Abstract: An accumulated statistics CFAR method and device operates using integrated data to maximize the probability of target detection for a given false alarm rate. The CFAR hardware varies its detection criteria as a function of the statistics of the range gate in question. The detection threshold is based on other range gates seen in the past which contain the same terrain type.

Abstract: A two-parameter clutter map for storing two variables for every spatial location in order to define both the intensity of the interference and the fluctuation characteristics of the interference from scan-to-scan. The two variables are obtained by processing input data from an integrator in two n-pole integrators having different orders. The ratio of the two variables or their difference in logarithmic form is employed as a measure of the scan-to-scan fluctuation characteristics. An option to control alarms and the leading edge of moving rain storms is also provided.

Abstract: A radar system includes N Doppler filters (N is an integer larger than 1), N CFAR (Constant False Alarm Rate) processing means, a video selector, automatic target detecting means, a video integrator, and a D/A converter. The N CFAR processing means are respectively connected to output terminals of the Doppler filters and automatically adapt amplitude distribution characteristics of a signal, such as clutter and receiver noise, and convert the signal into a signal having the same amplitude distribution characteristics as the receiver noise and suppressing the converted signal. The video selector is connected to output terminals of the N CFAR processing means and selects an output signal from any one thereof in units of radar range bins and synthesizes an N channel signals into a single channel signal. The automatic target detecting means is connected to an output terminal of the video selector.

Abstract: A crystal video receiver having CW and pulse detection capability includes a threshold signal generator which switchably provides fixed and noise riding threshold signals, used to determine initial signal detection. Track and hold circuits provide a second threshold, derived from the peak received signal level, for establishing the termination of received video pulses. A pulse width counter is coupled to determine the time a received pulse signal is between the two thresholds and is set to overflow at a predetermined time after the reception of a signal to establish a pulse representative of a received CW signal and to prevent receiver lock up.

Abstract: A method of operating a computing machine for reducing speckle noise in video images, particularly radar images, utilizes a complementary hulling technique on vertical pixel grids of the array. The vertical pixel contours which are subjected to the complementary hulling are derived from intersections of vertical grids with conceptual superposed gray-scale surfaces which have front end values corresponding to the gray-scale pixel values. The invention provides the significant advantages of decaying small image features, such as speckle noise at a significantly faster rate than large image features, such as target returns.

Abstract: Method for determining and using clutter estimates in a radar clutter map. The method does not require synchronization of the transmitted radar pulses with the azimuth coordinates of the map cells. Data inputs close to each map azimuth location are used to estimate the echo amplitude in the map cell which would result if the antenna beam was pointing directly at the clutter when one data sample occurred. A burst of pulses are transmitted and return echoes are processed to produce clutter signals at least twice within the time it takes for the antenna to scan one beamwidth. Clutter echoes received adjacent in azimuth to the map cell for which the value is being calculated are converted by a formula into a value for adjusting the present map cell value. The formula takes into consideration the magnitude of the values, the difference between the values, the antenna beam width, and the azimuth spacing of the samples.

Abstract: A monopulse receiver, wherein a desired wide dynamic range is achieved for range gated monopulse sum and difference signals, is shown to incorporate: (a) a multiplexer for time-multiplexing such signals; (b) a first and a second receiver channel responsive to the time-multiplexed signals, each such channel having a dynamic range less than the desired wide dynamic range and greater than one-half the desired wide dynamic range, the gains in such channels being offset so that together such channels have the desired dynamic range; (c) a first and a second sampler and analog-to-digital converter, respectively, responsive to the signals out of the first and the second receiver channel, for producing digital words indicative of the amplitude of each component signal in the time-multiplexed signals; and (d) logic and control means for forming bytes from predetermined portions of each one of the digital words and for selecting the byte indicative of the amplitude of each component signal.

Abstract: A method of recognizing targets and suppressing spurious signals in radar equipment, in which the surveillance area is divided, in azimuth and range, into a plurality of radar cells. The method comprises comparing the echo signal of each radar cell with a threshold value, producing a sequence of magnitude related amplitude values of echo signals in certain neighboring cells and deriving the threshold value from a value situated in a specific position in said sequence.

Abstract: A technique and apparatus are disclosed for determining the performance of a pulse doppler radar system every integration period. The test is accomplished by injecting into the front end of the radar a highly calibrated signal during initialization or during a periodic test and measuring the signal at the Fast Fourier Transform (FFT) output. This measured signal is used by the radar signal processor as a reference signal which is adjusted for internally induced changes by the radar's signal processing system then summed with the in-phase amplitude of the selected range gate filter cell. The sumed signal and the cell quadrature amplitude are then envelope detected, and a detection counter is incremented when the envelope detection compares favorably with the cell's constant false alarm rate. Each integration period, the process is repeated for all range gate filter cells to obtain a detection count. Then the probability of detection is estimated using the equation: ##EQU1## where N.sub.

Abstract: A frequency modulated continuous wave radar wherein analog signals received from a target are converted to digital form, processed by correlation with differently delayed signals, also in digital form, of a modulation waveform repetitively applied to the transmitted signals and the frequency spectra of the resulting signals are determined, such spectra being indicative of range of the target. In addition, a digital correlator adapted to perform the desired correlation is shown.