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The results of international comparisons in the field of fiber-optic communication and information transmission systems, in particular, for the average power of optical radiation (COOMET PR-S6 and APMP PR-S2 projects) and chromatic dispersion in an optical fiber (EURAMET PR-S3 project), are considered. Data on comparisons as regards the length of the optical fiber (APMP PR-S8), polarization mode dispersion (COOMET PR-S9 project), and wavelength for fiber optics (COOMET PR-S8 project), all of which are now being performed, are presented. [ABSTRACT FROM AUTHOR]

A new method of data transmission in DWDM systems along existing long-distance fiber-optic communication lines is proposed. The existing method, e.g., uses 32 wavelengths in the NRZ code with an average power of 16 conventional units (16 units and 16 zeros on the average) and transmission of 32 bits/cycle. In the new method, one of 124 wavelengths with a duration of one cycle each (at any time instant, no more than 16 obligatory different wavelengths) and capacity of 4 bits with an average power of 15 conventional units and rate of 64 bits/cycle is transmitted at every instant of a 1/16 cycle. The cross modulation and double Rayleigh scattering are significantly decreased owing to uniform distribution of power over time at different wavelengths. The time redundancy (forward error correction (FEC)) is about 7% and allows one to achieve a coding enhancement of about 6 dB by detecting and removing deletions and errors simultaneously. [ABSTRACT FROM AUTHOR]