METHOD OF AND APPARATUS FOR PROCESSING WIDE BAND SIGNAL HAVING LARGE DYNAMIC RANGE

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.