A dynamic braiding process for reducing coaxial cable signal reflections

Abstract

The application relates to the technical field of cable manufacturing, in particular to a dynamic braiding process for reducing signal reflection of a coaxial cable, which comprises the following steps: determining an initial center pitch of a braiding layer based on a target working frequency band and signal propagation speed of the coaxial cable, determining a regular mapping function of the braiding layer based on the initial center pitch, determining a theoretical braiding pitch based on the regular mapping function to determine a traction speed control function, determining an impedance sequence of the braiding layer based on a theoretical braiding pitch sequence of a preset time window to determine total return loss generated by a braiding shielding layer, determining reflection suppression effects of the whole coaxial cable based on the total return loss, determining the cause of unqualified reflection suppression effects based on spectral characteristics of the total return loss to determine an adjustment strategy for the regular mapping function. The application significantly improves the signal transmission performance of the coaxial cable in a wide frequency band range.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing technology, and in particular to a dynamic braiding process for reducing signal reflection in coaxial cables. Background Technology

[0002] Coaxial cables are widely used in radio frequency signal transmission. Their outer conductors typically employ a braided metal wire structure, offering both excellent electromagnetic shielding and flexibility. In traditional braiding processes, the spindle speed and traction speed of the braiding machine are kept in a constant ratio, resulting in a strictly periodic geometric structure in the braided layers—a uniform diamond grid—with a fixed braiding pitch.

[0003] The aforementioned periodic structure is equivalent to a weakly periodic distributed load along the cable's length. When a high-frequency radio frequency signal propagates along the cable, each repeating grid node in the braided layer will generate a weak reflection of the signal. At a single node, the reflection is extremely small and can usually be ignored. However, at a specific frequency, the reflected signals from all periodic nodes are completely in phase, resulting in in-phase superposition and forming a strong return loss peak. This peak frequency is determined by the braid pitch: the smaller the pitch, the higher the corresponding resonant peak frequency. For a typical coaxial cable, this resonant peak may fall within the range of 2GHz to 20GHz, severely degrading the cable's transmission performance at this frequency, leading to a sharp increase in insertion loss and a significant deterioration in the voltage standing wave ratio (VSWR), thus limiting the cable's broadband capability.

[0004] Chinese Patent Publication No. CN109473203A discloses a quad coaxial cable for aerospace and its manufacturing method. The cable core is provided with a multi-layer shielding structure, and the overall shielding effectiveness is improved by stacking the number of shielding layers. However, each braided layer in the multi-layer braided structure still adopts a fixed pitch process, and each layer still has an independent periodic resonance peak. Although the amplitude of the resonance peak is suppressed after the multi-layer stacking, the peak position is not eliminated. Significant frequency selective reflection degradation can still be seen during high-frequency broadband testing. In addition, increasing the number of braided layers will significantly increase the cable's outer diameter, weight and production cost, which is not conducive to the promotion of lightweight and miniaturized application scenarios.

[0005] Therefore, it is evident that existing technologies have not fundamentally destroyed the periodic structure of the braided layer at the process level, and the resonance peak problem still exists. Thus, there is an urgent need for a new braiding method that can completely eliminate periodic resonance peaks by addressing the braiding process itself. Summary of the Invention

[0006] To address this issue, the present invention provides a dynamic braiding process for reducing signal reflection in coaxial cables, thereby overcoming the problem in the existing fixed-pitch braiding process where the periodicity of the braiding structure causes signal reflections at specific frequencies to overlap in phase and form resonance peaks.

[0007] To achieve the above objectives, the present invention provides a dynamic braiding process for reducing signal reflection in coaxial cables, comprising: The initial center pitch of the braided layer is determined based on the target operating frequency band and signal propagation speed of the coaxial cable, and the regular mapping function of the braided layer is determined based on the initial center pitch. The theoretical weaving pitch is determined based on the aforementioned regularity mapping function, in order to determine the traction speed control function; The impedance sequence of the braided layer is determined based on the theoretical braiding pitch sequence within a preset time window, in order to determine the total return loss generated by the braided shielding layer. Based on the total return loss, the reflection suppression effect of the entire coaxial cable is determined; Based on the spectral characteristics of the total return loss, the attribution for the unsatisfactory reflection suppression effect is determined, so as to determine the adjustment strategy for the regularity mapping function.

[0008] Furthermore, the initial center pitch is determined based on the ratio of signal propagation speed to resonant wavelength; The signal propagation speed is determined based on the ratio of the speed of light to the square root of the dielectric constant; The resonant wavelength is determined based on twice the center frequency of the target operating frequency band.

[0009] Furthermore, the regular mapping function includes a sinusoidal function that continuously varies with the theoretical braiding pitch along the cable length direction in a sinusoidal waveform.

[0010] Furthermore, the regular mapping function also includes a linearly gradual function in which the theoretical braiding pitch changes linearly, monotonically, and continuously along the cable length direction.

