Optical spread spectrum decoder

A method of optically decoding non-linear and discontinuous radio frequency signals, said method comprising the steps of:

• (a) optically processing optical radiation modulated with a broadband radio frequency signal to remove unwanted spectral components;
• (b) introducing an adaptive optical weighting function for accommodating changing modulated conditions in said optical radiation, said weighting function being introduced via a gradient density filter, said gradient density filter introducing one of the group of functions consisting of cosine squared, cosine squared with pedestal, hamming and unscaled Gaussian functions;
• and
• (c) down-converting said optical radiation, including combining the processed optical radiation with a local oscillator beam, to recover said radio frequency signal.

An optical system for decoding a spread spectrum signal, said optical system comprising:

• means for optically processing optical radiation modulated with a radio frequency signal to remove unwanted spectral components;
• optical weighting function means for introducing an adaptive optical weighting function into the modulated optical radiation;
• and
• down-converting means for down-converting the optical radiation to recover said radio frequency signal, said down-converting means comprising a local oscillator beam and means for combining said local oscillator beam with the processed optical radiation, and optical weighting function means comprising a gradient density filter for introducing one of the group of functions consisting of cosine squared, cosine squared with pedestal, hamming and unscaled Gaussian functions.

An optical spread spectrum decoding system for decoding linear, non-linear and discontinuous radio frequency signals, said decoding system comprising:

• a source of substantially coherent collimated optical radiation;
• means defining an optical path for said radiation;
• modulating means for modulating said radiation with a broadband radio frequency signal;
• optical processing means for optically processing the modulated radiation to remove unwanted spectral components;
• optical compression means for compressing the optically processed radiation;
• weighting function means disposed along said optical path for introducing a weighting function into said optical radiation to accommodate the decoding of the signal to changes in said modulated radiation;
• down-converting means for down-converting said optically processed and compressed radiation to provide a decoded radio frequency signal, said down-converting means including a local oscillator beam having said weighting function introduced thereinto, said weighting function means comprising a gradient density filter introducing one of the group of functions consisting of cosine squared, cosine squared with pedestal, hamming and unscaled Gaussian functions;
• and
• means providing a noncoherent write-light beam for controlling and modulating said gradient density filter.

An optical spread spectrum decoding system for decoding linear, non-linear and discontinuous radio frequency signals, said decoding system comprising:

• a source of substantially coherent collimated optical radiation;
• means defining an optical path for said radiation;
• modulating means for modulating said radiation with a broadband radio frequency signal;
• optical processing means for optically processing the modulated radiation for removing unwanted spectral components;
• optical compression means for compressing the optically processed radiation;
• weighting function means disposed along said optical path for introducing a weighting function into said optical radiation for accommodating the decoding of the signal to changes in said modulated radiation;
• down-converting means for down-converting said optically processed and compressed radiation to provide a decoded radio frequency signal, said down-converting means including a local oscillator beam having said weighting function introduced thereinto, said weighting function means comprising a gradient density filter introducing one of the group of functions consisting of cosine squared, cosine square with pedestal, hamming and unscaled Gaussian functions and consisting of a filter material selected from a group consisting of photochromic, liquid crystal and photorefractive materials.

A method of optically decoding non-linear and discontinuous radio frequency signal, said method comprising the steps of:

• (a) optically processing optical radiation modulated with a broadband radio frequency signal to remove unwanted spectral components;
• (b) introducing an adaptive optical weighting function for accommodating changing modulated conditions in said optical radiation, said weighting function being introduced via a gradient density filter, said gradient density filter introducing one of the group of functions consisting of cosine squared, cosine squared with pedestal, hamming and unscaled Gaussian functions;
• (c) down-converting said optical radiation, including combining the processed optical radiation with a local oscillator beam, to recover said radio frequency signal;
• and
• (d) controlling and modulating the gradient density filter via noncoherent write-light beam.

A method optically decoding non-linear and discontinuous radio frequency signals, said method comprising the steps of:

• (a) optically processing optical radiation modulated with broadband radio frequency signal to remove unwanted spectral components;
• (b) introducing an adaptive optical weighting function for accommodating changing modulated conditions in said optical radiation, said weighting function being introduced via a gradient density filter, said gradient density filter introducing one of the group of functions consisting of cosine squared, cosine squared with pedestal, hamming and unscaled Gaussian functions and consisting of a filter material selected from a group consisting of photochromic, liquid crystal and photorefractive materials;
• and
• (c) down-converting said optical radiation, including combining the processed optical radiation with a local oscillator beam, to recover said radio frequency signal.

An optical system for decoding a spread spectrum signal, said optical system comprising:

• means for optically processing optical radiation modulated with a radio frequency signal to remove unwanted spectral components;
• optical weighting function means for introducing an adaptive optical weighting function into the modulated optical radiation;
• down-converting means for down-converting the optical radiation to recover said radio frequency signal, said down-converting means comprising a local oscillator beam and means for combining said local oscillator beam with the processed optical radiation, said optical weighting function means comprising a gradient density filter for introducing one of the group of functions consisting of cosine squared, cosine squared with pedestal, hamming and unscaled Gaussian functions;
• and
• means providing a noncoherent write-light beam for controlling and modulating said gradient density filter.

An optical system for decoding a spread spectrum signal, said optical system comprising:

• means for optically processing optical radiation modulated with a radio frequency signal to remove unwanted spectral components;
• optical weighting function means for introducing an adaptive optical weighting function into the modulated optical radiation;
• and
• down-converting means for down-converting the optical radiation to recover said radio frequency signal, said down-converting means comprising a local oscillator beam and means for combining said local oscillator beam with the processed optical radiation, said optical weighting function means comprising a gradient density filter for introducing one of the group of functions consisting of cosine squared, cosine squared with pedestal, hamming and unscaled Gaussian functions, said gradient density filter consisting of a filter material selected from a group consisting of photochromic, liquid crystal and photorefractive materials.