Technical data

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Fig.1. The flowchart of AncVoiceCoder-2400 operation, where SCD is the speech
conversion unit used for parametric compression of speech; codec – codes/decodes speech
signals; E – encryptor; PTN – public telephone network.
DB-25RS – a system board with implemented parametric speech compression
algorithms for IP telephony
The board uses TMS320C25 digital signal processor and is designed for real-time
implementation of high-quality speech parametric compression algorithms at 2400 bps ( LPC-
10 with tabular excitement signal), 4800 and 9600 bps (CELP). The board operates in Intel x-
86 based personal computers and can be used for IP purposes as a speech co-processor (for
digitizing and compression of speech in order to reduce volumes of transmitted data). The
board is delivered with a telephone handset and has a standard COM port for connection to
external modems.
The following software is included in the board package of deliverables:
A set of libraries for parametric compression of speech signals;
A load image for secure digital telephone connections;
System and tuning-up software for developers of digital signal processing
algorithms based on TMS20C25.
The DB-25RS board, installed in a personal computer equipped with an external
modem, allows the user to make totally secure phone calls over standard two-wire public
S
CD
E
S
CD
Cod
ec
E
m
odem
PTN
Cod
ec
m
odem