[0011] Furthermore, the traction speed control function is determined based on the theoretical weaving pitch, spindle speed, and equivalent weaving coefficient; The equivalent weaving coefficient is determined based on the total number of spindles and the basic weaving angle.

[0012] Furthermore, the impedance sequence is determined based on the sum of the nominal characteristic impedance and the local impedance correction. The local impedance correction amount is determined based on the weaving angle; The braiding angle is determined based on the theoretical braiding pitch and the cable core diameter.

[0013] Furthermore, the total return loss is determined by substituting the small-signal reflection coefficient of each grid cell into the cumulative reflection model; The small signal reflection coefficient is determined based on the local impedance correction amount and nominal characteristic impedance of each grid cell; The cumulative reflection model is the vector sum of the small-signal reflection coefficients of each grid cell multiplied by the phase factor.

[0014] Furthermore, the process of determining the reflection suppression effect of the entire coaxial cable includes: The minimum total return loss within the target operating frequency band of the coaxial cable is compared with the preset total return loss. Based on the fact that the minimum value is less than the preset total return loss, the reflection suppression effect of the entire coaxial cable is determined to be unqualified.

[0015] Furthermore, the peak frequency corresponding to the global minimum value of the total return loss spectrum within the target operating frequency band is obtained, and the peak frequency is compared with the upper limit frequency and the lower limit frequency. If the peak frequency is less than the lower limit frequency or greater than the upper limit frequency, it is determined to be a frequency band edge problem, and the initial center pitch is adjusted accordingly. Based on the fact that the peak frequency is greater than or equal to the lower limit frequency and less than or equal to the upper limit frequency, it is determined to be an issue within the frequency band.

[0016] Furthermore, the peak width parameter is determined based on the ratio of the -3dB bandwidth of the reflection peak to the peak frequency, and the average return loss of the entire frequency band is determined based on the return loss value of each sampling frequency point within the target operating frequency band. Based on the fact that the peak width parameter is greater than or equal to the preset width parameter, and the average return loss across the entire frequency band is less than the preset average, it is determined to be a broadband multi-peak or overall noise floor increase problem, so as to reduce the pitch variation amplitude. Based on the fact that the peak width parameter is greater than or equal to the preset width parameter, and the average return loss across the entire frequency band is greater than or equal to the preset average, it is determined to be a randomly distributed glitch problem, so as to reduce the spindle speed.

[0017] Compared with existing technologies, the beneficial effects of this invention are that by dynamically determining the initial center pitch based on the target operating frequency band and signal propagation speed, and constructing a regular mapping function based on this, the theoretical braiding pitch is no longer fixed, but changes continuously along the cable length according to a sine or linear law. As a result, the resonant frequencies at each local position are dispersed and cover the entire target operating frequency band. The phases of the signals at each reflection point are incoherently distributed and cannot be superimposed in phase. This fundamentally eliminates the problem of in-phase superposition of reflections at specific frequency points and the formation of resonant peaks caused by the periodicity of the braiding structure in traditional processes. This significantly improves the signal transmission performance of coaxial cables in a wide frequency range and is more effective at suppressing resonant peaks at the process level than the solution of simply increasing the number of braiding layers to enhance shielding effectiveness.

[0018] Furthermore, the sinusoidal function continuously modulates the braiding pitch with a sine wave whose wavelength is the spatial modulation period, making the braiding pitch smoothly and repeatedly change on both sides of the initial center pitch, so that the probability density of each local resonant frequency is evenly distributed throughout the target operating frequency band; the linear gradient function makes the braiding pitch monotonically and gradually change along the cable length, so that the local resonant frequency linearly sweeps from one end to the other to cover the target frequency band. Both modes can effectively disperse the resonant frequency, and can be flexibly selected according to the target operating frequency band width and cable production process conditions, taking into account both the resonance suppression effect and the adaptability of the production process.

[0019] Furthermore, this invention achieves precise dynamic tracking of the braiding pitch by maintaining a constant spindle speed and deriving a traction speed control function based on the kinematic equations of the braiding machine, thus corresponding the traction speed to the output value of the regular mapping function in real time. Simultaneously, it performs online prediction of the theoretical braiding pitch sequence within a preset time window, accurately quantifying the reflection suppression effect of the braided shielding layer in the target operating frequency band. This approach achieves closed-loop control in the production process more effectively than relying on offline testing to detect resonance problems, fundamentally preventing the outflow of substandard finished cables.

