Virtual noise radar waveform for reduced radar detectability

Apparatus for generating a virtual noise waveform comprising:

• generation means for generating a series of coded digital electrical pulses in a pseudo-random pattern;
• means for modulating a carrier wave with the pulses to produce a modulated waveform;
• means filtering the resulting modulated waveform for an output waveform from the filter to fall within a null portion of the filter for the waveform energy of the output from the filter to be at a minimum level, the bandwidth of the filtered waveform being sufficient to enable the waveform to obtain desired information when directed at an area of interest;
• and,
• attenuation means attenuating the filtered waveform to sufficiently suppress any remaining features of the waveform so to produce a virtual noise waveform which will appear as a random noise signal having no discernible attributes and conveying no information about the waveform or its source.

A method of generating a virtual noise waveform comprising:

• generating a first and a second series of digital pulses in a pseudo-random pattern;
• combining said respective series of pulses to produce an offset frequency;
• modulating a carrier wave with the offset frequency to produce a modulated waveform;
• and, suppressing the characteristics of the resulting modulated waveform for the waveform to have no discernible attributes which would convey any information about the existence of the waveform or its source.

A method of generating a radar waveform comprising:

• generating an in-phase series and a quadrature-phase series of coded pulse sequences in a pseudo-random pattern;
• combining the two series of coded pulse sequences into an offset frequency;
• generating a carrier wave having a frequency within a predetermined frequency band;
• modulating said carrier wave with said offset frequency;
• filtering the modulated waveform so the waveform energy is concentrated within a narrow bandwidth corresponding to the bandwidth required for information gathering, the energy of the resulting filtered waveform being substantially less than that of the unfiltered modulated waveform;
• attenuating the filtered waveform to suppress any features therein and to eliminate any discernible features of the filtered waveform;
• and,
• transmitting the resulting waveform and receiving a return waveform, said transmitted waveform, if received and analyzed by a detection means other than that associated with the source of the waveform, appearing as a random noise signal having no discernible attributes and conveying no information about the waveform or its source.