidth can be represented by a frequency value within that bandwidth; that is, each bandwidth has a one-to-one corresponding frequency value. In this way, the remote control device can scan these bandwidths sequentially until it can determine which bandwidth the center frequency of the target signal falls within, i.e., which smaller bandwidth it falls within. In this embodiment, this bandwidth is referred to as the target bandwidth. For example, these multiple bandwidths can be scanned in descending or ascending order of frequency values.

[0041] Since the target bandwidth is a small range, it can only be determined that the center frequency of the target signal is near the frequency value corresponding to the target bandwidth. Therefore, the frequency value corresponding to the target bandwidth can be used as the estimated value of the center frequency of the target signal, and then the precise center frequency can be determined.

[0042] In one embodiment, sub-step S110 may include sub-steps S111 to S115.

[0043] Sub-step S111: Generate a second in-phase local carrier and a second quadrature local carrier. The frequencies of the second in-phase local carrier and the second quadrature local carrier are both the frequency values ​​corresponding to the m-th bandwidth, where m is a positive integer.

[0044] Sub-step S112: Mix the target signal with the second in-phase local carrier and the second quadrature local carrier respectively to obtain the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal.

[0045] Sub-step S113: Filter the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal respectively to filter out components that are not related to the intermediate frequency.

[0046] Sub-step S114: Determine whether both the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal include intermediate frequency components.

[0047] Sub-step S115: If all are included, then the m-th bandwidth is determined as the target bandwidth; otherwise, the next second in-phase local carrier and the next second quadrature local carrier are regenerated for judgment until the target bandwidth is determined. The frequencies of the next second in-phase local carrier and the next second quadrature local carrier are the frequency values ​​corresponding to the (m+1)-th bandwidth.

[0048] In this embodiment, the target signal is typically a radio frequency analog signal, i.e., a high-frequency analog signal. Therefore, it can be down-converted to an intermediate frequency (IF) signal by mixing, and then filtered. The purpose of this filtering is to remove components unrelated to the IF, such as high-frequency components. In this way, it can be determined whether the required IF component exists in the filtered IF signal. If it does, it means that the frequency value corresponding to the current bandwidth is close to the center frequency of the target signal, and it can be used as the estimated center frequency. Otherwise, the next judgment is performed.

[0049] Specifically, a second in-phase local carrier and a second quadrature local carrier, both with frequencies corresponding to the m-th bandwidth, can be generated using a local oscillator. Here, m is a positive integer less than the number of bandwidths. Next, the target signal is mixed with the second in-phase local carrier to obtain a second I-channel intermediate frequency (IF) signal; simultaneously, the target signal is mixed with the second quadrature local carrier to obtain a second Q-channel IF signal. Both the second I-channel and second Q-channel IF signals include two components: a high-frequency component and a difference-frequency component. Therefore, they can be filtered using a narrow-bandwidth complex filter whose parameters are related to the IF frequency; that is, the filter only allows the IF signal to pass through. Thus, the high-frequency components in both the second I-channel and second Q-channel IF signals will be filtered out. However, whether the difference-frequency component in these two signals will be filtered out depends on the frequencies of the two local carriers at this point. Specifically, if the frequencies of the two local carriers are close to the center frequency of the target signal, the difference frequency components in the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal will not be filtered out; in this case, the difference frequency component is the intermediate frequency component. Otherwise, they will be filtered out. Therefore, if it is determined that both the second I-channel and the second Q-channel intermediate frequency signals contain intermediate frequency components, then the current bandwidth (i.e., the m-th bandwidth) can be determined to be the target bandwidth, meaning that the center frequency of the target signal falls within the m-th bandwidth. Otherwise, it can be determined that the frequency corresponding to the current bandwidth (i.e., the m-th bandwidth) is not close to the center frequency of the target signal. The next second in-phase local carrier and the next second quadrature local carrier are then regenerated for judgment until the target bandwidth is determined. It can be understood that the frequencies of the next second in-phase local carrier and the next second quadrature local carrier are both the frequency values ​​corresponding to the (m+1)-th bandwidth.

[0050] In some implementations, sub-step S114 may include sub-steps S1141 to S1144. Sub-step S1141 involves performing analog-to-digital conversion on the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal respectively to obtain a second I-channel intermediate frequency digital signal and a second Q-channel intermediate frequency digital signal. For example, these two signals can be converted into digital signals using an analog-to-digital converter (ADC).

