Showing papers on "Moving target indication published in 1970"

Adaptive signal processor for clutter elimination

Abstract: An adaptive signal processing system for enhancing the signal-to-interference characteristics of a pulse radar system exposed to clutter signals as well as to desired target signals is disclosed. The time-extended clutter signals, along with specially generated phase reference signals are employed in a multi-element adaptive filter-correlator system to reduce the clutter presence in the radar receiver output to a minimum value for all target ranges and for both volume and surface clutter.

Digital motion compensation system for radar platforms

Abstract: A digital motion compensation system for radar platforms wherein motion of the radar platform is detected by a digital process using data which has already been digitized and stored for MTI (moving target indication) purposes.

Adaptive digital automatic gain control for mti radar systems

Abstract: An adaptive digital automatic gain control (DAGC) system is disclosed for pulsed radar moving target indicator (MTI) systems to reduce the input dynamic range requirements of a data processing and display system by dividing each range sweep into a number of range elements of one or more range bins, comparing the signal level in each range element to a selected reference level, and providing a digital error signal indicating whether or not the video signal is greater than the reference signal. The radar video signal is processed by an MTI filter, the output of which is compared with a selected reference level to similarly provide digital error signals for AGC control based on not only the raw radar video signal, but also the MTI video signal. These digital error signals are integrated separately for each range element, thereby developing for each range element an AGC signal in digital form based on the past history in the raw radar video signal and the MTI video signal over a continuous succession of range sweeps. After conversion into analog form, these digital AGC signals developed for all range bins of a given sweep are filtered by a low pass filter to provide an analog AGC signal which is smooth over approximately 16 range bins. A noise AGC signal is similarly developed and combined with the radar video and MTI video AGC, but at a much slower rate of one sample per azimuth scan.

Anticlutter radar receiver

Abstract: The application discloses an anticlutter signal-processing radar receiver used as an air traffic control radar. The radar receiver uses a single receiving channel including an intermediate-frequency logarithmic amplifier which operates without loss of phase information in a received signal, and the intermediate frequency output of which is applied to a phase detector effective to produce a bipolar video signal. The channel also includes a canceller and a full wave rectifier, arranged to eliminate ground clutter from the processed input signal and a fast-time-constant circuit in conjunction with a logarithmic video amplifier effective to reduce rain clutter in the processed input signal which enables a target signal, occurring in rain clutter in a received signal, to be observed.

Noise suppressor for surveillance and intrusion-detecting system

Abstract: A surveillance and intrusion detection system is provided using a scanning-type sensor to monitor a field of view and transmit a video signal to a moving target indicator (MTI) the output of which is applied to an alarm system through a threshold level detector having a relatively low-threshold level for higher system sensitivity. A correlation unit minimizes false alarms which could occur from high-level noise by transmitting pulses to the alarm system only when they occur at approximately the same place in three successive scanning lines. Other units are provided for correlation of other possible moving targets in the same line. When transmitted pulses are added to the video signal from the sensor for display, the outline of a moving target is brightened.

Pulse doppler signal simulator

Abstract: A device for providing signals which may be connected to the signal processing portion of a doppler radar to test the performance of the signal processor. The device may provide any preselected clutter level or target sizes. An audio signal is supplied to stage 1. The target size, a.c. signal level, is chosen by the appropriate set of relay contacts and is connected to stage 3 via a buffer stage 2. A preselected clutter level is supplied by stage 3. The continuous target size and clutter level outputs are converted to video pulses in coincidence with the input pulses from the pulse repetition frequency (PRF) generator of the doppler radar. The video pulses are supplied to the processor of the radar.

Fixed target detector for use with doppler radar

Abstract: A return radar signal processing system which may be connected to existing doppler radar for detecting a stationary target or normally moving target which has stopped. The return radar signal is sampled in the clutter portion and moving target (or doppler) portion thereof, the noise energy in the clutter portion being compared with the noise scintillation products energy in the doppler portion. An unbalance or change in the ratio of these two energy levels is detected as a fixed target.

Range-gated moving target indicator

Abstract: A range-gated moving target indicator comprises a plurality of sequentially actuated input sampling gates couping a video input to a corresponding plurality of storage capacitors. Each capacitor is coupled to a corresponding band-pass Doppler filter. A plurality of sequentially actuated output sampling gates coupled the Doppler filters to a single full-wave detector, the output of which controls the intensity input of a display device.

Clutter suppression circuit

Abstract: In a Moving Target Indicator (MTI) radar system, false alarms caused by large clutter signals are eliminated by using a limiter in Doppler bandwith to limit the maximum power at the input to predetection filters and, thus, the maximum signal levels at the threshold circuits.