Patent GB-733024-A (GB)
Title: Improvements in or relating to navigation aid apparatus
IPC: G01C19/32
Filed: 1953-06-12
Abstract: 733,024. Aircraft indicators. SPERRY CORPORATION. June 12, 1953 [June 14, 1952], No. 16232/53. Class 4 [Also in Groups XXXV and XL (c)] An aircraft radio navigation system for enabling an aircraft to approach and follow a desired course line consists of means for obtaining a signal related to the displacement of the craft from the desired course, means for deriving a second signal dependent on the rate of change of the craft's displacement from said course line, an integrator for integrating the displacement signals and combining means combining the first, second and integrated signals to produce a resultant control signal for application to an indicator or autopilot. In one embodiment a gyroscope spinning about a normally vertical axis in a suitable casing is situated inside a hollow truncated sphere indicator 7. The casing is pivoted about an axis 2 in bearings 41 carried by a yoke 3 rotatable about the axis 2<SP>1</SP> in bearings 5 and 6. Thus the horizon line 9 and scale 8 in conjunction with the fixed reference mark 10 indicate the roll and pitch of the craft. There is also provided a movable index 11 passing across the front of the indicator and moved about the axis 2 by meter movement 18 carried by yoke 13 mounted for rotation about axis 2<SP>1</SP> by movement 20. Restoring springs 18<SP>1</SP> and 50 are provided for normally maintaining index 11 in coincidence with reference 10 but it is deflected about the axis 2 in accordance with deviations from a desired glide path as determined by receiver 19 and about the axis 2<SP>1</SP> in accordance with signals relating to deviation in azimuth from a desired course. These are obtained by feeding the output of localizer receiver 25 to ring modulator 26 to give a corresponding A.C. signal amplified at 27 and fed to further amplifier 28 to provide a displacement signal. The output of amplifier 27 is also fed through isolating stage 29 to motor amplifier 30 controlling motor 31, which drives generator 32<SP>1</SP> giving an A.C. output proportional to speed which is supplied to rate amplifier 34 and also fed back to the input of amplifier 30. A feed-back path is also provided from generator 35 driven at a reduced speed from motor 31 to oppose and wipe out the input signal as soon as the angle through which the motor has been turned is adequate. The rate signal derived from unit 34 which is proportional to the integral of the deviation is added to the deviation and applied over lines AB to movement 20. If the pilot flys to maintain indicator 11 in coincidence with line 9 the craft will asymptotically approach the desired course. In another embodiment of the invention (Fig. 2, not shown) the output from the localiser receiver after conversion to an A.C. signal is fed to the indicator movement 20, (Fig. 1) and also to a motor driving one element of a selsyn generator which is fed electrically from a gyromagnetic compass take off generator. The output element of the generator is positioned manually to correspond with the compass bearing of the course to be flown and the output itself is combined in series with the A.C. signal mentioned above and applied to the indicator movement. Specifications 480,776, [Group XXIX], and 591,400, [Group XX], are, referred to.