Time domain reflection compensation design method for high-frequency signal transmission loss

Abstract

The invention relates to the technical field of high-frequency multichannel synchronous transmission, in particular to a time domain reflection compensation design method for high-frequency signal transmission loss, which comprises the following steps of: 1, responding to a synchronous trigger signal to generate an active reflection reference signal with a determined time domain position; 2, aligning time marks between channels through cross-correlation operation; 3, extracting a reflection feature template of the channel from the alignment signal, and recognizing and eliminating crosstalk components through convolution operation with an adjacent channel template; 4, constructing a time-varying transfer function model according to the amplitude envelope attenuation characteristic and the carrier phase jump characteristic of the reflection characteristic template; and 5, generating a compensation filter based on the time-varying transfer function model, and verifying the compensation effect through secondary reflection. Through cross-correlation operation, accurate alignment of multi-channel signal time scales is realized, the time delay difference between different transmission channels is overcome, signal synchronization of each channel is ensured, and the beam forming precision is improved.

Description

Technical Field

[0001] This invention relates to the field of high-frequency multi-channel synchronous transmission technology, and in particular to a time-domain reflection compensation design method for high-frequency signal transmission loss. Background Technology

[0002] In high-frequency signal transmission (especially multi-channel antenna arrays for 5G / 6G communication base stations and millimeter-wave radar systems), signal integrity is severely affected by transmission loss and reflection interference. Traditional technologies mainly suffer from the following drawbacks:

[0003] Existing frequency domain compensation methods (such as S-parameter equalization and frequency domain filters) rely on Fourier transform to convert signals to the frequency domain for processing, but they cannot solve the multi-channel delay deviation caused by differences in physical transmission line lengths. For example, in a 64-channel phased array antenna, the difference in transmission line length between channels can reach the centimeter level (due to PCB wiring space constraints), resulting in a delay difference of tens of picoseconds at high frequencies (>24GHz). This delay manifests as a linear phase shift in the frequency domain, but frequency domain equalization can only compensate for a fixed phase difference and cannot correct the nonlinear effect of the delay itself. This leads to misalignment of signals in the time domain during beamforming, resulting in beam pointing distortion (measured sidelobe level deterioration >3dB).

[0004] Furthermore, in high-frequency environments (such as the millimeter-wave band), the electromagnetic coupling effect between adjacent transmission channels is significantly enhanced. When a signal is reflected at a point of impedance discontinuity in the transmission line (such as a connector or pad), the reflected wave from this channel and the crosstalk reflected wave from the adjacent channel are superimposed in the time domain. Although existing time-domain reflectometers (TDRs) can locate the reflection point, they assume that the reflected signal originates only from this channel and do not establish a separation model for crosstalk reflections from adjacent channels. Experiments show that in dense arrays with channel spacing less than λ / 4, crosstalk from adjacent channels can contribute more than 35% of the total reflected energy, causing traditional single-channel compensation schemes to fail.

[0005] Therefore, there is an urgent need for a time-domain reflection compensation design method for high-frequency signal transmission loss to solve the above problems. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides a time-domain reflection compensation design method for high-frequency signal transmission loss, comprising:

[0007] Step 1: Connect a programmable impedance switching circuit to the end of the high-frequency transmission channel under test, and generate an active reflection reference signal with a defined time domain position in response to the synchronous trigger signal;

[0008] Step 2: Acquire a mixed signal containing active reflection reference signals from multiple channels, and align the time scales between channels through cross-correlation calculation;

[0009] Step 3: Extract the reflection feature template of the current channel from the aligned signal, and identify and remove the crosstalk component through convolution operation with the template of the adjacent channel;

[0010] Step 4: Construct a time-varying transfer function model according to the amplitude envelope attenuation characteristics and carrier phase jump characteristics of the reflection feature template;

[0011] Step 5: Generate a compensation filter based on the time-varying transfer function model, and verify the compensation effect through secondary reflection.

[0012] Preferably, step 1 specifically comprises:

[0013] Periodic trigger pulses are generated by a clock division circuit of the signal source and transmitted to each channel programmable impedance switching circuit through an optical fiber;

[0014] When the programmable impedance switching circuit detects the rising edge of the trigger pulse, it switches to a full reflection state within a window less than the single period length of the high-frequency signal;

[0015] The impedance value of the full reflection state is determined by measuring the real part and the imaginary part of the characteristic impedance of the transmission line. The specific method is as follows: send a sweep test signal to the transmission line, collect the frequency point corresponding to the phase zero crossing point of the reflection coefficient, calculate the modulus inverse of the reflection coefficient at this frequency point to obtain the real part of the impedance, and calculate the imaginary part according to the frequency difference between adjacent zero crossing points.

[0016] Preferably, step 2 specifically comprises:

[0017] Synchronously collect mixed signals of each channel at a sampling rate higher than twice the highest frequency of the signal;

[0018] Select common period data of the reference channel and the target channel, fix the reference channel signal and slide the target channel signal, and calculate the cumulative sum of the point-by-point product of the two signals;

[0019] When the cumulative sum reaches the maximum value, record the sliding point number of the target channel, and calculate the fixed transmission time delay offset combined with the sampling interval;

[0020] An interpolation algorithm based on Bezier curve is used to resample the target channel signal to the reference channel time axis.

