A Research Of The Transient Pulser In Radar Imaging Well-Logging

Transient pulse radar imaging logging technology is a new geophysical method,which is based on the deepening and development of borehole radar technology. As the emitting part of the transient pulse radar imaging logging technology, which is very narrow pulse width, related to resolution of target detection and the distance of target detected, mainly in nanosecond pulse width, rich spectral content and the amplitude is hundreds of volts. At the same time as an underground detection equipment is required to have some advantages,which is a light weight, small size, pulse has high stability waveform. This paper studies the transient pulse source mainly from pulse width,amplitude, size, and several aspects of the pulse waveform stability.The research of this paper is transient pulse source, the first step is to study the theories, which is studied the time domain and frequency domain characteristics of Gauss signal, and than we should analyze the characteristics of semiconductor solid-state switching device, which can generating a Gaussian signal, and by comparing the properties of the whole system,we decided to use Marx avalanche transistor circuit as a basic circuit pulses, MARX circuit combining the reflected rays coupling theory or differential circuit can be formed first order Gaussian pulse what we needed. Use Marx avalanche transistor circuit as a basic circuit, the transient pulse circuit is consist by solid state components. Through the simulation software Pspice,we can simulate the working state of the circuit, and summed the factor,which influence the output waveform, followed make the PCB production according to the selected device, the volume requirements. Finally, the transient pulse source circuit is processed according to the design. Finally, in accordance with the development of design and processing of the transient pulse source circuit, appears during debugging of the circuit device heating and other issues, has taken a series of measures and its success will be resolved.Eventually produce a pulse, the amplitude of the transient pulse source line with two design goals, time-domain waveform and spectrum and transient pulse source is analyzed, smoothness and symmetry of the waveform is good.Secondly,we do a series of applied research experiments of the transient pulse source, experimental waveform shift aimed sporadic phenomenon shift output waveform analysis for data logging system provides a culling after error message basedanalysis; high-temperature aging experimental analysis of the status of their work in high temperature conditions, and the presence of the cause of the problem is analyzed, it proves transient pulse source can maintain a good working state at a temperature of90 ℃; the article describes the radar imaging logging system metal plate reflection experiment proved that the system can identify the object.Finally, the transient pulse sources do a high temperature test, aging the circuit and analyze the working state of it in high temperature conditions, and the problem in this experiment is analyzed. Another experiment is matched debugging,which should combined Pulse signal source and transceiver antenna of Logging the transient pulse radar. The bandwidth and the center frequency of transient pulse source, transmitting and receiving antennas, should match well, also the output impedance, there are the key of how to obtain a complete reflected waveform.