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Appendix J: Telecom Technology Basic SDH Signal The basic format of an SDH signal allows it to carry many different services in its Virtual Container (VC) because it is bandwidth flex- ible. This capability will allow for such things as the transmission of high speed, packet switched services, ATM, contribution video and distribution video. However, SDH still permits transport and networking at the 2 Mbit/s, 34 Mbit/s and 140 Mbit/s levels, accommodating the existing digital hierarchy signals. In addition, SDH supports the transport of signals based on the 1.5 Mbit/s hierarchy. CTS850 Test Set, SDH/PDH Transmission hierarchies The following tables compare the Non synchronous and Synchronous transmission hierarchies. Table J 1. Non SynchronousHierarchy Signal Digital Bit Rate Channels 64 kbit/s 64 kbit/s One 64 kbit/s E1 2.048 Mbit/s 32 E0 E2 8.448 Mbit/s 128 E0 E3 34.368 Mbit/s 16 E1 E4 139.264 Mbit/s 64 E1 CTS850 Test Set, SDH/PDH User Manual J 1 Appendix J: Telecom Technology Table J 2. SDH Hierarchy Bit Rate Abbr. SDH SDH Capacity 51.840 Mbit/s 51 Mbit/s STM 0 21 E1 155.520 Mbit/s 155 Mbit/s STM 1 63 E1 or 1 E4 622.080 Mbit/s 622 Mbit/s STM 4 252 E1 or 4 E4 2488.320 Mbit/s 2.4 Gbit/s STM 16 1008 E1 or 16 E4 9953.280 Mbit/s 10 Gbit/s STM 64 4032 E1 or 64 E4 STM = Synchronous Transport Module PDH Basics Plesiochronous Data Hierarchy (PDH) is a telecommunications transmission technology, implemented thirty years ago, based on PCM (Pulse Code Modulation) and TDM (time division multiplex- ing). PDH is tailored to voice communication; has dedicated bandwidth for each voice channel and a fixed channel assignment. PDH is worldwide compatible only at the 64 kbit/s digitized voice level. Pulse Code Modulation (PCM) In the early 1970's, digital transmission began to appear in the world's telephone network, utilizing a method known as Pulse Code Modulation. PCM allowed analogue waveforms, such as the human voice, to be represented in binary form. Using this PCM method, it was possible to represent a standard 4 kHz analogue telephone signal as a 64 kbit/s digital bit stream. J 2 CTS850 Test Set, SDH/PDH User Manual Appendix J: Telecom Technology Anti Alias Sample Filter Quantizer Encoder 8,000 samples/second x 8 bits/sample = 64 kb/s digital bit stream (one timeslot) Figure J 1:Pulse Code Modulation Engineers saw the potential to produ