Wide band signal processor coping with wide dynamic range - has linear preamplifier supplying logarithmic amplifier and A=D converter for digitalised test signal

摘要

The signal processing method is esp. for echo signals arising in ultrasonic fissure fault testing of materials. An analogue test signal from a detector is amplified in a linear preamplifier. After this amplification the test signal is directly logarithmically digitalised. A logarithmic amplifier, rectifier and a-d converter can be made into an integral unit from which the components cannot be separated out. The logarithmic characteristic of a selected dynamic can be created from the logarithmic characteristics of separate, identical modules. The a-d converter specification can be a conversion rate of 150 MHz and a dynamic of 60dB with a resolution of 0.5 dB. An analogue input signal of 5 volts provides a digital output of 60, and an input of 2.5 volts the number 54. This range is coded in 7 bits the eighth representing the polarity.