United States of America As Represented by the Secretary of the Air Force

Westinghouse Electric Corporation

Robert R Willmore

Ronald W Minarik

Frederick H Harris

William B McCartney

Improved performance in electronic countermeasure systems that utilize main lobe shifting techniques to jam track while scan threat radars are achieved through the use of a modulation sweep program that overcomes scan rate frequency and phase uncertainties. The modulation sweep program is used in conjunction with a conventional swept repeater modulation program. The modulation sweep program is disabled and the swept repeater modulation program is enabled when constant illumination sources or track while scan saturation conditions are encountered.

Main lobe shifting means

A variable analog delay line apparatus utilizing a plurality of tapped SAW devices that are connected in series by single pole multi-throw switch units. The amount of delay is determined by the switch throw arm of the switch unit that is associated with the SAW device. The delay times are added serially to obtain the needed delay.

Variable analog delay line

An angle set on apparatus for an electronic countermeasure system utilizing a single dual mode phased array antenna which is operated under receiver/processor control to serve as both a transmit and receive element thereby avoiding the need for a separate direction finding system and, since transmit and receive functions share the same antenna, eliminating the need for precision pointing accuracy. The receiver/processor unit would continue to identify emitters using the jamming unit's receive antenna element and, where appropriate, PRI trackers would be assigned. The time of arrival window would then be used to blank the transmitter signal and to switch the phased array to the receive mode. During sequential time of arrival windows the receiver/processor would vary the pointing angle of the phase array until the emitter angle of arrival is determined and stored in memory. At periodic intervals in the future, the receiver/processor unit would again output a time of arrival blanking window and update the stored angle of arrival. During all other time of arrival windows the beam would be pointed to the stored angle of arrival value for high effective radiated power jamming.

Angle set-on apparatus

A digital noise generator, wherein pseudo-random rapidly changing analog input voltages to a voltage controlled oscillator are used to generate corresponding rapidly changing discrete frequency outputs, is disclosed. Means are provided to delay the oscillator output by an amount at least equal to the rise time between each frequency change. The delayed and non-delayed oscillator outputs are electrically coupled through a switch that operates at times and at a rate to eliminate the rise time between frequency changes and thus improve the frequency spectrum.

Digital noise generating apparatus

The RF power and video modulation monitoring circuit of the invention provides the unique capability of monitoring the performance of a repeater/noise jammer countermeasures system when the system is operating in either the repeater or the noise jamming mode. In the repeater mode the systems noise level is measured in an unused portion of the countermeasures system frequency band to provide a monitor of system gain and antenna VSWR. In the noise mode crystal detection and threshold comparison provides an indication of RF power output. In either jamming mode the measurement of AC in the detected output provides a monitor of modulation.

R.F. Power and video modulation monitoring circuit for countermeasures

A filter network for separating a transmitted communication frequency into discrete channels. A separator, exemplified by a triplexer, includes a pluggable mid-range high Q bandpass filter and a diplexer of low Q bandpass filters. Circulators receive signals reflected from the high Q filter and pass them to the low Q filters. A combiner circuit takes the attenuated signal from the low Q filters and sends it through a circulator to a high Q plug in filter where the signal passes through a circulator where it is combined with the signal from the high Q filter of the separator as output.

Plug-in filter network for separating a communication frequency into

A shift register generator feedback tap identification system in which a received code is fed to a register which detects when the code contains all 1's at which time a bit position counter and a variable tap shift register generator are reset and a null-filter is enabled. The bit position counter controls the tap positions of the variable tap shift register generator and the output thereof is fed to the null-filter which compares the received code with the code from the variable tap shift register generator.

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Millersville, MD, United States of America

Robert R Willmore