Mls channel delay time comparison calibration method, apparatus, medium, and device

Abstract

This application discloses an MLS channel delay time comparison and calibration method, apparatus, medium, and device. The method includes: measuring the round-trip propagation delay of a signal through bidirectional pulse interaction to complete the preliminary calibration of the relative delay between devices; based on the preliminary calibration, extracting the delay characteristics of the pulse signal within the channel using envelope signal analysis; demodulating the intermediate frequency signal based on the extracted delay characteristics to obtain the propagation delay in pseudocode ranging; introducing delay control based on the demodulation result to evaluate the delay error of the receiving channel and perform dynamic correction; and generating a standard intermediate frequency signal based on the corrected delay error to perform delay calibration of the MLS channel. This application can achieve accurate calibration of the MLS channel delay.

Description

Technical Field

[0001] This application belongs to the field of communication technology, specifically relating to MLS channel delay time comparison calibration methods, apparatus, media and equipment. Background Technology

[0002] Current microwave landing systems (MLS) generally employ static calibration methods for channel delay calibration. These methods suffer from insufficient accuracy, sensitivity to environmental changes, and the inability to achieve real-time dynamic correction in practical operation. Especially in high-precision navigation, complex electromagnetic environments, or highly dynamic flight platform applications, traditional solutions struggle to meet the system's requirements for high-precision, low-error delay calibration. Therefore, a dynamic and adaptive channel delay calibration technique is urgently needed to improve the accuracy of signal propagation time measurement and the overall system stability. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this application is to provide an MLS channel delay time comparison calibration method, apparatus, medium and equipment, which aims to achieve more accurate and robust MLS channel delay calibration capabilities.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] A method for comparing and calibrating the delay time of an MLS channel includes: measuring the round-trip propagation delay of a signal through bidirectional pulse interaction to achieve preliminary calibration of the relative delay between devices; based on the preliminary calibration, extracting the delay characteristics of the pulse signal within the channel using envelope signal analysis; demodulating the intermediate frequency signal based on the extracted delay characteristics to obtain the propagation delay in pseudocode ranging; introducing delay control based on the demodulation results to evaluate and dynamically correct the delay error of the receiving channel; and generating a standard intermediate frequency signal based on the corrected delay error to perform delay calibration on the MLS channel.

[0006] Optionally, the preliminary calibration of the relative time delay between devices by measuring the round-trip propagation delay of the bidirectional pulse signal includes: the airborne equipment transmitting an interrogation pulse signal to the ground beacon to initiate the time delay measurement; after receiving the interrogation pulse signal, the ground beacon sends a response pulse after a preset delay; the airborne equipment receives the response pulse and calculates the round-trip propagation delay of the bidirectional pulse signal; and the clock synchronization between the airborne equipment and the ground beacon is calibrated using the round-trip propagation delay of the bidirectional pulse signal to complete the calibration between the two.

[0007] Optionally, the step of extracting the time delay characteristics of the pulse signal in the channel by analyzing the envelope signal based on the preliminary calibration includes: after the preliminary calibration is completed, collecting the envelope information of the pulse signal to identify the effective pulse characteristics; setting a time gate to lock the signal time window to accurately capture the pulse edge; generating a double pulse signal based on the comparison results of the signal strength within the gate; and extracting the propagation time delay parameters in the channel based on the double pulse signal.

[0008] Optionally, the step of demodulating the intermediate frequency signal based on the extracted time delay features to obtain the propagation delay in pseudo-code ranging includes: converting the intermediate frequency signal to the radio frequency band and performing low-noise amplification processing; downconverting the received radio frequency signal back to the intermediate frequency and sampling it; demodulating the sampled signal using an adaptive DPSK algorithm based on the intermediate frequency sampled signal and the envelope signal to obtain the pseudo-code ranging signal; and extracting the propagation delay based on the pseudo-code ranging signal.