[0051] Sub-step S1142: Determine the estimated amplitude of the target signal based on the second I-channel intermediate frequency digital signal and the second Q-channel intermediate frequency digital signal. For example, the square root of these two digital signals can be calculated using the Cordic algorithm, and the result is the estimated amplitude of the target signal. It should be noted that since the center frequency of the target signal is not yet available, residual frequency components may exist when using this algorithm to determine the amplitude; therefore, only the estimated amplitude can be obtained. It should also be noted that the Cordic algorithm is existing technology and will not be elaborated upon in this embodiment.

[0052] Sub-step S1143: Smooth the estimated amplitude of the target signal to obtain the target signal indication intensity (RSSI).

[0053] As mentioned earlier, OOK is a modulation scheme where one amplitude is set to 0 and the other to a non-zero amplitude. Since the modulation scheme of the target signal is unknown, it's unsuitable to use the estimated amplitude of the target signal for judgment. Therefore, it's necessary to smooth the estimated amplitude of the target signal. For example, a peak detection algorithm can be used to detect and locate the amplitude maxima, while a moving average filter is used to smooth the data between adjacent maxima, for example, by slowly changing from one maxima to the next. This allows the indication strength of the target signal to be obtained. For example, the estimated amplitude of the target signal can be as follows: Figure 3 As shown in the figure, after smoothing, the indicated intensity can be obtained as shown in the figure. It can be seen that the indicated intensity is smoother than the estimated amplitude. Therefore, regardless of whether the modulation mode of the target signal is 2FSK or OOK, the indicated intensity can be used to make a judgment, ensuring reliability.

[0054] Sub-step S1144: Determine whether the indication intensity is greater than the first preset threshold. If it is greater, determine that both the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal include intermediate frequency components; otherwise, determine that they do not both include them.

[0055] The first preset threshold can be set reasonably, for example, by obtaining it after multiple experiments. Therefore, if the difference frequency component in both the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal is not filtered out, the indication intensity determined by the amplitude at this time will be greater than the first preset threshold. That is, the difference frequency component at this time is the intermediate frequency component, meaning that both the second I-channel and the second Q-channel intermediate frequency signals include intermediate frequency components. Therefore, the indication intensity can be determined by judging the relationship between the magnitude of the indication intensity and the first preset threshold.

[0056] For example, sub-steps S110 and S120 can be implemented in combination as follows: Figure 4The structure shown is implemented as follows. Specifically, the target signal is received through a receiving antenna, and simultaneously, a second in-phase local carrier and a second quadrature local carrier are generated by a local oscillator, both with frequencies corresponding to the current bandwidth. Next, the target signal is amplified by an LNA and then mixed with the second in-phase local carrier and the second quadrature local carrier, respectively, to obtain the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal. The target signal, local carrier, and intermediate frequency signal can be represented by the following formulas:

[0057] Target signal: cos(ω) C t+θ1)

[0058] Second in-phase local carrier: cos(ω) LO t+θ2)

[0059] Second orthogonal local carrier: sin(ω) LO t+θ2)

[0060] Second I-channel intermediate frequency signal:

[0061] Second Q-channel intermediate frequency signal:

[0062] Next, the second I-channel intermediate frequency (IF) signal and the second Q-channel IF signal are filtered separately using a narrow-bandwidth complex filter. It can be understood that the high-frequency components in these two IF signals will be filtered out at this time. as well as The difference frequency component in these two intermediate frequency signals will be filtered out. as well as Whether filtering is necessary requires further assessment. Specifically, the second I-channel and second Q-channel intermediate frequency (IF) signals are amplified by gain amplifiers and then converted into digital signals by analog-to-digital converters (ADCs). After obtaining these two digital signals, the estimated amplitude can be determined using the Cordic algorithm, and then smoothed to obtain the indication strength. Next, the indication strength is compared to a first preset threshold. If it is greater than the threshold, it is determined that both the second I-channel and second Q-channel IF signals contain IF components, and the frequency value corresponding to the current bandwidth is the estimated center frequency. If it is less than the threshold, the local oscillator regenerates the next second in-phase local carrier and the next second quadrature local carrier for further assessment, until the estimated center frequency is determined.

[0063] Sub-step S130: Generate the first in-phase local carrier, the frequency of which is the estimated center frequency.

[0064] Sub-step S140: Mix the target signal with the first in-phase local carrier to obtain the first I-channel intermediate frequency signal.

[0065] Sub-step S150: Filter the high-frequency components in the first I-channel intermediate frequency signal to obtain the intermediate frequency components in the first I-channel intermediate frequency signal.

