PEB2080 SIEMENS [Siemens Semiconductor Group], PEB2080 Datasheet - Page 19

• Manufacturer Part Number: PEB2080
• Description: S/T Bus Interface Circuit(SBC)
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Functional Description
2.3
Interfaces
S Interface
According to CCITT recommendation I.430, pseudo-ternary encoding with 100 % pulse width is
used on the S interface. A logical 1 corresponds to a neutral level (no current), whereas logical 0´s
are encoded as alternating positive and negative pulses. An example is shown in figure 5.
Figure 5
S-Interface Line Code
One S frame consists of 48 bits, at a nominal bit rate of 192 kbit/s. Thus each frame carries two
octets of B1, two octets of B2, and four D bits, according to the B1 + B2 + D structure defined for
the ISDN basic access (total useful data rate: 144 kbit/s). Frame begin is marked using a code
violation (no mark inversion). The frame structures (from network to subscriber, and subscriber to
network) are shown in figure 6.
Figure 6
Frame Structure at Reference Ponts S and T (CCITT I.430)
Semiconductor Group
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