Transmission signal verification method and track circuit system

Abstract

The invention discloses a transmission signal verification method and a track circuit system, and relates to the technical field of railway signals. The method comprises the following steps: a transmitter modulates a first carrier signal and a second carrier signal with a modulation signal of a target modulation frequency to form a first signal and a second signal; the transmitter transmits the first signal to the receiver through the track and directly transmits the second signal to the receiver; the receiver modulates the first signal and the second signal to obtain a first low frequency and a first amplitude, and a second low frequency and a second amplitude; and when the receiver determines that the first amplitude is greater than the preset amplitude, the first signal is verified based on the first low frequency and the second low frequency. According to the track circuit system, the verification channel directly from the transmitter to the receiver is added, so that a verification mechanism for the first signal is added, the anti-interference capability of the track circuit system is improved, the stability and reliability of the track circuit system are ensured, and the influence of interference signals on normal work of the track circuit system is avoided.

Description

Technical Field

[0001] This application relates to the field of railway signaling technology, and in particular to a method for verifying transmitted signals and a track circuit system. Background Technology

[0002] Track circuitry is a crucial component of railway signaling systems, used to detect the position of trains and ensure their safe operation. It utilizes the railway tracks as conductors to form circuits, thereby detecting whether a train is on a specific track section, playing a vital role in railway automation and safety control.

[0003] In current technology, the track circuit system operates as follows: the transmitter uses Frequency Shift Keying (FSK) to modulate a high-frequency carrier wave with a low-frequency modulation frequency, obtaining a modulated signal, which is then transmitted through the track to the receiver. The receiver demodulates the modulated signal to obtain the corresponding low-frequency signal and amplitude. When a train is running on the track, the train wheelset short-circuits the signal transmission, causing the signal strength received by the receiver to be significantly weakened, even reduced to an extremely low level. Therefore, if the amplitude obtained by the receiver demodulation is lower than a specified threshold, it is determined that the track is occupied by a train; otherwise, the track is determined to be empty.

[0004] In current technology, track circuit systems have poor anti-interference capabilities and are easily affected by interference signals, which can affect the stability and reliability of the track circuit system and thus affect its normal operation. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a transmission signal verification method and a track circuit system. This method incorporates a verification mechanism, enhances the anti-interference capability of the track circuit system, ensures the stability and reliability of the track circuit system, and avoids the impact of interference signals on the normal operation of the track circuit system.

[0006] The embodiments of this application disclose the following technical solutions:

[0007] In a first aspect, this application provides a transmission signal verification method applied to a track circuit system, the track circuit system comprising: a transmitter, a track, and a receiver, the method comprising:

[0008] The transmitter modulates the first carrier signal and the second carrier signal with a modulation signal of the target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal;

[0009] The transmitter transmits the first signal to the receiver via the track, and transmits the second signal directly to the receiver;

[0010] The receiver demodulates the first signal and the second signal respectively to obtain the first low frequency and the first amplitude corresponding to the first signal, and the second low frequency and the second amplitude corresponding to the second signal;

[0011] When the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency.

[0012] Optionally, when the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency, including:

[0013] When the receiver determines that the first amplitude is greater than the preset amplitude, it determines whether the difference between the first low frequency and the second low frequency is greater than the preset difference.

[0014] If the difference between the first low frequency and the second low frequency is greater than a preset difference, then the first signal is determined to be invalid.

[0015] If the difference between the first low frequency and the second low frequency is not greater than a preset difference, then the first signal is determined to be valid.

[0016] Optionally, the preset difference is determined based on the target modulation frequency and the preset range.

[0017] Optionally, before verifying the first signal based on the first low frequency and the second low frequency when the receiver determines that the first amplitude is greater than a preset amplitude, the method further includes:

[0018] The receiver determines whether the second amplitude is within a preset amplitude range; if the second amplitude is within the preset amplitude range, the second signal is determined to be valid; if the second amplitude is within the preset amplitude range, the second signal is determined to be invalid.

[0019] When the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency, including:

[0020] When the receiver determines that the second signal is valid and the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency.

[0021] Optionally, the transmitter modulates the first carrier signal and the second carrier signal with a modulation signal of the target modulation frequency to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal, including:

[0022] The transmitter performs frequency shift keying (FSK) modulation on the first carrier signal using a modulation signal at the target modulation frequency to form a first signal corresponding to the first carrier signal, and performs minimum frequency shift keying (MSK) modulation on the second carrier signal using the modulation signal at the target modulation frequency to form a second signal corresponding to the second carrier signal.

[0023] Optionally, the transmitter includes: a first processor and a second processor; the transmitter modulates the first carrier signal and the second carrier signal with a modulation signal of the target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal, including:

[0024] The first processor modulates the first carrier signal with a modulation signal at the target modulation frequency to form a first signal corresponding to the first carrier signal;

[0025] The second processor modulates the second carrier signal with the modulation signal of the target modulation frequency to form a second signal corresponding to the second carrier signal.

[0026] Optionally, the transmitter further includes: a signal conversion device, a power amplifier, a first AND gate, and a second AND gate; the transmitter transmits the first signal to the receiver via the track and directly transmits the second signal to the receiver, including:

[0027] The first processor transmits the first signal to the second processor, and the second processor transmits the second signal to the first processor;

[0028] The first processor checks the carrier frequency and modulation frequency of the second signal to obtain a first check result, and the second processor checks the carrier frequency and modulation frequency of the first signal to obtain a second check result;

[0029] When both the first and second test results are passed, the first AND gate conducts the transmission channel, so that the first processor transmits the first signal to the signal conversion device and the second processor transmits the second signal to the signal conversion device.

[0030] The signal conversion device converts the first signal and the second signal from square waves to sine waves; the signal conversion device transmits the converted second signal to the first processor and the first signal to the power amplifier, so that the power amplifier can amplify the first signal and then transmit it to the second processor;

[0031] The first processor checks the amplitude of the second signal to obtain a third check result, and the second processor checks the amplitude of the first signal to obtain a fourth check result;

[0032] When both the third and fourth test results are passed, the second AND gate conducts the transmission channel, so that the power amplifier transmits the first signal to the receiver through the track, and the signal conversion device transmits the second signal directly to the receiver.

