Systems and methods for detecting targets using pulse-compressed radar signals are disclosed. In one application, relatively small targets that are masked by the time-sidelobes of a larger target's return signal can be detected. The methods include a signal expansion type algorithm that is used to process the pulse-compressed return signal. Specifically, a generalized Fourier expansion expression having a summation of PSF terms is used to expand the pulse-compressed signal. Each term represents a respective target and includes a point spread function and a complex coefficient. The signal expansion procedure can be used to determine a set of optimum complex coefficients, with one coefficient for each range bin. Doppler frequency can be used together with range to optimize the complex coefficients. Next, targets are detected by analyzing each range bin to determine whether the corresponding complex coefficient has an absolute magnitude greater than a pre-determined threshold.
System And Method For Sidelobe Reduction Using Detect-And-Subtract Techniques
A radar system and method for detecting targets using pulse-compressed signals is disclosed. In one application, the systems and methods can be used to detect one or more relatively small targets whose pulse-compressed signals are masked by the time-sidelobes of a larger target's return signal. The method includes an iterative, detect-and-subtract signal algorithm that processes the post-compressed signal to detect multiple targets. Specifically the processing algorithm operates on the post-compressed signal to identify a point spread function (PSF) that corresponds to the relatively large target. Once identified, the PSF corresponding to the largest target in the post-compressed signal is subtracted from the post-compressed signal to generate a residual signal. This residual signal, in turn, includes the PSFs for the other targets. This process of identifying and subtracting the PSF of the largest target in the residual signal is then repeated until all targets are detected.
J. Doss Halsey - Severna Park MD, US Katsumi Ohnishi - Centreville VA, US
Assignee:
Information Systems Laboratories, Inc. - San Diego CA
International Classification:
G01S 7/40 G01S 7/02 G01S 13/00
US Classification:
342 20, 342 13, 342 89, 342 91, 342175, 342195
Abstract:
A hybrid radar receiver includes an antenna array for receiving an input signal having a radar signal from a signal emitter. Each array element outputs an analog signal on a respective data channel. For each data channel, an activatable A/D converter is provided. A dedicated hardware circuit, which typically includes a detector/log video amplifier that is coupled to a threshold/pulse digitizer, is included to determine when a radar pulse is being received. When the circuit determines that a pulse is being received, the circuit activates each A/D converter to generate a digital signal on each channel. When a pulse is not currently being received, the circuit deactivates each A/D converter and digital signals are not produced. Pulse parameter(s) generated by the hardware circuit and the digital signals on each channel are sent to a software equipped processor which implements a signal emitter identification algorithm.