W66910 Datasheet, PDF (16/81 Pages) Winbond – TE Mode ISDN S/T-Controller with Microprocessor Interface

Data Sheet
7.2 Layer 1 Functions Descriptions
W66910 PCI ISDN S/T-Controller
The layer 1 functions includes :
- Transmitter/Receiver which conform to the electrical specifications of ITU-T I.430
- Receiver clock recovery and timing generation
- Output phase delay (deviation) compensation
- Layer 1 activation/deactivation procedures
- D channel access control
- Frame alignment
- Multi-frame synchronization
- Test functions
7.2.1 S/T Interface Transmitter/Receiver
According to ITU-T I.430, pseudo-ternary code with 100% pulse width is used in both directions of transmission on the S/T
interface. The binary "1" is represented by no line signal (zero volt), whereas a binary "0" is represented by a positive or negative
pulse.
Data transmissions on the S/T interface are arranged as frame structures. The frame is 250 µs long and consists of 48 bits, which
corresponds to a 192 kbit/s line rate. Each frame carries two octets of B1 channel, two octets of B2 channel and four D channel
bits. Therefore, the 2B+D data rate is 144 kbit/s. The frame structure is shown in Fig.7.1.
The frame begin is marked by a framing bit, which is followed by a DC balancing bit. The first binary "0" following the framing
bit balancing bit is of the same polarity as the framing bit balancing bit, and subsequent binary zeros must alternate in polarity.
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Publication Release Date: Feb,2001
Revision 1.0