[0033] Optionally, the method further includes:

[0034] If neither the first test result nor the second test result is passed, the first AND gate disconnects the transmission channel.

[0035] If neither the third nor the fourth test result is passed, the second AND gate will disconnect the transmission channel.

[0036] Optionally, the receiver demodulates the first signal and the second signal respectively to obtain a first low frequency and a first amplitude corresponding to the first signal, and a second low frequency and a second amplitude corresponding to the second signal, including:

[0037] The receiver demodulates the first signal and the second signal respectively, and uses windowed interpolation fast Fourier transform to analyze and obtain the first low frequency and first amplitude corresponding to the first signal, and the second low frequency and second amplitude corresponding to the second signal.

[0038] Secondly, this application provides a track circuit system, including: a transmitter, a track, and a receiver; the transmitter is connected to the track, the receiver is connected to the track; and the transmitter is also connected to the receiver;

[0039] The transmitter is used to modulate the first carrier signal and the second carrier signal with a modulation signal of the target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal;

[0040] The transmitter is also configured to transmit the first signal to the receiver via the track, and to transmit the second signal directly to the receiver;

[0041] The receiver is configured to demodulate the first signal and the second signal respectively to obtain a first low frequency and a first amplitude corresponding to the first signal, and a second low frequency and a second amplitude corresponding to the second signal;

[0042] The receiver is further configured to verify the first signal based on the first low frequency and the second low frequency when it determines that the first amplitude is greater than a preset amplitude.

[0043] Compared to existing technologies, this application has the following advantages: In this application, a verification channel directly from the transmitter to the receiver is added, thereby increasing the verification mechanism between the second signal and the first signal, improving the anti-interference capability of the track circuit system, ensuring the stability and reliability of the track circuit system, and avoiding the impact of interference signals on the normal operation of the track circuit system. Furthermore, it avoids serious safety problems caused by the influence of interference signals on the track circuit system. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A flowchart illustrating a transmission signal verification method provided in an embodiment of this application;

[0046] Figure 2 A spectral comparison example diagram of frequency shifting processing provided in an embodiment of this application;

[0047] Figure 3 A spectral example diagram of an interpolation process provided in an embodiment of this application;

[0048] Figure 4 A schematic diagram illustrating the specific process of the transmitter forming and transmitting the first and second signals provided in this application embodiment;

[0049] Figure 5 A structural example diagram of a transmitter provided in an embodiment of this application;

[0050] Figure 6 This is a schematic diagram of a track circuit system provided in an embodiment of this application. Detailed Implementation

[0051] As described earlier, in current track circuit systems, interference signals (such as electromagnetic interference, electrical noise, lightning signals, and signals generated by high-powered trains traveling at high speeds) can easily be transmitted through the track to the receiver, causing misjudgment / malfunction by the receiver and resulting in poor anti-interference capability of the current track circuit system. Furthermore, receiver misjudgment / malfunction affects the stability and reliability of the overall track circuit system, thereby affecting its normal operation.

[0052] For example, in a current track circuit system where a train is running on the track, the receiver of the track circuit system should receive a very weak modulation signal so that the amplitude obtained by demodulating the modulation signal is lower than a specified threshold, thus determining that the track in the track circuit system is occupied by the train. However, because interference signals are transmitted to the receiver through the track, the receiver will receive a strong interference signal, so that the receiver demodulates the interference signal to obtain an amplitude. Since the amplitude obtained by demodulating the interference signal is large, it will be higher than the specified threshold, causing the receiver to determine that the track in the track circuit system is empty, that is, not occupied by the train, resulting in a judgment error and affecting the stability and reliability of the overall track circuit system.

[0053] Furthermore, interference signals can cause the track circuit system to misjudge whether the track is occupied by a train, that is, it may judge a track that is occupied by a train as an empty track, which may affect the speed of subsequent trains and thus potentially cause serious safety problems, such as train collisions.

[0054] This application provides a transmission signal verification method applied to a track circuit system. The method includes: a transmitter modulating a first carrier signal and a second carrier signal with a modulation signal at a target modulation frequency to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal; the transmitter transmitting the first signal to a receiver via the track and directly transmitting the second signal to the receiver; the receiver modulating the first signal and the second signal to obtain a first low frequency and a first amplitude corresponding to the first signal, and a second low frequency and a second amplitude corresponding to the second signal; when the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency. In this embodiment, a verification channel directly from the transmitter to the receiver is added, thereby increasing the verification mechanism of the second signal against the first signal, improving the anti-interference capability of the track circuit system, ensuring the stability and reliability of the track circuit system, and avoiding the impact of interference signals on the normal operation of the track circuit system. Furthermore, it avoids serious safety problems caused by the influence of interference signals on the track circuit system.

[0055] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0056] Example 1:

[0057] The following is combined Figures 1-3 This application provides a detailed description of a transmission signal verification method based on an embodiment.

[0058] This application provides a transmission signal verification method applied to a track circuit system, which includes a transmitter, a track, and a receiver. Figure 1 As shown in the figure, a transmission signal verification method provided in this application includes the following steps:

[0059] S101, The transmitter modulates the first carrier signal and the second carrier signal with a modulation signal of the target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal.

[0060] The target modulation frequency is a predefined frequency selected by the transmitter based on the information to be transmitted, and is typically stored in the transmitter's configuration. The modulation frequency refers to the frequency of the modulating signal, specifically the frequency of the low-frequency signal used to control changes in the carrier signal parameters.

[0061] For example, for the ZPW-2000A track circuit system, there are 18 modulation frequencies for the low-frequency modulation signal, which are (10.3 + 11 × n) Hz (Hertz), where n = 0, 1, 2, ..., 17 (n is a positive integer from 0 to 17), that is, the range is from 10.3 Hz to 29.0 Hz, and each modulation frequency represents different information.