[0009] Optionally, the delay control based on demodulation results, which evaluates and dynamically corrects the delay error of the receiving channel, includes: introducing a controllable delay path in the receiving channel to adjust the system response based on the extracted propagation delay; adjusting the attenuation of the pilot pulse to match the reference signal; measuring the actual delay time of each frequency point in the receiving channel and recording the measurement data; performing root mean square error statistics on the delay values ​​of each frequency point, and combining the clock error calculation results to complete the dynamic correction of the device delay error.

[0010] Optionally, the step of generating a standard intermediate frequency signal based on the corrected delay error and performing delay calibration includes: converting the corrected DME / P digital intermediate frequency signal into an analog intermediate frequency signal; generating a standard-compliant DME / P analog intermediate frequency signal waveform; performing dynamic adjustment and verification of delay control based on the standard signal; and completing the final calibration of the MLS channel delay time through synchronous comparison and sampling judgment with the reference signal.

[0011] This application also provides an MLS channel delay time comparison and calibration device, the device comprising: a calibration module for measuring the round-trip propagation delay of a signal through bidirectional pulse interaction to complete the preliminary calibration of the relative delay between devices; an extraction module for extracting the delay characteristics of the pulse signal within the channel based on the preliminary calibration using envelope signal analysis; a demodulation module for demodulating the intermediate frequency signal based on the extracted delay characteristics to obtain the propagation delay in pseudocode ranging; an evaluation module for introducing delay control based on the demodulation results to evaluate the delay error of the receiving channel and perform dynamic correction; and a calibration module for generating a standard intermediate frequency signal based on the corrected delay error to perform delay calibration on the MLS channel.

[0012] This application also provides a storage medium including instructions that, when executed on a computer, cause the computer to perform the method as described in the preceding claim.

[0013] This application also provides an electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method as described in any of the preceding claims.

[0014] Compared with the prior art, the beneficial effects of this application are as follows:

[0015] This application achieves precise calibration of MLS channel delay through bidirectional pulse interaction, envelope signal analysis, intermediate frequency signal demodulation, and dynamic delay control mechanisms. This application can improve the accuracy of inter-device delay calibration, accurately extract the delay characteristics of pulse signals within the channel, and dynamically correct the delay error of the receiving channel, thereby optimizing signal propagation delay measurement. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating an MLS channel delay time comparison and calibration method according to an embodiment of this application;

[0017] Figure 2 This is a schematic diagram of the structure of an MLS channel delay time comparison and calibration device provided in another embodiment of this application. Detailed Implementation

[0018] Specific embodiments of this application will now be described in detail with reference to the accompanying drawings. While specific embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0019] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0020] To facilitate understanding of the embodiments of this application, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of this application.

[0021] Figure 1 This is a flowchart illustrating an exemplary embodiment of an MLS channel delay time comparison and calibration method provided in this application, as shown below. Figure 1 As shown, the method includes the following steps:

[0022] S100: The round-trip propagation delay of the signal is measured by bidirectional pulse interaction to complete the preliminary calibration of the relative time delay between devices;

[0023] S200: Based on the initial calibration, the time delay characteristics of pulses within the channel are extracted using envelope signal analysis;

[0024] S300: Based on the extracted time delay features, the intermediate frequency signal is demodulated to obtain the propagation time delay in pseudo-code ranging;

[0025] S400: Introduces a delay control mechanism based on propagation delay to evaluate the delay error of the receiving channel and make dynamic corrections;

[0026] S500: Generates a standard intermediate frequency signal based on the corrected delay error to perform delay calibration on the MLS channel.

[0027] In another exemplary embodiment, step S100, which involves measuring the round-trip propagation delay of the signal via bidirectional pulse interaction to complete the preliminary calibration of the relative time delay between devices, includes the following steps:

[0028] S101: The airborne equipment transmits an interrogation pulse signal to the ground beacon station to initiate time delay measurement;

[0029] S102: After receiving the interrogation pulse signal, the ground beacon station sends out a response pulse after a preset delay (e.g., within 5ms);

[0030] S103: The airborne equipment receives the response pulse and calculates the round-trip propagation delay of the bidirectional pulse signal, wherein the round-trip propagation delay is calculated as follows:

[0031]

[0032] in, Indicates the pulse round-trip time delay; Indicates the distance between the airborne equipment and the ground beacon station; This indicates the speed at which electromagnetic waves propagate through the air.

