APPARATUS FOR DISPLAYING AN EXTREME VALUE AMONG A SUCCESSION OF DIGITAL VALUES AND METHOD OF TESTING PULSE CODE MODULATION EQUIPMENT USING SUCH APPARATUS

摘要

1485616 Testing PCM channels POST OFFICE 4 July 1974 19143/73 HeadingGlU [Also in Division G4] A succession of digital values, e.g. from a selected PCM multi-plex time slot, are entered in a register 5 and are transferred to a further register 8 when the value in register 5 exceeds that in register 8, and when a predetermined number of values entered in register 5 are all less than that in register 8, a counter 21 resets register 8 and is itself reset. The apparatus is used for testing PCM equipment to check the A/D conversion of a known amplitude test oscillation applied to the channel under test by displaying, 24, the peak value. The contents of register 8 are transferred to a display register 20 whenever the value in register 5 is equal to that in register 8 or when the count in counter 21 reaches a threshold level, whereby the display can be made to follow a drop in signal level. A sign selector switch 26 enables a selected polarity of signal to be tested.