[0062] The first carrier signal is a carrier signal with a frequency of the first carrier frequency.

[0063] The first carrier frequency is the standard carrier frequency, which refers to the carrier frequency defined according to standard specifications to ensure compatibility and interoperability between different track circuit systems. The carrier frequency refers to the frequency of the high-frequency carrier signal, that is, the frequency of the high-frequency signal before modulation.

[0064] For example, for the ZPW-2000A track circuit system, there are 8 standard carrier frequencies: 1700-1, 1700-2, 2300-1, 2300-2, 2000-1, 2000-2, 2600-1, and 2600-2. Here, "-1" represents -1.3Hz and "-2" represents +1.4Hz. That is, the carrier frequency corresponding to 1700-1 is 1700Hz-1.3Hz=1698.7Hz, and the carrier frequency corresponding to 1700-2 is 1700Hz+1.4Hz=1701.4Hz.

[0065] Specifically, during the design phase of the track circuit system, engineers divide the entire track into multiple segments based on the track layout and requirements, assigning a suitable standard carrier frequency to each segment, and using different standard carrier frequencies for adjacent segments. This use of different standard carrier frequencies for adjacent segments reduces interference between them, thereby improving the anti-interference capability and reliability of the track circuit system. The standard carrier frequencies pre-assigned to each segment are recorded in the track circuit system's configuration file. During initialization, the transmitter reads this configuration information to obtain the standard carrier frequencies corresponding to one or more track segments. In other words, the transmitter has pre-determined the first carrier frequency corresponding to the track based on the configuration information, thus determining the first carrier signal corresponding to the first carrier frequency.

[0066] The second carrier signal is a carrier signal with a frequency of the second carrier frequency.

[0067] The second carrier frequency is the design carrier frequency that uniquely corresponds to the first carrier frequency. The design carrier frequency refers to the corresponding carrier frequency that is designed / set in advance based on the standard carrier frequency. For example, taking the ZPW-2000A track circuit system as an example, the design carrier frequency is set to (650-1.5)Hz for standard carrier frequency 1700-1, (650+1.5)Hz for 1700-2, (750-1.5)Hz for 2000-1, (750+1.5)Hz for 2000-2, (850-1.5)Hz for 2300-1, (850+1.5)Hz for 2300-2, (950-1.5)Hz for 2600-1, and (950+1.5)Hz for 2600-2.

[0068] Furthermore, taking the correspondence between the standard carrier frequency and the design carrier frequency mentioned above as an example, when the first carrier frequency is 2000-1, the second carrier frequency is (750-1.5)Hz. Therefore, the first carrier signal of 2000-1 (i.e., 1998.7Hz) and the second carrier signal of (750-1.5)Hz are modulated by the modulation signal of the target modulation frequency.

[0069] The first signal is a signal modulated by the first carrier signal, and the second signal is a signal modulated by the second carrier signal.

[0070] In one possible implementation, the transmitter performs frequency shift keying modulation on the first carrier signal with a modulation signal at the target modulation frequency to form a first signal corresponding to the first carrier signal; and performs minimum frequency shift keying modulation on the second carrier signal with a modulation signal at the target modulation frequency to form a second signal corresponding to the second carrier signal.

[0071] Frequency Shift Keying (FSK) is a modulation technique that uses changes in the frequency of a carrier signal to represent different digital information. Minimum Shift Keying (MSK) is a special type of FSK modulation that features continuous phase. The frequency offset of MSK is 1 / 4 of the symbol rate, and MSK offers lower bandwidth occupancy and better anti-interference performance.

[0072] Specifically, for the target modulation frequency, different modulation methods (FSK and MSK) are used to make the spectra of the first signal and the second signal different, so that the first signal and the second signal are distinct. After the receiver receives the first signal and the second signal, it can accurately distinguish the first signal and the second signal and avoid mutual interference.

[0073] S102, The transmitter transmits the first signal to the receiver via the track and transmits the second signal directly to the receiver.

[0074] Specifically, in the track circuit system, the transmitter transmits a first signal to the receiver via the track, and the transmitter also transmits a second signal directly to the receiver without going through the track. That is, in this embodiment, the track circuit transmission system has two transmission channels: one is the transmission channel from the transmitter to the receiver via the track, and the other is the transmission channel from the transmitter directly to the receiver.

[0075] Among them, the transmission channel from the transmitter to the receiver is not easily affected by interference signals. Therefore, the second signal transmitted through this transmission channel can serve as a standard to verify the first signal, avoiding the impact of interference signals on the stability and reliability of the track circuit system due to misjudgment / malfunction of the receiver.

[0076] S103, the receiver demodulates the first signal and the second signal respectively to obtain the first low frequency and the first amplitude corresponding to the first signal, and the second low frequency and the second amplitude corresponding to the second signal.

[0077] Specifically, the receiver demodulates the first signal and the second signal respectively to obtain a first original signal corresponding to the first signal and a second original signal corresponding to the second signal; based on the first original signal, the center frequency and the amplitude corresponding to the center frequency of the first original signal are obtained, wherein the center frequency of the first original signal is the first low frequency corresponding to the first signal and the value corresponding to the center frequency of the first original signal is the first amplitude corresponding to the first signal; and based on the second original signal, the center frequency and the value corresponding to the center frequency of the second original signal are obtained, wherein the center frequency of the second original signal is the second low frequency corresponding to the second signal and the value corresponding to the center frequency of the second original signal is the second amplitude corresponding to the second signal.

[0078] Specifically, the receiver uses Fast Fourier Transform (FFT) to perform spectral analysis on the first original signal to obtain the center frequency of the first original signal as the first low frequency. Then, based on the center frequency and the first original signal, the amplitude corresponding to the center frequency is calculated as the first amplitude. Similarly, the receiver uses Fast Fourier Transform to obtain the second low frequency and the second amplitude corresponding to the second signal.

