| 摘要 |
<p>1512612 Analogue to digital converter, pulse width modulator STANDARD TELEPHONES & CABLES Ltd 1 April 1976 13160/76 Addition to 1450989 Headings H3H and H4L In an analogue-mark/space ratio converter the analogue input is applied via R4 and Rl to a threshold device 10, which outputs to the conditioning input of first clocked flip-flop 11 the complementary output of which conditions a second clocked flip-flop which gives a mark/space output from its normal output. Both flip-flop outputs are fed back via integrating means to summing points with the analogue input so that in an idling condition the mark/space ratio is unity. In modifications the feedback from the second flip-flop may switch a constant current source to an integrator, and the centring kept constant by a voltage on a capacitor derived from the most significant bit of a counter operating on mark/ space output. To select a desired offset the counter may be reset to a non-zero condition. (For figure see next page)</p> |