[0033] S104: The clock synchronization between the airborne equipment and the ground beacon is calibrated by measuring the round-trip propagation delay of the bidirectional pulse signal, thus completing the calibration between the two. The clock synchronization between the airborne equipment and the ground beacon is calibrated using the following formula:

[0034]

[0035] in, This indicates the clock discrepancy between the two locations. Indicates the round-trip propagation delay of the pulse. This indicates the transmission timestamp of the interrogation pulse signal sent by the airborne equipment to the ground beacon station. This indicates the timestamp of when the airborne equipment received the response signal from the ground beacon.

[0036] In another exemplary embodiment, step S200, based on the preliminary calibration, involves extracting the time delay characteristics of the pulse signal within the channel using envelope signal analysis, which includes the following steps:

[0037] S201: After the initial calibration is completed, the envelope information of the pulse signal is collected to identify the characteristics of the effective pulse;

[0038] In this step, the envelope information of the pulse signal includes, for example, amplitude envelope, time domain envelope and frequency domain envelope, and the effective pulse characteristics include time domain characteristics (e.g., pulse duration, pulse width, pulse position), frequency domain characteristics (e.g., spectral bandwidth, frequency center, spectral flatness) and modulation characteristics (e.g., modulation type, modulation depth, modulation period).

[0039] S202: Set the time window for locking the signal with a time gate to accurately capture the pulse edge;

[0040] In this step, the setting time gate locking signal time window specifically includes the following steps:

[0041] Step 1: Based on the current position, speed, and heading of the flight platform, estimate the distance between the aircraft and the ground beacon (this can be obtained through known positioning systems or navigation information).

[0042] Step 2: Based on the estimated distance, calculate the round-trip propagation time of the signal from the aircraft to the ground beacon station. The specific calculation is shown in step S103.

[0043] Step 3: Fixed delay time based on ground beacon station The total propagation delay of the signal is obtained by calculating the pulse round-trip time delay from the aircraft to the ground beacon. :

[0044]

[0045] in, This indicates the pulse round-trip time delay.

[0046] Step 4: Set the initial time gate window;

[0047] In this step, a time window is set, which is based on the theoretical time delay and the fixed delay time of the ground beacon station, and the initial time window is determined by the following formula:

[0048]

[0049] in, Indicates the initial time window. Indicates the total propagation delay. Indicates the time offset.

[0050] Step 5: Dynamically adjust the time gate window based on the difference between the actual received signal time and the theoretical delay, as well as the change in the distance between the aircraft and the ground beacon.

[0051] In this step, the actual arrival time is first calculated using the received pulse signal. ;

[0052] Secondly, calculate the total propagation delay. and actual arrival time Differences between :

[0053]

[0054] Finally, based on the differences Dynamically adjust the initial time window To ensure that it is consistent with the actual arrival time Consistency:

[0055]

[0056] It should be noted that the signal propagation delay changes as the distance between the aircraft and the ground beacon changes. Therefore, the time window needs to be dynamically adjusted continuously based on the actual reception time and distance changes to ensure accurate capture of the pulse signal.

[0057] S203: Generate a double pulse signal based on the comparison results of the signal strength inside the gate;

[0058] In this step, the process of generating a dual-pulse signal involves identifying two critical edges of the signal by comparing the signal strength within a gate. First, based on the signal envelope information, a valid pulse signal is captured within a set time gate. Then, by comparing the signal strength changes, the rising and falling edges of the signal are identified, each corresponding to one of the two pulses. By analyzing the amplitude changes and time characteristics of the signal, two pulse signals are generated, typically one positive pulse (rising edge) and the other a negative pulse (falling edge). The dual-pulse signal provides a crucial time-domain reference for subsequent extraction of time delay parameters, enabling: first, the elimination of errors introduced by single-pulse jitter or distortion through time difference analysis of the dual-pulse edges, improving the measurement accuracy of propagation delay to sub-nanosecond levels; second, the time delay parameters based on the dual pulses can quantify the group delay variation of the channel for different frequency signals (such as dispersion effects), providing input for dynamic compensation algorithms (such as adaptive equalizers) and eliminating nonlinear distortion in broadband signal transmission; and third, it can reduce the number of retransmissions of redundant signals, lower the power consumption of the RF front-end, and simultaneously maintain ranging reliability.