[0020] Furthermore, when the reflection suppression effect is unqualified, this invention can identify frequency band edge problems, single-frequency narrowband spike problems, broadband multi-peak or overall noise floor increase problems, and randomly scattered glitch problems by accurately extracting the features of the total return loss spectrum. Differentiated adjustment strategies are adopted to adjust the initial center pitch, reduce the variation amplitude, or reduce the spindle speed, so that the optimization of process parameters no longer relies on manual experience and trial and error, but establishes a clear inverse mapping relationship between the spectrum morphology and physical causes, and completes directional correction in one go, which greatly reduces the iterative cost of process debugging and the scrap rate. Attached Figure Description

[0021] Figure 1 This is a flowchart of the dynamic braiding process for reducing signal reflection in coaxial cables according to an embodiment of the present invention; Figure 2 This is a logic diagram illustrating the determination of the reflection suppression effect of the entire coaxial cable according to an embodiment of the present invention; Figure 3 This is a logic diagram illustrating the factors that determine the failure of reflection suppression effect as described in an embodiment of the present invention. Figure 4 This is a logic diagram for determining the internal problems of a frequency band as described in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] Please see Figure 1 As shown, it is a flowchart of the dynamic braiding process for reducing signal reflection in coaxial cables according to an embodiment of the present invention.

[0025] The dynamic braiding process for reducing signal reflection in coaxial cables according to embodiments of the present invention includes the following steps: Step S1: Determine the initial center pitch of the braided layer based on the target operating frequency band and signal propagation speed of the coaxial cable, and determine the regular mapping function of the braided layer based on the initial center pitch; Step S2: Determine the theoretical weaving pitch based on the aforementioned regularity mapping function, in order to determine the traction speed control function; Step S3: Determine the impedance sequence of the braided layer based on the theoretical braiding pitch sequence within a preset time window, so as to determine the total return loss generated by the braided shielding layer; Step S4: Based on the total return loss, determine the reflection suppression effect of the entire coaxial cable; Step S5: Determine the attribution for the unsatisfactory reflection suppression effect based on the spectral characteristics of the total return loss, so as to determine the adjustment strategy for the regularity mapping function.

[0026] In this embodiment of the invention, the fundamental reason for the generation of periodic resonance peaks is that the theoretical braiding pitch is constant, which causes the reflection phase of each rhomboid grid node to increase linearly along the cable length. When the signal frequency meets certain conditions, the reflection phases of all nodes differ by an integer multiple of 2π, resulting in coherent superposition. To solve this problem, the theoretical braiding pitch needs to change continuously along the cable length direction according to a certain rule, thereby destroying the phase period matching condition.

[0027] Specifically, the initial center pitch is determined based on the ratio of signal propagation speed to resonant wavelength, and is used as a reference value for the regular mapping function, so that the resonant frequency of the braided layer in the unmodulated state falls at the center of the target operating frequency band, ensuring that the local resonant frequency after dynamic modulation can symmetrically cover the entire target operating frequency band. The signal propagation speed is determined based on the ratio of the speed of light to the square root of the dielectric constant; The resonant wavelength is determined based on twice the center frequency of the target operating frequency band.

[0028] In this embodiment of the invention, the target operating frequency band of the coaxial cable is set to be from the lower limit frequency to the upper limit frequency, and the center frequency of the target operating frequency band is half of the frequency band sum, which is the sum of the lower limit frequency and the upper limit frequency.

[0029] As an optional embodiment, the target operating frequency band of a certain coaxial cable is set to 2GHz to 18GHz, the calculated frequency band sum is 20GHz, the center frequency of the target operating frequency band is determined to be 10GHz, the dielectric constant of the insulating material is known to be 2.25, and the speed of light in vacuum is taken as 3.0 × 10⁻⁶. 8 If the speed of signal propagation is m / s, then the speed of signal propagation is 2.0 × 10� 8 m / s, thus determining the resonant wavelength as 20mm and the initial center pitch as 10mm; this initial center pitch serves as the reference value for the regular mapping function, ensuring that the resonant frequency of the braided layer in the unmodulated state falls exactly at the center position of the target operating frequency band, 10GHz. This ensures that when the braiding pitch is dynamically adjusted according to a sinusoidal or linear gradient pattern, the local resonant frequency can be symmetrically dispersed around 10GHz, completely covering the entire target operating frequency band from 2GHz to 18GHz.

[0030] Specifically, the regular mapping function includes a sinusoidal function or a linearly gradual function, which makes the theoretical braiding pitch change continuously along the cable length direction according to a preset law, thereby dispersing the local resonant frequencies at different locations to cover the entire target operating frequency band, so as to destroy the phase matching condition of the reflected signals superimposed in phase, and fundamentally eliminate the resonant peak at a specific frequency point.

[0031] In this embodiment of the invention, the sinusoidal function is a mapping function that shows a continuous sinusoidal waveform change in the theoretical braided pitch along the cable length direction. Specifically, based on the initial center pitch, a variable that fluctuates according to a sinusoidal pattern is superimposed. The variable is controlled by the spatial modulation period, which represents the axial distance of the cable corresponding to a complete wavelength of the sinusoidal wave, i.e., the length interval between two adjacent points with the same theoretical braided pitch. The sinusoidal function is used to break the periodicity of the braided structure, so that the theoretical braided pitch changes smoothly and repeatedly with the cable length position.

