N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 5 - SONET, WDM, DWDM and B-ISDN Technologies                                                             Slide 33 of 76 _________________                                                                                  __________

                                                   Who Developed SDH?

                                      European Transmission System Rates Different
                                        than North American Rates

                                      CCITT

                                      ITU-T 

_________________                                                                                  __________

The European Transmission System's basic rates are different than North American basic rates. The basic North American Rate is DS-0, 64 K bps. The European basic rate is 34 K bps. CCITT recommended an international optical transmission standard based on 155.20 M bps as the starting line rate that allowed to multiplex 34 M bps signals.

ITU-T standardized optical transmission rates for all the countries in the world. ITU-T brought North American SONET standard and European standard together for global usage.

The CCITT incorporated the SONET standard in to global standards through ITU-T. The first level for both standards is the same at 155.20 M bps. All the higher levels are also the same.