Digital optical transmitter
First Claim
1. An optical transmitter, comprising:
- an analog-to-digital (A/D) converter for converting an analog information signal to a digital information signal;
a pilot tone generator for generating a digital pilot tone;
a summer coupled to the A/D converter and the pilot tone generator for adding the digital pilot tone to the digital information signal to result in a summed signal; and
a laser diode coupled to the summer for providing an optical signal in accordance with the summed signal.
2 Assignments
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Accused Products
Abstract
A cable television system (100) having forward and reverse paths includes, in the reverse path, a digital optical transmitter (200) for receiving an RF signal, converting it to a digital signal, and adding a digital pilot tone thereto. A laser is driven in accordance with the summed digital signal to generate a digital optical signal representative of the pilot tone and the RF signal. The cable television system (100) also includes an optical receiver (305)for receiving the digital optical signal and recovering therefrom the RF signal and the pilot tone. The optical transmitter (200) and receiver (305) are coupled by fiber optic communication media (110).
19 Citations
16 Claims
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1. An optical transmitter, comprising:
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an analog-to-digital (A/D) converter for converting an analog information signal to a digital information signal;
a pilot tone generator for generating a digital pilot tone;
a summer coupled to the A/D converter and the pilot tone generator for adding the digital pilot tone to the digital information signal to result in a summed signal; and
a laser diode coupled to the summer for providing an optical signal in accordance with the summed signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A cable television system for providing signals, the cable television system comprising:
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an optical transmitter for receiving an analog information signal and transmitting in accordance therewith a digital optical signal representative of the analog information signal;
an optical receiver for receiving the digital optical signal and recovering therefrom an analog signal representative of the analog information signal; and
an optical communication medium for coupling the optical transmitter and the optical receiver. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A cable television system having forward and reverse paths for respectively transmitting forward and reverse signals, the cable television system comprising:
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first and second distribution systems for providing information to system subscribers located, respectively, in first and second geographic regions;
a headend for generating and transmitting optical signals;
an optical node, remotely located from the headend, for converting the optical signals to electrical signals and for transmitting the electrical signals over the first and second distribution systems, wherein, in the reverse path, the optical node comprises an optical transmitter, including;
a first A/D converter for receiving a first analog information signal from subscriber equipment included in the first distribution system and converting the first analog information signal to a first digital information signal;
a second A/D converter for receiving a second analog information signal from subscriber equipment included in the second distribution system and converting the second analog information signal to a second digital information signal;
a digital pilot tone generator for generating a digital pilot tone;
summers coupled to the first and second A/D converters and the digital pilot tone generator for adding the digital pilot tone to the first digital information signal to result in a first summed signal and for adding the digital pilot tone to the second digital information signal to result in a second summed signal;
serializers coupled to the summers to convert the first and second summed signals to first and second serial signals;
an interleaver coupled to the serializers for interleaving bits of the first summed signal with bits of the second summed signal to generate an interleaved signal; and
a laser diode coupled to the interleaver for emitting a digital optical signal in accordance with the interleaved signal.
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Specification