Patent GB-500647-A (GB)
Title: Improvements relating to systems for transmitting indications
Filed: 1937-05-07
Abstract: 500,647. Electric control systems. SPERRY GYROSCOPE CO., Ltd., HARDING, W. G., 'and NISBET, R. H. May 7, 1937, No. 13125. [Class 40 (i)] Indications are transmitted from an instrument such as a master compass to a repeater, the rotor of which is so connected to the rotor of a transmitter that they turn through angles at all times proportional to each other, and a correction (such as a correction for Northsteaming-error) is introduced by causing relative angular movement between the normally stationary parts of the transmitter and the repeater. The signals from the transmitter operate remote receivers. In the arrangement shown in Fig. 1, the compass 1 operates a step-by-step transmitter 2 which transmits currents to the stator of a repeater motor 5. The shaft 6 of the motor 5 is directly coupled to that of a relay transmitter 7. A " true " compass card is driven by a worm 10 on the shaft 6. The correction for the Northsteaming-error is determined by means of an eccentric 14 which rotates with the card about an axis 17 and oscillates a lover 15 about a pivot 16. Specifications 433,494, and 461,424, [both in Group XX], describe suitable correction devices. A gear sector 18 carried by the lever 15, engages a rack 19 which rotates the stator of the motor 5 and thereby applies the correction to the transmitter 7 and the compass card. The corrected reading of the compass is indicated by a fixed index 13 and the uncorrected reading by an index 29 carried by a parallelogram linkage 30, 31 and 32. In the modification shown in Fig. 2, the correction is applied to the stator of the transmitter motor 7. The eccentric 14 engages a member 201 which slides between guides 22<1> and 21<1> as the cam rotates. The member 20<1> is adjustably secured to a cursor 30 by a thumb screw 32 and carries a rack 33 which turns the stator of motor 7. The eccentric corrects for the North-steaming- error whilst adjustment of screw 32 corrects for the damping error. In this modification the index 29 for the uncorrected reading is fixed and the index 13 for the corrected reading is carried by a member rotated by the rack 34 and gear sector 36 as corrections are applied. In the modification shown in Fig., 3, the correction is applied as in Fig. 1, but the transmitter 7 is driven by a servomotor 34. Signals from a "selsyn" transmitter 2 are applied to the rotor of a receiver 5<1> through slip rings 9. The stator of the receiver 5<1> is connected through a synchronizer 38 and an amplifier 37 to the servomotor 34. The receiver 5<1> acts as a rotary transformer and supplies a control voltage to the servomotor. The follow-up system used in the compass may be of the kind described in Specification 417,995 or 480,115 and supplies a voltage which is a measure of the lag between the directional and follow-up elements of the compass. This voltage is added to that supplied by the receiver 5 so that the final reading is also corrected for lag of the follow-up member. The synchronizer 38 in Fig. 3, enables the compass element and card to be adjusted to the same uncorrected reading before the apparatus is put into use. Specifications 500,648 and 500,652 also are referred to.