| 摘要 |
<p>1533221 Analogue to digital conversion HAWKER SIDDLEY DYNAMICS ENG Ltd 17 Nov 1975 [15 Aug 1974] 35956/74 Heading H3H An a-d and d-a converter circuit comprises a V.C.O. which outputs a frequency dependent on its input value. In converting a voltage on line I to digital output from a counter IS, multiplexer 2 passes the voltage to the oscillator which outputs a frequency via clocked gate G3 to the counter. In this mode either of two feedback routes, via gate G1 and frequency#analogue converter 7 or via frequency divider 10 and gate G2 may be used, the second extending the range of the converter. Amplitude modulated frequency input is halfwave rectified in the multiplexer and converted in a similar manner. Frequency modulated input is applied to multiplexer 16, then to a phase comparator 11, which is in a phase locked loop comprising the divider 10 and input multiplexer 2, this stabilizes the V.C.O output as a multiple of the input frequency, the gate G3 and counter integrating this to give a digital output. In its d#a mode a reference frequency 17 derived from clock 13 is applied to the multiplexer 16 and the phase locked loop stabilizes at frequency dependent on the ratio set in divider 10 by the digital input. A f.m. output is obtained at 20 and a d.c. output at 19.</p> |