[0059] S204: Extract the propagation delay parameters in the channel based on the dual-pulse signal.

[0060] In this step, based on the envelope extraction characteristics of the pulse signal, two key time points—the rising edge and the falling edge—are first identified, corresponding to the start and end characteristics of the dual-pulse signal, respectively. By capturing these two edges, the precise arrival time of each pulse at the receiver can be obtained. Subsequently, the time difference between these two pulses is calculated, thereby estimating the actual propagation delay of the signal in the channel. This propagation delay not only reflects the path characteristics of the signal from the transmitter to the receiver but also reveals propagation effects such as dispersion or nonlinear distortion that may exist in the channel. Through repeated measurements and statistical analysis of the above propagation delay parameters, the stable propagation delay of the channel can be effectively extracted, and delay error compensation and calibration can be carried out accordingly, thereby significantly improving the accuracy of delay measurement and system synchronization performance.

[0061] In another exemplary embodiment, step S300, which involves demodulating the intermediate frequency signal based on the extracted time delay features to obtain the propagation time delay in pseudo-code ranging, includes the following steps:

[0062] S301: Converts the intermediate frequency signal to the radio frequency band and performs low-noise amplification;

[0063] In this step, low-noise amplification is achieved by selecting gallium arsenide (GaAs) process chips to provide high gain and low noise characteristics. A common-emitter amplification structure is employed to ensure high signal gain and stability. Simultaneously, an LC filter circuit is used to achieve input impedance matching, reduce signal reflection loss, and improve signal transmission efficiency. Furthermore, a metal shield is used to isolate external electromagnetic interference, further reducing noise impact and ensuring a high signal-to-noise ratio during amplification, providing a clear and stable signal for subsequent processing.

[0064] S302: The received radio frequency signal is down-converted back to intermediate frequency and sampled by the baseband system;

[0065] In this step, the received RF signal is down-converted back to the intermediate frequency (IF) by multiplying the RF signal with the local oscillator signal using a mixer to generate a difference frequency signal. The frequency resulting from this difference is typically chosen as the IF signal. This process not only helps reduce the signal frequency, facilitating subsequent processing, but also reduces the complexity of high-frequency signal processing. During down-conversion, the signal undergoes low-noise amplification to ensure the signal amplitude is suitable for processing. Next, the down-converted IF signal is sampled, i.e., converted from a continuous analog signal to a discrete digital signal using an analog-to-digital converter (ADC) for digital processing and analysis. The sampling process typically follows the Nyquist sampling theorem to ensure a sufficiently high sampling frequency to avoid aliasing and maintain signal integrity.

[0066] S303: Based on the intermediate frequency sampling signal and the envelope signal, the adaptive DPSK algorithm is used to demodulate the sampling signal to obtain the pseudo-code ranging signal;

[0067] In this step, this embodiment uses an adaptive differential phase keying (DPSK) algorithm for demodulation based on the intermediate frequency (IF) sampled signal and the envelope signal to extract the pseudo-code ranging signal. First, a high-resolution digital signal is obtained by synchronously sampling the IF signal and the envelope signal. Then, the adaptive DPSK algorithm begins operation, utilizing its key feature of demodulating the signal by detecting phase changes between adjacent symbols. Unlike traditional phase demodulation methods, adaptive DPSK can dynamically adjust the decision threshold to cope with noise and interference in the signal, maintaining high-precision demodulation performance. During this process, the algorithm calculates the phase change of each symbol based on the phase difference between the received signal and a preset reference signal, thereby obtaining pseudo-code ranging information. The pseudo-code ranging signal is obtained by calculating the phase difference between adjacent symbols in the signal; it represents the time delay of signal propagation and can accurately provide distance information between the target and the signal source. Furthermore, the adaptive DPSK algorithm continuously optimizes phase determination to adapt to different channel conditions, effectively improving the robustness and accuracy of demodulation, especially ensuring a low bit error rate in environments with high noise or severe signal attenuation.

