Upgrade for forward error correction device

Edited by the Electronicstalk editorial team Nov 19, 2003

The AHA4540 is an improved version of the Astro-OC3 Turbo Product Code forward error correction integrated circuit from Comtech AHA Corp.

The AHA4540 is an improved version of the Astro-OC3 Turbo Product Code (TPC) forward error correction (FEC) integrated circuit (IC) from Comtech AHA Corp.

The original AHA4540A device was released in June 2000 and has found widespread acceptance in satellite modems and broadband wireless systems.

The speed improvements of the AHA4540B will offer new and existing customers the ability to implement more powerful error correction codes at lower code rates that still meet OC3 datarate requirements.

Giving designers the power to decide what combination and level of benefits work best for their application, the AHA4540B allows designers to: reduce required bandwidth; or increase data throughput; or increase range by 40%; or reduce antenna size by 30%; or reduce transmitter power by 2x; or reduce the required noise figure of the receiver by 3dB.

The first commercially available chip of its kind, the AHA4540B is designed for use in satellite communications, broadband wireless links and wireless digital broadcast applications or in any application that requires very high data rates and demonstrates bandwidth efficiency issues, or stringent data reliability requirements.

The AHA4540B provides up to 3dB of coding gain (compared with Reed-Solomon coding) and is the only commercially available turbo product code technology to achieve channel rates of 200Mbit/s.

In applications requiring high code and data rates, TPC's perform significantly better than Turbo Convolutional Codes (TCC) in real world applications.

"Turbo Product Codes continue to offer the highest performing forward error correction available in hardware today", said Bill Thomson, Comtech AHA Corp President.

"Our newest TPC chip, the AHA4540B, provides great value for system designers of satellite modems and terrestrial broadband wireless communication links.

The performance gain afforded to users of the AHA4540B TPC chip allows the designer to increase both the transmission distance and speed of the data link while reducing the transmission power".

The AHA4540B is a single-chip Turbo Product Code (TPC) forward error correction (FEC) encoder/decoder capable of 155Mbit/s datarates, with maximum coded channel rates of 200Mbit/s.

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

The AHA4540B supports block sizes up to 16Kbit.

In addition to TPC coding, support is included for helical interleaving, synchronisation, scrambling, and higher order modulation symbol mapping.

Unlike single-pass decoding technology with hard-decision output, the AHA4540B chip is based on Comtech AHA'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.

Prototypes of the AHA4540B-PROTO are available in limited quantities now with volume shipping in Q1 2004.