Method and arrangement for generating an analog signal, which, by means of the difference between two vera sufficient lichen digital quantities depends

摘要

1,186,528. Digital/analogue converters. CEAPEREGO S.p.A. 2 Oct., 1967 [4 Oct., 1966], No. 44702/67. Heading G4H. The difference between two digital numbers, by which counters C1-C2, C3-C4 are preset, is determined in analogue form by feeding clock pulses to the counters which, when they reach their maximum counts, apply signals to generators G1, G2. The generators G1, G2 feed squarewave signals to a phase discriminator D, the output voltage from which varies in accordance with the time interval between its inputs. The apparatus may be used for positioning a movable member, the required and actual positions of which are entered by switches I 1 -I 6 , I 7 -I 12 (Fig. 4) into counter C 1 -C 6 , C 7 -C 12 respectively. Each counter comprises three parts, each of two decades, each part being fed with clock pulses of frequency fo. The discriminator D1 receiving the signals from generators G1, G4 associated with the two most significant digits of each counter is first used to control the member until its output becomes zero when the output from the discriminator D2 is used. In the embodiment of Fig. 5 (not shown), all except the most significant part of the counters have three decades, the least significant decade in one part being repeated as the most significant decade of the next part. A frequency divider is included in the most significant part of each counter to equalize the output frequencies of the pulse generators.