Abstract: A logarithmetic sidelobe blanking system operable in a pulse compression radar system in which the dynamic range of the blanking system is not limited by the compression dynamic range. A sidelobe blanking receiver is provided to process the sidelobe signals in a manner identical to the processing in the radar receiver. The uncompressed IF pulses in both the sidelobe receiver and the main lobe receiver are sampled prior to their being amplitude limited, and are applied through logarithmetic amplifiers whose dynamic range capability is at least equal to the dynamic range of the preceding circuits. The output signals of the logarithmetic amplifiers are then compared and if the sidelobe signal is larger than the main lobe signal the compressed pulse at the output of the pulse compressor is located and used for blanking to ensure that only the time interval of the compressed pulse width is removed.

Abstract: A charge coupled device to provide a multi-channel selective transversal filter in which a plurality (N) of channels are sequentially processed in a common transversal filter unit to provide a desired transfer function such as a high pass filter. The analog signals from a plurality of sources or channels are fed into the selective transversal filter in serial fashion with the signal from each channel being nondestructively sampled and multiplied by appropriate weighting coefficients as provided by split electrodes separated by (N-1) charge coupled device storage bits. By having storage electrodes between the split electrodes equal to the number of input channels, the split electrodes, which provide the output signals, operate upon signal information from one channel at a time. The displacement current differences between the two halves of all of the split electrodes provide output signals having the desired filter characteristics.

Abstract: 1. In an automatic target tracking radar system for tracking selected target signals in the presence of interfering signals, a range tracking circuit for automatically tracking selected received video signals, and means for modifying the video signals applied to said range tracking circuit, said means being selectively operable for placing an inverted replica of each received video signal either before or after each of said received signals, said inverted replica effecting the cancellation in said means of any non-inverted signals occurring in time coincidence therewith.

Abstract: Real time histogram equalization systems for a television type display that performs equalization with one or two dimensional processing on a local area or sliding window basis. For the two dimensional system, the intensity for any particular point in the image is adjusted according to a histogram of the area contained within a window immediately surrounding the point to be equalized. The histogram forming window provided by the system moves across the image in two dimensions both horizontally along each of a plurality of overlapping segments arranged parallel in the vertical dimension, and at each window position reassigned center picture elements are equalized. The processing of the histograms area or the sliding process is continued over the entire surface of the raster with the process being then repeated in a continuous fashion.

Abstract: A histogram equalization system that adaptively redistributes the intensity coding of the video in order to provide an equal number of elements at all display intensity levels. The actual amplitude value of the input video as stored in an integrator, for example, is utilized to address a random access memory which originally is loaded with all zeros. The memory is organized such that there are as many addressable words as there are possible video intensity values carried in the integrator thereby building up a histogram within the memory. Upon completion of the histogram, a constant equal to the number of picture elements corresponding to the data used to form the histogram divided by the number of values to which it is desired to truncate, is utilized in a comparator as the histogram memory is sequentially read out and accumulated to determine the truncation points.

Abstract: A thinned array real time radar system having an antenna array with receiving elements spaced more than one wavelength apart and having a dynamic means for programming the focus of the array so that it is time sequentially focused to accommodate radar echoes over a range interval from a near range out to infinity to provide an improvement in azimuth resolution, the improvement being substantially large for the near ranges. The system includes a separate mixer for every element of the array for receiving return energy therefrom and with each mixer having a separate local oscillator input. The local oscillator frequency varies as a prescribed first function during each period of processing over the selected range interval and the path length distribution of the feeds between the local oscillator and each individual mixer vaires as a prescribed second function.

Abstract: 4.

Abstract: An improved MTI (Moving Target Indicator) cancelling system that provides cancellation in the first canceller stage of clutter at a first frequency and cancellation in a second or subsequent canceller stage of clutter such as weather or chaff with a substantial doppler frequency offset from that cancelled in the first MTI canceller. The first canceller stage may be a conventional in-phase (I) and in-quadrature (Q) digital MTI unit to develop the I and Q first differences followed by a conversion of these differences into a combined first difference designated as a quantity M and representing an angle times an amplitude multiplier. This M signal is then applied to a second canceller to develop a second difference signal which is then normalized to represent a pure angle term.

Abstract: A moving target indicating radar that includes a coherent on receive system and a clutter referenced velocity compensator operating in association with a linear predictor to produce coherent IF (intermediate frequency) receive signals shifted in frequency to compensate for the radar platform's motion. A synchronous detector, with pulse repetition frequency modulation, translates the coherent IF received signals to video signals at a desired frequency offset. A storage processor processes and range gates the video signals prior to doppler filtering and displaying the signals as a representation of moving targets.

