Abstract: A method of analyzing return signals of successive range cells in a scene using constant false alarm rate adaptive control comprising, for each successive range cell in turn is disclosed mathematically. The return signal is processed mathematically and averaged over a predetermined number of cells near that cell. A first variable factor and the return signal for that cell, to derive a first result. The first variable is adapted depending upon that first result. A second variable factor is derived in accordance with a predetermined relationship between the first and second factors are mathematically processed. The second factor is mathematically processed. The second averaged return signal and the return signal for the cell, to derive a second result. The second result is used as an indication of the presence of an object of interest in the scene.

Abstract: A method of analysing return signals of successive range cells in a scene using constant false alarm rate adaptive control comprising, for each successive range cell in turn is disclosed mathematically. The return signal is processed mathematically and averaged over a predetermined number of cells near that cell. A first variable factor and the return signal for that cell, to derive a first result. The first variable is adapted depending upon that first result. A second variable factor is derived in accordance with a predetermined relationship between the first and second factors are mathematically processed. The second factor is mathematically processed. The second averaged return signal and the return signal for the cell, to derive a second result. The second result is used as an indication of the presence of an object of interest in the scene.

Abstract: A method and apparatus estimate the detection range R.sub.1 of a radar in the presence of noise and clutter. The radar return signals from a range cell under test and from a plurality of surrounding range cells on either side of the range cell under test are measured. From the values of the return signals from the surrounding cells, a factor .alpha. is determined. The mean value of those signals is then multiplied to form a threshold value for determining the presence or absence of a target. A desired false alarm rate is maintained, however. A number of radar return signals sufficient substantially to average out local variations in clutter are used to determine a mean clutter value m.sub.c. A value which is a function of .alpha. and m.sub.c is output as the estimate of detection range R.sub.1.

Abstract: A circuit for generating an output signal L indicative of the mean clutter level at a selected location in the field of view of a radar apparatus, particularly the sea surface which exhibits a swell pattern. The circuit includes processing circuits which generate weighting coefficients (a.sub.1, a.sub.2, . . . a.sub.N) used to weight the amplitudes of returns derived respectively from a group of N discrete locations which precede in range and or succeed in range the selected location. The circuit generates the elements r(n) of a matrix [r] which represents the auto correlation function of the amplitude of returns derived from w discrete locations encompassing the group of N locations. Circuit then uses the matrix [r] to compute the weighting coefficients (a.sub.1, a.sub.2. . . a.sub.N) which are stored at 13 applied to respective multiplying circuits to weight corresponding amplitudes accessed to respective locations of a shift register.

Abstract: There is disclosed a synthetic aperture radar arranged to survey a region from a mobile location. The radar returns received from the region are first phase weighted by a series of predetermined factors. They are then stored and combined with later returns to give an output signal which has a maximum value when any target present in the region is in a predetermined direction from the location.