Author: Noyafa–Cable Tester Manufacturer
Why does the cable fault tester use internal impedance balance technology? Internal impedance balance technology in the cable fault tester Will the tester use the internal impedance balance technology? The internal impedance balance technology in the cable fault tester 1. Why use the internal impedance balance technology? The pulse sent by the pulse reflection instrument has a certain width, because the output impedance of the instrument does not match the cable wave impedance , the transmission pulse obtained on the cable or sensed by the receiving circuit of the instrument drags a tail, and the reflected pulse at the fault point overlaps the transmitted pulse, which will cause a significant measurement blind area; the instrument receives and displays the transmitted pulse and reflected pulse on the display at the same time. When the fault point is far away, the amplitude of the transmitted pulse is much larger than the reflected pulse at the fault point. For example, by increasing the gain of the amplifier to achieve the purpose of increasing the amplitude of the reflected pulse at the fault point, the signal amplifier circuit will be saturated and the so-called so-called“block”Phenomenon. The purpose of using internal impedance balance technology is to compress or even eliminate the transmitted pulse received (and displayed) by the instrument, thereby reducing or eliminating the measurement dead zone, and can maximize the gain of the amplifier circuit and increase the amplitude of the reflected pulse at the fault point. without making the amplifier circuit“block”Causes the pulse reflection waveform to be distorted. 2. Internal impedance balance technology The instrument transmits pulses to the cable under test and the internal balance network at the same time, and the signal received by the instrument is the difference between the signal on the cable under test and the internal balance network. Adjust the parameters of the internal balance network to make it match the cable. If the wave impedance is the same, the signal generated by the sending pulse on the cable and the internal balance network is the same, the signal received by the instrument is zero, and when the reflected pulse arrives, there is no signal on the internal balance network, and all the reflected pulses are sent to the receiving circuit of the instrument go up.
Instruments with or without internal balancing act to measure waveforms.
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