[0021] Preferably, the operation of separating the crosstalk component in step 3 specifically comprises:

[0022] Cut off the signal segment centered on the peak value time of the active reflection reference signal and extending to the left and right by a first preset time length as the reflection feature template of the current channel;

[0023] Perform time reversal convolution on the remaining segment of the mixed signal after removing the current channel template and the reflection feature template of the adjacent channel;

[0024] Energy normalization of the convolution result: divide each point of the convolution sequence by the geometric mean of the remaining segment energy of the current channel and the template energy of the adjacent channel;

[0025] Detect the peak position and peak size of the normalized convolution result, and if the peak size exceeds the dynamic threshold calculated according to the noise base, the peak size is taken as a scaling factor, and the product of the adjacent channel template and the scaling factor is subtracted from the mixed signal.

[0026] Preferably, the amplitude envelope decay characteristic in step 4 is obtained in the following way:

[0027] Orthogonal demodulation of the current channel reflection feature template to generate in-phase and quadrature components;

[0028] Calculate the square sum of the in-phase and quadrature components and take the square root to obtain the amplitude envelope curve;

[0029] Identify the first percentage amplitude point on the rising edge and the second percentage amplitude point on the falling edge of the amplitude envelope curve;

[0030] Calculate the time width between the two points as the decay time parameter, and obtain the decay factor function by linear fitting after logarithmic conversion.

[0031] Preferably, the carrier phase jump characteristic is obtained in the following way:

[0032] Orthogonal down-conversion of the reflection feature template and the local oscillator to generate baseband in-phase and quadrature signals;

[0033] Track the instantaneous phase of the baseband signal through a phase-locked loop, extract the phase mean in a preset time period before and after the active reflection reference signal action window, and calculate the difference value;

[0034] Calculate the phase offset factor function according to the rate of change of the phase difference value with time.

[0035] Preferably, the compensation filter in step 5 is generated in the following way:

[0036] Perform discrete Fourier inverse transform on the time-varying transfer function model to obtain a time-domain impulse response sequence;

[0037] Design a finite-length unit impulse response filter to minimize the mean square error of its coefficient sequence and the impulse response sequence;

[0038] The mean square error minimization is implemented in the following way: construct a Toeplitz matrix to represent the convolution operation, and solve the filter coefficients by orthogonal decomposition method.

[0039] Preferably, the verification method of the compensation effect is:

[0040] After the compensation filter is accessed, the programmable impedance switching circuit is triggered again to generate a secondary reflection signal;

[0041] An energy value corresponding to a time window of the active reflection reference signal in the secondary reflection signal is extracted;

[0042] A ratio of the energy value to energy of the original transmission signal in the corresponding window is calculated as a residual reflection energy ratio;

[0043] When the residual reflection energy ratio is lower than an adaptive threshold set according to a system noise level for three consecutive measurements, it is determined that the compensation is effective.

[0044] Preferably, the calculation method of the dynamic threshold is as follows:

[0045] A pure noise segment far from the time window of the active reflection reference signal in the mixed signal is intercepted;

[0046] A statistical variance of the pure noise segment is calculated, and a preset signal-to-noise ratio coefficient is multiplied to obtain a basic threshold;

[0047] The basic threshold is adjusted according to a spectral overlap degree of the adjacent channel template and the residual segment of the mixed signal, and the higher the overlap degree, the greater the threshold adjustment ratio.

[0048] Preferably, a dynamic updating mechanism is further included:

[0049] During system operation, steps 1 to 5 are re-executed at fixed time intervals;

[0050] The time interval is determined according to an environmental temperature drift rate: the temperature change rate of the metal skin of the transmission line is monitored, and when the change rate exceeds a critical value, the update interval is shortened;

[0051] The compensation filter coefficients are stored after each update, and if the difference between the coefficients of two consecutive updates is less than a convergence threshold, the subsequent update interval is extended.

[0052] The beneficial effects of the present application are:

[0053] 1、The present application accurately aligns each channel signal in the time domain reflection compensation process, synchronizes the multi-channel signals by using cross-correlation operation, thereby eliminating the influence of time delay deviation on beam pointing. Through the design of the compensation filter, the nonlinear time delay effect caused by the length difference of the transmission line can be compensated, the beam pointing distortion problem can be effectively corrected, and the system performance can be improved.

[0054] 2、The present application directly processes signals in the time domain, generates a compensation filter based on a time-varying transfer function model, can compensate the time delay mismatch caused by the length difference of the transmission line and the time-varying distortion caused by reflection, thereby realizing accurate compensation of the multi-channel signal, and avoiding the limitations of the traditional method in the nonlinear time delay case.

[0055] 3. The application proposes a scheme for separating adjacent channel crosstalk through convolution operation. By intercepting the time domain window of the reflected signal, convolution and energy normalization processing, the crosstalk component of the adjacent channel is effectively eliminated, thereby improving the compensation accuracy and avoiding the negative impact of crosstalk on signal quality. This effectively avoids the failure of the traditional scheme in dense arrays, greatly improving the compensation effect and system reliability.

