GB1404769A - Waveform synthesisers - Google Patents

Abstract

1404769 Waveform synthesiser BRITISH AIRCRAFT CORP Ltd 1 Dec 1972 [8 Dec 1971] 57075/71 Heading H3H In a waveform synthesizer, the ordinates of the waveform are stored in binary form in a memory store and read out in parallel at a fixed frequency into a multibit digital to analogue converter in a predetermined sequence. A square wave of the same frequency is fed to an additional least significant bit input of the A/D converter and its phase is inverted at the peaks and troughs of the resulting analogue waveform so that it is made "1" during the second half of each upward step and the first half of each downward step to smooth the resulting waveform. The ordinates are entered into store 10 in 8 bit parallel binary on lines D 1 -D 8 from computer 11 under the control of addresses and enabling signals from clocked counter 13. During waveform generation the six most significant figures are clocked from the addressed store section via register 16 to D/A converter 15. The two least significant figures are processed in clock pulse regulator 17 to give a square wave which is "1" during the second half of each upward step and the first half of each downward. This is supplied to the seventh least significant input of the D/A converter. The counter 13 may count alternately up and down for symmetrical waveforms.