[0066] Sub-step S160: Convert the intermediate frequency component in the first I-channel intermediate frequency signal into a square wave and then measure the frequency to obtain the corrected frequency value.

[0067] Sub-step S170: The sum of the estimated center frequency and the corrected frequency value is taken as the center frequency of the target signal.

[0068] As mentioned earlier, after determining the center frequency estimate, the frequency value corresponding to the target bandwidth can be used as the center frequency estimate of the target signal, and then the precise center frequency can be determined. Specifically, a first in-phase local carrier with a frequency equal to the center frequency estimate can be generated by a local oscillator. Then, the target signal is mixed with the first in-phase local carrier to obtain the first I-channel intermediate frequency signal. It can be understood that the first I-channel intermediate frequency signal includes two components: a high-frequency component and a difference frequency component (i.e., the intermediate frequency component). Next, it can be filtered by a narrow-bandwidth complex filter. The parameters of this filter are related to the intermediate frequency, that is, this filter only allows the intermediate frequency signal to pass through. Therefore, it can be understood that the high-frequency component in the first I-channel intermediate frequency signal will be filtered out. Then, the intermediate frequency component in the first I-channel intermediate frequency signal can be converted into a square wave by a hysteresis comparator, and then frequency measurement can be performed, for example, by using a timer to capture and measure the square wave signal, thereby obtaining the corrected frequency value. Finally, the center frequency estimate is corrected by adjusting the frequency value. The corrected value is the center frequency of the target signal. In other words, the sum of the center frequency estimate and the corrected frequency value can be used as the center frequency of the target signal.

[0069] For example, sub-steps S130 to S170 can be implemented in combination with, for instance, the following methods. Figure 5 The structure shown is implemented as follows. Specifically, the target signal is received by a receiving antenna, and simultaneously, a first in-phase local carrier with a frequency estimated to be the center frequency is generated by a local oscillator. Then, the target signal is amplified by an LNA and mixed with the first in-phase local carrier to obtain the first I-channel intermediate frequency signal. The target signal, the first in-phase local carrier, and the first I-channel intermediate frequency signal can be represented by the following formulas:

[0070] Target signal: cos(2πf) C t+θ1)

[0071] First in-phase local carrier: cos(2πf) LO t+θ2)

[0072] First I-channel intermediate frequency signal:

[0073] Next, the first I-channel intermediate frequency signal is filtered through a narrow-bandwidth complex filter. It can be understood that the high-frequency components in the first I-channel intermediate frequency signal are filtered at this time. It will be filtered out; understandably, the filtered first I-channel intermediate frequency signal only includes the intermediate frequency component. Next, the intermediate frequency component is converted into a square wave signal using a hysteresis comparator. Finally, the square wave signal is captured and its frequency measured using a timer to obtain the corrected frequency value. Thus, the sum of the predicted center frequency and the corrected frequency value is taken as the center frequency of the target signal, that is, the center frequency f. C =Estimated center frequency f LO + Correct frequency value f IF .

[0074] S20. Perform frequency mixing and analog-to-digital conversion on the target signal to obtain I-channel intermediate frequency digital signal and Q-channel intermediate frequency digital signal.

[0075] S30. Determine the amplitude of the target signal based on the I-channel intermediate frequency digital signal and the Q-channel intermediate frequency digital signal.

[0076] As mentioned earlier, OOK modulation uses one amplitude value as 0 and the other as a non-zero value. However, 2FSK modulation uses two frequencies to carry binary 1s and 0s, regardless of amplitude. Therefore, the modulation method can be determined by the amplitude of the target signal. Based on this, since the center frequency of the target signal has been determined in step S10, the amplitude determined is more accurate because there are no residual frequency components. It is understandable that using a more accurate amplitude value ensures reliability.

[0077] Specifically, since the target signal is usually a high-frequency analog signal, it can be processed into an I-channel intermediate frequency (IF) digital signal and a Q-channel IF digital signal through mixing and analog-to-digital conversion. Then, the amplitude of the target signal is determined based on these two digital signals. For example, the square root of the I-channel and Q-channel IF digital signals can be calculated using the Cordic algorithm, and the result is the amplitude of the target signal.

[0078] In one embodiment, step S20 may include sub-steps S210 to S240.

[0079] Sub-step S210: Generate a third in-phase local carrier and a third quadrature local carrier. The frequencies of the third in-phase local carrier and the third quadrature local carrier are both the center frequency of the target signal minus the preset intermediate frequency value.