[0056] 4. The application generates an accurate compensation filter through time domain reflection compensation design. The filter generated by the time-varying transfer function model can directly compensate the time domain characteristics of the signal, and the time domain impulse response is obtained through inverse discrete Fourier transform, and the filter coefficient is designed using the method of minimizing mean square error, thereby improving the compensation accuracy and ensuring the recovery of signal quality.

[0057] 5. The application also includes a dynamic updating mechanism that can dynamically adjust the compensation filter coefficients according to environmental changes. By regularly updating the compensation filter, the stability of the compensation effect in long-term operation is ensured. If the difference between the two consecutive updates is less than the convergence threshold, the system will extend the update interval, thereby optimizing the update efficiency and improving the adaptive ability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0058] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0059] Figure 1 The step flow chart of the method of the application;

[0060] Figure 2 The step flow chart of the calculation method of the dynamic threshold of the method of the application;

[0061] Figure 3 The step flow chart of the dynamic updating mechanism of the method of the application. DETAILED DESCRIPTION

[0062] The application will be described in detail below in combination with the drawings and specific embodiments. It should be noted here that in order to make the embodiments more detailed, the following embodiments are the best, preferred embodiments, and other alternative ways can also be used by those skilled in the art to implement them; and the drawings are only used to more specifically describe the embodiments, and are not intended to specifically limit the application.

[0063] Please refer to Figures 1-3The embodiment of the application provides a time-domain reflection compensation design method of high-frequency signal transmission loss, in step 1, the time-domain characteristics of the reflection signal are crucial to the compensation effect. In this step, a programmable impedance switching circuit is connected at the end of the transmission channel to be measured, and a reference signal with a known time-domain position is generated by a synchronous trigger signal. The reflection signal provides a known reference signal for the subsequent reflection compensation process, and the time-domain characteristics of the signal can be compensated more accurately.

[0064] Step 2 solves the time delay difference caused by different transmission paths of the channels by collecting multi-channel mixed signals containing the active reflection reference signal and aligning the time scales of the channels by using cross-correlation operation. By aligning the time scales of the signals of different channels, the multi-channel signals can be accurately synchronized in the time domain, laying a foundation for subsequent crosstalk separation and signal compensation. The beneficial effect of this step is to significantly improve the time-domain alignment accuracy of the multi-channel signals, and to avoid the time delay deviation problem that cannot be handled by the traditional frequency domain method.

[0065] In step 3, the reflection feature template of each channel is first extracted from the aligned multi-channel signal, and the convolution operation is used to separate the crosstalk signals between adjacent channels. This process is particularly important because in high-frequency signal transmission, the electromagnetic coupling effect between adjacent channels is significant, and the crosstalk signal often has a great impact on signal quality. Through convolution operation, the independent reflection characteristics of each channel can be effectively extracted, and the interference of adjacent channels can be eliminated, thereby improving the accuracy of compensation and system performance.

[0066] In step 4, the amplitude envelope attenuation characteristics and carrier phase jump characteristics of the reflection signal reflect the attenuation and phase shift of the signal during transmission. In this step, by analyzing these characteristics of the reflection features of each channel, a time-varying transfer function model is constructed. The model can describe the dynamic changes in the signal transmission process, effectively compensate for the time delay and phase distortion caused by factors such as transmission path, transmission line non-uniformity, and thus realize accurate compensation of high-frequency signals.

[0067] Finally, in step 5, based on the time-varying transfer function model, a compensation filter is generated to correct the distortion in the signal. The compensation filter effectively eliminates the reflection loss in the signal by accurately matching the time-domain reflection characteristics. The compensation effect is verified by secondary reflection, which can ensure the accuracy and effectiveness of the compensation filter, thereby improving the quality of the signal and the stability of the system.

[0068] The cross-correlation operation realizes the accurate alignment of the time scales of the multi-channel signals, overcomes the time delay difference between different transmission channels, ensures the synchronization of the signals of the channels, and improves the beamforming accuracy. The convolution operation separates the crosstalk signals between adjacent channels, avoids the signal pollution caused by crosstalk in the traditional method, and improves the purity and quality of the signal.

[0069] In a possible implementation, at the signal transmitting source end, a clock dividing circuit generates a periodic trigger pulse, which is transmitted to the programmable impedance switching circuit of each channel through an optical fiber. The clock dividing circuit provides accurate time synchronization signals to ensure accurate control of the reflection signals of each channel in the time domain. In this way, multiple signal channels can respond to the trigger signal at the same time, effectively avoiding the problem of asynchronous signals.

[0070] When the programmable impedance switching circuit detects the rising edge of the trigger pulse, it switches to a full reflection state within a time window shorter than a single cycle of the high-frequency signal. The setting of this short time window ensures that the reflection of the signal does not interfere with the original signal during high-frequency signal transmission. At this time, the impedance switching circuit changes the transmission channel of the signal to a full reflection mode, which causes the signal to be fully reflected back, providing an accurate reference signal for subsequent time domain compensation.

