AHA4541 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

AHA4541

311 MBITS/SEC TURBO PRODUCT CODE ENCODER/DECODER

Unspecified 

FUNCTIONAL OVERVIEW

comtech aha corporation

The channel encoder is designed to input data in

a byte-wide fashion. This data is CRC encoded and

randomized before coding by the TPC encoder.

Synchronization marks are then inserted into the

data before it is mapped to a user programmable

constellation. The blocks may be bypassed if not

needed.

Each symbol for modulation is output

synchronous to the transmit clock, with one symbol

transferred for each rising edge of the clock. The

format for output data depends on the modulation

format chosen.

The channel decode data path begins with

received symbols input to the device synchronous to

the receive clock, with one symbol transferred per

rising edge.

When using internal soft metric computation,

the input data is an I and Q sample value for the

given symbol. The soft metric computation engine

converts each I and Q sample to the soft metrics

required by the TPC decoder.

When soft metric computation is disabled, the

input data is a soft metric value for each bit in the

TPC block with up to 4 bits transferred on each

clock edge. Each bit would consist of up to 4

confidence bits per data bit. If enabled, all

synchronization is controlled by the device

including phase ambiguity resolution. Output is in a

byte wide fashion with packet start, end and error

signals.

CODE PERFORMANCE

Figure 2: Bit Error Rate (BER) Performance (simulated) on a QPSK Channel

bpsk_oc3

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