Data handling systems

Claim 1

A date handling system comprising a scanning means for scanning a number of analogue signals from independent input lines, cyclicly a test signal injection means by which test signals are interleaved between at least two of said number of analogue signals, an analogue to digital converter means receiving said analogue signals and said test signals and delivering equivalent digital output signals, a primary measurement shift register (PMR) connected to receive said digital output signals and operable to overwrite or recycle said digital signals after each complete scan made by the scanning means with freshly scanned signals, signal extraction means for extracting signals from the shift register (PMR), comparator means for receiving extracted signals and comparing them with stored threshold data to yield a binary 1 or 0 according to the value of each extracted signal relative to said threshold data, a primary status register (PSR) in which the digital bits yielded by the comparator means are assembled as a binary word in which the positions of bits are advanced by one space on each cycle of the scanning means and a majority voting circuit responsive to a majority m out of n status bits indicating an out of tolerance condition.