[0071] The impedance value in the full reflection state is one of the key parameters in the present technology. To accurately calculate this impedance value, a method of measuring the real and imaginary parts of the characteristic impedance of the transmission line is used. First, a sweep test signal is sent to the transmission line to obtain the reflection coefficient at different frequencies. Then, by collecting the frequency points where the reflection coefficient phase crosses zero, the inverse of the modulus of the reflection coefficient at that frequency point can be determined, and the real part of the reflection impedance can be calculated. For the imaginary part, based on the analysis method of the frequency difference between adjacent zero-crossing points, the imaginary part of the impedance can be accurately obtained. Through this method, the impedance characteristics of the transmission line can be accurately measured, providing necessary parameters for the design of subsequent compensation filters.

[0072] By accurately controlling the reflection signal and accurately measuring the impedance characteristics of the transmission line, the signal quality during high-frequency signal transmission is significantly improved, effectively solving the problems of inaccurate time synchronization and excessive reflection loss in traditional methods. It has a wide application prospect, especially in the fields of high-frequency communication and radar systems.

[0073] In a possible implementation, first, in order to obtain accurate signal contrast data, the system synchronously collects the mixed signals of each channel at a sampling rate twice the highest frequency of the signal. According to the sampling theorem, a sampling rate twice the highest frequency of the signal (i.e. the Nyquist sampling rate) can ensure that the collected signal has sufficient time resolution, avoiding signal distortion or information loss due to insufficient sampling. Synchronous acquisition is to ensure that the data of all channels are consistent in time, so that accurate time domain reflection compensation operations can be performed subsequently.

[0074] After obtaining the signal data of multiple channels, the common time period data of the reference channel and the target channel are selected for comparison. This process is achieved by fixing the reference channel signal and sliding the target channel signal, so that the two are gradually aligned in time. By calculating the product of the reference channel and the target channel signal point by point, the correlation of the target channel signal and the reference channel signal at different time offsets can be evaluated.

[0075] During the sliding process of the target channel signal, when the calculated cumulative sum reaches the maximum value, it means that the alignment of the target channel signal and the reference channel signal at this time is optimal. At this time, the sliding point number of the target channel is recorded, and the fixed transmission time delay offset is calculated combined with the sampling interval. This offset represents the time delay of the target channel signal relative to the reference channel signal, and through this offset, the time domain deviation of the target signal can be effectively corrected.

[0076] In order to accurately align the target channel signal to the time axis of the reference channel, a Bezier curve-based interpolation algorithm is used to resample the target channel signal. The Bezier curve interpolation algorithm is a smooth interpolation method that can avoid the non-smoothness or signal distortion problems caused by traditional linear interpolation by controlling the points and the properties of the curve, and can more accurately restore the time domain characteristics of the target channel signal.

[0077] Through accurate time delay compensation and the application of the Bezier curve interpolation algorithm, efficient and accurate time domain reflection compensation can be achieved in high-frequency signal transmission, thereby improving signal quality and transmission stability, and having wide application prospects.

[0078] In one possible implementation, first, according to the peak time of the active reflection reference signal, a signal segment centered on the peak time is extracted from the signal, and each side is expanded by a first preset time length, forming a reflection characteristic template of the channel. This template captures the reflection characteristics of the channel, representing the basic waveform and time delay information of the signal. In this way, it can be ensured that the template reflects the characteristics of the target channel and is not affected by crosstalk.

[0079] After obtaining the reflection characteristic template of the channel, the system removes the signal segment corresponding to the template to obtain the remaining part of the mixed signal. Then, the remaining segment is time-reversed convolved using the reflection characteristic template of the adjacent channel. The purpose of time-reversed convolution is to reverse the influence of the adjacent channel on the remaining segment, helping to identify and separate the crosstalk components introduced by the adjacent channel in the mixed signal.

[0080] The energy normalization processing is performed on the convolution result. Specifically, each point in the convolution sequence is divided by the geometric mean of the remaining segment energy of the current channel and the template energy of the adjacent channel. The energy normalization eliminates the deviation of the convolution result caused by the difference in signal intensity, ensuring that the convolution result effectively reflects the real impact of the crosstalk component. The geometric mean as a standardization factor helps to balance the energy contribution of both sides and avoid the dominance of one side.

[0081] The peak position in the normalized convolution result is detected. If the peak value of the convolution result exceeds the dynamic threshold calculated based on the noise base, it indicates that the part represented by the peak value is an effective crosstalk signal. At this time, the adjacent channel reflection feature template is multiplied by the peak value of the proportion factor, and the result is subtracted from the mixed signal, thereby effectively removing the crosstalk component. After removing the crosstalk, the quality of the remaining signal is improved, reducing unnecessary interference.

[0082] Through the precise crosstalk separation method, not only the transmission quality of the signal is improved, but also the strong noise suppression ability and efficient signal processing performance are achieved through dynamic adjustment of the threshold, which has significant technical advantages, especially suitable for application in multi-channel and high-frequency signal environment.

[0083] In one possible implementation, first, the reflection feature template of the current channel is subjected to orthogonal demodulation. Orthogonal demodulation is a process of decomposing a signal into two orthogonal components, usually including in-phase component (I component) and quadrature component (Q component). The purpose of this operation is to convert the time-domain signal into a combination of amplitude and phase information, so that the signal can more accurately reflect the attenuation characteristics. Through this decomposition, the system can independently process the amplitude and phase parts of the signal.

