ITU-T G.703/G.707 155520 kbit/s interface (the classic STM-1 (Synchronous Transfer Mode) interface) is a four-wired, whole duplex interface with transmission capabilities multiplexed according to the principle of time-sharing. This interface is used widespreadly. This interface is used in the SDH to the realization of connections between the "section-layers".
Elements of the standard, recommendation describing the interface:
Services:
Interface can provide the following services towards the higher layers:
Interface topology:
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Interface realizes a point=to-point connection.
Data changing between the network nodes can be realized either through a metallic conductor, or an optical fibre.
Data changing wires:
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For the realization of STM-1 interface we need an asymmetric metallic transmission medium consisting of 2x2 wire, with a transmission capacity of 155520 kbit/s to both directions.
Electronic characteristics:
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* bit rate: 155520 kbit/s +/- 20 ppm
* line coding: CMI
* nominal impedance: 75 ohm
* pulse amplitude 1,0 V +/-0.1 V
* pulse waveform (see figure in G.703 recommendation!)
* reflexion: > 15 dB (8 - 240 MHz)