[0032] In this embodiment of the invention, the linearly gradual function is a mapping function that shows a linearly monotonically continuous change in the theoretical braided pitch along the cable length direction. Specifically, starting from the initial center pitch, a fixed rate of change of theoretical braided pitch is added per unit distance along the cable length direction, so that the theoretical braided pitch monotonically increases or decreases with the cable length position. The absolute value of the product of the theoretical braided pitch rate of change and the total cable length is less than or equal to the maximum change range of the theoretical braided pitch. The linearly gradual function is used to break the periodicity of the braided structure, so that the theoretical braided pitch changes unidirectionally and continuously with the cable length position.

[0033] In this embodiment of the invention, the regularity mapping function is preferably a sinusoidal function.

[0034] As an optional embodiment, the initial center pitch is set to 10mm, the variation range is 2mm, and the spatial modulation period is 20000mm. Then, along the cable length, the theoretical braided pitch changes according to the following pattern: At the cable starting point, the theoretical braided pitch is equal to the initial center pitch of 10mm; as the cable length increases, the theoretical braided pitch gradually increases to 5000mm, corresponding to a sine function phase of π / 2, reaching a maximum value of 12mm; then it gradually decreases to 10000mm, corresponding to a phase of π, returning to 10mm; it continues to decrease to 15000mm, corresponding to a phase of 3π / 2, reaching a minimum value of 8mm; at 20000mm, corresponding to a phase of 2π, it returns to 10mm again, completing a full sine wave cycle. The above pattern repeats with a period of 20000mm, ensuring that the theoretical braided pitch continuously varies within the range of 8mm to 12mm in a sinusoidal waveform throughout the entire cable length. Through the sinusoidal mapping function, the local resonant frequency periodically sweeps across the range of 8.33 GHz to 12.5 GHz as the theoretical weaving pitch changes, symmetrically covering the target operating frequency band centered at 10 GHz, thereby effectively disrupting the phase matching condition of the in-phase superposition of reflected signals and eliminating the resonant peak at specific frequency points.

[0035] In this embodiment of the invention, the current cable length position is substituted into the regular mapping function, and the function output value is the theoretical braiding pitch that the braided layer should achieve at the current position.

[0036] In this embodiment of the invention, the spindle rotation speed is kept constant so that the traction speed of the braiding machine is dynamically adjusted according to the cable length position according to the traction speed control function.

[0037] Specifically, the traction speed control function is determined based on the theoretical braiding pitch, spindle speed, and equivalent braiding coefficient. More specifically, the traction speed control function is determined by multiplying the spindle speed by the theoretical braiding pitch and dividing by the equivalent braiding coefficient. This is used to dynamically adjust the traction speed according to the change of the theoretical braiding pitch in real time with the cable length position when the spindle speed is constant. This ensures that the braiding machine can accurately achieve the preset theoretical braiding pitch at different positions, thereby transforming the regular mapping function into the actual braiding geometry.

[0038] The equivalent braiding coefficient is determined based on the total number of spindles and the basic braiding angle. Specifically, the equivalent braiding coefficient is determined based on the tangent of the total number of spindles divided by twice the basic braiding angle. The basic braiding angle is the angle between the braiding wire and the direction of the cable axis.

[0039] In this embodiment of the invention, each rotation of the spindle forms a complete braided cross loop on the cable surface. Since the braided wires move along the spiral path, the equivalent traction distance in the cable axial direction is related to the theoretical braiding pitch and the tangent of the basic braiding angle. The intersection of half of the total number of spindles in the upper and lower layers is formed simultaneously in each spindle cycle to determine the relationship between the traction speed of the braiding machine, the spindle speed, and the theoretical braiding pitch. Specifically, the traction speed is directly proportional to the spindle speed and the theoretical braiding pitch, and inversely proportional to the equivalent braiding coefficient. When the spindle speed is kept constant, the traction speed increases with the increase of the theoretical braiding pitch and decreases with the decrease of the theoretical braiding pitch, thereby realizing dynamic control of the braiding pitch.

[0040] In this embodiment of the invention, the braiding machine is equipped with a traction device, which includes a traction wheel or a tracked traction belt, driven to rotate by an independent servo traction motor. The cable moves forward between the traction wheel and the pressure wheel through friction. The rotational speed of the traction motor directly determines the traction speed of the cable.

[0041] In this embodiment of the invention, the control system of the braiding machine reads the current cable length position in real time by integrating the encoder of the traction motor, and calculates the current required traction speed by substituting it into the traction speed control function; the control system converts the traction speed into the rotation speed command of the traction motor, and drives the traction motor to rotate according to the command through a speed closed-loop control algorithm, such as PID adjustment, so that the traction device pulls the cable forward at the target speed.