[0084] After orthogonal demodulation, the square sum of the in-phase component and the quadrature component is calculated and the square root is obtained to obtain the amplitude envelope curve. Specifically, the amplitude envelope refers to the instantaneous amplitude variation trend of the signal, which can effectively describe the attenuation or enhancement of the signal. In this way, the amplitude variation of the signal can be extracted from the decomposed signal, thereby obtaining the accurate characteristics reflecting the signal attenuation process.

[0085] By analyzing the amplitude envelope curve, the first percentile amplitude point of the rising edge and the second percentile amplitude point of the falling edge are identified. These two points correspond to important time nodes in the signal increasing and decreasing processes in the amplitude envelope curve, respectively. Through these nodes, the degree of signal attenuation and the time characteristics of the attenuation in the transmission process can be effectively measured.

[0086] The time width between the two amplitude points is calculated, which is the decay time parameter. By taking the logarithmic transformation of this time parameter, the regularity of signal decay can be obtained, and the decay factor function can be obtained through linear fitting. This decay factor function can describe the relationship between signal decay and time, reflecting the speed and degree of signal attenuation in the transmission process.

[0087] Through orthogonal demodulation and amplitude envelope calculation, the signal attenuation characteristics can be accurately extracted. This process not only reflects the amplitude change of the signal, but also eliminates errors caused by noise and other interference factors, providing a more reliable description of signal attenuation characteristics.

[0088] By identifying the rising and falling edge amplitude points of the amplitude envelope curve and calculating the time width, the dynamic process of signal attenuation can be analyzed in detail. This helps the system to monitor the attenuation characteristics in real time in high-frequency signal transmission, so as to make timely compensation and optimization.

[0089] In one possible implementation, the reflection feature template is down-converted in quadrature with the local oscillator. The purpose of quadrature down-conversion is to convert the signal from high frequency domain to baseband frequency band, so as to facilitate the analysis and processing of the signal. By mixing with the local oscillator, the in-phase signal and quadrature signal (I / Q signal) in the baseband signal are generated. This operation effectively removes the high frequency part of the carrier signal, so that the phase and amplitude changes of the signal can be more clearly reflected in the baseband signal.

[0090] A phase-locked loop (PLL) is used to track the instantaneous phase of the baseband signal. The phase-locked loop is a control system that realizes phase tracking through feedback mechanism. In this step, the phase-locked loop is used to accurately extract the instantaneous phase of the baseband signal, especially the phase fluctuation of the signal over time. Through the stability of the PLL, the phase change of the signal can be effectively tracked, and the phase jump at the beginning and end of the signal can be identified.

[0091] The average phase values within a predetermined time period before and after the active reflection reference signal action window are extracted, and the difference is calculated. The purpose of this step is to calculate the phase change amount of the signal near the starting time and the ending time, which is an important basis for evaluating the phase jump of the signal. By observing the phase mutation of the signal on the time axis, the phase jump characteristics of the signal can be effectively reflected.

[0092] According to the rate of change of the phase difference value with time, a phase offset factor function is calculated. This function describes the speed and amplitude of the signal phase change, and can accurately quantify the phase offset of the signal. The calculation of the phase offset factor helps to understand the phase distortion in the signal transmission process, and thus provides a basis for subsequent compensation design. Through this factor function, the system can compensate the signal according to the phase change law, so as to improve the quality of the signal.

[0093] In one possible implementation, first, a time-domain impulse response sequence is obtained by performing an inverse discrete Fourier transform on the time-varying transfer function model. The time-varying transfer function is a mathematical model that describes the signal variation during signal transmission, and the inverse transform operation converts it from the frequency domain back to the time domain, so that the signal variation process is presented in time. The time-domain impulse response sequence describes the instantaneous response characteristics of the signal after passing through the system, which is the basis for designing a compensation filter.

[0094] Second, a finite-length unit impulse response (FIR) filter is designed to minimize the mean square error (MSE) of the coefficient sequence and the time-domain impulse response sequence. The unit impulse response filter is used to perform convolution processing on the signal, and the filter coefficients are adjusted to compensate for signal distortion during transmission. The goal of minimizing the mean square error (MSE) is to ensure that the designed filter can accurately restore the time-domain impulse response and reduce signal distortion.

[0095] To achieve the minimum mean square error, a method of constructing a Toeplitz matrix to represent the convolution operation is adopted. The Toeplitz matrix is a matrix with diagonal symmetry, which can effectively represent the relationship between the input signal and the filter coefficients in the convolution operation. By constructing the Toeplitz matrix, the problem can be converted into solving a system of linear equations. Then, the orthogonal decomposition method (such as QR decomposition) is used to solve the filter coefficients. The orthogonal decomposition method is a high-efficiency numerical calculation method that can ensure the stability and accuracy of the solving process.

[0096] In one possible implementation, after the compensation filter successfully accesses the signal transmission path, a programmable impedance switching circuit is triggered to generate a secondary reflection signal. The programmable impedance switching circuit can simulate the actual reflection conditions by adjusting the line impedance, and further reflect the signal. The purpose of this step is to simulate the possible further signal reflection in the system, to ensure that the compensation filter can effectively cope with the influence of multiple reflections on signal quality.