[0079] The Fast Fourier Transform (FFT) is an efficient algorithm used to compute the Discrete Fourier Transform (DFT). By recursively decomposing the DFT into smaller subproblems, it greatly reduces computational complexity.

[0080] In one possible implementation, the receiver demodulates the first signal and the second signal respectively, and uses windowed interpolation fast Fourier transform to analyze and obtain the first low frequency and the first amplitude corresponding to the first signal, and the second low frequency and the second amplitude corresponding to the second signal.

[0081] Furthermore, before the receiver demodulates the first signal and the second signal respectively, the first signal and the second signal are subjected to frequency shifting processing, shifting the center frequency of the first signal to zero and the center frequency of the second signal to zero, so as to facilitate subsequent spectrum analysis.

[0082] To make it easier to understand, the following will be combined with... Figure 2 Let's take a frequency shifting example. We'll use the first signal as an example.

[0083] like Figure 2As shown in (a), this is the spectrum of the first signal before frequency shifting. After frequency shifting the first signal, its center frequency is moved to zero. The spectrum of the first signal after frequency shifting is shown in (a). Figure 2 As shown in (b) of the diagram.

[0084] In this embodiment, due to frequency leakage in Fast Fourier Transform, especially in cases of non-integer period and asynchronous sampling, the peak values ​​in the spectrum no longer accurately reflect the center frequency of the signal. Frequency leakage refers to the phenomenon where, when the period of a signal is not an integer multiple of the sampling window, the signal energy spreads across multiple frequency points in the spectrum, instead of being concentrated at a theoretically single frequency point. For example, the center frequency of a signal, f0, should appear as a peak value at a frequency point k0 in the spectrum. However, due to frequency leakage, the energy spreads to multiple frequency points, resulting in multiple small peaks in the spectrum, making it impossible to accurately read the center frequency and its corresponding amplitude.

[0085] Therefore, using windowed interpolation Fast Fourier Transform can reduce frequency leakage and estimate the center frequency with higher accuracy, thereby improving the reliability of the overall track circuit system.

[0086] Specifically, the receiver performs frequency shifting on the first signal and the second signal respectively, and demodulates the frequency-shifted first signal and the second signal to obtain the first original signal corresponding to the first signal and the second original signal corresponding to the second signal; it then performs windowing on the first original signal, performs fast Fourier transform on the windowed first original signal, and uses interpolation to perform high-precision estimation of the center frequency domain and its corresponding value to obtain the first low frequency and the first amplitude; similarly, the second low frequency and the second amplitude are obtained.

[0087] In one possible implementation, the window function used when windowing the first original signal and / or the second original signal is the Hanning window.

[0088] To facilitate understanding, the following example, using formulas (1) and (2), illustrates the windowing process when the window function is a Hanning window.

[0089] As shown in formula (1), the time-domain expression of the Hanning window is:

[0090]

[0091] Where w(n) is the Hanning window function; N is the length of the Hanning window function, i.e., the total number of sampling points; and n is the index of the sampling point, ranging from 1 to N.

[0092] As shown in formula (2), the frequency domain expression of the Hanning window is:

[0093]

[0094] Where W(k) is the Hanning window function response in the frequency domain; k is the frequency variable; m is 0 or 1, corresponding to a m The value can be 0.5 or -0.5.

[0095] This allows for windowing of the offset original function using the Hanning window function.

[0096] To make it easier to understand, the following will be combined with... Figure 3 Formulas (3), (4), and (5) are used to illustrate how to accurately estimate the center frequency domain and its corresponding values ​​using interpolation. Figure 3 The spectrum shown is the spectrum obtained after performing a Fast Fourier Transform on the original signal after windowing.

[0097] like Figure 3 As shown, it is pre-assumed that the signal frequency point k0 is the center frequency, and the value corresponding to k0 is assigned as A. The frequency points of the two spectral lines immediately adjacent to k0 are set as k2 and k3, and the frequency points of the two outermost spectral lines are k1 and k4, where k1 < k2 < k3 < k4, and k4 = k2 + 2, k3 = k2 + 1, and k1 = k2 - 1. Then the amplitudes of these four spectral lines are: X1 = |X(k1Δf)|, X2 = |X(k2Δf)|, X3 = |X(k3Δf)|, and X4 = |X(k4Δf)|.

[0098] Where X1 is the amplitude corresponding to frequency point k1, X2 is the amplitude corresponding to frequency point k2, X3 is the amplitude corresponding to frequency point k3, and X4 is the amplitude corresponding to frequency point k4; X(·) is the original signal after fast Fourier transform; Δf represents the frequency interval between adjacent frequency points in the spectrum.

[0099] Furthermore, from the four spectral lines k1, k2, k3, and k4 immediately adjacent to k0, and their corresponding amplitudes X1, X2, X3, and X4, we can obtain formula (3):

[0100]

[0101] Here, η is an index used to evaluate the location of a signal frequency point. Specifically, η is a parameter calculated using the amplitude of four adjacent frequency points, used to accurately locate the center frequency of the signal.

[0102] Based on formula (3), we introduce the parameter α = k0 - k2 - 0.5, and α ∈ (-0.5, 0.5), and construct the formula η = f(α), as shown in formula (4):

[0103]

[0104] Wherein, W(·) is a function of the spectral line amplitude in the window function spectrum, that is, the frequency domain expression of the window function, which is used to calculate the amplitude at different frequency points. When the window function is the Hanning window function, it can be understood as the frequency domain expression of the Hanning window function shown in formula (2).

[0105] Based on the functional relationship shown in formula (4), within the range of α∈(-0.5,0.5), α is taken at certain step intervals, and the corresponding η value is obtained simultaneously, finally obtaining the coefficient pair (α). i η i Polynomial fitting of this series of coefficient pairs yields α = f -1 The (η) functional relationship can be used to correct the signal frequency value, thus obtaining a more accurate estimated frequency value. Specifically, the center frequency is estimated using formula (5):

[0106] f0=k0Δf=(α+k2+0.5)Δf (5)

[0107] Where f0 is the center frequency corresponding to frequency point k0.

