Accession Number : ADD008095

Title :   Frequency Compression and Expansion Using an Electrooptical Processor.

Descriptive Note : Patent,


Personal Author(s) : Bromley,Keith

Report Date : 25 Nov 1980

Pagination or Media Count : 19

Abstract : A method of compressing or expanding the frequency of signals while keeping the signals' original gross temporal relationship relies upon an electrooptical processor. An apertured mask is interposed between an area-array charge coupled device (CCD) and a light emitting diode (LED). Optical signals are emitted from the LED at a clock rate which is the same as the vertical shift rate of charge packets in the CCD. Sampling the CCD's horizontal shift register output at varying rates allows a changing of the frequencies of the optical signals or a reoccurring reversal of sequential portions. Weighting the apertured mask to define at least one Gaussian curve or triangular waveform smooths and eliminates breaks in the compressed or expanded frequencies. Sampling the CCD output at a slower rate than the vertical clock rate compresses the frequency of the representative optical signals and if the CCD output is sampled at a faster rate then the signals will be expanded or rearranged in a sequentially reoccurring order. Thus, the electrooptic processor accomplishes a compression or expansion of signals with the signal's original gross temporal relationship and does not rely upon any mechanically displaceable parts. An optional approach employs a line-array CCD detector and a bidirectionally movable apertured mask to accomplish substantially the same end results; however, this introduces the problems usually associated with mechanical devices. (Author)

Descriptors :   *Patents, *Processing equipment, *Optical processing, *Electrooptics, *Charge coupled devices, Light emitting diodes, Shift registers, Signal processing, Mechanical components, Horizontal orientation, Vertical orientation, Photomasking, Aperture, Shifting, Sampling, Output, Compression, Frequency, Expansion, Signals, Optics, Clocks, Rates

Subject Categories : Electrooptical and Optoelectronic Devices

Distribution Statement : APPROVED FOR PUBLIC RELEASE