ITU V.32bis Modem
for TMS320C3x/'C4x
by DSP Software Engineering, Inc.

Software Overview

The ITU (formerly CCITT) V.32bis software is an implementation of ITU V.32bis for the TMS320C3x. 
V.32bis is an international standard for full-duplex data communication on the General Switched 
Telephone Network (GSTN) and on point-to-point two-wire leased telephone-type circuits at rates 
from 4,800 to 14,400 bps. The ITU V.32bis software also includes fall-back capability to provide 
compatibility with V.32 modems.
V.32bis software operates on 5-ms frames sampled at 8 kHz. The demodulator processes 40 sample 
frames of linear PCM data and returns 12 symbols every frame. The modulator processes 12 symbols 
and generates 40 sample frames of linear PCM data. The modulator and the demodulator symbol word 
size ranges from 2 bits for 4,800-bps operation to 6 bits for 14,400-bps operation.

Features and Benefits

•	Full Avatar™ implementation
•	ITU V.25 answer-tone capability
•	ITU V.32bis and V.32 compatible and interoperable
•	Rate-retrain and rate-renegotiation capability
•	Communications at 4,800, 7,200, 9,600, 12,000, and 14,400 bits per second
•	V.54 local loopback test (loop 3) capability
•	Full-duplex echo-cancellation modem operation at all rates
•	Object-based, C-callable functions
•	Trellis coding at rates from 7,200 bps to 14,400 bps
•	SPOX compatible

Processor and System Requirements

•	Devices supported: TMS320C3x, TMS320C4x
•	Algorithm category: Vocoder
•	Requirements:
All memory requirements are in units of 32-bit words. The MIPs ratings presented require the listed 
amounts of on-chip, zero wait-state program and data memory, and a processing frame size of 40 
samples at 8 kHz. All measurements were made using an executable demo built for a third-party PC 
plug-in board.
Function
MIPS
Chip RAM
Data
Program
Transmitter/Receiver
18.0
1.2 k
8.5 k
16.0 k
Total *
18.0
1.2 k
10.0 k
21.0 k
* Total includes Avatar common memory requirements.

User Functions

The V.32bis implementation consists of a set of C-callable functions that perform 
modulationdemodulation, data pump control, and status reporting. It also includes functions that 
reflect the implementation's object-based interface. The modulator/demodulator interfaces with 
arrays of linear PCM samples and 2-, 3-, 4-, 5-, or 6-bit symbols.
V.32bis modem
V32_create (...)
Dynamically allocates and initializes data memory for encoder
V32_delete (...)
Frees encoder's usage of dynamically-allocated data memory
V32_control (...)
Implements run-time control of V.32bis modem
V32_status (...)
Provides run-time status of V.32bis modem
V32_modem (...)
Performs V.32bis modulation and demodulation at the data frame rate

Algorithm Verification

•	Call DSPSE for verification details

Availability

•	Source and object code currently available for licensing.

Company Background and Contact Information

DSP Software Engineering, Inc. is a leading provider of highly-complex digital-signal-processing 
software used in telecommunications and multimedia applications such as computer telephony, digital 
wireless, PSTN, and satellite communications, and videoconferencing. 
Contact:	DSP Software Engineering, Inc.
		175 Middlesex Turnpike
		Bedford, MA 01730  USA
		(617) 275-3733
		Fax: (617) 275-4323
		e-mail:  info@dspse.com
		www:  http://www.dspnet.com