[0108] S104. When the receiver determines that the first amplitude is greater than the preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency.

[0109] When the receiver determines that the first amplitude is not greater than the preset amplitude, it indicates that the track in the track circuit system is occupied by a train. Furthermore, the presence of interference signals means that the first amplitude obtained from the demodulation of the first signal will not be too small, i.e., it will not be less than the preset amplitude. Therefore, it is assumed that when the first amplitude is not greater than the preset amplitude, there is no interference signal. Moreover, even if interference signals exist, causing the receiver to determine that the track in the track circuit system is occupied by a train, it will not cause more serious consequences, such as a train collision. Therefore, it is assumed that when the first amplitude is not greater than the preset amplitude, there is no interference signal, and no verification of the first signal is required.

[0110] When the receiver determines that the first amplitude is greater than the preset amplitude, it indicates that the track in the track circuit system is not occupied by the train (i.e., it is in an idle state) or there is an interference signal that causes the first amplitude of the first signal to be greater than the preset amplitude. In order to avoid the situation that the first amplitude of the first signal is greater than the preset amplitude due to interference signals, the first signal is checked based on the first low frequency and the second low frequency.

[0111] In this embodiment, a verification channel is added, enabling the first signal to be verified using the second low frequency of the second signal and the first low frequency of the first signal. This enhanced verification mechanism improves the anti-interference capability of the track circuit system, ensuring its stability and reliability and preventing interference signals from affecting its normal operation. Furthermore, it avoids serious safety issues caused by receiver malfunctions.

[0112] In one possible implementation, when the receiver determines that the first amplitude is greater than a preset amplitude, it determines whether the difference between the first low frequency and the second low frequency is greater than a preset difference; if the difference between the first low frequency and the second low frequency is greater than the preset difference, the first signal is determined to be invalid; if the difference between the first low frequency and the second low frequency is not greater than the preset difference, the first signal is determined to be valid.

[0113] Specifically, if the difference between the first low frequency and the second low frequency exceeds a preset difference, the receiver determines that the first signal is invalid, meaning the first signal verification fails. This indicates that the first signal has been affected by interference; specifically, during transmission from the transmitter to the receiver via the track, interference caused the difference between the first and second low frequencies to be too large, thus rendering the first signal invalid. When the first signal is invalid, the track circuit system will not perform the corresponding operation based on the information carried by the first signal, thereby improving the anti-interference capability of the track circuit signals.

[0114] Specifically, if the difference between the first low frequency and the second low frequency is not greater than a preset difference, the receiver determines that the first signal is valid, meaning the first signal verification is successful. At this point, it indicates that the first signal has not been affected by interference signals, and the track circuit system can perform / implement corresponding operations based on the information carried by the first signal.

[0115] In one possible implementation, the preset difference is determined based on the target modulation frequency and a preset range. For example, if the preset range is 3%, then the preset difference is 3% of the target modulation frequency.

[0116] In one possible implementation, before verifying the first signal based on the first low frequency and the second low frequency when the receiver determines that the first amplitude is greater than the preset amplitude, the receiver determines whether the second amplitude is within the preset amplitude range; if the second amplitude is within the preset amplitude range, the second signal is determined to be valid; if the second amplitude is not within the preset amplitude range, the second signal is determined to be invalid; when the receiver determines that the second signal is valid and the first amplitude is greater than the preset amplitude, the first signal is verified based on the first low frequency and the second low frequency.

[0117] The preset amplitude range is the predefined amplitude range of the second signal. That is, when the transmitter modulates the second carrier signal with the target modulation signal to form the second signal, it also sets the amplitude of the second signal.

[0118] If the second amplitude of the second signal is within the preset amplitude range, the second signal is considered valid. Only when the second signal is valid can the first signal be verified based on its second low frequency and the first low frequency of the first signal. If the second amplitude of the second signal is outside the preset amplitude range, the second signal is considered invalid, meaning it may contain interference or errors. Therefore, even if the first signal is verified based on its second low frequency and the first low frequency of the first signal, the verification result will be incorrect or inaccurate. Thus, verifying the second signal before verifying the first signal improves the accuracy of the first signal verification, further enhancing the stability and reliability of the track circuit system.

[0119] This application provides a transmission signal verification method applied to a track circuit system. The method includes: a transmitter modulating a first carrier signal and a second carrier signal with a modulation signal at a target modulation frequency to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal; the transmitter transmitting the first signal to a receiver via the track and directly transmitting the second signal to the receiver; the receiver modulating the first signal and the second signal to obtain a first low frequency and a first amplitude corresponding to the first signal, and a second low frequency and a second amplitude corresponding to the second signal; when the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency. In this application embodiment, a verification channel directly from the transmitter to the receiver is added, thereby increasing the verification mechanism of the second signal against the first signal, improving the anti-interference capability of the track circuit system, ensuring the stability and reliability of the track circuit system, and avoiding the impact of interference signals on the normal operation of the track circuit system. Furthermore, it avoids serious safety problems caused by the influence of interference signals on the track circuit system.

[0120] Furthermore, before verifying the first signal, the second signal is verified by setting a preset amplitude range, which improves the accuracy of the verification of the first signal and further enhances the stability and reliability of the track circuit system.

[0121] The above embodiment 1 details the overall process of a transmission signal verification method provided by this application. The following embodiment 2 details the specific process of the transmitter forming and transmitting the first and second signals in the transmission signal verification method.

[0122] Example 2:

[0123] The following is combined Figure 4 and Figure 5 This paper will describe in detail the specific process of the transmitter forming and transmitting the first and second signals in the embodiments of this application.

[0124] The transmitter includes a first processor and a second processor. The first processor modulates the first carrier signal with a modulation signal at the target modulation frequency to form a first signal corresponding to the first carrier signal; the second processor modulates the second carrier signal with a modulation signal at the target modulation frequency to form a second signal corresponding to the second carrier signal.