[0080] Sub-step S220: Mix the target signal with the third in-phase local carrier and the third quadrature local carrier respectively to obtain the third I-channel intermediate frequency signal and the third Q-channel intermediate frequency signal.

[0081] Sub-step S230: Filter the high-frequency components in the third I-channel intermediate frequency signal and the third Q-channel intermediate frequency signal respectively.

[0082] Sub-step S240: Perform analog-to-digital conversion on the intermediate frequency component in the third I-channel intermediate frequency signal to obtain an I-channel intermediate frequency digital signal; and perform analog-to-digital conversion on the intermediate frequency component in the third Q-channel intermediate frequency signal to obtain a Q-channel intermediate frequency digital signal.

[0083] Specifically, a third in-phase local carrier and a third quadrature local carrier can be generated using a local oscillator. The frequencies of both are the center frequency of the target signal minus a preset intermediate frequency (IF) value. This setup ensures that a single IF signal is obtained in subsequent steps. The preset IF value can be set appropriately. Next, the target signal is mixed with the third in-phase local carrier and the third quadrature local carrier, respectively, to obtain the third I-channel IF signal and the third Q-channel IF signal. Then, a narrow-bandwidth complex filter is used to filter these signals. The filter's parameters are related to the IF frequency; that is, the filter only allows IF signals to pass through. Therefore, it can be understood that high-frequency components in both the third I-channel and third Q-channel IF signals are filtered out. Finally, an analog-to-digital converter (ADC) converts the two IF components into digital signals, resulting in the I-channel and Q-channel digital IF signals.

[0084] For example, the implementation of step S20 can be combined with, as shown in the example Figure 6 The structure shown is implemented as follows. Specifically, the target signal is received by a receiving antenna, and simultaneously, a third in-phase local carrier and a third quadrature local carrier are generated by a local oscillator. The frequencies of both are the center frequency minus a preset intermediate frequency value. Next, the target signal is amplified by an LNA and then mixed with the third in-phase local carrier and the third quadrature local carrier, respectively, to obtain the third I-channel intermediate frequency signal and the third Q-channel intermediate frequency signal. The target signal, local carrier, and intermediate frequency signal can be represented by the following formulas:

[0085] Target signal: 2A cos(ω) C t+θ1)

[0086] Third in-phase local carrier: cos(ω) LO t+θ2)

[0087] Third orthogonal local carrier: sin(ω) LO t+θ2)

[0088] Third I-channel intermediate frequency signal: A{cos[(ωC +ω LO )t+θ1+θ2]+cos[(ω C -ω LO )t+θ1-θ2]}

[0089] Third Q-channel intermediate frequency signal: A{sin[(ω C +ω LO )t+θ1+θ2]-sin[(ω C -ω LO )t+θ1-θ2]}

[0090] Next, the third I-channel intermediate frequency (IF) signal and the third Q-channel IF signal are filtered using a narrow-bandwidth complex filter. It can be understood that the high-frequency components in these two IF signals will be filtered out, i.e., Acos[(ω C +ω LO )t+θ1+θ2] and Asin[(ω C +ω LO [t+θ1+θ2] will be filtered out, but the intermediate frequency components Acos[(ω] in these two intermediate frequency signals will remain. C -ω LO )t+θ1-θ2] and Asin[(ω C -ω LO The intermediate frequency (IF) components [t+θ1-θ2] will not be filtered out. Next, the IF components in the third I-channel IF signal and the third Q-channel IF signal are amplified and then converted into digital signals by analog-to-digital converters (ADCs), resulting in the I-channel and Q-channel IF digital signals. It can be understood that after obtaining these two digital signals, the amplitude of the target signal can be determined using the CORDIC algorithm.

[0091] S40. Determine the modulation method used by the target signal based on the change in the amplitude of the target signal within a preset time period.

[0092] Since OOK modulation can result in an amplitude of 0, while 2FSK modulation does not, the modulation scheme of the target signal can be determined by observing the amplitude variation over a period of time. For example, if the amplitude does not approach zero within a preset duration, the modulation scheme can be determined to be 2FSK; otherwise, the modulation scheme can be determined to be OOK.

[0093] In one embodiment, step S40 may include the following: if the amplitude of the target signal is greater than the second preset threshold within a preset time period, then the modulation method is determined to be 2FSK; otherwise, the modulation method is determined to be OOK.

