Virtual noise radar waveform for reduced radar detectability
First Claim
1. In apparatus generating a radar waveform and including a psuedo-random noise generator generating pulses in a pseudo-random pattern which are combined to produce an offset frequency signal, means generating a carrier wave having a frequency within a predetermined band of frequencies, and a modulator modulating the carrier wave with the offset frequency signal, the improvement wherein said psuedo random noise generator includes a pulse shaping filter suppressing modulation characteristics of said psuedo-random noise generator, said filter having a spectral response characteristic including raised cosine shapes;
- and, a propagation means transmitting the modulated waveform and for receiving a return waveform, the transmitted waveform having no discernible attributes by which the waveform, if received and analyzed by a detector other than the propagation means, would convey any intelligence as to the presence of the transmitted waveform or the source thereof.
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Accused Products
Abstract
Apparatus (10) for generating a radar waveform (W). A noise generator (20) generates a series of pulses in a pseudo-random pattern, and a frequency generator (16) generates a carrier wave having a frequency within a predetermined band of frequencies. The carrier wave is modulated with the pseudo-random pattern of pulses, and the resulting modulated carrier wave passed through both a filter (30) and an attenuator (32) to suppress any discernible feature or signal characteristics of the resulting waveform. The modulated carrier is transmitted by an antenna (42) and a received return signal is processed by a signal processor (100) to obtain pertinent information about a target. The transmitted waveform has no discernible attributes by which the waveform, if processed and analyzed by someone else'"'"'s radar detector (E) would convey any intelligence as to the presence or source of the transmitted waveform.
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Citations
30 Claims
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1. In apparatus generating a radar waveform and including a psuedo-random noise generator generating pulses in a pseudo-random pattern which are combined to produce an offset frequency signal, means generating a carrier wave having a frequency within a predetermined band of frequencies, and a modulator modulating the carrier wave with the offset frequency signal, the improvement wherein said psuedo random noise generator includes a pulse shaping filter suppressing modulation characteristics of said psuedo-random noise generator, said filter having a spectral response characteristic including raised cosine shapes;
- and, a propagation means transmitting the modulated waveform and for receiving a return waveform, the transmitted waveform having no discernible attributes by which the waveform, if received and analyzed by a detector other than the propagation means, would convey any intelligence as to the presence of the transmitted waveform or the source thereof.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- 10. In apparatus for generating a virtual noise waveform and including a generator generating a series of coded digital electrical pulses in a pseudo-random pattern, means modulating a carrier wave with the pulses to produce a modulated waveform, a filter 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 an attenuator attenuating the filtered waveform to sufficiently suppress any remaining features of the waveform so to produce a virtual noise waveform which appears as a random noise signal having no discernible attributes and conveying no information about the waveform or its source, the improvement comprising a pulse shaping filter suppressing modulation characteristics of said electrical pulse generator, said filter having a spectral response characteristic including raised cosine shapes.
- 17. In a method of generating a virtual noise waveform including the steps of generating two series of digital pulses in a pseudo-random pattern, combining the 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, the improvement comprising filtering said digital pulses with a pulse shaping filter to suppress modulation characteristics of said waveform, said filter having a spectral response characteristic including raised cosine shapes.
- 24. In a method of generating a radar waveform including 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, the improvement comprising filtering said coded pulse sequences with a pulse shaping filter to suppress modulation characteristics of said waveform, said filter having a spectral response characteristic including raised cosine shapes.
Specification