[0042] The control system updates the speed command every 10-100ms and uses an S-shaped acceleration / deceleration curve to limit acceleration. When the traction speed needs to change with the theoretical weaving pitch, the controller converts the speed command into an S-shaped trajectory with a maximum acceleration of 200mm / s². 2 To ensure a smooth transition and maintain the spatial distribution accuracy of the weaving pitch, thereby ensuring stable weaving tension and avoiding tension fluctuations caused by sudden speed changes.

[0043] As an optional embodiment, the total number of spindles is set to 32, the basic braiding angle is 45°, the calculated equivalent braiding coefficient is 16, and the spindle speed is set to 60 revolutions per minute. A sinusoidal mapping function is used, with the theoretical braiding pitch varying between 8mm and 12mm depending on the position. Substituting the above parameters, the traction speed is dynamically adjusted between 30mm / s and 45mm / s depending on the position. Specifically, when the cable reaches 5 meters, the theoretical braiding pitch reaches its maximum value of 12mm, and the traction speed is adjusted accordingly to 45mm / s; when it reaches 15 meters, the theoretical braiding pitch reaches its minimum value of 8mm, and the traction speed is reduced to 30mm / s. Through this dynamic adjustment, the traction speed can follow the changes in the theoretical braiding pitch in real time, ensuring that the actual braiding geometry remains consistent with the theoretical mapping function.

[0044] Specifically, the impedance sequence is determined based on the sum of the nominal characteristic impedance and the local impedance correction. The impedance sequence is used to characterize the local characteristic impedance distribution at each grid cell of the braided layer along the cable length direction, providing input parameters for subsequent calculation of the reflection coefficient of each grid cell and the total return loss of the entire cable based on the small reflection theory of transmission lines, thereby quantitatively evaluating the impact of the braided shielding layer on the signal reflection suppression effect.

[0045] The local impedance correction amount is determined based on the product of the proportionality constant and the natural logarithm of the cocution value of the braiding angle; in this embodiment of the invention, the proportionality constant is determined by the braiding yarn material, wire diameter and braiding density, and can be determined by calibration experiments, and its value ranges from 2 to 5 ohms, preferably 3.5 ohms.

[0046] The braiding angle is determined based on the theoretical braiding pitch and the cable core diameter. Specifically, the tangent of the braiding angle is equal to pi multiplied by the cable core diameter divided by the theoretical braiding pitch.

[0047] The nominal characteristic impedance is determined based on the outer diameter of the inner conductor, the inner diameter of the outer conductor, and the dielectric constant of the insulation layer. Specifically, the nominal characteristic impedance is directly proportional to the outer diameter of the inner conductor and inversely proportional to the square root of the inner diameter of the outer conductor and the dielectric constant. In this embodiment of the invention, the nominal characteristic impedance is a known parameter determined during the cable design stage, with a value of 50Ω or 75Ω, which can be directly used for the calculation of local characteristic impedance.

[0048] In this embodiment of the invention, the theoretical braided pitch sequence within a preset time window is converted into a corresponding local characteristic impedance sequence. The conversion process is based on the analytical relationship between braided geometry and characteristic impedance: the braiding angle of each grid cell is calculated based on the theoretical braided pitch and the cable core diameter, i.e., the angle between the braided wire and the cable axis; the local impedance correction of the grid cell is calculated based on the braiding angle to calculate the local characteristic impedance of a single grid cell in the braided layer, i.e., the nominal characteristic impedance of the cable without a braided layer plus the local impedance correction of the grid cell; through the above conversion, the theoretical braided pitch sequence can be mapped to a local characteristic impedance sequence for subsequent calculation of the cumulative reflection model; wherein, the impedance correction of each grid cell satisfies the following with respect to the braiding angle: the impedance correction is proportional to the natural logarithm of the cosecant of the braiding angle, i.e., the smaller the braiding angle, the more the braided wires tend to be aligned axially, and the more significant the disturbance to the characteristic impedance.

[0049] Specifically, based on the transmission line small reflection theory, when the impedance change is much smaller than the nominal characteristic impedance, the small signal reflection coefficient generated by each grid cell is approximately equal to the local impedance correction of that grid cell divided by twice the nominal characteristic impedance.

[0050] In this embodiment of the invention, the grid unit is a diamond-shaped grid node formed by the interweaving of adjacent upper and lower braided wires in the braided layer. Along the cable length direction, there is one grid unit within each theoretical braiding pitch period. The grid unit is the smallest repeating unit of the geometric structure of the braided layer. All grid units in the braided layer are arranged sequentially along the cable length direction. Each grid unit will generate a weak reflection of the transmitted signal once.

[0051] Specifically, the total return loss is determined by substituting the small signal reflection coefficient of each grid cell into the cumulative reflection model. Specifically, the total return loss is equal to the logarithm of -20, and its argument is the vector sum of the small signal reflection coefficient of each grid cell multiplied by the phase factor. The propagation constant in the phase factor is determined by the sweep frequency variable and the signal propagation speed, and the node position in the phase factor represents the axial distance from each grid cell to the cable input end.

