Transmission of AM-VSB video signals over an optical fiber
AssigneesGeneral Instrument Corporation, Corning Incorporated
InventorsDavid R. Huber, Douglas W. Hall, Edward F. Murphy
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Abstract
The use of a doped optical fiber amplifier enables the transmission of multi-channel AM-VSB television signals. An Erbium doped fiber amplifier is disclosed. The amplifier is also useful for reducing second order distortion products produced in an amplitude modulated subcarrier optical communication system. The amplifier may be used in a tree and branch structure optical fiber television network.
Claims22
Apparatus for transmitting an amplitude modulated vestigial-sideband (AM-VSB) signal over an optical fiber comprising:
- a light source for providing light at a wavelength .lambda.;
- means for modulating light from said source with a signal having an AM-VSB subcarrier, said SM-VSB subcarrier having a periodic waveform defining a period;
- means for passing the modulated light through a doped optical fiber amplifier having an excited state lifetime which is greater than the period of said AM-VSB subcarrier and said amplifier exhibiting gain at said wavelength .lambda.;
- and
- means for introducing the amplified modulated light output from said amplifier to an optical fiber.
Apparatus for reducing second order distortion in an amplitude modulated subcarrier optical communication system, said amplitude modulated subcarrier having a periodic waveform defining a period, comprising:
- a doped fiber optical amplifier having an excited state lifetime which is greater than the period of an AM subcarrier and exhibiting gain at a wavelength .lambda.;
- and
- means for connecting said amplifier in series with said optical communication system;
- wherein an optical beam of wavelength .lambda. modulated by said AM subcarrier and carried on said optical communication system will be amplified by said amplifier, thereby reducing second order distortion in said AM subcarrier.
A method for reducing second order distortion in an amplitude modulated subcarrier optical communication system comprising the steps of:
- providing a doped fiber optical amplifier exhibiting gain at a wavelength .lambda.;
- coupling said amplifier in series with a communication path of an optical communication system;
- and
- amplifying an AM subcarrier modulated optical beam of wavelength .lambda. carried on said communication path in said amplifier to reduce second order distortion in said AM subcarrier.
Dependencies are inferred from the claim text.