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ÜBER DIE DIMENSIONIERUNG UND DAS VERHALTEN VON REGELKREISEN IM SEISMISCHEN VERSTÄRKER *
Author(s) -
WACHHOLZ HELMUT,
WEISSENSTEINER KARL
Publication year - 1964
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1964.tb01907.x
Subject(s) - limit (mathematics) , constant (computer programming) , time constant , signal (programming language) , amplifier , physics , energy (signal processing) , automatic gain control , electronic circuit , computer science , electrical engineering , mathematics , mathematical analysis , quantum mechanics , engineering , optoelectronics , cmos , programming language
The purpose of the automatic gain control in seismic amplifiers is to balance the slow decrease of the signal in such a manner that its energy does not exceed the capacity of the recording system. At the same time the interesting seismic content of the signal has to be preserved as undistortedly as possible. At first, the technical data of AGC circuits are calculated. The characteristic curves of circuits with one, two, and three time constants are computed. In circuits with two and more time constants an oscillating of the AGC is possible. In order to guarantee aperiodic operation, the ratio of the time constants must not fall below a certain value. As long as these technical conditions are complied with, the free choice of the largest time constant remains open and can be accommodated to the geophysical conditions. From the endeavour to balance the slow decrease of the signal as well as possible, an upper limit for the choice of the time constants can be derived. A lower limit is obtained from the condition that the seismic content of the signal has to be preserved. The determinant time constant should lie between the two limits and differ from them as much as possible. Finally, the problem of the amplifier “squeezed” by energy pulses is touched.