Itu-t rec. G. 957 (06/99) Optical interfaces for equipments and systems relating to the synchronous digital hierarchy
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- Table 1/G.957 – Classification of optical interfaces based on application and showing application codes Inter-office Application Intra
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Recommendation G.957 (06/99) 3 5 Classification of optical interfaces It is expected that optical fibres will be used in SDH-based systems for both inter-office transport between stations and in intra-office applications for connecting equipment within a single station. By appropriate combinations of transmitters and receivers, power budgets for optical fibre line systems can be achieved which are optimized in terms of attenuation/dispersion and cost with respect to the various applications. However, to simplify the development of transverse compatible systems, it is desirable to limit the number of application categories and corresponding sets of optical interface specifications for standardization. As shown in Table 1, this Recommendation recognizes three broad application categories: – intra-office corresponding to interconnect distances less than approximately 2 km; – short-haul inter-office corresponding to interconnect distances of approximately 15 km; – long-haul inter-office corresponding to interconnect distances of approximately 40 km in the 1310 nm window and approximately 80 km in the 1550 nm window. Table 1/G.957 – Classification of optical interfaces based on application and showing application codes Inter-office Application Intra- office Short-haul Long-haul Source nominal wavelength (nm) 1310 1310 1550 1310 1550 Type of fibre Rec. G.652 Rec. G.652 Rec. G.652 Rec. G.652 Rec. G.652 Rec. G.654 Rec. G.653 Distance (km) a) ≤ 2 ∼ 15 ∼ 40 ∼ 80 STM-1 I-1 S-1.1 S-1.2 L-1.1 L-1.2 L-1.3 STM-4 I-4 S-4.1 S-4.2 L-4.1 L-4.2 L-4.3 STM level STM-16 I-16 S-16.1 S-16.2 L-16.1 L-16.2 L-16.3 a) These are target distances to be used for classification and not for specification. The possibility of applying the set of optical parameters in this Recommendation to single-channel systems on G.655 fibre is not to be precluded by the designation of the fibre types in the application codes. Within each category, it is possible to consider use of either nominal 1310 nm sources on optical fibre complying with Recommendation G.652 or nominal 1550 nm sources on optical fibre complying with Recommendations G.652, G.653 or G.654. This Recommendation covers both possibilities for the two inter-office applications and considers only nominal 1310 nm sources on G.652 fibre for the intra-office application. Since the overall system characteristics and specific values for the optical parameters generally depend on system bit rate, it is convenient to classify the SDH optical interfaces based on applications considered in this Recommendation using the set of application codes shown in Table 1. This application code is constructed in the following way: Application-STM level. Suffix number |