The Design Of Narrow-pulse Time Domain Reflectometry

In this paper, we give a pulse reflection method, which can detect the location of the broken point in the cable precisely without damage based on analysis of transmitting theory and transmitting character of the electromagnetic wave in the transmission line.Based on time domain reflectometry (TDR) and pulse reflection method we design the narrow-pulse time domain reflectometry. This instrument has some innovative characters comparing to early TDR. Firstly, it uses narrow-pulse transmitting circuit, so measuring blind spot should be less than 3m theoretically. Secondly, it can identify and process reflected wave automatically and display the location of the broken point on the control board dispensing with manual work. Finally, signal processing of TDR uses 100MHz frequency as its clock for counting, so the measuring differentiation rate should be 1m.The principle of conductor breakpoint location non-destructive testing was validated through testing the cables of various lengths. Moreover, distributed parameter circuit models were established. In addition, the testing of breakpoint location was simulated and simulation result coherent with experimental result well.This instrument is used to locate the broken point of conduct. It can measure open circuit fault in types of transmission line such as aerial cable, lines of communication etc. The whole system has many features: simple operation, high accuracy, broad prospect of application and market.