User Guide

PAMS
System Module DB6
NHB–3
Technical Documentation
Original 26/97
Page 4–24
DSPU
Introduction
Main interfaces of the DSP:
– MCU via ASIC mailbox
– RFI via ASIC
– ASIC
– audio codec
– data bus interface (DBUS) for accessories
– digital audio interface (DAI) for type approval measurements
Main features of the DSP block:
– speech processing
speech coding/decoding
– RPE–LTP–LPC (regular pulse excitation long term
prediction linear predictive coding)
voice activity detection (VAD) for discontinuous transmission (DTX)
comfort noise generation during silence
acoustic echo cancellation
– channel coding and transmission
block coding (with ASIC)
convolutional coding
interleaving
ciphering (with ASIC)
burst building and writing it to ASIC
– Reception
reading A/D conversion results from ASIC
impulse response calculation
matched filtering
bit detection (with Viterbi on ASIC)
deinterleaving of soft decisions
convolutional decoding (with Viterbi)
block decoding (with ASIC)