Communications: directive radio wave systems and devices (e.g. – Return signal controls radar system – Receiver
Reexamination Certificate
1987-04-27
2001-05-08
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls radar system
Receiver
C342S090000, C342S091000, C342S159000, C342S194000, C342S196000
Reexamination Certificate
active
06229475
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to tracking and guidance systems. More specifically, the present invention relates to pulse doppler radar systems having a cluster target resolution capability.
While the present invention is described herein with reference to a illustrative embodiment for a particular application, it is understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof.
2. Description of the Related Art
In many applications, it is desirable to identify and track one target among a group or“cluster” of targets. Accordingly, many modern tracking and guidance systems include a cluster target resolution capability. Most such current systems utilize range rate or doppler data and employ a dichotomous angle processing technique.
In a typical doppler only dichotomous angle processing scheme, the amplitude of radar returns corresponding to two targets traveling at the same velocity (and therefore having the same doppler or range rate) are compared. Conventional angle detection techniques are employed to ascertain the angle of the target having the highest amplitude. The angle measurements are averaged over a predetermined time interval to remove the effects of scintillation and additive noise. If the processing were mathematically ideal, the average measurement would be the angle to the target in the resolution cell with the largest amplitude.
Unfortunately, there are many shortcomings associated with the conventional dichotomous processing technique for cluster target resolution. First, the conventional dichotomous processing technique is a two target technique. As such, systems employing a dichotomous processing technique experience considerable difficulty in discriminating between more than two targets at the same velocity. Secondly, the dichotomous processing scheme has difficulty discriminating between two targets at the same velocity and at or near the same angle and range. Thirdly, the dichotomous processing scheme is limited in response time by the fact that the angle measurement on a selected target can only be obtained when the natural amplitude scintillation produced a stronger return on that target. Finally, the effects of additive noise on conventional dichotomous processing schemes is such as to limit the resolution of the system within the constraint of a specified false alarm probability.
There is therefore a need in the art for a processing system having an improved cluster target resolution capability. Ideally, the system would employ a high speed, high resolution processing scheme capable of discriminating between multiple closely spaced targets simultaneously.
SUMMARY OF THE INVENTION
The need in the art for an improved radar processing system is provided by the unique cluster target resolution capability of the present invention. In its simplest form, the invention provides a system and method for processing radar returns and generating first and second contiguous range/doppler cells. Within the cells, first and second dichotomous angle measurements corresponding to radar returns in the first and second contiguous range/doppler cells are derived. An adaptive threshold is then applied to the angle measurements to determine whether the first and second measurements correspond to first and second targets in the first and second range/doppler cells respectively.
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Collins David W.
Gregory Bernarr E.
Lenzen, Jr. Glenn H.
Raytheon Company
Rudd Andrew J.
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