[0097] In the generated secondary reflection signal, the energy value corresponding to the active reflection reference signal time-domain window is extracted. This time-domain window is set according to the timing position of the reference signal, and it is usually located between the beginning and the end of the reflection signal, ensuring that the energy extracted is related to the reflection signal. This step helps to evaluate the signal quality after compensation by accurately quantifying the energy of the secondary reflection signal within the time-domain window.

[0098] The extracted secondary reflection signal energy value is compared with the energy of the original transmitted signal within the same window, and the energy ratio of the two is calculated. This ratio is used as the residual reflection energy proportion, which quantifies the compensation effect. If the residual reflection energy proportion is low, it indicates that the compensation filter effectively reduces the strength of the reflection signal and improves the transmission quality; otherwise, further optimization of the compensation strategy may be needed.

[0099] An adaptive threshold is set according to the noise level of the system. If the residual reflection energy proportion of three consecutive measurements is below the threshold, it can be determined that the compensation effect is effective. The adaptive threshold is adjusted according to factors such as system environment, noise interference, etc., to ensure that the determination standard is adapted to the actual signal conditions. The reliability and stability of the verification results are ensured through three consecutive measurements.

[0100] By generating secondary reflection signals and extracting energy values and calculating residual reflection energy proportions, combined with adaptive threshold determination, the effect of the compensation filter can be effectively verified, ensuring that the reflection loss in the signal transmission process is effectively compensated, greatly improving the quality and stability of high-frequency signal transmission.

[0101] In one possible implementation, a pure noise segment far from the active reflection reference signal time window is extracted from the mixed signal. The purpose of this step is to ensure that the extracted noise segment is not affected by the reflection signal, therefore, selecting a part far from the reflection signal time window can avoid interference from other signal components and obtain more accurate noise data.

[0102] The variance of the extracted pure noise segment is calculated through statistical analysis. Variance is an important measure of noise intensity, which can reflect the fluctuation degree of noise in this time period. The calculated noise variance is used to determine the intensity of noise in the signal, providing a basis for subsequent threshold calculation.

[0103] The statistical variance of the pure noise segment is multiplied by the preset signal-to-noise ratio coefficient to obtain the basic threshold. The signal-to-noise ratio coefficient is preset according to the design requirements of the system, and it is closely related to the noise tolerance and signal quality requirements of the system. In this way, the setting of the basic threshold will take into account the actual level of system noise, so that the threshold is adapted to the current environmental conditions.

[0104] The basic threshold is further adjusted according to the spectral overlap degree of the adjacent channel template and the remaining segment of the mixed signal. The spectral overlap degree represents the degree of overlap between the spectrum of the adjacent channel and the current signal spectrum. When the overlap degree is high, it indicates that the signals of the adjacent channels will have a large interference on the current signal, and the threshold needs to be increased at this time to avoid false determination of the reflection signal. When the spectral overlap degree is low, the signal interference is small, and the threshold can be appropriately reduced to avoid excessive adjustment.

[0105] By dynamically calculating the threshold and adjusting it according to the noise statistical characteristics and spectral overlap, the reflection compensation effect in high-frequency signal transmission can be improved, the adaptability of the system to noise interference and spectral overlap can be enhanced, and thus the signal quality and transmission stability can be improved.

[0106] In one possible implementation, during system operation, a fixed time interval is set, and steps 1 to 5 are re-executed every certain time to recalculate the dynamic threshold. This means that the system will periodically adjust the compensation strategy to cope with possible changes in signal transmission conditions, such as noise intensity, signal attenuation, etc., to maintain the stability and reliability of the system.

[0107] In practical applications, signal transmission performance can be affected by temperature changes, especially the temperature changes of the metal transmission line skin, which have a significant impact on high-frequency signal attenuation and reflection. Therefore, the system will monitor the temperature change rate of the metal skin of the transmission line in real time and adjust the update interval according to this change rate. When the temperature change rate exceeds a set threshold, the system will shorten the update interval and increase the update frequency. This is done to ensure that the compensation algorithm can respond to environmental changes in a timely manner and reduce transmission loss and reflection problems caused by temperature drift.

[0108] After each update, the system will store the calculated compensation filter coefficients. In order to improve system efficiency and avoid excessive frequent updates, the system will compare the compensation coefficient differences after two consecutive updates. If the coefficient difference between the two updates is less than a set convergence threshold, it indicates that the system is close to a stable state, and the subsequent update interval can be extended to reduce unnecessary calculations and save resources, while ensuring that the system maintains a low update frequency when it is stable.

[0109] With this dynamic update mechanism, the system can adjust its working state in a timely manner according to temperature changes, optimize computing resources, improve signal transmission stability, and improve the intelligence level and reliability of the overall system, which has significant engineering application value.

[0110] The following is described in detail by example:

[0111] The present application is applied to high-frequency signal transmission in a communication system, particularly for signal loss and reflection compensation in high-speed data transmission lines. The system operates in an environment where the temperature may fluctuate greatly, such as a power communication system or a communication base station, the transmission line is a metal cable, and the working frequency is 5 GHz.

[0112] Specifically, every 1 second, the temperature sensor measures the temperature change of the metal skin of the transmission line. In the embodiment of the present application, the initial temperature is 25°C, and the environmental temperature change rate is 0.2°C / s. In the embodiment of the present application, the length of the transmission line is 100 meters.