[0125] The processor (Central Processing Unit, CPU) is located in the transmitter of the track circuit system. It is responsible for processing various signals and control tasks, ensuring that signals can be correctly generated, modulated and transmitted, while monitoring the status of the track circuit system and making necessary adjustments.

[0126] Furthermore, the transmitter also includes: a signal conversion device, a power amplifier, a first AND gate, and a second AND gate, that is, the transmitter includes: a first processor, a second processor, a signal conversion device, a power amplifier, a first AND gate, and a second AND gate.

[0127] Signal conversion devices are used to convert signals from square waves to sine waves. Examples of signal conversion devices include low-pass filters (LPFs) and digital signal processing (DSP) chips.

[0128] A power amplifier (PA) is an amplification circuit used to amplify the power of an input signal to a sufficiently high level so that it can be effectively transmitted to a receiver.

[0129] The AND gate is a basic logic gate used to perform the logical AND operation.

[0130] like Figure 4 As shown, the specific process of the transmitter forming and transmitting the first signal and the second signal in this embodiment of the application includes the following steps:

[0131] S401, the first processor modulates the first carrier signal with a modulation signal of the target modulation frequency to form a first signal corresponding to the first carrier signal; the second processor modulates the second carrier signal with a modulation signal of the target modulation frequency to form a second signal corresponding to the second carrier signal.

[0132] S402, the first processor transmits a first signal to the second processor, and the second processor transmits a second signal to the first processor.

[0133] S403, the first processor checks the carrier frequency and modulation frequency of the second signal to obtain a first check result, and the second processor checks the carrier frequency and modulation frequency of the first signal to obtain a second check result.

[0134] The test results include pass and fail.

[0135] Specifically, the first processor transmits the first signal to the second processor so that the second processor can verify the carrier frequency and modulation frequency of the first signal; similarly, the second processor transmits the second signal to the first processor so that the first processor can verify the carrier frequency and modulation frequency of the second signal. This achieves cross-checking of the carrier frequency and modulation frequency of the two signals (the first signal and the second signal), thereby ensuring the correctness of the first signal and the second signal.

[0136] S404. When both the first and second test results are passed, the first AND gate conducts the transmission channel, so that the first processor transmits the first signal to the signal conversion device and the second processor transmits the second signal to the signal conversion device.

[0137] Specifically, when both the first and second test results pass, that is, when the cross-checking of the carrier frequency and modulation frequency of the first and second signals passes, ensuring that the first and second signals are correct / valid, the first AND gate conducts the transmission channel, thereby transmitting the first and second signals to the signal conversion device.

[0138] In one possible implementation, when neither the first test result nor the second test result is passed (for example, the first test result is failed but the second test result is passed; the first test result is passed but the second test result is failed; or both the first test result and the second test result are failed), it indicates that at least one of the first signal and the second signal is invalid / erroneous. In this case, the first AND gate switches the transmission channel to prevent the erroneous signal from continuing to be transmitted.

[0139] Furthermore, when the first AND gate switches the transmission channel, S401 can be re-executed.

[0140] S405, the signal conversion device converts the first signal and the second signal from square wave to sine wave; the signal conversion device transmits the converted second signal to the first processor and the first signal to the power amplifier, so that the power amplifier can amplify the first signal and then transmit it to the second processor.

[0141] In a track circuit system, the transmitter and receiver are typically located in one area, for example, the transmitter and receiver are located on two racks in the same room.

[0142] Specifically, the first signal is transmitted from the transmitter to the receiver via a track. Therefore, the transmission of the first signal not only requires traveling a relatively long distance via the track, but also involves exiting the building from the transmitter to the track and similarly entering the building from the track to the receiver. This entire transmission process consumes a significant amount of power for the first signal. Therefore, a power amplifier is used to amplify the power of the first signal, ensuring that it can be transmitted from the transmitter to the receiver via the track. The second signal, on the other hand, is transmitted directly from the transmitter to the receiver. The transmission of the second signal does not require exiting or entering the building, and the transmission distance is shorter, so no power amplification is needed.

[0143] S406. The first processor checks the amplitude of the second signal to obtain a third check result, and the second processor checks the amplitude of the first signal to obtain a fourth check result.

[0144] Specifically, the power amplifier transmits the amplified first signal to the second processor, allowing the second processor to verify the amplitude of the first signal; similarly, the signal conversion device transmits the second signal to the first processor, allowing the first processor to verify the amplitude of the second signal. This achieves cross-validation of the amplitudes of the two signals (the first signal and the second signal), thereby ensuring the correctness of both signals.

[0145] S407. When both the third and fourth test results are passed, the second AND gate conducts the transmission channel, so that the power amplifier transmits the first signal to the receiver through the track, and the signal conversion device transmits the second signal directly to the receiver.

[0146] Specifically, when both the third and fourth test results are passed, that is, when the cross-check of the amplitudes of the first and second signals is passed, ensuring that the first and second signals are correct / valid, the second AND gate conducts the transmission channel, thereby transmitting the first signal to the receiver through the track and directly transmitting the second signal to the receiver.

[0147] In one possible implementation, when neither the third nor the fourth check result is passed (for example, the third check result is failed but the fourth check result is passed; the third check result is passed but the fourth check result is failed; or both the third and fourth check results are failed), it indicates that at least one of the first and second signals is invalid or erroneous. In this case, the second AND gate switches the transmission channel to prevent the erroneous signal from continuing to be transmitted.

[0148] In this embodiment, the transmission of dual signals is controlled by a first AND gate and a second AND gate. When the carrier frequency, modulation frequency, and amplitude verification of the first and second signals are all correct, the first and second signals are transmitted to the receiver respectively. This design can directly cut off the signal transmission at the source of the transmitter when the transmitter malfunctions, preventing the receiver from continuing to receive interference signals and causing malfunctions that could affect the track circuit system.