[0094] The value of the second preset threshold can be set reasonably, for example, determined through multiple experiments. For instance, the amplitude of the target signal can be as follows: Figure 7 As shown in the figure, the preset duration can be reasonably set. It can be seen from the figure that the amplitude of the target signal does not exceed the second preset threshold within the preset duration; therefore, it can be determined that the modulation method used by the target signal is OOK. For example, the amplitude of the target signal can be as follows: Figure 8 As shown, similarly, the preset duration can be set reasonably. As can be seen from the figure, the amplitude of the target signal is greater than the second preset threshold within the preset duration. Therefore, it can be determined that the modulation method used by the target signal is 2FSK.

[0095] S50. If the modulation method is determined to be OOK, then the average amplitude of the target signal is determined, and the target signal is demodulated to obtain the baseband signal based on the relationship between the amplitude and the average amplitude of the target signal.

[0096] If the target signal is determined to use OOK modulation, then as mentioned earlier, OOK modulates the amplitude of the carrier wave using a digital signal; that is, one amplitude is set to 0, and another amplitude is set to a non-zero value. Therefore, the target signal can be demodulated by its amplitude. Specifically, the average amplitude of the target signal can be determined, for example, by taking multiple amplitude values ​​over a period of time and averaging them. Then, demodulation is performed based on the relationship between the amplitude and the average value, thus obtaining the baseband signal.

[0097] In one embodiment, step S50 may include the following: demodulating the portion of the target signal whose amplitude is greater than the average amplitude to logic 1, and demodulating the portion of the target signal whose amplitude is less than the average amplitude to logic 0, so as to obtain the baseband signal.

[0098] For example, the amplitude of the target signal can be as follows: Figure 9 As shown, the demodulation of the target signal can demodulate the part with amplitude greater than the mean to logic 1, and at the same time demodulate the part with amplitude greater than the mean to logic 0, thus obtaining the baseband signal as shown in the figure.

[0099] S60. If the modulation method is determined to be 2FSK, then the estimated mean value of the frequency offset and the frequency offset of the target signal are determined, and the target signal is demodulated to obtain the baseband signal based on the relationship between the frequency of the target signal, the center frequency of the target signal and the estimated mean value of the frequency offset.

[0100] If the target signal is determined to use 2FSK modulation, as mentioned earlier, 2FSK uses two frequencies to carry binary 1s and 0s. Therefore, the target signal can be demodulated by frequency, and the frequency offset associated with the two frequencies can also be determined. Specifically, to demodulate the target signal, the estimated mean of the frequency offset can be determined first, that is, the mean of the estimated frequency offset values ​​can be determined. For example, multiple estimated frequency offset values ​​can be taken over a period of time and then averaged to obtain the estimated mean frequency offset. Then, demodulation is performed based on the target signal's frequency, center frequency, and estimated mean frequency offset, thus obtaining the baseband signal.

[0101] In one embodiment, determining the estimated mean frequency offset of the target signal in step S60 may include the following: downconverting the I-channel intermediate frequency digital signal and the Q-channel intermediate frequency digital signal to zero intermediate frequency, respectively, to obtain the I-channel zero intermediate frequency digital signal and the Q-channel zero intermediate frequency digital signal; calculating the arctangent of the I-channel zero intermediate frequency digital signal and the Q-channel zero intermediate frequency digital signal to obtain the frequency offset phase; differentiating the frequency offset phase to obtain the frequency offset estimate; and determining the estimated mean frequency offset based on the frequency offset estimate.

[0102] Specifically, the I-channel and Q-channel intermediate frequency (IF) digital signals can be down-converted to zero IF using the CORDIC algorithm, resulting in two zero IF digital signals. Next, the arctangent of these two zero IF digital signals is calculated using the CORDIC algorithm; that is, the arctangent of the Q-channel zero IF digital signal divided by the I-channel zero IF digital signal is used to obtain the frequency offset phase. Then, the derivative of the frequency offset phase is calculated to obtain the frequency offset prediction. In this way, multiple frequency offset predictions can be determined and averaged to obtain the frequency offset mean.

[0103] In one embodiment, step S60, which involves demodulating the target signal to obtain a baseband signal based on the relationship between the target signal's frequency, center frequency, and the estimated mean of frequency offset, may include the following: demodulating the portion of the target signal whose frequency differs from its center frequency by more than the estimated mean of frequency offset to logic 1, and demodulating the portion of the target signal whose frequency differs from its center frequency by less than the estimated mean of frequency offset to logic 0, thereby obtaining the baseband signal.

