HC4GX15 Datasheet, PDF (433/668 Pages) Altera Corporation – HardCopy IV Device Handbook

Chapter 1: HardCopy IV GX Transceiver Architecture
Functional Modes
Figure 1–138 shows the SONET/SDH frame structure.
Figure 1–138. SONET/SDH Mode
Nx3 Bytes
Transport Overhead
Nx3 Bytes
Payload
NxA1 NxA2 NxJ0/Z0
9 Rows
1–169
Transport overhead bytes A1 and A2 are used for restoring frame boundary from the
serial data stream. Frame sizes are fixed, so the A1 and A2 bytes appear within the
serial data stream every 125 μs. In an OC-12 system, 12 A1 bytes are followed by
12 A2 bytes. Similarly, in an OC-48 system, 48 A1 bytes are followed by 48 A2 bytes.
In SONET/SDH systems, byte values of A1 and A2 are fixed as follows:
■ A1 = 11110110 or 8'hF6
■ A2 = 00101000 or 8'h28
You can employ HardCopy IV GX transceivers as physical layer devices in a
SONET/SDH system. These transceivers provide support for SONET/SDH
protocol-specific functions and electrical features; for example, alignment to A1A2 or
A1A1A2A2 pattern.
HardCopy IV GX transceivers are designed to support the following three
SONET/SDH sub-protocols:
■ OC-12 at 622 Mbps with 8-bit channel width
■ OC-48 at 2488.32 Mbps with 16-bit channel width
■ OC-96 at 4976 Mbps with 32-bit channel width
© June 2009 Altera Corporation
HardCopy IV Device Handbook Volume 3