Pseudonoise guidance system with spillover rejection

DETAILED DESCRIPTION In accordance with the system of the present invention, the above-described and other disadvantages of the prior art are overcome by providing first means for collapsing a substantial portion or all of the electromagnetic energy in the spillover spectrum to an intemediate signal of substantially a single frequency while, at the same time, leaving the desired signal energy broadbanded, and second means adapted to receive the intermediate signal and the broadband desired signal from the output of the first means, the second means being adapted to attenuate the intermediate signal selectively without substantially attenuating the desired signal energy.
One embodiment of the spillover rejector of the present invention utilizes a notch filter to suppress the spillover.
In another embodiment, a high pass filter or a single direct current blocking capacitor is employed.
The capacitor may, by its own simplicity, be by far the least expensive device for a large number of applications.
One embodiment of the spillover rejector of the present invention may include an auxiliary demodulator, a notch filter, and a modulator connected in succession from the receiver output to an output system for decoding signals reflected from distant targets.
The spillover rejector can also include an auxiliary decoder which operates both the auxiliary demodulator and the modulator.
Normally, the transmitter has an oscillator which provides a signal relatively pure in frequency.
When the transmitter oscillator output signal is coded, the energy of the signal radiated from the transmitter is spread out in a relatively large band of frequencies.
The auxiliary decoder includes a code generator synchronized so as to demodulate the incoming signal according to the transmitter code.
The transmitter code is conventionally a serial binary code which is periodically repeated.
The auxiliary decoder reproduces an identical code in the proper time phase to decode spillover.
However, due to the fact that the output code of the auxiliary decoder is not in the proper time phase to decode signals from the distant targets, these signals pass through the auxiliary demodulator with an additional coding