[0068] S304: Extracting propagation delay based on pseudocode ranging signal.

[0069] In this step, during the extraction of propagation delay from the pseudo-code ranging signal, it is first necessary to generate a pseudo-random noise (PN) code consistent with the beacon station according to the communication protocol. The PN code is a signal sequence with good autocorrelation properties and a known timing sequence, used to identify time points in the received signal to help accurately measure the propagation delay.

[0070] Next, the length of the sliding correlation window is set. This window determines the time range of the signal correlation operation, ensuring that enough signal cycles are captured within a certain time window for accurate calculation. By sliding the correlation window, the signal can be progressively multiplied bit by bit with the received pseudo-code ranging signal and accumulated to produce a correlation value. The purpose of this process is to find the maximum matching degree between the signal and the locally generated PN code, thereby determining the signal propagation delay.

[0071] After obtaining the initial correlation values, adaptive step size adjustment is performed. Adaptive step size adjustment dynamically adjusts the search step size within the correlation window based on signal quality and noise level, optimizing search accuracy and speed. This process avoids local errors that may arise from a fixed step size and adapts to different signal conditions.

[0072] Next, a dynamic threshold is set to ensure the stability of the correlation process. The dynamic threshold is adjusted in real time according to changes in the signal to avoid the influence of noise on the results. When the correlation value reaches its maximum, the peak phase of the signal can be determined. At this point, the system locks the peak phase and enters tracking mode.

[0073] Upon entering tracking mode, a phase-locked loop (PLL) is used to maintain PN code synchronization. The PLL continuously adjusts the phase of the local PN code generator to keep it synchronized with the received signal, thereby eliminating timing deviations caused by signal propagation delays. Error signals are fed back to the local PN code generator through the PLL, automatically adjusting its phase to ensure that the locally generated PN code maintains the same phase as the received signal.

[0074] In the above process, the phase-locked loop (PLL) can not only compensate for the time delay error caused by signal propagation, but also adapt to the relative time delay changes caused by aircraft motion or platform changes. By dynamically adjusting the phase, the PLL enables the system to adapt to different channel conditions and motion states in real time, providing high-precision pseudocode ranging and propagation delay measurement.

[0075] In another exemplary embodiment, step S400, which introduces a delay control mechanism based on the demodulation result to evaluate the delay error of the receiving channel and perform dynamic correction, includes the following steps:

[0076] S401: Based on the extracted propagation delay, a controllable delay path is introduced in the receiving channel to adjust the system response;

[0077] In this step, the difference in propagation delay between the received signal and the reference signal is first determined by analyzing the extracted propagation delay. Then, a controllable delay path is introduced into the receiving channel to adjust the system's response time. This delay path is implemented using an adjustable time delay element (such as a digital delay line or delay adjustment circuit), which can precisely adjust the signal transmission timing based on the measured propagation delay. By adjusting this delay path, the timing of the received signal can be better matched with the reference signal, thereby optimizing the overall system delay performance and response speed. At this point, by dynamically adjusting the delay path, the system can adapt to different propagation conditions and channel delay variations, ensuring signal synchronization and system stability.

