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Showing papers on "Moving target indication published in 1969"


Patent
17 Mar 1969
TL;DR: In this paper, two matched filters are used to match the frequency responses of two pulse sequences of different pulse repetition frequencies reflected from a radially moving target and noise or clutter signals reflecting from a relatively stationary background.
Abstract: Apparatus for processing target detection system signals consisting of two pulse sequences of different pulse repetition frequencies reflected from a radially moving target and noise or clutter signals reflected from a relatively stationary background. The apparatus comprises two matched filters responsive to the signals having frequency responses matched respectively to the frequency spectra of the two pulse sequences. A multiplier provides an output signal representative of the product of the signals from the two matched filters.

22 citations


Patent
11 Mar 1969
TL;DR: In this paper, a frequency diversity moving target indicator radar system utilizing a combination of coherent and incoherent processing to improve performance in clutter interference is presented, including a multiple frequency waveform which is processed in a multiple channel receiver and further including a frequency multiplexer, a broad band delay line IF canceller and a demultiplexer.
Abstract: A frequency diversity moving target indicator radar system utilizing a combination of coherent and incoherent processing to improve performance in clutter interference, including a multiple frequency waveform which is processed in a multiple channel receiver and further including a frequency multiplexer, a broad band delay line IF canceller and a demultiplexer. Normalizers producing digital signals, and digital delays for aligning the signals in the time domain combine with a binomial detector to produce target information.

12 citations


Journal ArticleDOI
TL;DR: In this article, a quantitative analysis of the effect of saturation on the performance of cancelling circuits has been conducted, with an analytical expression chosen for the limitation characteristic, and a high degradation of both single and double cancellation performance has been obtained.
Abstract: In moving target indicator radar receivers a saturation is always present in the IF stages in order to compress the dynamic range of large clutter inputs. This nonlinearity greatly affects the performances of the cancelling circuits, because of the spreading of the spectra. A quantitative analysis of this effect has been conducted, with an analytical expression chosen for the limitation characteristic. A high degradation of both single-and double-canceller improvement factors has been obtained. Losses of 20 dB for the double canceller are not uncommon. Clutter residue levels at the receiver output have also been computed in order to see how the performance compares with ideal constant false alarm rate behavior.

10 citations


Patent
22 Oct 1969
TL;DR: In this article, a dual harmonic frequency phase signature technique is applied to a radar system which uses doppler frequency to discriminate moving targets from stationary targets, which is called Doppler radar.
Abstract: A radar system in which a dual harmonic frequency phase signature technique is applied to a radar system which uses doppler frequency to discriminate moving targets from stationary targets.

5 citations


Journal ArticleDOI
TL;DR: In this article, a vertical difference pattern was used to detect small surface targets in sea clutter, where the null is laid on the sea surface as a fence, and a true-motion display was used.
Abstract: Doppler techniques do not aid detection by shipborne radar of small (drifting) surface targets in sea clutter, and such targets have no velocity spectrum distinguishable from that of the clutter. However, clutter decorrelation by rapid antenna scan, followed by camera or direct-view storage-tube integration, can give impressive gains in target/clutter visibility. With relative-motion displays, own ship's motion severely limits possible integration time by shifting the effective spot area of integration as the target is approached; this is neatly avoided by using a ‘true-motion’ display. Further gains may be possible (at least for hovercraft radar) by using an antenna with a vertical difference pattern in which the null is laid on the sea surface as a fence.

2 citations


01 Sep 1969
TL;DR: In this article, a study of ground clutter at grazing incidence using a 10 cm. surveillance radar is presented, where a clutter map of the area of interest describing the clutter echo in terms of the median cross-section and interquartile range of each resolution cell has been made.
Abstract: : The note reports on some results of a study of ground clutter at grazing incidence using a 10 cm. surveillance radar. The digitized amplitudes of the clutter signals are processed in a computer to produce probability distributions of the clutter radar cross-section in dB w.r.t. 1 square meter. A clutter map of the area of interest describing the clutter echo in terms of the median cross-section and interquartile range of each resolution cell has been made. Echoes from individual resolution cells within the area have probability distributions that fit well known mathematical expressions. Probability distributions of clutter cross-section fluctuations with a rotating aerial operating at two different pulse lengths (10:1) have been computed and show a cross-section difference of between 18dB and 22dB for the same probability compared with the predicted 10 dB. An explanation for this is given by postulating a non-uniform spatial distribution of clutter. (Author)

2 citations