Passive non-linear synthetic aperture radar and method thereof

An assembly for receiving signals at spaced frequencies from an unknown transmitting source comprising:

• a receiver operative to receive signals;
• the receiver comprising a series of channels, each channel comprising:
• a low pass filter configured to allow passage of the signal received from an unknown transmitting source, a mixer configured to combine the received signal with a signal generated by a signal generator for providing a common phase for each of the receive channels;
• an analog to digital converter configured to transform the signal from the unknown transmitting source to a digital signal, a Hilbert transform processor configured to transform the digital signal from the unknown transmitting source into a single sideband signal, a Fourier transform processor configured to transform the single sideband signal into a plurality of regularly spaced frequency samples, and an inverse Fourier transform processor configured to extract the regularly spaced time-domain samples from the unknown transmitting source;
• and an image processor configured to generate an image from the inverse Fourier transformed frequency components from the unknown transmitting source of each of the series of channels,
• whereby the extracted pulses form a train of pulses that are inputted into the image processor which utilizes synthetic aperture radar to form an image of the area of interest containing the unknown transmitting device.

A method for receiving signals from an unknown transmitting source and providing the location of the unknown transmitting source comprising:

• providing at least one processor for processing a signal from the unknown transmitting source;
• providing a series of channels controlled by a common clock pulse;
• for each channel in the series of channels:
• amplifying the received signals;
• selectively allowing passage of signals within a predetermined frequency band;
• combining the received signal with a signal generated by a signal generator for providing a common phase for each of the receive channels;
• performing an analog to digital conversion to convert the combined signal into a digital signal;
• performing one of a Hilbert transform or in-phase quadrature process on the digital signal to create a single-sideband signal;
• performing a Fourier Transform on the single-sideband signal to convert the signal from a signal expressed as a function of time to the frequency components of which it is composed;
• extracting the frequency component signals originating from the unknown transmitting source;
• performing an inverse Fourier transform on the frequency components from the unknown transmitting source for storage;
• generating a synthetic aperture radar (SAR) image from the inverse Fourier transformed frequency components from the unknown transmitting source of each of the series of channels.