[comtech aha corporation]

The AHA4540 device is a single-chip Turbo Product Code (TPC) Forward Error Correction (FEC) Encoder/Decoder capable of 155 Mbit/sec (OC-3) data rates (up to 200 Mbit/sec channel rates). 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.

The channel interface supports direct connection to various modulators and demodulators. Support for an arbitrary constellation mapping is included with external logic.

FEATURES

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

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:

• 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