[0113] The noise variance of the signal monitored by the sensor during operation is calculated as follows:

[0114]

[0115] wherein, is the amplitude value of the signal, is the mean value of the signal, is the number of sample points. In the embodiment of the present application, the sample number is 10000, and the calculated noise variance is 0.05. According to the noise variance and the spectral overlap degree, the compensation threshold is dynamically calculated. In the embodiment of the present application, the spectral overlap degree is 0.4, and the dynamic threshold calculation formula is:

[0116]

[0117] wherein, is the adjustment coefficient, which is an empirical constant and can be preset in the range of [0.5, 2.5] according to the system signal-to-noise ratio requirement to balance the detection sensitivity and the false alarm rate. In the embodiment, the value is 1.5, and overlap is the spectral overlap degree. The calculated dynamic threshold is:

[0118]

[0119] In the embodiment of the present application, the temperature change rate is 0.2°C / s, and when the critical value 0.1°C / s is exceeded, the system enters the update mode. At this time, the system will re-calculate and execute the compensation algorithm. The update interval is shortened to 30 seconds.

[0120] At each update, the compensation filter coefficient is stored and compared with the previous coefficient. In the embodiment of the present application, the difference between the two updated coefficients is 0.001, which is lower than the set convergence threshold 0.005. Therefore, the system determines that it is convergent, and the subsequent update interval is extended to 90 seconds.

[0121] The compensation filter coefficient after each update is stored in the data storage module. For the difference between the coefficients after two consecutive updates, the following convergence judgment formula is used:

[0122]

[0123] wherein, and are the compensation coefficients before and after the update. If is less than the convergence threshold 0.005, it is considered that the system is convergent, and the subsequent update interval is extended.

[0124] Without a dynamic update mechanism, the traditional time domain reflection compensation method updates the filter coefficient every 5 minutes, without considering the change of the environmental temperature. ​​​​

[0125] The method of the present application dynamically adjusts the update interval based on temperature changes, and performs convergence judgment after each update.

[0126] The experimental results are as follows:

[0127] Ambient conditions Signal loss (dB) for conventional method Signal loss (dB) for inventive method Small temperature fluctuations (±1 °C) 1.5 0.8 Large temperature fluctuations (±5 °C) 3.2 1.1

[0128] In the case of large temperature fluctuations, the traditional method cannot respond to temperature changes in time, resulting in a significant increase in signal loss. In contrast, the present application can effectively reduce the impact of temperature changes on signal transmission through dynamic update mechanism and temperature change monitoring, reducing signal loss by nearly 65%.

[0129] Through the convergence determination mechanism, unnecessary frequent updates are avoided, system resource consumption is reduced, and compensation accuracy is improved.

[0130] The present application can dynamically adjust the update interval according to the change of environmental temperature, and is particularly suitable for environments with large temperature fluctuations.

[0131] Through convergence determination, frequent invalid updates are avoided, calculation resources are saved, and system power consumption is reduced.

[0132] In the signal transmission process, due to the dynamic adjustment of the compensation strategy, the signal loss and time domain reflection problem are significantly improved, and the system stability is improved.

[0133] The present application describes in detail the application process, algorithm formula and specific implementation steps of the time domain reflection compensation design method of high frequency signal transmission loss. Through dynamic update mechanism, temperature change monitoring and convergence determination of compensation filter coefficient, the present application can effectively improve the transmission quality of high frequency signal, and has significant advantages in environments with large temperature changes. Through comparison experiments, the outstanding effect of the method in signal loss and system stability is proved, and the method is suitable for various scenes requiring high frequency signal transmission compensation.

[0134] The present application covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present application. In order to make the public have a thorough understanding of the present application, specific details are described in the following preferred embodiments of the present application, and the present application can also be completely understood without the description of these details. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, flows, elements and circuits are not described in detail.

[0135] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principle of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be regarded as the protection scope of the present application.

Claims

1. A time domain reflection compensation design method for high frequency signal transmission loss, characterized by, The method comprises the following steps: Step 1: A programmable impedance switching circuit is connected at the end of the high-frequency transmission channel to be tested, and a driven reflection reference signal with a determined time domain position is generated in response to a synchronous trigger signal; Step 2: A multi-channel mixed signal containing the driven reflection reference signal is collected, and the time scales of the channels are aligned through cross-correlation operation; Step 3: A reflection characteristic template of the current channel is extracted from the aligned signal, and a crosstalk component is identified and removed through convolution operation with the template of the adjacent channel; Step 4: A time-varying transfer function model is constructed according to the amplitude envelope decay characteristic and the carrier phase jump characteristic of the reflection characteristic template; Step 5: A compensation filter is generated based on the time-varying transfer function model.

2. The time domain reflection compensation design method for high frequency signal transmission loss according to claim 1, characterized in that, Step 1 specifically comprises: Periodic trigger pulses are generated by a clock dividing circuit of a signal transmitting source and transmitted to programmable impedance switching circuits of each channel through an optical fiber; When the programmable impedance switching circuit detects the rising edge of the trigger pulse, it switches to a full reflection state within a window smaller than the single period length of the high-frequency signal; The impedance value of the full reflection state is determined by measuring the real part and the imaginary part of the characteristic impedance of the transmission line, specifically by sending a sweep test signal to the transmission line, collecting the frequency point corresponding to the phase zero crossing point of the reflection coefficient, calculating the modulus inverse of the reflection coefficient at the frequency point to obtain the real part of the impedance, and calculating the imaginary part according to the frequency difference between adjacent zero crossing points.

