| 摘要 |
<p>1529851 Waveform generators GENERAL INSTRUMENT MICROELECTRONICS Ltd 8 Jan 1976 [10 Jan 1975] 1203/75 Heading H3H [Also in Division G4] In a 2 out of 8 tone generator, clock pulses are frequency divided in dividers 3A, 3B whose division ratios are set in accordance with respective ones of the 2 frequencies to be generated, the divided clock pulses are fed to stochastic conversion means which produces respective pulse trains whose repetition frequencies vary at the respective frequencies and these are then interleaved in time and filtered to produce the desired 2 out of 8 tone signal. In Figs. 1A, 1B, a keyboard (not shown) marks one of leads 13A and one of leads 13B to set the division ratios of dividers 3A, 3B. For some frequencies, non-integral division is used, this being achieved by varying an integral division factor by unity for alternate cycles, Fig. 3 (not shown). The outputs of the dividers are fed to respective sine-wave value generators 4A, 4B which produce sequences of 3-bit binary numbers: 6, 3, 1, 0, 1, 3, 6 and positive and negative half cycle signals to respective comparators 6A, 6B, receiving 4-bit pseudo-random signals from a noise generator 8, and outputting respective stochastic pulse trains whose instantaneous frequencies vary in an approximately sinusoidal manner at the desired 2 of 8 frequencies. These pulse trains are interleaved in circuit 9, Fig. 12 (not shown) which includes means for varying the proportions in which the trains are interleaved to provide adjustable preemphasis for the higher frequency. Details of all the circuit blocks and frequencies are given.</p> |
