US 5,194,874 AGranted

Satellite antenna tracking system

AssigneeSelenia Spazio S.p.A.

InventorGiorgio Perrotta

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Abstract

An integrated antenna system for signal error tracking and correction capable of performing a mechanical conical scan. The mechanical conical scan imposes a modulation upon a received RF signal. This modulation is in turn imposed on an AGC circuit in the receiver of the antenna system, which modulates the AGC signal of the receiver in accord with the modulation imposed on the RF signal by the conical scan. This modulated AGC signal is compared in a detector circuit to a reference sinusoidal signal generated by a local oscillator in the system. This detector circuit outputs an error signal which is added to a reference sinusoidal signal which in combination drive an actuator. This actuator is responsible for imparting nutative motion to the antenna, for the purposes of producing the conical scan pattern. The error detection and correction which result from the conical scan and the error detection circuitry, are capable of operating at multiple RF frequencies and modulation schemes, since the error signal of the system is generated by a modulated AGC signal as opposed to the modulated RF signal itself.

Claims9

Dependent claims

An integrated antenna system for the control of antenna tracking comprising:

a movable antenna for receiving radio frequency (RF) signals having a signal strength, said antenna being mechanically movable for variable nutative movement in a variable conic pattern of a mechanical conical scan;
an actuator connected to said antenna for imparting said variable nutative movement to said antenna;
a receiver connected to said antenna for receiving said RF signal from said antenna, said receiver comprising means for generating an Automatic Gain Control (AGC) signal related to the signal strength of an RF signal received by said antenna;
a local oscillator for supplying a sinusoidal reference signal;
an error detector connected to said receiver and said local oscillator, said error detector comprising means for comparing the AGC signal from the receiver and the sinusoidal reference signal from the local oscillator and for generating an error signal in response to the comparing of the AGC signal from the receiver and the sinusoidal reference signal from the local oscillator;
and
an adding circuit connected to said actuator and said local oscillator and said error detector, said adding circuit comprising means for adding said sinusoidal reference signal from said local oscillator and said error signal from said error detector and for generating therefrom an actuating signal that varies in direct relation to said error signal, said actuating signal being supplied to said actuator for controlling said nutative movement of said antenna.

4 more elements

Dependencies are inferred from the claim text.