[0052] Please see Figure 2 As shown, it is a logic diagram for determining the reflection suppression effect of the entire coaxial cable according to an embodiment of the present invention.

[0053] Specifically, the process of determining the reflection suppression effect of the entire coaxial cable includes: The minimum total return loss within the target operating frequency band of the coaxial cable is compared with the preset total return loss. If the minimum value is greater than or equal to the preset total return loss, then the reflection suppression effect of the entire coaxial cable is determined to be qualified. If the minimum value is less than the preset total return loss, then the reflection suppression effect of the entire coaxial cable is determined to be unqualified.

[0054] In this embodiment of the invention, the minimum value within the target operating frequency band of the coaxial cable represents the state of most severe reflection of the cable throughout the entire operating frequency band, which is the performance bottleneck of the cable; the preset total return loss is a qualified critical value determined based on system requirements and experimental data. By comparing the minimum value within the target operating frequency band of the coaxial cable with the preset total return loss, the dynamic braiding process can be evaluated most efficiently to determine whether it has successfully disrupted the periodicity of the braided structure, thereby achieving a quantitative, objective, and reliable qualification judgment of the reflection suppression effect.

[0055] In this embodiment of the invention, within the framework of transmission line theory, the braided layer can be considered as multiple tiny discontinuities distributed along the cable length. Each theoretical braiding pitch period corresponds to a local impedance change, which generates weak signal reflection. For the dynamic braiding process used in this invention, since the theoretical braiding pitch changes continuously with position, the impedance change corresponding to each pitch period is no longer constant, but exhibits a fluctuating pattern along the cable length. At this time, the total return loss of the entire cable can be calculated by the cumulative reflection model, that is, by superimposing the reflected signals generated by each discontinuity according to the phase relationship to obtain the comprehensive reflection characteristics in the frequency domain.

[0056] Please see Figure 3 As shown, it is a logic diagram for determining the dominant factors of unqualified reflection suppression effect according to an embodiment of the present invention.

[0057] Specifically, a characteristic analysis is performed on the target operating frequency band of the total return loss, and the dominant factors causing the reflection suppression effect to be unqualified are determined based on the spectral morphology. Obtain the peak frequency corresponding to the global minimum of the total return loss within the target operating frequency band, and compare the peak frequency with the target operating frequency band. Based on the fact that the peak frequency is less than the lower limit frequency, it is determined to be a frequency band edge problem, that is, the reflection peak appears at the low frequency end of the target frequency band, indicating that the initial center pitch is too large, resulting in the overall low dispersion range of local resonant frequencies, and the initial center pitch needs to be reduced. Based on the fact that the peak frequency is greater than the upper limit frequency, it is determined to be a frequency band edge problem, that is, the reflection peak appears at the high end of the target frequency band, indicating that the initial center pitch is too small, resulting in the overall high dispersion range of local resonant frequencies, and the initial center pitch needs to be increased. Based on the fact that the peak frequency is greater than or equal to the lower limit frequency and less than or equal to the upper limit frequency, it is determined to be an issue within the frequency band.

[0058] Please see Figure 4 As shown, it is a logic diagram for determining the internal problems of the frequency band according to an embodiment of the present invention.

[0059] Specifically, based on the issues within the frequency band, the -3dB bandwidth of the reflection peak is determined, which is the width of the frequency range extending from the peak frequency to both sides until the return loss value increases by 3dB. The spike width parameter is determined based on the ratio of the -3dB bandwidth to the peak frequency. Based on the fact that the peak width parameter is less than the preset width parameter, it is determined to be a single-frequency narrowband peak problem, indicating that there is harmonic coupling between the spatial modulation period and the target frequency band, and the spatial modulation period needs to be adjusted. Based on the fact that the peak width parameter is greater than or equal to the preset width parameter and the average return loss across the entire frequency band is less than the preset average, it is determined to be a problem of broadband multi-peak or overall increase in noise floor, indicating that the pitch change is too large and the pitch change needs to be reduced. Based on the fact that the peak width parameter is greater than or equal to the preset width parameter and the average return loss across the entire frequency band is greater than or equal to the preset average, it is determined to be a randomly scattered burr problem, indicating that the weaving process is unstable and the spindle speed needs to be reduced.

[0060] In this embodiment of the invention, the average return loss across the entire frequency band is the arithmetic mean of the total return loss values ​​at all sampling frequency points within the target operating frequency band. Specifically, the average return loss across the entire frequency band is the sum of the return losses at each frequency point divided by the number of sampling points.

