A method and apparatus for processing cochannel signals received at a sensor array (110) in a cumulant-based signal processing and separation engine to obtain a desired set of output signals (38) or parameters. For use in a signal recovery system, the output signals are recovered and separated versions of the originally transmitted cochannel signals. An important feature that distinguishes the cumulant-based system from other signal separation and recovery systems is that it generates an estimated generalized steering vector associated with each signal source, and representative of all received coherent signal components attributable to the source. This feature enables the invention to perform well in multipath conditions, by combining all coherent multipath components from the same source. In a receiver/transmitter system (316), the estimated generalized steering vectors associated with each source are used to generate transmit beamformer weight vectors that permit cochannel transmission to multiple user stations (310). The basic cumulant-based processing and separation engine can also be used in a variety of applications, such as high density recording, complex phase angle equalization, receiving systems with enhanced effective dynamic range, and signal separation in the presence of strong interference. Various embodiments and extensions of the basic cumulant-based system are disclosed.

Cochannel signal processing system

A weapons detector (12) and method utilizing radar. The system comprises a transmitter for producing an output (14) of frequencies of a set of self-resonant frequencies of weaponry; an antenna directing the transmitter output toward locations potentially having weaponry and collecting backscattered signals (15); a receiver receiving the backscattered signals (15) and operating over a range of the self-resonant frequencies; and a signal processor for detecting the presence of a plurality of the self-resonant frequencies in the backscattered signals (15). Accuracies of greater than 98 % can be obtained at distances, preferably between 4-15 yards. The weapons detector (12) is capable of detecting metal and non-metal weapons (16) on a human body (13) in purses, briefcases and under clothing; and discerning weapons (16) from objects such as belt buckles, coins, keys, calculators, cellular phones.

Concealed weapons detection system

An apparatus for identifying a buried object using ground penetrating radar (GPR) in a system containing at least one GPR sensor, comprises a data processor for detecting spatial correlations in data received from a GPR sensor in the apparatus and an image processor capable of building a data structure corresponding to an image of the buried object from data processed by the data processor. A method for identifying a buried object using GPR in a system containing a GPR sensor comprising detecting spatial correlations in data received from the GPR sensor in the system and building a data structure corresponding to an image of the buried object from the received data.

Method and apparatus for identifying buried objects using ground penetrating radar

The present invention is a multi-purpose portable imaging device. The device is small enough to be hand-held or wearable and has embedded on its surface at least one sensor. These sensors may be active or passive. Analog energy received from the sensors is converted into a digital format and sent to an advanced computer. The computer is constructed on parallel architecture platform. The computer has the capability of taking data from multiple sensors and providing sensor fusion features. The data is processed and displayed in a graphical format in real time which is viewed on the imaging device. A keypad for entering data and commands is available on the device. The device has the capability of using a removable cartridge embedded with read only memory modules containing application software for manipulating data from the sensors. The application cartridge provides the imaging device with its multi-purpose functionality. Methods of utilizing expert systems to match generated images, or dielectric constants is provided.

System for A multi-purpose portable imaging device and methods for using same

Arrangements are disclosed for producing images based upon diffusional wave theory and frequency domain analysis. A medium to be imaged is illuminated with amplitude modulated radiation, and diffusional radiation transmitted or reflected by the medium is detected at a plurality of detection locations, as by a television camera. The phase and also the amplitude demodulation of the amplitude modulated diffusional radiation is detected at each detection location. A relative phase image and also a demodulation amplitude image of the medium are then generated from respectively the detected relative phase values and the detected demodulation amplitudes of the diffusional radiation at the plurality of locations. The present invention is particularly suited for medical applications for generating images of internal anatomical details of the body by using a near infrared amplitude modulated source for illumination of the body. In such medical applications, the body is illuminated with near infrared radiation having a wavelength between 600 and 1200 nanometers which is amplitude modulated at a frequency in the megahertz to gegihertz range, and internal images of the patient are generated for medical diagnosis. In preferred embodiments, a laser is utilized to generate the near infrared radiation near or below a 10 watt power level which is coupled by fiber optic cables to the body of the patient. Detection is also with fiber optic cables placed in direct contact with an opposed surface of the body which couple the transmitted diffusional radiation to an image intensifier placed in front of a television camera detector. The gain of the image intensifier is modulated at a frequency to obtain a heterodyned output frequency of less than 60 hertz which is within the detection bandwidth of the television camera.

Frequency domain optical imaging using diffusion of intensity modulated radiation

A method and apparatus for classifying objects based upon information conned in the fourth order cumulant derived from energy from the object. Successive pulse returns in active systems and samples in passive systems are converted into vectors based upon the fourth order cumulant information for each successive return or sample. The vectors for each such pulse are compared to corresponding class information based upon the corresponding fourth order cumulant information. The comparison uses loglikelihood ratios of the different pairs of classes. Decision making is based upon the value of each loglikelihood ratio in comparison with a class threshold.

Method and apparatus for classifying targets

Apparatus and method for discriminating against non-Gaussian noise. Analog signals from an array of sensors are converted to real and imaginary digital representations and processed such that non-Gaussian noise is separated from signals of interest. The processor uses estimates of Kurtosis and quantiles from either past or adjacent frequency components to construct non-linear elements, which are then used to process remaining signal data to improve the signal-to-noise ratio thereof by removing non-Gaussian noise therefrom.

Frequency domain non-linear signal processing apparatus and method for discrimination against non-Gaussian interference

A method of extracting target range and Doppler information from a Dopplepread signal is provided. An acoustic waveform is transmitted underwater and impinges upon a submerged Doppler-spread target. Doppler-spread sonar echoes resulting from the transmitted waveform are received and digitized. The received sonar echo is separated into its inphase and quadrature components thereby forming a complex vector function. A fourth-order cumulant spectrum is generated from the complex vector function based upon three time delays. In order to extract the range and Doppler information from the Doppler-spread signal, the first of the time delays is set equal to zero while the second and third time delays are set equal to one another.

Roger F. Dwyer

Papers

Method and apparatus for classifying targets

Frequency domain non-linear signal processing apparatus and method for discrimination against non-Gaussian interference

Method of extracting target range and Doppler information from a Doppler-spread signal