Apparatus for indicating errors in inclination for inertial navigation

Claim 1

An inertia navigation and guidance system comprising at least one gyroscope and one accelerometer, a platform means for establishing a common normally horizontal plane in which both the gyroscope and the accelerometer are mounted, a gimbal mounting for said gyroscope comprising inner and outer gimbals mounted on an inner and outer gimbal shaft, respectively, means for precessing the gyroscope at a constant rate with reference to the horizontal about the outer gimbal shaft, a first indicating means connected with the precessing gyroscope for generating a low frequency pulse signal, the frequency of which varies when the platform means deviates from the horizontal about an axis parallel to the outer gimbal shaft, an electronic gate including two inputs and one output and means for supplying said low frequency pulse signal to one input and means for supplying a constant frequency reference signal to the other input, said gate producing an output signal whose frequency is a function of the frequency difference between said input signals, an adder having a plurality of inputs, one of which is connected with the output of the electronic gate, a second indicating means connected with the accelerometer for generating a pulse signal in response to the accelerational forces acting on the accelerometer in the said common plane along an axis perpendicular to the outer gimbal shaft, means for supplying said accelerometer pulse signal to a second input of the adder and means for supplying a constant frequency reference signal to a third input of the adder, said adder adding the frequencies of the input signals thereto.