High-precision coaxial cable measuring system based on TDC7200

Abstract

The utility model discloses a high-precision coaxial cable measuring system based on TDC7200. The high-precision coaxial cable measuring system is characterized by comprising a square wave shaping module, a time measuring module and a data processing module, wherein the time measurement module is respectively connected with the square wave shaping module and the data processing module, the START end of the time measurement module accesses an input signal sent by the data processing module, and the rear end of the time measurement module is connected with the receiving end of the data processing module. The square wave shaping module comprises a high-speed buffer circuit, a coaxial cable interface and a comparator circuit, wherein the high-speed buffer circuit at the front end is connected with the data processing module, and the comparator module at the rear end is connected with the STOP signal input end of the time measuring module. And the data output end of the time measuring module is directly connected with the data processing module. According to the device, multiple times of measurement are carried out through a filtering algorithm, errors caused by manual analysis are reduced, and rapid and accurate measurement can be achieved through simple calibration before measurement.

Description

Technical Field

[0001] This utility model belongs to the field of applied electronic product technology and relates to a high-precision coaxial cable measurement system based on TDC7200. In particular, the combination of multiple functional circuits enables accurate measurement of the electrical characteristics of coaxial cables, and has broad application prospects in PCB loop impedance measurement, high-speed signal transmission line characteristic impedance measurement, and PCB signal integrity verification. Background Technology

[0002] Electrical performance measurements of coaxial cables are central to evaluating their signal transmission quality and reliability, and are widely used in communications, electronics, and high-frequency transmission fields. Key measurements include characteristic impedance, transmission loss (insertion loss and reflection loss), time-domain reflection characteristics, capacitance and inductance distribution parameters, as well as shielding effectiveness and signal integrity testing. These tests evaluate the impedance matching, signal attenuation, shielding capability, and high-frequency performance of coaxial cables using high-precision equipment such as vector network analyzers and time-domain reflectometers. Simultaneously, withstand voltage and insulation resistance tests ensure cable safety and insulation quality. Comprehensive electrical performance measurements provide technical support for the reliable application of coaxial cables in complex environments.

[0003] Time Domain Reflectometry (TDR), a key technology for evaluating the electrical performance of coaxial cables, has seen significant development in recent years, but it also faces several challenges. Common high-precision measuring equipment is expensive, limiting its adoption in small and medium-sized enterprises. Furthermore, equipment calibration and maintenance require substantial expertise and resources. In daily use, environmental noise, temperature, and humidity can all affect measurement results, and these factors must be considered or compensated for in practical measurements. Summary of the Invention

[0004] This invention solves the problem of impedance measurement in the electrical performance measurement of coaxial cables, providing a fast and accurate impedance measurement method. The purpose of this invention is to address the problems of high cost and inaccurate measurement in coaxial cable impedance measuring instruments.

[0005] To achieve the above objectives, the utility model discloses the following technical content:

[0006] The utility model discloses a high accuracy coaxial cable measurement system based on TDC7200, it is characterized by including square wave shaping module, time measurement module, and data processing module, wherein time measurement module is linked with square wave shaping module, data processing module respectively, and time measurement module START end accesses the input signal that data processing module sent, and back end is connected with data processing module receiving end.

[0007] The utility model discloses in the following detailed description:

[0008] A kind of high accuracy coaxial cable measurement system based on TDC7200, it includes square wave shaping module, time measurement module, and data processing module, to realize the measurement to coaxial cable length and characteristic impedance.The system utilizes TDR time domain detection method, using the square wave of STM32 of data processing module, square wave is input to the START end of time measurement module and the input end of high-speed buffer circuit simultaneously.The square wave is input to coaxial cable by connector after reducing its rising time by high-speed buffer circuit.Reflected signal and input signal are superimposed, and after being input to the STOP signal input end of TDC7200 time measurement module by comparator circuit, the time interval of START signal and STOP signal is measured by time measurement module;Time measurement module exports time result to data processing module, and actual time is calculated by data processing module, and the characteristic impedance and actual length of coaxial cable are calculated according to calibration data.

