Itu-t rec. G. 957 (06/99) Optical interfaces for equipments and systems relating to the synchronous digital hierarchy
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Recommendation G.957 (06/99) 4 with the application designations being I (Intra-office), S (Short-haul), or L (Long-haul), and the suffix number being one of the following: – (blank) or 1 indicating nominal 1310 nm wavelength sources on G.652 fibre; – 2 indicating nominal 1550 nm wavelength sources on G.652 fibre for short-haul applications and either G.652 or G.654 fibre for long-haul applications; – 3 indicating nominal 1550 nm wavelength sources on G.653 fibre. NOTE – The use of the term intra-office is not meant to exclude any other applications consistent with the set of optical parameters specified (e.g. B-ISDN user network interfaces – physical layer specifications defined in Recommendation I.432.2). The distances chosen for the application codes in Table 1 are based on parameter values that are achievable with present technology and which are thought to suit network requirements. The intra- office and short-haul inter-office application codes have been proposed as low-cost equipment implementations. The long-haul application codes have been proposed to provide maximum length repeater spans consistent with limits set by present technology and the objective of transverse compatibility. The distances proposed may allow for the upgrading of present systems by exploiting the 1550 nm region. The distances in Table 1 represent approximate maximum repeater span distances. Specific distance limits consistent with the attenuation limits given in Tables 2 to 4, but including allowances for extra connectors or margins, can be derived through consideration of maximum fibre attenuation and dispersion values for each application in Tables 2 to 4. 5 Recommendation G.957 (06/99) Table 2/G.957 – Parameters specified for STM-1 optical interfaces tải về 235.99 Kb. Chia sẻ với bạn bè của bạn:
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