[0078] S402: Adjusts the attenuation of the pilot pulse in real time to match the reference signal;

[0079] In this step, the system adjusts the attenuation of the pilot pulse in real time to ensure that the signal amplitude matches the reference signal. To maintain signal quality and stability, an automatic gain control (AGC) circuit is typically used to adjust the signal attenuation. When the received signal amplitude is weak, the AGC circuit automatically increases the gain to ensure that the signal strength is sufficient for subsequent processing; conversely, when the signal strength is high, the AGC circuit decreases the gain to prevent signal oversaturation or distortion. Through this dynamic adjustment, the AGC circuit enables the system to maintain good signal quality and stable amplitude under different signal strength conditions. This real-time adjustment process helps reduce errors caused by signal fluctuations or noise, ensuring accurate amplitude and timing matching between the signal and the reference signal.

[0080] S403: Measure the actual delay time of each frequency point in the receiving channel and record the measurement data;

[0081] In this step, the system performs detailed time delay measurements for each received frequency point. By analyzing the propagation delay of signals at different frequencies in the receiving channel, the system can accurately determine the actual delay time of each frequency point. Specifically, the signal is analyzed at the receiving end and compared with a reference signal to calculate the actual time delay of each frequency point. During the measurement process, the system takes into account the propagation characteristics of each frequency, as signals of different frequencies may have different propagation delays in the channel. The measurement results are recorded, generating corresponding delay data. This measurement data will be used for subsequent time delay calibration and system optimization to ensure accurate signal synchronization and provide a basis for dynamically correcting time delay errors in the system.

[0082] S404: Perform root mean square error (RMSE) statistics on the delay values ​​at each frequency point. Based on the statistical results, dynamically correct the equipment delay error. Specifically, the RMS error can be calculated using the following formula:

[0083]

[0084] in, This represents the measured delay values ​​at each frequency point; This indicates the reference delay value for each frequency point.

[0085] In another exemplary embodiment, step S500, generating a standard intermediate frequency signal based on the corrected delay error to perform delay calibration on the MLS channel, includes the following steps:

[0086] S501: Converts the corrected DME / P digital intermediate frequency signal into an analog intermediate frequency signal;

[0087] This step first requires converting the corrected DME / P digital intermediate frequency (IF) signal into an analog IF signal. Since digital signals are suitable for computer processing, while analog signals are suitable for practical radio frequency (RF) transmission, a digital-to-analog converter (DAC) is needed to convert the digital IF signal into a continuous analog signal. The conversion process must ensure that the signal waveform is not distorted and that its frequency and amplitude meet the required standards. During the conversion, the DAC generates a corresponding analog voltage output based on the input digital data. Through filtering and amplification, the analog signal is ensured to meet system requirements in terms of signal quality, spectral characteristics, and power level. The goal of this step is to provide a suitable analog IF signal for subsequent signal conditioning and calibration, ensuring stable signal transmission in the actual communication link.

[0088] S502: Generates DME / P analog intermediate frequency signal waveforms that conform to standards;

[0089] In this step, the system generates a conforming analog intermediate frequency (IF) signal waveform according to the standard DME / P signal waveform requirements. A DME / P signal is a specific type of ranging signal with predetermined spectral characteristics, modulation schemes, and timing requirements. When generating this waveform, the system processes the signal using appropriate modulation techniques (such as amplitude modulation and frequency modulation) according to the standards specified in the DME / P protocol to ensure the accuracy of the signal waveform. The generated waveform simulates the characteristics of an actual DME / P signal, such as symbol period, modulation scheme, and bandwidth, to ensure compatibility with other devices and systems. This process also ensures that the signal amplitude and frequency conform to the standard, avoiding signal waveform distortion or deviation, thereby enabling the signal to be correctly identified and subsequent calibration and synchronization to be performed.

[0090] S503: Dynamic adjustment and verification of delay control based on standard signals;

[0091] In this step, the system achieves dynamic adjustment and verification of delay control through the following closed-loop mechanism:

[0092] First, the generated DME / P analog intermediate frequency signal and the ideal reference signal are sampled synchronously, and the time delay deviation between the two is calculated using a cross-correlation algorithm. The calculation formula is:

[0093]

[0094] in, Indicates the generation of a signal; This represents the reference signal.

[0095] Secondly, based on time delay deviation Real-time update delay control :

[0096]

[0097] in, Indicates the previous time step Delay control, Indicates the current time step. and This represents the adjustable gain coefficient.

