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Browse Prior Art Database

Two Channel Analog Fiber Optic Link Using FM Modulation

IP.com Disclosure Number: IPCOM000122076D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Johnson, DWJ: AUTHOR

Abstract

Disclosed is an implementation of a two-channel analog fiber- optic link. The method used could be extended to support multiple analog sources. The use of fiber-optic technology helps make the circuit operate well in an electromagnetically noisy environment. Plastic core fiber and commercial parts were used to create a very low-cost circuit.

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Two Channel Analog Fiber Optic Link Using FM Modulation

      Disclosed is an implementation of a two-channel analog fiber-
optic link.  The method used could be extended to support multiple
analog sources.  The use of fiber-optic technology helps make the
circuit operate well in an electromagnetically noisy environment.
Plastic core fiber and commercial parts were used to create a very
low-cost circuit.

      Each channel is FM modulated onto its own carrier. These are
superimposed, with the resulting signal modulating an ILD which
drives the fiber.  The zero crossings are used to demodulate the
signal.  In this way, as long as the zero crossings are intact, the
signals can be recovered.  This also makes the signal inherently less
susceptible to noise.

      A commercial VCO circuit is used to modulate and demodulate the
signal.  The high frequency effects of modulation and demodulation
are filtered out of the signals.

      The resulting circuit is very low-cost, can support multiple
channels and has good performance for audio use.

      Disclosed anonymously.