[0104] As mentioned earlier, 2FSK uses two frequencies to carry binary 1s and 0s. Therefore, it's understandable that subtracting the center frequency from the larger frequency will result in a value greater than the estimated frequency offset, and conversely, subtracting the center frequency from the smaller frequency will result in a value less than the estimated frequency offset. This characteristic can be used to demodulate the target signal. For example, the difference between the target signal and the center frequency can be expressed as follows: Figure 10As shown, the demodulation of the target signal can demodulate the part of the frequency difference between the center frequency and the frequency difference greater than the estimated mean of the frequency offset into logic 1, and at the same time demodulate the part of the frequency difference between the center frequency and the frequency difference less than the estimated mean of the frequency offset into logic 0, thus obtaining the baseband signal as shown in the figure.

[0105] In one embodiment, determining the frequency offset of the target signal in step S60 may include sub-steps S610 to S650.

[0106] Sub-step S610: Generate the fourth in-phase local carrier. The frequency of the fourth in-phase local carrier is the center frequency minus the preset intermediate frequency value.

[0107] Sub-step S620: Mix the target signal with the fourth in-phase local carrier to obtain the fourth I-channel intermediate frequency signal.

[0108] Sub-step S630: Filter the high-frequency components in the fourth I-channel intermediate frequency signal to obtain the intermediate frequency components in the fourth I-channel intermediate frequency signal.

[0109] Sub-step S640: Convert the intermediate frequency component in the fourth I-channel intermediate frequency signal into a square wave, and determine the maximum and minimum frequencies based on the square wave.

[0110] Sub-step S650: Divide the difference between the maximum frequency and the minimum frequency by two to obtain the frequency offset.

[0111] Specifically, a fourth in-phase local carrier can be generated using a local oscillator, with its frequency being the center frequency of the target signal minus a preset intermediate frequency (IF) value. Next, the target signal is mixed with the fourth in-phase local carrier to obtain the fourth I-channel IF signal. This fourth I-channel IF signal contains two components: a high-frequency component and an IF component. A narrow-bandwidth complex filter can then be used to filter out the high-frequency component. Next, a hysteresis comparator can be used to convert the IF component of the fourth I-channel IF signal into a square wave. Since 2FSK uses two frequencies to carry binary 1s and 0s, the square wave will also have two frequency representations. Therefore, based on these two frequency representations, the two frequencies—that is, the maximum and minimum frequencies—can be determined. Finally, subtracting the minimum frequency from the maximum frequency and dividing by two yields the frequency offset. It should be noted that the frequency offset obtained here is relatively accurate.

[0112] For example, determining the frequency offset of the target signal can be implemented in conjunction with, for instance, the following methods. Figure 11The structure is shown. Specifically, the target signal is received by a receiving antenna, and simultaneously, a fourth in-phase local carrier with a frequency equal to the center frequency minus the intermediate frequency (IF) is generated by a local oscillator. Then, the target signal is amplified by an LNA and mixed with the fourth in-phase local carrier to obtain the fourth I-channel IF signal. The target signal, the fourth in-phase local carrier, and the fourth I-channel IF signal can be represented by the following formulas:

[0113] Target signal: 2Acos(ω) C t±Δω n t+θ1)

[0114] Fourth in-phase local carrier: cos(ω) C t-ω IF t+θ2)

[0115] Fourth I-channel intermediate frequency signal: A{cos[2ω C t-ω IF t±Δω n t+θ1+θ2]+cos[ω IF t±Δω n t+θ1-θ2]}

[0116] Next, the fourth I-channel intermediate frequency signal is filtered through a narrow-bandwidth complex filter. It can be understood that the high-frequency component Acos[2ω] in the fourth I-channel intermediate frequency signal is then filtered. C t-ω IF t±Δω n [t+θ1+θ2] will be filtered out, and the filtered first I-channel intermediate frequency signal will only include the intermediate frequency component Acos[ω]. IF t±Δω n [t+θ1-θ2]. Next, the intermediate frequency component is converted into a square wave signal using a hysteresis comparator. For example... Figure 12 As shown, a square wave signal can exhibit two frequency characteristics, thus these two frequencies can be measured. For example, using a preset number (e.g., 8) rising edges as the test period, the frequency values ​​within the test period can be measured. In this way, the maximum and minimum frequencies can be determined. Finally, the difference between the maximum and minimum frequencies is divided by two to obtain the frequency offset.

[0117] S70. Measure the frequency of the baseband signal to determine the symbol rate.

