Abstract:
A novel methodology for automatically linearizing a harmonic radar transmitter—termed Feed-Forward Filter Reflection (FFFR)—is disclosed. The method combines the reflected second harmonic from a filter with the signal passing directly through the filter. The second harmonic from these two paths are combined with equal and opposite amplitudes to reduce the second harmonic beyond filtering alone. This methodology has been experimentally verified at transmit frequencies between 800 and 1000 MHz. Implemented properly, the technique provides greater than 100 dB rejection between 1.6 and 2.0 GHz. Although the tuning has been automated, further optimization is possible. Automated tuning is demonstrated over 400 MHz of bandwidth with a minimum cancellation of 110 dB. One application for the harmonic cancellation is to create a linear radar transmitter for the remote detection of non-linear targets.
Abstract:
Embodiments of the present invention concern locating targets using non-linear radar with a matched filter which uses exponential value of the transmit signal. According to embodiments, a method of non-linear radar target location includes: transmitting a signal of a transmit waveform towards a target; receiving a signal from the target; creating a matched filter by generating an exponential function of the transmit waveform corresponding to a particular harmonic of the interest; and applying the matched filter to the received signal to generate and output a signature waveform for the target of the particular harmonic of interest. In other embodiments, the matched filtering may be combined with sidelobe reduction.
Abstract:
Method for determining distance to target using a multitone nonlinear radar system comprising providing a transmitter that transmits a signal comprising at least two predetermined frequency components; receiving transmitted signal upon reflection from target; determining the phase relationships of the frequency components when signal strikes target; determining distance the signal has travelled to target based upon the phase relationship of the frequency signal components at the time of reflection from target; computing the distance to target. A system comprising a transmitter subsystem that transmits radar signal comprising at least two frequency components; a receiver subsystem configured to receive a return signal comprising intermodulation and harmonic products; at least one processor configured to extract frequency samples from the return signal within a frequency range, apply a window function to the extracted frequency samples and perform an inverse fast Fourier transform on the resulting function to create a range profile.
Abstract:
Embodiments of the present invention concern locating targets using non-linear radar with a matched filter which uses exponential value of the transmit signal. According to embodiments, a method of non-linear radar target location includes: transmitting a signal of a transmit waveform towards a target; receiving a signal from the target; creating a matched filter by generating an exponential function of the transmit waveform corresponding to a particular harmonic of the interest; and applying the matched filter to the received signal to generate and output a signature waveform for the target of the particular harmonic of interest. In other embodiments, the matched filtering may be combined with sidelobe reduction.
Abstract:
Method for determining distance to target using a multitone nonlinear radar system comprising providing a transmitter that transmits a signal comprising at least two predetermined frequency components; receiving transmitted signal upon reflection from target; determining the phase relationships of the frequency components when signal strikes target; determining distance the signal has travelled to target based upon the phase relationship of the frequency signal components at the time of reflection from target; computing the distance to target. A system comprising a transmitter subsystem that transmits radar signal comprising at least two frequency components; a receiver subsystem configured to receive a return signal comprising intermodulation and harmonic products; at least one processor configured to extract frequency samples from the return signal within a frequency range, apply a window function to the extracted frequency samples and perform an inverse fast Fourier transform on the resulting function to create a range profile.