DIGITAAL-ANALOOGOMZETTER, ALSMEDE EEN TELEVISIE-ONTVANGER MET EEN AFSTEMSCHAKELING, DIE DE DIGITAAL-ANALOOGOMZETTER BEVAT.

摘要

1498369 Digital to stochastic converter; TV receiver station selection PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 5 April 1976 [8 April 1975] 13677/76 Headings H3H and H3Q In a digital to stochastic converter the n-bit input is compared at 1 to a periodically recurring series of n-digit numbers C, in which series the m most significant digits form a number D which increases or decreases monotonically to a maximum or minimum repetitively and the n-m other digits are the reverse order of a further number which increases or decreases monotonically at every D cycle, the numbers having constraints n#m, m > 1 n#3. In the embodiment the numbers C are generated by an n-bit counter B with its m least significant bits being compared with the m most significant input bits, the remaining n-m bits being reversely presented to the remaining comparator inputs. The stochastic output has a maximum of 2n-m pulses of variable width which may be converted to analogue by a low pass filter. The converter is also described in relation to a timing circuit for a television receiver where the derived analogue voltage is applied to the tuning signal input of a tuning circuit. The tuning signal is selected by a bi-directional counter (11, Fig. 3, not shown) including three integrated 4-bit counters.