[0149] To make it easier to understand, the following will be combined with... Figure 5 This application provides an example of how the transmitter forms and transmits the first and second signals in an embodiment of the application.

[0150] The first processor 501 modulates the first carrier signal with a modulation signal at the target modulation frequency to form signal A, and transmits signal A to the second processor 502; at the same time, the second processor 502 modulates the second carrier signal with a modulation signal at the target modulation frequency to form signal B, and transmits signal B to the first processor 501.

[0151] The first processor 501 checks the carrier frequency and modulation frequency of signal B, obtains a first verification result, and transmits the first verification result to the first AND gate 503; at the same time, the second processor 502 checks the carrier frequency and modulation frequency of signal A, obtains a second verification result, and transmits the second verification result to the first AND gate 503.

[0152] When both the first and second verification results are passed, the first AND gate 503 is turned on, and signals A and B are transmitted to the signal conversion device 504.

[0153] Signal conversion device 504 converts signal A from a square wave to a sine wave and transmits signal A to power amplifier 505; power amplifier 505 amplifies signal A and then transmits it to second processor 502. Signal conversion device 504 converts signal B from a square wave to a sine wave and transmits signal B to second processor 502.

[0154] The first processor 501 performs amplitude verification on signal B, obtains a third verification result, and transmits the third verification result to the second AND gate 506; at the same time, the second processor 502 performs amplitude verification on signal A, obtains a fourth verification result, and transmits the fourth verification result to the second AND gate 506.

[0155] When both the third and fourth verification results are passed, the second AND gate 506 is turned on, and signals A and B are output.

[0156] Example 3:

[0157] The following is combined Figure 6This application provides a detailed description of a track circuit system provided in its embodiments.

[0158] like Figure 6 As shown in the figure, an embodiment of this application provides a track circuit system including: a transmitter 610, a track 620, and a receiver 630.

[0159] The transmitter 610 is connected to the track 620, and the receiver 630 is also connected to the track 620, thus forming a transmission channel from the transmitter 610 to the receiver 630 via the track 620. Furthermore, the transmitter 610 is also connected to the receiver 630, thus forming a transmission channel from the transmitter 610 to the receiver 630.

[0160] Transmitter 610 is used to modulate a first carrier signal and a second carrier signal respectively with a modulation signal of a target modulation frequency to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal;

[0161] The transmitter 610 is also used to transmit the first signal to the receiver 630 via the track 620, and to transmit the second signal directly to the receiver 630;

[0162] Receiver 630 is used to demodulate the first signal and the second signal respectively to obtain the first low frequency and the first amplitude corresponding to the first signal, and the second low frequency and the second amplitude corresponding to the second signal;

[0163] The receiver 630 is also used to verify the first signal based on the first low frequency and the second low frequency when it determines that the first amplitude is greater than the preset amplitude.

[0164] In one possible implementation, the receiver 630 is specifically used to determine whether the difference between the first low frequency and the second low frequency is greater than a preset difference when the first amplitude is greater than a preset amplitude; if the difference between the first low frequency and the second low frequency is greater than the preset difference, the first signal is determined to be invalid; if the difference between the first low frequency and the second low frequency is not greater than the preset difference, the first signal is determined to be valid.

[0165] In one possible implementation, the receiver 630 is further configured to determine whether the second amplitude is within a preset amplitude range; if the second amplitude is within the preset amplitude range, the second signal is determined to be valid; if the second amplitude is within the preset amplitude range, the second signal is determined to be invalid.

[0166] Specifically, receiver 630 is used to verify the first signal based on the first low frequency and the second low frequency when it is determined that the second signal is valid and the first amplitude is greater than the preset amplitude.

[0167] In one possible implementation, the transmitter 610 is specifically used to perform frequency shift keying (FSK) modulation on the first carrier signal with a modulation signal at the target modulation frequency to form a first signal corresponding to the first carrier signal, and to perform minimum frequency shift keying (MSK) modulation on the second carrier signal with a modulation signal at the target modulation frequency to form a second signal corresponding to the second carrier signal.

[0168] In one possible implementation, the transmitter 610 includes a first processor and a second processor.

[0169] A first processor is configured to modulate a first carrier signal with a modulation signal at a target modulation frequency to form a first signal corresponding to the first carrier signal.

[0170] The second processor is used to modulate the second carrier signal with a modulation signal at the target modulation frequency to form a second signal corresponding to the second carrier signal.

[0171] In one possible implementation, the transmitter 610 further includes a signal conversion device, a power amplifier, a first AND gate, and a second AND gate.

[0172] The first processor is also used to transmit the first signal to the second processor; the second processor is also used to transmit the second signal to the first processor.

[0173] The first processor is further configured to verify the carrier frequency and modulation frequency of the second signal to obtain a first verification result; the second processor is further configured to verify the carrier frequency and modulation frequency of the first signal to obtain a second verification result.

[0174] A first AND gate is used to activate the transmission channel when both the first and second test results are passed, so as to transmit the first and second signals to the signal conversion device.

[0175] A signal conversion device is used to convert a first signal and a second signal from a square wave to a sine wave; to transmit the converted second signal to a first processor and to transmit the first signal to a power amplifier.

[0176] A power amplifier is used to amplify the power of the first signal before transmitting it to the second processor.

[0177] The first processor is also used to verify the amplitude of the second signal to obtain a third verification result; the second processor is also used to verify the amplitude of the first signal to obtain a fourth verification result.

[0178] The second AND gate is used to activate the transmission channel when both the third and fourth test results are passed, so that the first signal is transmitted to the receiver 630 via track 620, and the second signal is directly transmitted to the receiver 630.

