AHA4540B-086PQC [ETC]

155 MBITS/SEC TURBO PRODUCT CODE ENCODER/DECODER; 155兆位/秒Turbo乘积码编码/解码器


型号：	AHA4540B-086PQC
厂家：	ETC
描述：	155 MBITS/SEC TURBO PRODUCT CODE ENCODER/DECODER 155兆位/秒Turbo乘积码编码/解码器解码器编码器
文件：	总4页 (文件大小：211K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

comtech aha corporation

PRODUCT BRIEF *

AHA4540B

155 MBITS/SEC TURBO PRODUCT CODE

ENCODER/DECODER

The AHA4540 device is a single-chip Turbo

FEATURES

Product Code (TPC) Forward Error Correction

(FEC) Encoder/Decoder capable of 155 Mbit/sec

(OC-3)data rates (upto200Mbit/secchannelrates).

This device integrates both a TPC encoder and

decoder, and can be operated in a full duplex mode.

In addition to TPC coding, support is included for

helical interleaving, synchronization mark insertion

and detection, CRC computation, scrambling, and

higher order modulation symbol mapping. Figure 1

shows the functional block diagram.

PERFORMANCE:

• Maximum 200 Mbit/sec channel rate

• Payload data rates of at least 155 Mbit/sec for

code rates >0.7 and three iterations

• Symbol rates up to 50 MSym/sec

• Encode Latency of less than 10 clocks

• Integrated encoder/decoder;

scrambler/descrambler; and

interleaver/deinterleaver for full duplex operation

• Supports enhanced Turbo Product Codes (eTPCs)

• Corrections count and averaging for channel SNR

estimation

The channel interface supports direct

connectiontovariousmodulatorsanddemodulators.

Support for an arbitrary constellation mapping is

included with external logic.

FLEXIBILITY:

• Code Rates from .25 to 0.98

• Variable iterations up to 256 per block

• Block Sizes from 256 bits to 16 Kbits

• Programmable code shortening supports exact

block sizes

• 32 bit CRC Insertion and Checking with

programmable packet length

CHANNEL INTERFACE:

The encode path accepts byte-wide data,

computes and inserts a CRC, and scrambles the data

before TPC encoding. After the error correction

code (ECC) bits are inserted by the encoder, the data

is helically interleaved, and block synchronization

marks are inserted to assist the decoder. Finally, the

data is mapped according to the constellation and

output from the device.

The decoder accepts input symbols via the

demodulated in-phase (I) and quadrature (Q)

components or alternately as soft metric inputs from

an external demodulator. An internal block

synchronizer searches for synchronization marks,

rotating the input symbol phase as necessary. After

synchronization is achieved, the data is helically

deinterleaved and decoded by the TPC decoder. The

output of the decoder is descrambled, and the CRC

is computed to verify data integrity. Decoded data is

output in a parallel, byte-wide fashion.

Internal circuitry enables the transfer rate across

all ports, generating a constant, non-burst data flow.

In addition, control of an external VCO can be used

to generate data clocks, greatly simplifying system

clocking issues.

• Accepts in-phase and quadrature (I & Q) inputs,

up to 8 bits each

• Supports soft metric inputs at up to 4 soft metrics

of 4 bits each

• Soft metric computation for BPSK, QPSK, 8-

PSK, 16-QAM, 64-QAM, and 256-QAM

• Supports additional modulation formats with

external logic

• Encoder and decoder pass through modes

• Programmable packet and block level

synchronization

• Automatic phase ambiguity resolution

• Supports insertion and detection of sync marks up

to 32 bits in length

• 8-bit Parallel Data Input/Output

• Support for external VCO to generate data clocks

OTHERS:

• Intel or Motorola microprocessor interface

• 3.3V I/O, 1.8V core operation

• Commercial or industrial temperature rating

• RoHS compliant

This product is covered under multiple patents held or licensed by Comtech AHA Corp.

This product is covered by a Turbo Code Patent License from France Telecom - TDF -

Groupe des ecoles des telecommunications.

*Request the AHA4540B Product Specification for complete details.

comtech aha corporation

CODE TYPES

Table 1 shows a partial list of the codes supported by this product. Note that this is not a complete list

of base codes. In addition, each of the codes listed can be shortened to achieve smaller block size with only

minor changes to code rate.

Table 1: Partial Code List

CODING GAIN # ITERATIONS

AT 155 mBPS

CODE

(X)x(Y)x(Z)

BLOCK SIZE DATA SIZE

(bits)

RATE

(bits)

(dB)

(128,127)x(128,126)+

(128,120)x(128,126)+

(128,120)x(128,120)

(64,57)x(16,15)x(16,15)

(128,127)x(64,62)+

(128,120)x(64,62)+

(128,120)x(64,57)

(32,26)x(16,15)x(16,15)

(64,63)x(64,62)+

(64,57)x(64,57)

(64,63)x(32,30)+

(64,57)x(32,26)

(32,26)x(32,26)

16384

8192

4096

2048

1024

16002

15120

14400

12825

7874

7440

6840

5850

3906

3249

1890

1482

676

0.977

0.923

0.879

0.783

0.961

0.908

0.84

0.714

0.954

0.793

0.923

0.724

0.660

4.3

5.5

6.5

6.9

4.4

5.5

6.5

7.2

4.5

6.9

4.5

6.9

6.3

enhanced TPC (includes hyper diagonal axis).

Figure 1: Turbo Product Code Encoder/Decoder

ENCODER

CRC

Insertion

Helical

Interleaver

Sync

Insertion

Constellation

Mapper

TPC

Encoder

ENC_DATA

XMIT_DATA

REC_DATA

Scrambler

DECODER

Soft

Metric

Computation

CRC

Verification

Helical

Deinterleaver

Sync

Detection

TPC

Decoder

DEC_DATA

uP_INT

Descrambler

Microprocessor Interface,

Control and Status

Registers

AHA4540

comtech aha corporation

FUNCTIONAL OVERVIEW

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.

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.

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.

CODE PERFORMANCE

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

bpsk_oc3

comtech aha corporation

Figure 3: Performance (simulated) of Several Codes on a 64 QAM System

64qam_oc3

ORDERING INFORMATION

ABOUT AHA

Comtech AHA Corporation (AHA) develops

and markets superior integrated circuits, boards,

and intellectual property core technology for

communications systems architects worldwide.

AHA has been setting the standard in Forward Error

Correction and Lossless Data Compression

technology for many years and provides flexible,

cost-effective solutions for today’s growing

bandwidth and reliability challenges. Comtech

AHA Corporation is a wholly owned subsidiary of

Comtech Telecommuncations Corp. (NASDAQ:

CMTL). For more information, visit www.aha.com.

PART NUMBER

DESCRIPTION

155 Mbit/sec Turbo Product

AHA4540B-086 PQC Code Encoder/Decoder -

Commercial Temp

155 Mbit/sec Turbo Product

AHA4540B-086 PQI Code Encoder/Decoder -

Industrial Temp

comtech aha corporation

A subsidiary of Comtech Telecommunications Corporation

1126 Alturas Drive

tel: 208.892.5600

Moscow, ID 83843-8331

fax: 208.892.5601

e-mail: sales@aha.com

www.aha.com

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