System and method for detection and tracking of targets

Abstract

System and method for detection and tracking of targets, which in a preferred embodiment is based on the use of fractional Fourier transformation of time-domain signals to compute projections of the auto and cross ambiguity functions along arbitrary line segments. The efficient computational algorithms of the preferred embodiment are used to detect the position and estimate the velocity of signals, such as those encountered by active or passive sensor systems. Various applications of the proposed algorithm in the analysis of time-frequency domain signals are also disclosed.

Description

CLAIM OF PRIORITY [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 691,245 filed on Oct. 21, 2003, which in turn is a continuation of U.S. patent application Ser. No. 09 / 875,116 filed Jun. 6, 2001, issued as U.S. Pat. No. 6,636,174, which in turn claims priority of provisional application Ser. No. 60 / 209,758 filed Jun. 6, 2000.FIELD OF THE INVENTION [0002] The present invention relates to active and passive sensor applications, and more particularly is directed to efficient systems and methods for detection and tracking of one or more targets. BACKGROUND OF THE INVENTION [0003] Detection and tracking of targets by sensor systems have been the subject matter of a large number of practical applications. Sensor systems designed for this purpose may use propagating wave signals, such as electromagnetic or acoustical signals. Some sensor systems, such as radar and active sonar systems, are designed to receive reflections of a transmitted signal generated b...

AI Technical Summary

Benefits of technology

"The present invention is about a method to simultaneously compute distance and Doppler shift information using fast computation of the ambiguity function and / or Wigner distribution of received signals along on arbitrary line. The method utilizes fractional Fourier transformation of time domain signals to obtain closed form expressions for arbitrary projections of their auto or cross ambiguity function. The method also proposes efficient algorithms to compute samples of the Wigner distribution and the ambiguity function located on arbitrary line segments. The ability to obtain samples of the Wigner distribution and ambiguity function over both rectangular and polar grids is potentially useful in a wide variety of application areas."

Problems solved by technology

Although the use of the cross-ambiguity function for detection of scattering objects and estimation of their corresponding delay and Doppler shifts is known in the prior art, this approach has only been used in sophisticated sensor systems because of the high cost and difficulty of implementation.

Therefore, in most of the applications where the cost is a critical issue, the sensor systems are designed to detect the presence of scattering objects and estimate either their range or their velocities, but not both.

Unlike the active sensor systems where the range and the velocity of the objects can be estimated from the reflected signals, passive sensor systems cannot decide on the range and the velocity of the intercepted transmitter without extensive prior information about the transmitter.

As seen from FIG. 2B, the detection of the signal can be a difficult task, especially for intercepted signals that have low amplitudes.

However, in practice the auto-ambiguity function approach is almost never used in the detection of intercepted signals due to the associated high cost and complexity.

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