[0118] After obtaining the baseband signal, frequency measurement can be performed to determine the symbol rate. The specific implementation is already existing technology and will not be described in detail here.

[0119] In summary, in this embodiment, the center frequency of the target signal is first determined, followed by the modulation scheme. If the modulation scheme is determined to be OOK, the baseband signal is obtained by demodulating the target signal based on the amplitude. If the modulation scheme is determined to be 2FSK, the baseband signal is obtained by demodulating the target signal based on the frequency, and the frequency offset is determined. Finally, the symbol rate is determined based on the baseband signal. Therefore, the method provided in this embodiment can achieve blind demodulation and analysis of 2FSK / OOK signals. Furthermore, the method provided in this embodiment does not require time-frequency domain conversion during demodulation and analysis, resulting in lower computational complexity.

[0120] Furthermore, this application also provides a dedicated integrated chip for enabling a device equipped with the dedicated integrated chip to perform the methods described in the above embodiments.

[0121] Furthermore, embodiments of this application also provide a remote control device 300, such as... Figure 13 As shown, the system may include a processor 301 and a memory 302. Exemplarily, the processor 301 and the memory 302 can be connected to 303 via a bus, for example, through I / O. 2 C (Inter-Integrated Circuit) bus.

[0122] Specifically, processor 301 provides computing and control capabilities. Processor 301 can be a Central Processing Unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0123] Specifically, the memory 302 can be a Flash chip, a read-only memory (ROM), a disk, an optical disk, a USB flash drive, or a portable hard drive, etc.

[0124] Those skilled in the art will understand that Figure 13 The structure shown is merely a block diagram of a portion of the structure related to the embodiments of this application, and does not constitute a limitation on the terminal device to which the embodiments of this application are applied. Specifically, the terminal device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0125] The processor 301 is used to run a computer program stored in the memory 302, and implements the method described in the above embodiment when executing the computer program.

[0126] Furthermore, embodiments of this application also provide a storage medium for computer-readable storage, on which one or more computer programs are stored, and the one or more computer programs can be executed by one or more processors to implement the steps of the method provided in embodiments of this application.

[0127] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes described in the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0128] It should be understood that descriptions involving "first," "second," etc., in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0129] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A blind demodulation and analysis method for a signal, characterized in that, include: Generate a second in-phase local carrier and a second quadrature local carrier, wherein the frequencies of the second in-phase local carrier and the second quadrature local carrier are both the frequency values ​​corresponding to the m-th bandwidth, where m is a positive integer; The target signal is mixed with the second in-phase local carrier and the second quadrature local carrier respectively to obtain the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal; The second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal are filtered respectively to remove components that are not related to the intermediate frequency. Determine whether both the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal include intermediate frequency components; If all are included, then the m-th bandwidth is determined as the target bandwidth; otherwise, the next second in-phase local carrier and the next second quadrature local carrier are regenerated for judgment until the target bandwidth is determined. The frequencies of the next second in-phase local carrier and the next second quadrature local carrier are the frequency values ​​corresponding to the (m+1)-th bandwidth. The frequency value corresponding to the target bandwidth is used as the estimated center frequency value of the target signal; Generate a first in-phase local carrier, the frequency of which is the estimated center frequency; The target signal is mixed with the first in-phase local carrier to obtain the first I-channel intermediate frequency signal; Filter the high-frequency components in the first I-channel intermediate frequency signal to obtain the intermediate frequency components in the first I-channel intermediate frequency signal; The intermediate frequency component in the first I-channel intermediate frequency signal is converted into a square wave and then the frequency is measured to obtain the corrected frequency value. The sum of the estimated center frequency and the corrected frequency value is taken as the center frequency of the target signal; The target signal is subjected to frequency mixing and analog-to-digital conversion to obtain I-channel intermediate frequency digital signal and Q-channel intermediate frequency digital signal; The amplitude of the target signal is determined based on the I-channel intermediate frequency digital signal and the Q-channel intermediate frequency digital signal; If the amplitude of the target signal is greater than the second preset threshold within a preset time period, the modulation method is determined to be 2FSK; otherwise, the modulation method is determined to be OOK. If the modulation method is determined to be OOK, then the average amplitude of the target signal is determined, and the target signal is demodulated to obtain the baseband signal based on the relationship between the amplitude of the target signal and the average amplitude. If the modulation method is determined to be 2FSK, then the estimated mean frequency offset and frequency offset of the target signal are determined, and the target signal is demodulated to obtain the baseband signal according to the relationship between the frequency of the target signal, the center frequency of the target signal and the estimated mean frequency offset. Frequency measurement is performed on the baseband signal to determine the symbol rate.