[0098] Next, threshold verification is performed, where if the time delay deviation... If the absolute value exceeds the preset tolerance (e.g., ±5 ns), a warning is triggered and iterative adjustments are made; otherwise, the verification is marked as passed.

[0099] Finally, the above process is executed cyclically by the FPGA hardware (cycle ≤ 1 ms) to ensure that the delay error converges to nanosecond-level accuracy.

[0100] In summary, this application achieves dynamic and precise adjustment of delay control through a closed-loop feedback mechanism, wherein the delay deviation is based on real-time calculation. The system employs a proportional-integral (PI) control algorithm to iteratively update delay control. Furthermore, combined with real-time verification and threshold criteria accelerated by FPGA hardware, the delay error can be rapidly converged to nanosecond-level accuracy. The above mechanisms are as follows: First, the PPI control algorithm automatically compensates for the time-varying characteristics of the channel, addressing the environmental sensitivity of traditional static calibration. Second, the integral term suppresses steady-state errors, while the proportional term accelerates the response, ensuring that errors do not diverge under extreme conditions. Third, the hardware closed-loop achieves microsecond-level response speeds, meeting the real-time requirements of MLS systems in highly dynamic flight scenarios. Ultimately, this improves signal transmission synchronization accuracy by an order of magnitude, providing a reliable delay benchmark for pseudocode ranging.

[0101] S504: The final calibration of the MLS channel delay time is completed by synchronous comparison and sampling judgment with the reference signal.

[0102] In this step, the system completes the final calibration of the DME / P channel delay time through synchronous comparison and sampling with a reference signal. First, the system synchronously compares the generated DME / P signal with a known reference signal to confirm their timing alignment. During the comparison, the system meticulously measures the signal's phase and time delay, determining the delay difference between the two. Through precise signal sampling and analysis, the system can capture delay deviations during signal transmission and correct them accordingly. After the comparison is complete, the system adjusts the signal's delay parameters to ensure that the received DME / P signal is completely synchronized with the reference signal. Ultimately, through this calibration process, the system eliminates delay errors caused by channel, hardware, or other factors, ensuring that the propagation delay of the DME / P signal meets standard requirements and providing a reliable delay reference for accurate signal ranging.

[0103] In another exemplary embodiment, this application also provides an MLS channel delay time comparison and calibration apparatus, such as... Figure 2 As shown, the device includes: a calibration module 100, used to perform preliminary calibration of the relative time delay between devices by measuring the round-trip propagation delay of the signal through bidirectional pulse interaction; an extraction module 200, used to extract the time delay characteristics of the pulse signal in the channel by using envelope signal analysis based on the preliminary calibration; a demodulation module 300, used to demodulate the intermediate frequency signal based on the extracted time delay characteristics to obtain the propagation delay in pseudocode ranging; an evaluation module 400, used to introduce delay control based on the demodulation results, evaluate the time delay error of the receiving channel and perform dynamic correction; and a calibration module 500, used to generate a standard intermediate frequency signal based on the corrected time delay error to perform delay calibration on the MLS channel.

[0104] In another exemplary embodiment, this application also provides a storage medium including instructions that, when executed on a computer, cause the computer to perform the method as described in the preceding embodiment.

[0105] In another exemplary embodiment, this application also provides an electronic device, the electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method as described in any of the preceding embodiments.

[0106] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using 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 method for comparing and calibrating MLS channel delay time, characterized in that, The method includes: By measuring the round-trip propagation delay of signals through bidirectional pulse interaction, the preliminary calibration of the relative time delay between devices is completed; Based on the initial calibration, the time delay characteristics of the pulse signal within the channel are extracted using envelope signal analysis; Based on the extracted time delay features, the intermediate frequency signal is demodulated to obtain the propagation time delay in pseudocode ranging; Delay control is introduced based on the demodulation results to evaluate and dynamically correct the delay error of the receiving channel, including: Based on the extracted propagation delay, a controllable delay path is introduced in the receiving channel to adjust the system response; Adjust the attenuation of the pilot pulse to match the reference signal; Measure the actual delay time of each frequency point in the receiving channel and record the measurement data; The mean square error of the delay value at each frequency point is statistically analyzed, and the dynamic correction of the equipment delay error is completed based on the statistical results. Based on the corrected delay error, a standard intermediate frequency signal is generated to perform delay calibration on the MLS channel.

