Abstract: A synthesized aperture radar imaging system is disclosed. The system includes an antenna reflector and a radar signal transceiver configured to generate a plurality of radar transmission signals and to receive a respective plurality of reflected radar signals. The system also includes a wave reflection device configured to sequentially reflect each of the plurality of radar transmission signals onto separate respective spot-portions of the antenna reflector. The plurality of radar transmission signals can be transmitted from the antenna reflector to a target and reflected from the target as the respective plurality of reflected radar signals. The system further includes a synthesized aperture radar controller configured to integrate the plurality of reflected radar signals and to generate a high-resolution, three-dimensional image of the target from the integrated plurality of reflected radar signals.

Abstract: A synthesized aperture radar imaging system is disclosed. The system includes an antenna reflector and a radar signal transceiver configured to generate a plurality of radar transmission signals and to receive a respective plurality of reflected radar signals. The system also includes a wave reflection device configured to sequentially reflect each of the plurality of radar transmission signals onto separate respective spot-portions of the antenna reflector. The plurality of radar transmission signals can be transmitted from the antenna reflector to a target and reflected from the target as the respective plurality of reflected radar signals. The system further includes a synthesized aperture radar controller configured to integrate the plurality of reflected radar signals and to generate a high-resolution, three-dimensional image of the target from the integrated plurality of reflected radar signals.

Abstract: A local area positioning system which includes a plurality of platforms or nodes consisting of airborne and/or ground based vehicles that are coupled in a platform-to-platform local area network. The platforms themselves establish a spatial reference system for location and communication between platforms is accomplished using directive millimeter wave beams, and where measurements and communicated estimates of node locations, in a local inertial reference frame, are processed via Kalman tracking filters to generate updated estimates of position and velocity vectors associated with each node.

Abstract: A segmented stretch waveform for wide band high duty cycle tracking application. The waveform is divided into multiples of two spaced segments as the tracking range closes. Target returns received during spaced segments are combined to correspond to the complete waveform; and range is determined in accordance with the combined waveform. Tracking range can be varied without changing bandwidth, FM slope, duty cycle or processing time.

Abstract: An airborne bistatic radar synchronization apparatus and process is presented which receives clutter point echo returns from the bistatic radar receiver on a penetrator aircraft, and determines therefrom the location of the illuminator aircraft without the need of receiving direct path signals from the radar transmitter on board the illuminator aircraft. Once the state of the illuminator aircraft (position and velocity) has been determined, the estimate of the illuminator state may be refined using direct path data. Finally, a target location algorithm is applied to bistatic target echo returns to calculate an equivalent monostatic range for a desired target, and provide an estimate of the location of the target.

Abstract: A feature referenced error correction apparatus utilizing the multiple images of the interstage level image format to compensate for positional displacement errors in the synthetic aperture radar imaging. Error compensation is accomplished through the registration of key features of sub-aperture images and by the generation of an error correction signal in response to the sub-frame registration errors.

Abstract: The invention comprises a jam resistant radar system. The system comprises a primary radar transmitter which is coupled to a primary antenna having a predominant main beam and sidelobes. A second wide beam antenna is coupled to a second radar transmitter which transmits a signal having a frequency spectrum encompassing the main beam with the power density being substantially equal to the power density of the sidelobes of the primary antenna. The second transmitter is frequency modulated over a spectrum in discrete steps while the primary transmitter is pulse-to-pulse or look-to-look randomly modulated over the spectrum. This prevents a listening jammer positioned in the sidelobes from determining the pulse-to-pulse or look-to-look frequency being used by the primary radar transmitter.

Abstract: A system for adjusting the sidelobe response of a main antenna is disclosed. This iterative process results permits the sidelobe canceling in sequential step reduction in interference thereby greatly reducing the time required to respond to changes in the characteristics of the interference. The response of the phased array is adjusted by combining the composite signal from the main antenna with signals from auxiliary channels which have an adjustable phase and amplitude. The desired amplitude and phase of the auxiliary channels is determined using an iterative mathematical process which emphasizes the most recent data. Emphasizing the most recent data permits the system to be used in the scanning mode or to reduce interference from moving sources.

Abstract: A synthetic aperture radar in which radial motion compensation is provided by a monopulse null tracking loop which tracks the null position of a stabilized monopulse antenna, and in which tangential motion compensation is provided by a tangential velocity measurement loop which tracks the cross-over angle of the monopulse antenna pattern. Since the motion compensation for the synthetic aperture radar is made in relation to a stabilized monopulse antenna, the imaging process for the synthetic aperture radar may be controlled in response to the angular scan rate of the antenna.

Abstract: A target seeker circuit contained in a projectile having a trajectory guidance mechanism cross-correlates returns of a cross-polarized antenna pattern to distinguish between target returns reflected by man-made targets and clutter returns reflected by naturally occurring articles to cause the trajectory guidance mechanism to direct the projectile towards the target. One coordinate of diversity in the cross-polarized returns is achieved by changing the RF frequency of the antenna pattern while a second coordinate of diversity is achieved by changing the aspect range of the clutter. The target returns are distinguished from the clutter returns either by comparison to a threshold value which is set in relation to the worst case clutter level or, alternatively, by comparison to an adaptive threshold which is responsive to the dynamic clutter level.

Abstract: This invention is directed to an image processing arrangement used to estimate image displacement relative to a reference frame. It comprises a discrete complex correlator, an associated interpolator, and a displacement estimator. The unique nature of the system is its ability to estimate shifts of a fraction of a pixel for sparcely sampled data. This is accomplished by extracting the complex gradients from the gray scale data and in turn correlating the gradients via a discrete complex correlator. The resulting cross correlation function is then interpolated to yield an accurate estimate of the shift. The invention is particularly adapted for use in the autofocus portion of a synthetic aperture radar imaging system.