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 AHA4541 Product Specification for complete details.
comtech aha corporation
comtech aha corporation
PRODUCT BRIEF*
AHA4541
311 MBITS/SEC TURBO PRODUCT CODE
ENCODER/DECODER
The AHA4541 device is a single-chip Turbo
Product Code (TPC) Forward Error Correction
(FEC) Encoder/Decoder capable of 311 Mbit/sec
data rates (up to 360 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.
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.
FEATURES
PERFORMANCE:
• Maximum 360 Mbit/sec channel rate
• Payload data rates of at least 311 Mbit/sec for
code rates >0.86
• Symbol rates up to 90 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