3. The time domain reflectometry compensation design method for high frequency signal transmission loss according to claim 1, wherein, Step 2 specifically comprises: The mixed signals of each channel are synchronously collected at a sampling rate higher than twice the highest frequency of the signal; The common time period data of the reference channel and the target channel are selected, the reference channel signal is fixed, and the target channel signal is slid, and the cumulative sum of the point-by-point product of the two signals is calculated; When the cumulative sum reaches the maximum value, the sliding point number of the target channel is recorded, and the fixed transmission time delay offset is calculated in combination with the sampling interval; A Bezier curve-based interpolation algorithm is used to resample the target channel signal to the reference channel time axis.

4. The time domain reflectometry compensation design method for high frequency signal transmission loss according to claim 1, wherein, The operation of separating the crosstalk component in Step 3 specifically comprises: A signal segment with a first preset time length extended to the left and right of the peak value time of the driven reflection reference signal is intercepted as the reflection characteristic template of the current channel; The remaining segment of the mixed signal after removing the current channel template is time-reversed convolved with the reflection characteristic template of the adjacent channel; The convolution result is energy-normalized: each point of the convolution sequence is divided by the geometric mean of the energy of the remaining segment of the current channel and the energy of the template of the adjacent channel; The peak position and peak size of the normalized convolution result are detected, and if the peak size exceeds a dynamic threshold value calculated according to the noise floor, the peak size is taken as a scaling factor, and the product of the adjacent channel template and the scaling factor is subtracted from the mixed signal.

5. The time domain reflectometry compensation design method for high frequency signal transmission loss according to claim 1, wherein, The amplitude envelope decay characteristic in Step 4 is obtained in the following way: The reflection characteristic template of the current channel is quadrature demodulated to generate in-phase and quadrature components; The amplitude envelope curve is obtained by calculating the square sum of the in-phase and quadrature components and taking the square root; The first percentage amplitude point on the rising edge and the second percentage amplitude point on the falling edge of the amplitude envelope curve are identified; The time width between the two points is calculated as the decay time parameter, and the decay factor function is obtained through linear fitting after logarithmic conversion.

6. The time domain reflectometry compensation design method of high frequency signal transmission loss according to claim 5, characterized in that, The carrier phase jump characteristic is obtained in the following way: The reflection feature template is down-converted in quadrature with the local oscillator to generate a baseband in-phase signal and a quadrature signal; The instantaneous phase of the baseband signal is tracked by a phase-locked loop, and the average phase values in a preset time period before and after the active reflection reference signal action window are extracted, and the difference is calculated; The phase offset factor function is calculated according to the rate of change of the phase difference with time.

7. The time domain reflectometry compensation design method for high frequency signal transmission loss according to claim 1, wherein, The generation method of the compensation filter in step 5 is: Performing inverse discrete Fourier transform on the time-varying transfer function model to obtain a time-domain impulse response sequence; Designing a finite-length unit impulse response filter to minimize the mean square error of the coefficient sequence and the impulse response sequence; The implementation of the mean square error minimization is to construct a Toeplitz matrix to represent the convolution operation, and solve the filter coefficients by orthogonal decomposition method.

8. The time domain reflection compensation design method for high frequency signal transmission loss according to claim 7, characterized in that, 5 also includes verifying the compensation effect by secondary reflection, and the verification method of the compensation effect is: After the compensation filter is connected, the programmable impedance switching circuit is triggered again to generate a secondary reflection signal; Extracting the energy value of the secondary reflection signal corresponding to the time-domain window of the active reflection reference signal; Calculating the ratio of the energy value and the energy of the original transmission signal in the corresponding window as the residual reflection energy ratio; When the residual reflection energy ratio is continuously measured for three times and is lower than the adaptive threshold set according to the system noise level, it is determined that the compensation is effective.

9. The time domain reflectometry compensation design method for high frequency signal transmission loss according to claim 4, wherein, The calculation method of the dynamic threshold is: Cutting the pure noise segment away from the time window of the active reflection reference signal in the mixed signal; Calculating the statistical variance of the pure noise segment, multiplying the preset signal-to-noise ratio coefficient to obtain the basic threshold; Adjusting the basic threshold according to the spectral overlap degree of the adjacent channel template and the remaining segment of the mixed signal, the higher the overlap degree, the greater the threshold upscaling ratio.

10. The time domain reflectometry compensation design method for high frequency signal transmission loss according to claim 1, wherein, It also includes a dynamic updating mechanism: During system operation, steps 1 to 5 are re-executed at fixed time intervals; The time interval is determined according to the environmental temperature drift rate: monitor the temperature change rate of the transmission line metal skin, and shorten the update interval when the change rate exceeds the critical value; After each update, store the compensation filter coefficients, and if the difference between the coefficients of two consecutive updates is less than the convergence threshold, then extend the subsequent update interval.

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