[0061] As an optional embodiment, the target operating frequency band is set to 2GHz to 18GHz, the preset bandwidth parameter is 5%, and the preset average value is 22.5dB. If the measured peak frequency is 10.5GHz and the -3dB bandwidth is 0.3GHz, then the peak bandwidth parameter is 0.3 / 10.5≈2.86%, which is less than 5%, indicating a single-frequency narrowband peak problem, requiring adjustment of the spatial modulation period. If the peak bandwidth parameter is 8% and the average return loss across the entire frequency band is 20dB, then it is determined to be a broadband multi-peak or overall noise floor increase problem, requiring a reduction in the pitch variation amplitude. If the peak bandwidth parameter is 8% and the average return loss across the entire frequency band is 23.5dB, then it is determined to be a random scattered glitch problem, requiring a reduction in the spindle speed.

[0062] Specifically, when the attribution is a frequency band edge issue, the adjustment amount of the initial center pitch is determined based on the relative deviation of the peak frequency from the center frequency, and the adjustment range for each adjustment is less than or equal to 15% of the initial center pitch. Specifically, when the peak frequency is below the lower limit, the initial center pitch is reduced to shift the overall resonant frequency range upwards; when the peak frequency is above the upper limit, the initial center pitch is increased to shift the overall resonant frequency range downwards. In this embodiment of the invention, the relative deviation of the peak frequency from the center frequency reflects the degree to which the initial center pitch deviates from the ideal value, and determining the adjustment amount accordingly enables precise directional correction.

[0063] Specifically, when the attribution is a single-frequency narrowband spike problem, based on the single-frequency narrowband spike problem, the adjustment amount of the spatial modulation period is the product of the current spatial modulation period and the adjustment amplitude coefficient and the adjustment direction coefficient. The adjustment amplitude coefficient is 0.2 to 0.5, and the adjustment direction coefficient is +1 or -1. +1 indicates increasing the current spatial modulation period, and -1 indicates decreasing the current spatial modulation period, so as to break the harmonic coupling and eliminate the narrowband spike by changing the wavelength of the sinusoidal function.

[0064] In this embodiment of the invention, the cause of the single-frequency narrowband spike problem is that there is harmonic coupling between the spatial modulation period and the target frequency band. That is, the spatial frequency corresponding to the spatial modulation period and a certain frequency of the target frequency band satisfy an integer multiple relationship, causing the phases of all reflected signals to be exactly superimposed at that frequency. By adjusting the spatial modulation period and changing the wavelength of the sinusoidal function, the spatial frequency is shifted, thereby breaking the original harmonic matching condition, eliminating the phase matching relationship of the in-phase superposition of reflected signals, and finally eliminating the narrowband spike.

[0065] Specifically, when the cause is broadband multi-peak or overall increase in noise floor, the change amplitude coefficient is gradually reduced by a predetermined step size. The adjustment range is 10% to 20% of the current change amplitude coefficient. After adjustment, it is necessary to ensure that the change amplitude coefficient is greater than or equal to 0.1 to avoid the resonant frequency dispersion range being insufficient to cover the target operating frequency band due to the change amplitude being too small.

[0066] In this embodiment of the invention, the pitch variation amplitude directly determines the statistical variance of the local impedance correction. When the pitch variation amplitude is too large, the impedance correction of each grid cell fluctuates violently, resulting in too many impedance discontinuities along the cable length direction and excessive amplitude. In the spectrum, this manifests as an overall increase in the noise floor or multiple broadband peaks across the entire frequency band. By reducing the pitch variation amplitude, the impedance fluctuation amplitude is reduced, making the amplitude distribution of each reflected signal more uniform, thereby suppressing broadband multi-peaks and reducing the noise floor level.

[0067] Specifically, when the cause is attributed to random burrs, the spindle speed needs to be reduced. The new spindle speed is determined based on the product of the current spindle speed and the complement of the speed reduction coefficient, where the speed reduction coefficient is between 0.1 and 0.2. By reducing the spindle speed, dynamic tension fluctuations are reduced, the generation of random burrs is suppressed, and the smoothness of the return loss spectrum is improved.

[0068] In this embodiment of the invention, the root cause of the random burr problem is that the spindle speed is too high during the weaving process, which leads to increased tension fluctuations in each spindle strand and excessively fast movement speed of the braiding yarn. This causes the actual weaving pitch to deviate randomly from the theoretical value. Reducing the spindle speed can slow down the movement speed of the braiding yarn, reduce dynamic tension fluctuations, and make the yarn supply to each spindle more stable, thereby suppressing the generation of random burrs. When the spindle speed is reduced, the phase distribution of the reflected signal of each grid unit tends to be uniform, and the smoothness of the return loss spectrum is improved.