Abstract: A monopulse radar tracking system is disclosed employing four tracking channels, one for each of range, velocity, azimuth and elevation. The two angle channels are referenced directly to antenna coordinates. Each channel is mechanized by a stored program in a digital computer, and the mechanization employs Kalman filtering with gain factors continually optimized for measured signal-to-noise ratios. Angular rate commands for the antennas are obtained by passing pointing error estimates from the angle channels through a compensator for antenna motion and adding line-of-sight rate estimates from the angle filter channels. Cross-coupling between channels is provided, and each channel is aided by outputs from an inertial navigation platform. Preaveraging of discriminants received between computational cycles is provided.

Abstract: A high speed electromagnetic deflected electrostatic focus cathode ray tube display having a relatively short magnetic time constant by controlling the gun structure. The volume resistivity and the thickness of resistive materials used in the neck of the cathode ray tube that are cut by changing magnetic flux fields, are selected to provide a relatively short time constant. In one arrangement, the tube focusing control elements near the deflection yoke are formed on a precision ground structure of glass or other suitable ceramic materials. In another arrangement the elements of the tube that are intercepted by the changing magnetic flux are deposited or formed on a precision ground portion of the tube neck. Material deposited on the tube structure or on the tube neck is of a selected maximum volume resistivity and a selected small thickness so that the overall operation has a relatively short time constant.

Abstract: A dynamic vertical angle sensor operable on a vehicle that isolates the output device from the vehicle movement in that the rotor of the output data device is not directly coupled to the sensor mounting frame. The output rotor is driven by a low pass servo that is slaved to a level sensor, which in itself is driven by the same servo until it is nulled. The level sensor which may be a pendulum, is mounted free from the output device so as to rotate independently therefrom, thus allowing the error signal to be picked off of the pendulum mounting and applied to the low pass servo system. Because a low pass filter is in series with the servo drive, high frequency disturbances are greatly attenuated in the output device, to effectively provide a DC average angle signal that is required, for example, in a tank system, rather than instantaneous values.

Abstract: The recirculating tapped delay line in accordance with the invention is a combination electrical and acoustic recirculation network that includes a selected number of acoustic surface wave circulating subloops included in an electrical primary feedback loop or network with each subloop having a selected number of taps. Each acoustic subloop includes track changing multistrip couplers that inject the signal into the loop, multistrip reflecting track changers at each end of the surface wave path, tapping transducers or multistrip couplers in both forward and reverse acoustic paths and a multistrip loop cancelling switch for suppressing the recirculating signal as desired. Because the recirculation is entirely acoustic in each subloop, the components which contribute substantially to distortion are utilized with less frequency so that the overall distortion after specific storage time is reduced.

Abstract: This invention is applicable to display systems, such as in a helmet mounted display or a head-up display, utilizing a holographic lens operating at a relatively large off-axis angle in order to perform the dual function of a combiner glass and an eyepiece. The holographic lens is used in conjunction with more conventional optical elements (lenses, mirrors and prisms) to present a high quality collimated virtual image of an object, such as the face of a cathode ray tube, to an observer. The aberrations inherent in a holographic lens constructed to operate at a large off-axis angle and with a large field of view are corrected both by constructing the holographic lens with aberrated wavefronts and by the optical elements used in conjunction with the holographic lens during playback. Some arrangements of the playback systems of the invention include a relay lens having cylindrical surfaces and tilted and/or decentered elements used to compensate for the axial astigmatism and axial coma in the holographic lens.

Abstract: A direction coded digital stroke generator that allows arbitrary symbols to be defined in real time and in which these symbols consist of substantially an unlimited number of discrete segments. When interfaced with a memory source such as a digital computer the stroke generator provides highly flexible symbol generation capability at a relatively low cost in terms of memory requirements and with a relatively high writing speed. Each line segment is defined by four binary bits with three bits defining direction and one bit determining blanking. The three direction bits are decoded to control X and Y up/down counters orienting the segment in one of eight directions. A selectable segment length feature is provided allowing development of segments of selected lengths so that the symbols have a selected size and degree of detail.

Abstract: A pulse-doppler radar tracking system is disclosed employing four filter channels for tracking range, velocity, azimuth and elevation. Each channel is mechanized in a Kalman filter form by a stored program in a digital computer. The range channel estimates target range, R.sub.TPR, range rate, V.sub.TPV and acceleration a.sub.TPV from one of many received signal frequency spectra at multiples of the pulse repetition frequency (PRF). Once error in the range rate estimate, V.sub.TPR, is within a velocity corresponding to .lambda. PRF/4,the velocity channel is reinitialized in its estimate of target velocity, V.sub.TPV, with a corrected velocity computed from the less accurate but unambiguous estimate of velocity, V.sub.TPR, and the ambiguous estimate of velocity, V.sub.TPV.