Digital optical transmitter and digital optical receiver making communication by superposing subdata on modulated waveform of main data

A digital optical receiver receiving data through a modulation system utilizing subcarriers, comprising:

• a conversion part for receiving an optical modulated signal, converting the same to an electrical modulated signal formed of a subcarrier, and outputting said electrical modulated signal;
• and
• a subdata extraction part for detecting a distortion signal in said subcarrier and for extracting subdata that is superposed on said subcarrier;
• wherein said subdata extraction part detects two distortion signals in said subcarrier and extracts said subdata by a relative time interval between said two distortion signals.

A digital optical receiver receiving data through a modulation system utilizing subcarriers, comprising:

• a conversion part for receiving an optical modulated signal, converting the same to an electrical modulated signal formed of a subcarrier, and outputting said electrical modulated signal;
• and
• a subdata extraction part for detecting a distortion signal in said subcarrier and for extracting subdata that is superposed on said subcarrier;
• wherein said subdata extraction part extracts said subdata by detecting where a light emitting section in said subcarrier is replaced with a non-emitting section.

A digital optical receiver receiving data through a modulation system utilizing subcarriers, comprising:

• a conversion part for receiving an optical modulated signal, converting the same to an electrical modulated signal formed of a subcarrier, and outputting said electrical modulated signal;
• and
• a subdata extraction part for detecting a distortion signal in said subcarrier and for extracting subdata that is superposed on said subcarrier;
• wherein said subdata extraction part extracts said subdata by detecting where a non-emitting section in said subcarrier is replaced with a light emitting section.

A digital optical receiver receiving data through a modulation system utilizing subcarriers, comprising:

• a conversion part for receiving an optical modulated signal, converting the same to an electrical modulated signal formed of a subcarrier, and outputting said electrical modulated signal;
• and
• a subdata extraction part for detecting a distortion signal in said subcarrier and for extracting subdata that is superposed on said subcarrier;
• wherein said subdata extraction part extracts said subdata by detecting where a position of a light emitting section in said subcarrier is displaced.

A digital optical transmitter, comprising:

• a main/subdata modulator for modulating a main data waveform utilizing subcarriers, wherein said modulation distorts the subcarriers in accordance with preset values of received subdata;
• and
• a converter for converting an electrical modulated signal output from said main/subdata modulator into an optical modulated signal;
• and
• a selector part for selecting whether or not information of said subdata is superposed on said main data modulator waveform by distortion;
• wherein said main/subdata modulator part outputs a subcarrier modulator waveform when said selector part selects communication with no superposition of said subdata during distortion, and thereafter outputs the same when said selector part selects communication with superposition of said subcarrier.

A digital optical receiver, comprising:

• a converter for converting a received optical modulated signal to an electrical modulated signal that is formed of a subcarrier;
• and
• a main/subdata demodulator for extracting subdata superposed on said subcarrier in accordance with a detected distortion signal;
• and
• wherein said main/subdata demodulator part detects two distortion signals in said subcarrier and extracts said subdata by a relative time interval between said two distortion signals.