[0179] This application provides a track circuit system, including: a transmitter 610, used to modulate a first carrier signal and a second carrier signal with a modulation signal at a target modulation frequency, forming a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal; the transmitter 610 is also used to transmit the first signal to a receiver 630 via a track 620, and directly transmit the second signal to the receiver 630; the receiver 630 is used to demodulate the first signal and the second signal, respectively, to obtain a first low frequency and a first amplitude corresponding to the first signal, and a second low frequency and a second amplitude corresponding to the second signal; the receiver 630 is also used to verify the first signal based on the first low frequency and the second low frequency when the first amplitude is greater than a preset amplitude. This adds a verification channel directly from the transmitter to the receiver, thereby increasing the verification mechanism of the second signal against the first signal, improving the anti-interference capability of the track circuit system, ensuring the stability and reliability of the track circuit system, and avoiding the impact of interference signals on the normal operation of the track circuit system. Furthermore, it avoids serious safety problems caused by the influence of interference signals on the track circuit system.

[0180] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for the method and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiments. The method and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components indicated as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of the solution in this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0181] The above description is merely one specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for verifying transmitted signals, characterized in that, Applied to a track circuit system, the track circuit system comprising: a transmitter, a track, and a receiver, the method comprising: The transmitter modulates the first carrier signal and the second carrier signal with a modulation signal of the target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal; The transmitter transmits the first signal to the receiver via the track, and transmits the second signal directly to the receiver; The receiver demodulates the first signal and the second signal respectively to obtain the first low frequency and the first amplitude corresponding to the first signal, and the second low frequency and the second amplitude corresponding to the second signal; When the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency.

2. The method according to claim 1, characterized in that, When the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency, including: When the receiver determines that the first amplitude is greater than the preset amplitude, it determines whether the difference between the first low frequency and the second low frequency is greater than the preset difference. If the difference between the first low frequency and the second low frequency is greater than a preset difference, then the first signal is determined to be invalid. If the difference between the first low frequency and the second low frequency is not greater than a preset difference, then the first signal is determined to be valid.

3. The method according to claim 2, characterized in that, The preset difference is determined based on the target modulation frequency and the preset range.

4. The method according to claim 1, characterized in that, Before verifying the first signal based on the first low frequency and the second low frequency when the receiver determines that the first amplitude is greater than a preset amplitude, the method further includes: The receiver determines whether the second amplitude is within a preset amplitude range; if the second amplitude is within the preset amplitude range, the second signal is determined to be valid; if the second amplitude is within the preset amplitude range, the second signal is determined to be invalid. When the receiver determines that the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency, including: When the receiver determines that the second signal is valid and the first amplitude is greater than a preset amplitude, it verifies the first signal based on the first low frequency and the second low frequency.

5. The method according to claim 1, characterized in that, The transmitter modulates the first carrier signal and the second carrier signal with a modulation signal at the target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal, including: The transmitter performs frequency shift keying (FSK) modulation on the first carrier signal using a modulation signal at the target modulation frequency to form a first signal corresponding to the first carrier signal, and performs minimum frequency shift keying (MSK) modulation on the second carrier signal using the modulation signal at the target modulation frequency to form a second signal corresponding to the second carrier signal.

6. The method according to claim 1, characterized in that, The transmitter includes: a first processor and a second processor; the transmitter modulates a first carrier signal and a second carrier signal with a modulation signal at a target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal, including: The first processor modulates the first carrier signal with a modulation signal at the target modulation frequency to form a first signal corresponding to the first carrier signal; The second processor modulates the second carrier signal with the modulation signal of the target modulation frequency to form a second signal corresponding to the second carrier signal.

7. The method according to claim 6, characterized in that, The transmitter further includes: a signal conversion device, a power amplifier, a first AND gate, and a second AND gate; the transmitter transmits the first signal to the receiver via the track, and directly transmits the second signal to the receiver, including: The first processor transmits the first signal to the second processor, and the second processor transmits the second signal to the first processor; The first processor checks the carrier frequency and modulation frequency of the second signal to obtain a first check result, and the second processor checks the carrier frequency and modulation frequency of the first signal to obtain a second check result; When both the first and second test results are passed, the first AND gate conducts the transmission channel, so that the first processor transmits the first signal to the signal conversion device and the second processor transmits the second signal to the signal conversion device. The signal conversion device converts the first signal and the second signal from square waves to sine waves; the signal conversion device transmits the converted second signal to the first processor and the first signal to the power amplifier, so that the power amplifier can amplify the first signal and then transmit it to the second processor; The first processor checks the amplitude of the second signal to obtain a third check result, and the second processor checks the amplitude of the first signal to obtain a fourth check result; When both the third and fourth test results are passed, the second AND gate conducts the transmission channel, so that the power amplifier transmits the first signal to the receiver through the track, and the signal conversion device transmits the second signal directly to the receiver.

8. The method according to claim 7, characterized in that, The method further includes: If neither the first test result nor the second test result is passed, the first AND gate disconnects the transmission channel. If neither the third nor the fourth test result is passed, the second AND gate will disconnect the transmission channel.

9. The method according to claim 1, characterized in that, The receiver demodulates the first signal and the second signal respectively to obtain a first low frequency and a first amplitude corresponding to the first signal, and a second low frequency and a second amplitude corresponding to the second signal, including: The receiver demodulates the first signal and the second signal respectively, and uses windowed interpolation fast Fourier transform to analyze and obtain the first low frequency and first amplitude corresponding to the first signal, and the second low frequency and second amplitude corresponding to the second signal.

10. A track circuit system, characterized in that, include: A transmitter, a track, and a receiver; the transmitter is connected to the track, the receiver is connected to the track, and the transmitter is also connected to the receiver; The transmitter is used to modulate the first carrier signal and the second carrier signal with a modulation signal of the target modulation frequency, respectively, to form a first signal corresponding to the first carrier signal and a second signal corresponding to the second carrier signal; The transmitter is also configured to transmit the first signal to the receiver via the track, and to transmit the second signal directly to the receiver; The receiver is configured to demodulate the first signal and the second signal respectively to obtain a first low frequency and a first amplitude corresponding to the first signal, and a second low frequency and a second amplitude corresponding to the second signal; The receiver is further configured to verify the first signal based on the first low frequency and the second low frequency when it determines that the first amplitude is greater than a preset amplitude.

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