2. The method according to claim 1, characterized in that, The preliminary calibration of the relative time delay between devices is achieved by measuring the round-trip propagation delay of the signal through bidirectional pulse interaction, including: The airborne equipment transmits an interrogation pulse signal to the ground beacon to initiate time delay measurement; After receiving the interrogation pulse signal, the ground beacon station sends out a response pulse after a preset delay; The airborne equipment receives the response pulse and calculates the round-trip propagation delay of the two-way pulse signal; The clock synchronization between airborne equipment and ground beacon stations is calibrated by measuring the round-trip propagation delay of bidirectional pulse signals, thus completing the calibration between the two.

3. The method according to claim 1, characterized in that, Based on the initial calibration, the extraction of time delay characteristics of pulse signals within the channel using envelope signal analysis includes: After the initial calibration is completed, the envelope information of the pulse signal is collected to identify the characteristics of the effective pulse; Set a time gate to lock the signal time window in order to accurately capture the pulse edge; Based on the comparison of signal strength inside the gate, a double pulse signal is generated; The propagation delay parameters in the channel are extracted based on the dual-pulse signal.

4. The method according to claim 1, characterized in that, The step of demodulating the intermediate frequency signal based on the extracted time delay features to obtain the propagation time delay in pseudocode ranging includes: The intermediate frequency signal is converted to the radio frequency band and then amplified with low noise. The received radio frequency signal is down-converted back to intermediate frequency and sampled; Based on the intermediate frequency sampling signal and the envelope signal, the adaptive DPSK algorithm is used to demodulate the sampling signal to obtain the pseudo-code ranging signal; Propagation delay is extracted from pseudocode ranging signals.

5. The method according to claim 1, characterized in that, The process of generating a standard intermediate frequency signal based on the corrected time delay error and performing delay calibration includes: Convert the corrected DME / P digital intermediate frequency signal into an analog intermediate frequency signal; Generate DME / P analog intermediate frequency signal waveforms that conform to standards; Dynamic adjustment and verification of delay control based on standard signals; The final calibration of the MLS channel delay time is completed by synchronous comparison and sampling with the reference signal.

6. An MLS channel delay time comparison and calibration device, characterized in that, The device includes: The calibration module is used to perform preliminary calibration of the relative time delay between devices by measuring the round-trip propagation delay of signals through bidirectional pulse interaction. The extraction module is used to extract the time delay characteristics of the pulse signal in the channel by analyzing the envelope signal based on the initial calibration. The demodulation module is used to demodulate the intermediate frequency signal based on the extracted time delay features to obtain the propagation time delay in pseudocode ranging; The evaluation module, used to introduce delay control based on the demodulation results, evaluates the delay error of the receiving channel and performs dynamic correction, including: Based on the extracted propagation delay, a controllable delay path is introduced in the receiving channel to adjust the system response; Adjust the attenuation of the pilot pulse to match the reference signal; Measure the actual delay time of each frequency point in the receiving channel and record the measurement data; The mean square error of the delay value at each frequency point is statistically analyzed, and the dynamic correction of the equipment delay error is completed based on the statistical results. The calibration module generates a standard intermediate frequency signal based on the corrected delay error to perform delay calibration on the MLS channel.

7. A storage medium, characterized in that, It includes instructions that, when executed on a computer, cause the computer to perform the method described in any one of claims 1 to 5.

8. An electronic device, characterized in that, The electronic device includes: Memory, processor, and computer programs stored in memory and executable on the processor, wherein, When the processor executes the program, it implements the method as described in any one of claims 1 to 5.

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