IMPROVEMENTS OF AND RELATING TO THE STRATEGY DOWN TROGNITY DEVELOPMENT SYSTEM.

摘要

1508376 Analogue-to-digital conversion UNITED TECHNOLOGIES CORP 12 May 1975 [13 May 1974 (2)] 19794/75 Heading H3H Drift in a strapdown gyroscope is measured by sinusoidally modulating the rotational speed of the gyroscope, picking off a signal from the gyroscope containing a modulated true angular rate component and an unmodulated drift component, which is extracted. In Fig. 1, the wheel speed modulator 28 is a digital sine wave generator (Fig. 5, not shown) see Specification 1,508,377. The gyro 10 is torqued by a series of D.C. pulses of frequency proportional to the angular rate. These pulses are also fed on line 18 to a drift calculator, Fig. 2, in which they are multiplied, 34, by a factor (M + 1) during the negative half cycles of the modulation and (M - 1) during the positive half cycles, the multiplied signals being counted up and down respectively in a counter 52 from which the drift is read out into a register 62 after a preset, 46, number of complete modulation cycles. Theory given. Alternatively, filters may be used to separate the true angular rate and drift components (Fig. 4, not shown).