Adaptive waveform radar

In a radar system operating in an electromagnetic environment including in-band and out-of-band interferences, a method of maintaining signal detectability, optimizing resolution and restoring non-ambiguous performance for the system, comprising the steps of:

• sampling the environment;
• estimating from the sampled environment an electromagnetic profile including the interferences;
• determining from the profile an optimal channel for the environment and channel transmit waveform parameters, the channel having an optimum center frequency and maximum channel bandwidth with fewest in-band interferences;
• generating a receiver matched filter corresponding to the determined optimum channel;
• transmitting a test target signal based on the waveform parameters into the environment;
• receiving an echo of the target signal and converting the same into a corresponding frequency spectrum;
• multiplying the frequency spectrum with the matched filter for notching out the interferences in the signal spectrum;
• compressing the multiplied frequency spectrum into a responsive pulse;
• and
• utilizing the responsive pulse to calculate transversal equalizer filter coefficients for reducing temporal sidelobes of the responsive pulse to realize an uncontaminated pulse signal with a desirable main lobe to sidelobe ratio.

A radar system for operating in an electromagnetic environment including in-band and out-of-band interferences, comprising:

• means for sampling the environment to provide a spectral electromagnetic profile representative of the environment;
• processor means for obtaining from the profile an optimal channel for the environment and for generating a receiver matched filter corresponding to the channel, notch filter coefficients and equalizer coefficients from responsive pulses, the optimal channel having an optimal center frequency and maximum channel bandwidth with fewest in-band interferences;
• means including an antenna having an array of elements for receiving a plurality of reflected signals representing echoes of target signals transmitted by the antenna to the environment;
• a plurality of filter means each for notching out the interferences in the frequency spectrum of a corresponding one of the reflection signals;
• beam forming means for accepting all of the interference notched out reflection signals and for automatically combining the reflection signals to form a beam signal having pattern nulls in the direction of the interferences, the beam signal being substantially devoid of sidelobe interferences;
• compressor and equalizer means for utilizing information from the receiver matched filter and the equalizer coefficients to compress the beam signal and to perform equalization to compensate for possible temporal sidelobes introduced thereto by the notch filter means;
• whereby a substantially interference free signal having a desirable main lobe to sidelobe ratio is generated

In a radar system operating in an electromagnetic environment including in-band and out-of-band interferences, a method of maintaining signal detectability, optimizing resolution and restoring non-ambiguous performance for the system, comprising the steps of:

• sampling the environment;
• estimating from the sampled environment an electromagnetic profile including the interferences;
• determining from the profile an optimal channel for the environment and channel transmit waveform parameters, the channel having an optimum center frequency and maximum channel bandwidth with fewest in-band interferences;
• generating a receiver matched filter corresponding to the determined optimum channel, notch filter and equalizer coefficients;
• transmitting a plurality of target signals based on the waveform parameters to the environment;
• utilizing an array antenna to receive a plurality of reflection signals representative of echoes of the target signals, each array of the antenna receiving one of the reflection signals and any interference superposed thereon;
• suppressing the interference in each of the reflection signals and converting the reflection signals into corresponding frequency spectrums;
• combining the corresponding frequency spectrums to form a beam signal having pattern nulls in the direction of interferences and substantially eliminating sidelobe interferences from the beam signal;
• utilizing data relating to the receiver matched filter and the equalizer coefficients to compress and to equalize the beam signal for compensating possible temporal sidelobe interference introduced thereto during the suppressing step;
• thereby generating a substantially interference free signal having a desireable main lobe to sidelobe ratio.