1.0.1 This code is formulated with a view to unifying design criteria of railway digital microwave relay communication system and meeting development requirements of railway microwave relay communication.
1.0.2 This code is applicable to the design of constructed, extended and renovated railway digital microwave relay communication system.
1.0.3 Railway digital microwave relay communication is one of the important railway communication modes, and shall be able to support voice and non-voice service of toll and local communication of railway.
1.0.4 The majority of design transmission capacity of railway digital microwave relay communication system shall be short-term while long-term transmission capacity is also considered; sideband service may also be adopted.
1.0.5 Synchronous digital hierarchy (SDH) shall be adopted for digital microwave relay communication of toll main line of railway, and plesiochronous digital hierarchy (PDH) may be adopted for digital microwave relay communication of other sections.
1.0.6 Facilities such as original station site, machine room and antenna tower shall be fully used during extension or renovation of digital microwave relay communication engineering.
1.0.7 N+1 (N≥1) wave channel backup mode shall be adopted for digital microwave toll main line circuit of railway, and standby channel may not be arranged for other circuits.
1.0.8 The stereotype equipment adopted for railway digital microwave relay communication system shall be technology-advanced, economical, reasonable, safe and applicable.
1.0.9 Confidential measures shall be taken where digital microwave toll main line circuit of railway requires.
1.0.10 The design of railway digital microwave relay communication system shall meet the requirements stipulated in this code and those in relevant national current compulsory standards.
2 Terms
2.1 Terms about Line
2.1.1 turning angle
the horizontal included angle of communication directions from the microwave station to the previous microwave station and the next microwave station
2.1.2 branching angle
the horizontal included angle between the tributary and original lines in the communication direction of the tributary station where a tributary is separated from a microwave line
2.1.3 clearance
the distance between electric wave beam axis and obstacle in relay section in microwave relay communication
2.1.4 attenuation
the fluctuation of receiving level with time in microwave relay communication
2.1.5 half power angle (θ)
the beam width when the antenna radiation power is reduced by 3dB
2.2 Terms about Performance Indexes
2.2.1 Synchronous transmission module (STM)
a kind of information structure consisting of information payload (Payload), section overhead (SOH) and administration unit pointer (AU PTR), of which the repetition period is 125μs, the basic module is STM-1 and the higher-order module is STM-N
2.2.2 nth-order virtual container (VC-n)
the information structure used for supporting connection of the path layer in SDH; it is a block frame structure composed of information payload and path overhead (POH) with repetition period of 125μs or 500μs. n=12, 3, 4.
2.2.3 nth-order administration unit (AU-n)
the information structure providing adaptation between high-order path layer and multiplex section layer
2.2.4 administration unit group (AUG)
the administration unit group consisting of fourth-order administration unit AU-4
2.2.5 nth-order tributary unit (TU-n)
the information structure providing adaptation between low-order path layer and high-order path layer. n=12, 3.
2.2.6 tributary unit group (TUG-n)
the group consisting of tributary units of different sizes to increase the flexibility of transmission network
TUG-2 is assembled with the same TU-12 of the same order; TUG-3 is assembled with TUG-2 or TU-3 of the same order.