[0009] The hardware part of the utility model includes:

[0010] 1.Square wave shaping module is composed of NC7SZ125 high-speed buffer circuit and TLV3501 comparator circuit, and high-speed buffer circuit is used to reduce the rising time of the rising edge of square wave provided in STM32 in data processing module, and compresses it within 3ns-4ns.The driving ability of high-speed buffer circuit can also solve the attenuation of measurement signal on coaxial cable.Because reflected signal is a continuous rising process, and cannot meet the short rising edge required by time measurement module, so TLV3501 comparator is used to set comparison voltage, filter transmitted signal, only receive the square wave rising edge after the superposition of transmitted signal and reflected signal, and quickly reverse low level to high level at determined time.The output generated by the two circuits is respectively input to the START end and the STOP end of time measurement module.

[0011] 2.Time measurement module

[0012] The multi-time measurement module is mainly measured by TDC7200. TDC7200 is a precise time-to-digital converter (TDC) launched by Texas Instruments. It is mainly used for measuring the time difference from a start signal to a stop signal. It provides a picosecond level of time resolution, suitable for high-precision time measurement and supports multi-channel measurement. Compared with other TDC chips, it has higher resolution and lower cost. After the time measurement module measures the time, the data is sent to the data processing module with STM32F103 as the main processor through SPI communication, and the specific time value is obtained.

[0013] The utility model mainly solves the problem of impedance measurement in coaxial cable electrical performance measurement, mainly investigates the application of TDR time domain detection method in coaxial cable impedance measurement, focuses on verifying whether TDC7200 can be used for coaxial cable impedance measurement, the difficulty of the application lies in how to reduce the influence of environmental noise on signal processing and the influence of signal attenuation on the coaxial cable on the reflected signal, realize high-precision impedance measurement, simplify the calibration step and ensure the measurement accuracy. The utility model discloses the innovation lies in that a plurality of circuit modules are integrated, the application of TDC7200 in coaxial cable impedance measurement is realized, the accuracy of the measured data is improved, and the time and cost of coaxial cable impedance measurement are reduced.

[0014] The utility model test effect and test conclusion are as follows:

[0015] The system can effectively measure the length and characteristic impedance of the coaxial cable, and the error rate of the measured result and the actual value is within 0.2%.

[0016] The utility model discloses a kind of high-precision coaxial cable measurement system based on TDC7200, system has following several advantages:

[0017] (1) the device can accurately measure the characteristic impedance and actual length of the coaxial cable, and the error is less than that of other commonly used devices.

[0018] (2) the device measures multiple times through filtering algorithm, reduces the error caused by manual analysis, and can achieve rapid and accurate measurement through simple pre-measurement calibration.

[0019] (3) enough idle ports are reserved, so that other peripheral functions can be added at any time, such as measuring inductive and capacitive values.

[0020] (4) the system has the advantages of high measurement accuracy, convenient calibration operation, simple structure and low manufacturing cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a system structure schematic diagram of the utility model. DETAILED DESCRIPTION

[0022] The utility model is explained in detail below with reference to the drawings. The following implementation is only the best implementation of the utility model and cannot be understood as the limitation of the utility model. EMBODIMENT

[0023] The utility model discloses a kind of high-precision coaxial cable measurement system based on TDC7200, it is characterized by including square wave shaping module, time measurement module, and data processing module;Wherein time measurement module is connected with square wave shaping module, data processing module respectively, time measurement module START end accesses the input signal that data processing module issues, rear end is connected with data processing module receiving end.The square wave shaping module includes high-speed buffer circuit, coaxial cable interface and comparator circuit: wherein the high-speed buffer circuit of front end is connected with data processing module, the comparator module of rear end is connected with the STOP signal input end of time measurement module.The data output end of the time measurement module is directly connected with data processing module;Wherein time measurement module is by TDC7200 as main chip, and it is communicated with data processing module by SPI communication protocol, data processing module is by STM32F103RCT6 as main processor, and data processing result is printed to serial screen.

