Data transmission system

A data transmission system including:

• a plurality of subscriber units, having at least a subscriber unit with a video receiver and a subscriber unit without a video receiver, each of the plurality of subscriber units is configured to interconnect with a central office unit via optical fibers, the central office unit configured to multiplex a video signal with signals other than the video signal and to deliver them to the plurality of subscriber units, and said central office unit comprises:
• an optical amplifier configured to amplify the video signal to be transmitted;
• and
• an optical distributor configured to distribute the video signal output from said optical amplifier and to supply the video signal output to a wavelength division multiplexer/demultiplexer,
• wherein said subscriber unit without the video receiver comprises a first wavelength division multiplexer/demultiplexer configured to attenuate a particular wavelength signal,
• wherein the subscriber unit with the video receiver is configured to separate the video signal from the multiplexed signal received at a second wavelength division multiplexer/demultiplexer and to input the video signal to the video receiver,
• wherein the subscriber unit without the video receiver is configured to separate the video signal from the multiplexed signal received at the first wavelength division multiplexer/demultiplexer, to attenuate the video signal without a terminator to prevent further downstream transmission of the video signal with respect to the first wavelength division multiplexer/demultiplexer, to separate the signals other than the video signal, and to input the signals other than the video signal to a transmitting and receiving section, and
• the subscriber unit without the video receiver includes a transmitting laser diode and a receiving photodiode, the transmitting photodiode is disposed outside of the first wavelength division multiplexer/demultiplexer and on a first end surface of the first wavelength division multiplexer/demultiplexer, and the receiving photodiode is disposed outside of the second wavelength division multiplexer/demultiplexer and on second end surface, opposite the first end surface, of the first wavelength division multiplexer/demultiplexer.

A data transmission system including:

• a plurality of subscriber units, having at least a subscriber unit with a video receiver and a subscriber unit without a video receiver, the plurality of subscriber units configured to interconnect with a central office unit via optical fibers, the central office unit configured to multiplex a video signal with signals other than the video signal and to deliver them to the plurality of subscriber units, wherein each of the plurality of subscriber units is configured to demultiplex a received signal, and said central office unit comprises:
• a plurality of video signal generators configured to generate video signals with different wavelengths;
• a first wavelength division multiplexer/demultiplexer configured to multiplex the video signals supplied from said plurality of video signal generators;
• an optical amplifier configured to amplify the video signals output from said first wavelength division multiplexer/demultiplexer;
• and
• an optical distributor configured to distribute the video signals output from said optical amplifier to a second wavelength division multiplexer/demultiplexer,
• wherein the subscriber unit without the video receiver comprises a first wavelength division multiplexer/demultiplexer configured to eliminate a particular wavelength signal from said subscriber unit without the video receiver,
• the subscriber unit with the video receiver is configured to separate the video signal from the multiplexed signal received at a second wavelength division multiplexer/demultiplexer and to input the video signal to the video receiver,
• the subscriber unit without the video receiver is configured to separate the video signal from the multiplexed signal received at the first wavelength division multiplexer/demultiplexer, to attenuate the video signal without a terminator to prevent further downstream transmission of the video signal with respect to the first wavelength division multiplexer/demultiplexer, to separate the signals other than the video signal, and to input the signals other than the video signal to a transmitting and receiving section, and
• the subscriber unit without the video receiver includes a transmitting laser diode and a receiving photodiode, the transmitting photodiode is disposed outside of the first wavelength division multiplexer/demultiplexer and on a first end surface of the first wavelength division multiplexer/demultiplexer, and the receiving photodiode is disposed outside of the second wavelength division multiplexer/demultiplexer and on second end surface, opposite the first end surface, of the first wavelength division multiplexer/demultiplexer.

A data transmission system including:

• a plurality of subscriber units, having at least a subscriber unit with a video receiver and a subscriber unit without a video receiver, the plurality of subscriber units configured to interconnect with a central office unit via optical fibers, the central office unit configured to multiplex a video signal with signals other than the video signal and to deliver them to the plurality of subscriber units, and the subscriber unit without the video receiver comprises:
• a first wavelength division multiplexer/demultiplexer configured to demultiplex the video signals and signals other than the video signal;
• and
• a second wavelength division multiplexer/demultiplexer configured to attenuate a particular wavelength signal,
• wherein the subscriber unit with the video receiver is configured to separate the video signal from the multiplexed signal received at a third wavelength division multiplexer/demultiplexer and to input the video signal to the video receiver, and
• the subscriber unit without the video receiver is configured to separate the video signal from the multiplexed signal received at the second wavelength division multiplexer/demultiplexer, to attenuate the video signal without a terminator to prevent further downstream transmission of the video signal with respect to the second wavelength division multiplexer/demultiplexer, to separate the signals other than the video signal, and to input the signal other than the video signal to a transmitting and receiving section, and
• the subscriber unit without the video receiver includes a transmitting laser diode and a receiving photodiode, the transmitting photodiode is disposed outside of the second wavelength division multiplexer/demultiplexer and on a first end surface of the second wavelength division multiplexer/demultiplexer, and the receiving photodiode is disposed outside of the second wavelength division multiplexer/demultiplexer and on second end surface, opposite the first end surface, of the second wavelength division multiplexer/demultiplexer.