[0069] In this embodiment of the invention, the non-periodic pitch distribution generated by the dynamic braiding process is transformed into a quantifiable return loss index. Its physical basis comes from the small reflection theory of transmission lines: when the theoretical braiding pitch changes along the cable length, the local impedance change corresponding to each rhombic grid cell is no longer equal, and the weak signals generated by each reflection point carry different phase delays due to different propagation path lengths. By using the cumulative reflection model to vector-superimpose each reflection coefficient, the interference effect between reflected signals can be accurately reflected. That is, when the pitch change is sufficiently random, the phase of each reflected signal tends to be uniformly distributed in the frequency domain. The result of vector superposition is much smaller than algebraic addition, thereby achieving the suppression of resonance peaks. The preset time window is set to evaluate the statistical characteristics of the reflection suppression effect within a local length, avoiding smoothing out periodic residues due to an excessively long window or introducing random noise due to an excessively short window.

[0070] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dynamic braiding process for reducing signal reflection in coaxial cables, characterized in that, include: The initial center pitch of the braided layer is determined based on the target operating frequency band and signal propagation speed of the coaxial cable, and the regular mapping function of the braided layer is determined based on the initial center pitch. The theoretical weaving pitch is determined based on the aforementioned regularity mapping function, in order to determine the traction speed control function; The impedance sequence of the braided layer is determined based on the theoretical braiding pitch sequence within a preset time window, in order to determine the total return loss generated by the braided shielding layer. Based on the total return loss, the reflection suppression effect of the entire coaxial cable is determined; Based on the spectral characteristics of the total return loss, the attribution for the failure of the reflection suppression effect is determined, so as to determine the adjustment strategy for the regular mapping function; The attribution includes frequency band edge problems, single-frequency narrowband spike problems, broadband multi-peak or overall noise floor increase problems, and random scattered spike problems. The process of determining the adjustment strategy for the aforementioned regularity mapping function includes: The initial center pitch is adjusted based on the frequency band edge problem; Based on the aforementioned single-frequency narrowband spike problem, the spatial modulation period is adjusted; To reduce the pitch variation amplitude based on the aforementioned broadband multi-peak or overall noise floor rise problem; The problem of randomly scattered burrs is addressed to reduce spindle speed.

2. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 1, characterized in that, The initial center pitch is determined based on the ratio of signal propagation speed to resonant wavelength; The signal propagation speed is determined based on the ratio of the speed of light to the square root of the dielectric constant; The resonant wavelength is determined based on twice the center frequency of the target operating frequency band.

3. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 2, characterized in that, The regular mapping function includes a sinusoidal function that continuously varies with the theoretical braiding pitch along the cable length direction in a sinusoidal waveform.

4. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 2, characterized in that, The regular mapping function also includes a linearly gradual function in which the theoretical braiding pitch changes linearly, monotonically, and continuously along the cable length.

5. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 1, characterized in that, The traction speed control function is determined based on the theoretical weaving pitch, spindle speed, and equivalent weaving coefficient. The equivalent weaving coefficient is determined based on the total number of spindles and the basic weaving angle.

6. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 1, characterized in that, The impedance sequence is determined based on the sum of the nominal characteristic impedance and the local impedance correction. The local impedance correction amount is determined based on the weaving angle; The braiding angle is determined based on the theoretical braiding pitch and the cable core diameter.

7. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 6, characterized in that, The total return loss is determined by substituting the small-signal reflection coefficient of each grid cell into the cumulative reflection model. The small signal reflection coefficient is determined based on the local impedance correction amount and nominal characteristic impedance of each grid cell; The cumulative reflection model is the vector sum of the small-signal reflection coefficients of each grid cell multiplied by the phase factor.

8. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 1, characterized in that, The process of determining the reflection suppression effect of the entire coaxial cable includes: The minimum total return loss within the target operating frequency band of the coaxial cable is compared with the preset total return loss. Based on the fact that the minimum value is less than the preset total return loss, the reflection suppression effect of the entire coaxial cable is determined to be unqualified.

9. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 1, characterized in that, Obtain the peak frequency corresponding to the global minimum of the total return loss spectrum within the target operating frequency band, and compare the peak frequency with the upper limit frequency and the lower limit frequency; If the peak frequency is less than the lower limit frequency or greater than the upper limit frequency, it is determined to be a frequency band edge problem, and the initial center pitch is adjusted accordingly. Based on the fact that the peak frequency is greater than or equal to the lower limit frequency and less than or equal to the upper limit frequency, it is determined to be an issue within the frequency band.

10. The dynamic braiding process for reducing signal reflection in coaxial cables according to claim 9, characterized in that, The peak width parameter is determined based on the ratio of the −3dB bandwidth of the reflection peak to the peak frequency, and the average return loss of the entire frequency band is determined based on the return loss value of each sampling frequency point within the target operating frequency band. Based on the fact that the peak width parameter is greater than or equal to the preset width parameter, and the average return loss across the entire frequency band is less than the preset average, it is determined to be a broadband multi-peak or overall noise floor increase problem, so as to reduce the pitch variation amplitude. Based on the fact that the peak width parameter is greater than or equal to the preset width parameter, and the average return loss across the entire frequency band is greater than or equal to the preset average, it is determined to be a randomly distributed glitch problem, so as to reduce the spindle speed.

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