This study presents a novel motion parameters estimation technique for moving targets, including those with velocities beyond the Nyquist limit in multi-channel synthetic aperture radar data. The technique proposed in this study exploits the linear dependence between the fold factor of the cross-track velocity and the slope of the moving target trajectory in the range-compressed and azimuth time domain after performing Keystone transformation in the range frequency and azimuth time domain. The velocity ambiguity thus can be overcome. The along-track velocity can be retrieved from the chirp rate estimated by applying a new time-frequency analysis method called Keystone-Wigner transform. The algorithm of motion parameter estimation efficiently converts the two-dimensional (2-D) search into the two separate 1-D cases. The proposed method can robustly estimate the motion parameters of the fast-moving targets, which are illustrated both with simulated and real data.

Motion parameter estimation of multiple ground fast-moving targets with a three-channel synthetic aperture radar

A moving target simulator system for pulse Doppler radar includes a processor for processing received radar signal and transforming the signal into patterned pulses before subjecting the patterned pulses to an 180 degree phase-shift by a phase-shifter. The system also includes a reference signal provided by a corner reflector located in proximity of the simulator. The reference signal and a phase-shifted signal from the simulator are processed by the radar equipped with a phase corrector circuitry to correct a phase drift problem associated with the use of a small antenna with the simulator.

Apparatus and methods for moving target indicator simulation

Airborne weather radar is an important navigation equipment to ensure flight safety. A new adaptive clutter suppression method based on echoes power is proposed in this paper, which is for airborne weather radar operated in wind shear mode. By using the priori information and the polar coordinate centroid method, the centre frequency and bandwidth of clutter spectrum is validly estimated. The echo power in each range cell is used to design a dual-threshold controlled adaptive notch filter. Results of simulation have proved that this method has a superior clutter suppression performance. It can provide a maximum extent possibility to reject the ground clutter, and meanwhile improve the wind speed estimate accuracy of the wind shear signal effectively. (6 pages)

Adaptive ground clutter suppression for airborne weather radar based on echoes power

The invention discloses a telemetering antenna automatic tracking control method, and belongs to the technical field of telemetering antennas. After a task trajectory file is received from a center, atrajectory is loaded into a module in advance, and an antenna is rotated to a waiting point; when a flying target passes by the waiting point of the antenna, under a program guiding working mode or adigital guiding working mode, the antenna is driven to rotate to a position with a pitching angle larger than 2 degrees, a receiver is locked, and an automatic tracking working mode is switched on; when the signal of the flying target is lost halfway, a target flying track is extrapolated for 5 s, when the target signal is lost and the receiver is unlocked, the antenna is switched to a memory mode firstly, and once the tracking conditions are satisfied, the antenna is immediately switched to the automatic tracking mode; a target tracking elevation angle of the antenna is smaller than a presetvalue, the value of Rbyte is not equal to 1 or 2, and when the departure time is longer than 30 seconds, the antenna is immediately switched to an orientation working mode. The telemetering antenna automatic tracking control method improves the timeliness, accuracy, tracking stability and reliability of capture of a telemetering device, and improves the capability of completing an experimental task.

Telemetering antenna automatic tracking control method

In this paper, a new method of dual-threshold controlled adaptive clutter suppression is proposed for an airborne weather radar operated in the wind shear mode. To reliably estimate the center frequency and bandwidth of the clutter spectrum, the echo power in each range cell is used to design a dual-threshold controlled adaptive notch filter. This filter can reject the maximum amount of ground clutter, while reducing the effect of clutter residue on the wind shear signal. Results of our simulation have confirmed that this method has a superior clutter suppression performance, and can effectively improve the wind speed estimate accuracy of the wind shear signal.

Ground Clutter Suppression with Dual-threshold Controlled Method for Airborne Weather Radar

A new airborne MTI scheme that applies to non-homogeneous clutter environment is presented. Results of simulation have proved that the scheme has a superior ground clutter suppression performance and can effectively prevent the whitening of a target.

Airborne adaptive MTI scheme with preventing the whitening of the target

In this paper, the design plan of the tracking system of the telemetering antenna in a type of pilotless aircraft is introduced. The discussion centres on the controls. Then the format of control words and an algorithm, which are effectively used to control the stepping motor are given. This algorithm has a function of parallel control and has already been used in our research. The design of the antenna servo system and the fining step pitch (FSP) control of the stepping motor will benefit from this paper.

Design of tracking system of telemetering antenna in pilotless aircraft

For proficiently operating an unmanned aircraft, the aircrew must be thoroughly trained. However, using practical equipment to train the aircrew is work of high cost and risk. In this paper, a system of simulation training for unmanned aircraft is introduced. Its function and composition are explained in detail. In practice, the system not only decreases training cost and risk, but also strengthens training effectiveness and diversity.

Huang Yong

Papers

Airborne adaptive MTI scheme with preventing the whitening of the target

Design of tracking system of telemetering antenna in pilotless aircraft

System of simulation training for unmanned aircraft