1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU%.%2!,G0G0!30%#43G0G0/ further amended)The CCITT,considering(a) that different primary and second order multiplex equipments exist, depending upon the characteristics ofdifferent networks and the various types
2、of signals to be transmitted in those networks;(b) that, although studies will continue with the aim of reducing the differences between various systems, theexisting situation cannot be changed in the near future;recommends the following(1) when two countries, both using 2048 kbit/s primary multiple
3、x equipments such as the PCM multiplexequipment according to Recommendation G.732, have to be connected by a digital path at the second order bit rate, thatbit rate should be 8448 kbit/s;(2) when two countries, both using 1544 kbit/s primary multiplex equipments such as the PCM multiplexequipment ac
4、cording to Recommendation G.733, have to be connected by a digital path at the second order bit rate, thatbit rate should be 6312 kbit/s.In the meantime, it is extremely desirable to define a preferred method of interconnecting different systems.Recommendations G.742 and G.743 give the characteristi
5、cs of second order digital multiplex equipments usingpositive justification, and Recommendation G.745 gives the characteristics of second order multiplex equipment usingpositive/zero/negative justification. Recommendations G.744, G.746 and G.747 give the characteristics of second orderPCM multiplex equipments. Paragraphs 2 and 4 of Recommendation G.705 give the characteristics required to terminate6312 kbit/s and 8448 kbit/s digital paths on a digital exchange.