[0024] Square wave signal generated by data processing module is first passed through high-speed buffer circuit, and then is sent to coaxial cable.TDC7200 is collected and handled to reflection signal and transmission signal, and the interval duration is measured, and the data after analysis is sent to data processing module, and length and characteristic impedance are obtained by calculation, and then are sent to serial screen to display analysis result. Coaxial cable impedance measurement includes the following steps:

[0025] Data processing module generates square wave and is input to square wave shaping module;

[0026] Square wave handled by high-speed buffer circuit enters START end of time measurement module and coaxial cable simultaneously, and signal is reflected and superimposed at the impedance change of coaxial cable, and reflection signal is input to comparator circuit of square wave shaping module.

[0027] Reflection signal is input to the STOP end of time measurement module after shaping, and the time difference of START signal and STOP signal is measured by TDC7200, and the result is input to data processing module;

[0028] Data processing module displays to serial screen after data is calculated and handled.

[0029] Display measurement result uses as follows:

[0030] Turn on the system power, and connect the coaxial cable to be tested into the device.

[0031] Press the start measurement button, and wait for the measurement end light to turn on.

[0032] View the measurement result displayed on the screen. Embodiment

[0033] A system capable of checking the abrasion position of a cable, comprising a square wave shaping module, a time measurement module, and a data processing module; wherein the time measurement module is connected to the square wave shaping module and the data processing module respectively, the START end of the time measurement module is connected to the input signal from the data processing module, and the back end is connected to the receiving end of the data processing module. The square wave shaping module comprises a high-speed buffer circuit, a coaxial cable interface, and a comparator circuit; wherein the high-speed buffer circuit at the front end is connected to the data processing module, and the comparator module at the back end is connected to the STOP signal input end of the time measurement module. The data output end of the time measurement module is directly connected to the data processing module.

[0034] The square wave signal generated by the data processing module is first sent to the high-speed buffer circuit and then to the cable to be tested. One or more reflected signals are collected and processed, the interval time between the reflected signal and the transmitted signal is measured, and the result is sent to the data processing module after analysis. The length of the abrasion position from the cable inlet is calculated and sent to the serial screen to display the analysis result.

[0035] The steps for checking the abrasion position of the cable include the following:

[0036] The data processing module generates a square wave and inputs it to the square wave shaping module.

[0037] The signal is reflected and superimposed at the impedance change (abrasion position) of the cable, and the reflected signal is input to the comparator circuit of the square wave shaping module.

[0038] The reflected signal is input to the STOP end of the time measurement module after shaping, and the time difference between the START signal and one or more STOP signals is measured by the TDC7200, and the result is input to the data processing module.

[0039] The data processing module displays the processed data on the serial screen.

[0040] The measurement result is displayed as follows:

[0041] Turn on the system power, and connect the cable to be tested into the device.

[0042] Press the start measurement button, and wait for the measurement end light to turn on.

[0043] View the measurement result displayed on the screen.

[0044] The results show that the system can accurately measure the characteristic impedance of the cable, and the measured data can be used to calculate the characteristic impedance and the specific length of the coaxial cable (error 0.2%). After continuous measurement, the specific position of the impedance change in the cable (±2 cm) can be calculated from the measured data, effectively reflecting the degree of wear of the cable.

Claims

1. A high precision coaxial cable measurement system based on TDC7200 characterized by The application relates to a square wave shaping module, a time measurement module and a data processing module; wherein the time measurement module is connected with the square wave shaping module and the data processing module; the START end of the time measurement module is connected with an input signal emitted by the data processing module, and the back end of the time measurement module is connected with the receiving end of the data processing module; the square wave shaping module comprises a high-speed buffer circuit, a coaxial cable interface and a comparator circuit; wherein the high-speed buffer circuit at the front end is connected with the data processing module, and the comparator module at the back end is connected with the STOP signal input end of the time measurement module; the data output end of the time measurement module is directly connected with the data processing module.

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