Multiplexing digital communication system

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIG.
1 shows system components that can be incorporated into a broadband or high speed communication system, such as a cable television (CATV) system.
These components transport data from the set of input lines 105 of a transmitter 100 to the output lines 155 of a receiver 130 using a single-mode optical fiber 125.
In the ideal case, the output signals identically replicate the input signals.
In the general case, input data may be sent to the transmitter 100 using analog or digital modulation formats such as synchronous or asynchronous on/off digital keying, frequency shift keying (FSK), quadrature amplitude modulation (QAM), etc.
The speed of data transfer and modulation format may be different for each input.
Amplifiers external to the transmitter 100 may be used to adjust the input voltage states to a common range of values.
Inside the transmitter 100, a multiplexer 110 transfers the data from the multiple input lines 105 to a single high-speed serial output 115.
This output drives an optical transmitter 120 that excites a single-mode optical fiber 125.
At the receiver 130, an optical receiver 140 converts the transmitted lightwave signal to an on/off keyed electrical signal.
A demultiplexer 145 decodes the receiver output and transfers the data from a single high-speed serial line 143 to a series of outputs 155 that match the inputs 105 in number and modulation format.
The modulation formats for the high-speed optical link are established in accordance with existing standards.
For example, the data could be transmitted in blocks that are framed by a series of `start` bits.
Within a data block, different input data types could be assigned to specific time slots.
The multiplexer 110 then analyzes the signals on each of the input lines to determine the modulation format and to temporally position slices of data at defined locations (corresponding to time intervals) within the data block.
At the receiver 130, the demultiplexer 145 determines the modulation format for the data in a particular slot from its temporal displacement relative to the leading edge of the data block