GB1385891A - Recovery of data from magnetic wire recordings - Google Patents

Abstract

1385891 Data storage systems HAWKER SIDDELEY AVIATION Ltd 2 Feb 1972 [2 Feb 1971] 3728/71 Heading G4C Serial data from a magnetic wire flight recorder is supplied to an interface circuit for recording on multichannel magnetic tape which may subsequently be replayed at a higher rate. The serial input data is gated at 28 with high frequency clock pulses, and detectors 22, 23 compare the gated data, having a pulse at each transition, with ¥-bit duration pulses supplied by a divider 17 in order to derive bit clock and bit value pulses. The detected data pulses are entered in a register 48, each word assembled in the register 48 being gated out by a word pulse produced by detection at 18 of each interword gap. The input data comprises a plurality of channel words called a frame, the interframe gap being detected at 19 for gating out the contents of a frame code counter 44 which registers every fifth or tenth frame. The output channel words and frame codes are converted to NRZ and supplied to the write heads of a tape recorder. Manual switches 29 may be set to select a particular channel word for entry into a register 53 via gates 57 under control of a word counter 30. A counter 47 is then stepped by the high frequency clock pulses until the count equals the selected channel word in register 53, the number of pulses being counted and decoded at 45 for display 54 over approximately one frame period. A reference word recorded on the wire may be selected by switches 29 for comparison with a reference word set by switches into counter 47, which is then clocked in either direction to reach equality with the reference word in register 53, any error being displayed at 54. A comparator 46 produces an output to operate an audible alarm if the error exceeds a tolerance set up on switch 40.