text: PDH = Plesiochronous Digital Hierachy.\n\nE1 – a 2048 kbit/s framed PDH signal connected to electrical\ninterface E12. It has a basic frame structure of 32 timeslots or octets at a frame rate of 125 msec. Two octets (consecutive timeslots 0) are used for the transport overhead. For additional Quality of Service, a CRC–4 multi-frame is used consisting of 16 basic frames at a multiframe\nrate of 2 ms.\n\nE3 – a 34 368 kbit/s framed PDH signal connected to electrical interface E31. It has a frame structure of 59 octet columns and 9 rows plus 6 octets at a frame rate of 125 msec. 7 octets are used for the transport overhead.\n\nDS1 – a 1544 kbit/s framed PDH signal connected to electrical\ninterface E11. It has a basic frame structure of 24 timeslots or octets and a single bit transport overhead per frame at a frame rate of 125 msec. 24 basic frames form an extended superframe with a frame rate of 3 ms.\n\nDS3 – a 44 736 kbit/s framed PDH signal connected to electrical interface E32. It has a basic frame structure of 680 bit columns and 7 rows. Each row consists of 8 blocks containing 1 transport overhead bit and 84 payload bits. The frame rate is 106 msec.