Forward error correction chip doubles throughput

The AHA4541 is a Turbo Product Code (TPC) forward error correction (FEC) integrated circuit from Comtech AHA Corp (CAC).

The AHA4541 is a Turbo Product Code (TPC) forward error correction (FEC) integrated circuit from Comtech AHA Corp (CAC).

The AHA4541 is the first commercially available chip capable of 311Mbit/s payload datarates and channel rates up to 360Mbit/s.

The AHA4541 joins other CAC firsts in FEC technology, including production of the first single-chip Reed-Solomon IC and the first commercially available Turbo Product Code hardware.

The AHA4541, operating at OC6 speeds, is designed for use in any application that requires very high datarates and demonstrated bandwidth efficiency issues or stringent data reliability requirements.

Applications include satellite communications, cellular backhaul, microwave radios, mobile video surveillance equipment, cable modems, broadband wireless links and wireless digital broadcast equipment.

"As part of our commitment to provide the highest in forward error correction performance, we are pleased to announce this latest addition to our TPC family of products", said Bill Thomson, CAC President.

"The AHA4541 more than doubles the throughput of any previous turbo code device to keep pace with the ever growing demand for faster datarates.

Existing customers of TPC technology will also benefit from an improvement in error correction performance afforded by the increased processing clock frequencies in the AHA4541".

The AHA4541 is a single-chip Turbo Product Code forward error correction encoder/decoder capable of 311Mbit/s datarates, with maximum channel rates of 360Mbit/s.

The device integrates both a TPC encoder and decoder and can be operated in a full duplex mode.

The AHA4541 supports block sizes from 256bit to 16Kbit and the programmable code shortening supports exact block sizes.

In addition to TPC coding, the AHA4541 includes modulation and demodulation support for many common constellations.

Other features include flow control with dual format synchronisation, phase locking between channel and payload side clocks, DVB-type scrambler, helical interleaving and CRC computation.

Unlike single-pass decoding technology with hard-decision output, the AHA4541 chip is based on CAC's patented TPC technology that uses a soft-input, soft-output (SISO) decoder.

The SISO decoder makes intelligent correction decisions based on retained confidence information.

The turbo decoder iteratively corrects errors until it converges on the best results.

The AHA4541 device is fully backward compatible with the AHA4540 (a 155Mbit/s chip offered by CAC).

This allows current AHA4540 customers to easily migrate to the AHA4541 in the future when they need even greater performance.

Prototypes of the AHA4541A-PROTO are available in limited quantities now with volume shipping in Q1 2004.

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