2. The method according to claim 1, characterized in that, Determining whether both the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal include intermediate frequency components includes: The second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal are respectively converted from analog to digital to obtain the second I-channel intermediate frequency digital signal and the second Q-channel intermediate frequency digital signal; The estimated amplitude of the target signal is determined based on the second I-channel intermediate frequency digital signal and the second Q-channel intermediate frequency digital signal. The estimated amplitude of the target signal is smoothed to obtain the indicated intensity of the target signal; Determine whether the indicated intensity is greater than a first preset threshold; If the value is greater than the value, then it is determined that both the second I-channel intermediate frequency signal and the second Q-channel intermediate frequency signal include intermediate frequency components; otherwise, it is determined that they do not both include intermediate frequency components.

3. The method according to claim 1, characterized in that, The step of performing frequency mixing and analog-to-digital conversion on the target signal to obtain I-channel intermediate frequency digital signals and Q-channel intermediate frequency digital signals includes: A third in-phase local carrier and a third quadrature local carrier are generated, wherein the frequencies of the third in-phase local carrier and the third quadrature local carrier are both the center frequency of the target signal minus a preset intermediate frequency value; The target signal is mixed with the third in-phase local carrier and the third quadrature local carrier respectively to obtain the third I-channel intermediate frequency signal and the third Q-channel intermediate frequency signal; The high-frequency components in the third I-channel intermediate frequency signal and the third Q-channel intermediate frequency signal are filtered out respectively; The intermediate frequency component in the third I-channel intermediate frequency signal is converted from analog to digital to obtain the I-channel intermediate frequency digital signal, and the intermediate frequency component in the third Q-channel intermediate frequency signal is converted from analog to digital to obtain the Q-channel intermediate frequency digital signal.

4. The method according to any one of claims 1-3, characterized in that, The step of demodulating the target signal to obtain a baseband signal based on the relationship between the amplitude of the target signal and the average amplitude includes: The portion of the target signal whose amplitude is greater than the average amplitude is demodulated to logic 1, and the portion of the target signal whose amplitude is less than the average amplitude is demodulated to logic 0, to obtain the baseband signal.

5. The method according to any one of claims 1-3, characterized in that, Determining the estimated mean of the frequency offset of the target signal includes: The I-channel intermediate frequency digital signal and the Q-channel intermediate frequency digital signal are down-converted to zero intermediate frequency respectively to obtain the I-channel zero intermediate frequency digital signal and the Q-channel zero intermediate frequency digital signal; The arctangent of the I-channel zero-IF digital signal and the Q-channel zero-IF digital signal is calculated to obtain the frequency offset phase. Differentiating the frequency offset phase yields the frequency offset prediction value; The mean of the frequency offset prediction is determined based on the frequency offset prediction value.

6. The method according to any one of claims 1-3, characterized in that, The step of demodulating the target signal to obtain a baseband signal based on the relationship between the frequency of the target signal, the center frequency of the target signal, and the estimated average frequency offset includes: The portion of the difference between the frequency of the target signal and the center frequency of the target signal that is greater than the estimated average frequency offset is demodulated to logic 1, and the portion of the difference between the frequency of the target signal and the center frequency of the target signal that is less than the estimated average frequency offset is demodulated to logic 0, so as to obtain the baseband signal.

7. The method according to any one of claims 1-3, characterized in that, Determining the frequency offset of the target signal includes: A fourth in-phase local carrier is generated, the frequency of which is the center frequency of the target signal minus the preset intermediate frequency value. The target signal is mixed with the fourth in-phase local carrier to obtain the fourth I-channel intermediate frequency signal; Filter the high-frequency components in the fourth I-channel intermediate frequency signal to obtain the intermediate frequency components in the fourth I-channel intermediate frequency signal; The intermediate frequency component in the fourth I-channel intermediate frequency signal is converted into a square wave, and the maximum and minimum frequencies are determined based on the square wave. The frequency offset is obtained by dividing the difference between the maximum frequency and the minimum frequency by two.

8. A dedicated integrated chip, characterized in that, Used to cause a device equipped with the dedicated integrated chip to perform the method as described in any one of claims 1 to 7.

9. A remote control device, characterized in that, include: A memory, wherein the memory stores a computer program; A processor that, when executing the computer program, implements the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 7.

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