Multiplex transmission of analog signals by fiber optic channel
First Claim
1. In a multiplex transmission system having a plurality of sources of analog signals connected to multiplexing means for providing at least one group of amplitude modulated continuous signals at different frequencies, the combination therewith of:
- a frequency modulator connected to said multiplexing means for converting said group of amplitude modulated continuous signals into a group of frequency modulated continuous signals;
an optical transmitter connected to said frequency modulator for intensity modulation of the optical signal output of said optical transmitter by said group of frequency modulated continuous signals;
an optical fiber cable connected at one end to said optical transmitter for transmitting the optical signals at the output of said optical transmitter;
an optical receiver connected to said optical fiber cable for receiving optical signals from said optical transmitter; and
a frequency demodulator connected to said optical receiver for demodulating the signals at the output of said optical receiver.
2 Assignments
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Accused Products
Abstract
A communication system in which analog signals are multiplexed and then converted into frequency modulated signals which are applied to the laser of an optical transmitter to intensity modulate the laser output. The laser output is supplied to one end of an optical fiber, the other end of which is connected to an optical receiver. The output signals of the optical receiver are applied to a frequency demodulator, and the output signals of the frequency demodulator are demultiplexed to provide the corresponding analog signals. The system may include pilot tone signals for remote monitoring of conditions at an unmanned station, and preferably, some of the multiplexed signals are emphasized relative to the other signals prior to application to the frequency modulator and are correspondingly deemphasized at the frequency demodulator output.
59 Citations
8 Claims
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1. In a multiplex transmission system having a plurality of sources of analog signals connected to multiplexing means for providing at least one group of amplitude modulated continuous signals at different frequencies, the combination therewith of:
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a frequency modulator connected to said multiplexing means for converting said group of amplitude modulated continuous signals into a group of frequency modulated continuous signals; an optical transmitter connected to said frequency modulator for intensity modulation of the optical signal output of said optical transmitter by said group of frequency modulated continuous signals; an optical fiber cable connected at one end to said optical transmitter for transmitting the optical signals at the output of said optical transmitter; an optical receiver connected to said optical fiber cable for receiving optical signals from said optical transmitter; and a frequency demodulator connected to said optical receiver for demodulating the signals at the output of said optical receiver. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a telephone system in which analog signals are transmitted from a first station to a second station over an optical fiber cable, said first station comprising a plurality of sources of analog signals connected to multiplexing means for providing at least one group of amplitude modulated continuous signals at different frequencies, and an optical transmitter connected to one portion of said optical fiber cable for supplying the signals at the output of said optical transmitter to said one portion of said optical fiber cable and said second station comprising an optical receiver connected to another portion of said optical fiber cable for receiving optical signals from said optical transmitter and demultiplexing means for demultiplexing signals received by said optical receiver, the improvement comprising:
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a frequency modulator at said first station and connected to said multiplexing means for converting said group of amplitude modulated continuous signals into a group of frequency modulated continuous signals and connected to said optical transmitter for intensity modulating said signals at the output of said optical transmitter with the group of frequency modulated continuous signals; and a frequency demodulator at said second station and connected to said optical receiver and to said demultiplexing means for converting the signals received by said optical receiver into amplitude modulated signals and supplying the latter said signals to said demultiplexing means.
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Specification