DE1773707

1,204,763. Gyroscopic apparatus. SINGER GENERAL PRECISION Inc. June 6, 1968 [July 18, 1967], No.27077/68. Heading G1C. Airborne vehicle navigation apparatus comprises a platform 12, which for example comes a Doppler radar antenna and which is mounted for stabilization in a horizontal position; a gyro 210 having a vertical spin axis generating signals by way of synchro-transmitters 220, 222 representative of the vehicles' angular deviations from the horizontal about the vehicle pitch and roll axis, the signals being used to stabilize the platform 12, which also carries an inertially stabilized platform (not shown) by means of which, by comparison of the signals from the inertially stabilized platform and the Doppler radar, error signals are derived indicative of angular deviations of the platform 12 from the horizontal the error signals being applied to torques 215, 216 for continuous correction of the gyro 210. In this way since an inertial platform is used for erection of the gyro 210, the gyro may be of less than inertial quality with a relatively high drift rate. The error signals from the inertial platform on lines 200, 201 are compared with a similarly derived heading signal in a resolver 52a to give error signals corresponding to deviations of the platform 12 from horizontal about the vehicle pitch and wall axes. These are compared with outputs from the platform 12 synchro receivers 21, 23 to alter for any errors in the platform torquers 24, 26 and for any alignment errors in the signals from the gyro 210. These signals are further corrected at 257, 259 for the efforts earth rate and vehicle rate before being used to convert the attitude of the gyro 210 and maintain its spin axis truly vertical. The gyro 210 then supplies vertical reference signals to stabilize the platform 12 and these signals may also be fed to other auxilliary equipment 260. A vertical accelerometer 270 may be mounted on the rota gimbal of the gyro to provide vertical acceleration information. A gravity sensitive switch 213 is also provided for fast initial course erection of the gyro 210.