GB1154481A - Digitiser - Google Patents

Abstract

1,154,481. Selective signalling. HOLLANDSE SIGNAALAPPARATEN N.V. 16 June, 1966 [16 June, 1965], No. 26897/66. Heading G4H. A system for digitizing a shaft position of the type in which coarse and fine gear-coupled synchros each produce a group of three voltages representative of their rotor positions, each group of three voltages being appropriately combined, limited, amplified and differentiated so as to produce a single pulse differentially timed within a cycle of the single phase supply fed to the synchro rotors, and in which the durations between each differentially timed pulse and a reference pulse are determined by counting relatively high-frequency clock-pulses, is characterized in that (1) in both the coarse and the fine channels counting commences with the earlier of the first reference pulse and the first differentially timed data pulse that occurs after a " start to digitize " pulse has occurred and at the end of the period the count reached is either unmodified if the reference pulse initiated the count or is complemented if the differentially timed pulse initiated the count; (2) the coarse and fine counters have overlapping stages and at the end of both counts the non-overlapping stages of the coarse counter are modified in accordance with any carries that would occur from the overlapping stages if they were advanced to coincide with the overlapping stages of the fine counter; and (3) the coarse counter is reset to a negative number (e.g. -2 or 14) so that reverse stepping during the correction phase, is never necessary.