Full-Duplex Speakerphone
by HotHaus Technologies

Software Overview

The HotHaus Full-Duplex Speakerphone (FDS) software module provides a truly bi-directional voice 
link between calling parties, and is designed specifically for the desktop speakerphone 
environment. It is available stand alone or as a PSTN line service for HausWare.
The HotHaus FDS automatically detects near end speech, far end speech, double talk, and idle modes 
of operation, and automatically cancels out any echo. FDS consists of two adaptive filters for 
acoustic and side tone echo cancellation, three speech detectors, and a central loop controller. It 
continuously and automatically monitors and adapts to the quality of the line and the room 
characteristics.
A well written and thorough Technical Reference Manual is available describing the Full-Duplex 
Speakerphone and how to interface to it via C or assembly. Example C and Psuedocode are included in 
the manual.
All HotHaus software modules are all designed to operate with minimal MIPS and memory. FDS has been 
written entirely in assembly. 

Features and Benefits

•	Very efficient, less than  15 MIPS, 1K Word of ROM, and 1K Word of RAM required
•	Side tone echo canceller 30-dB ERLE, 6-ms side-tone echo
•	Acoustic echo canceller provides up to 25-dB ERLE without training
•	Fully re-entrant, each extra port requires only small additional RAM space
•	64-ms acoustic echo path

Processor and System Requirements

Runs on Texas Instruments TMS320C5x family of DSPs.
Requires 8-KHz sampling rate.

Usage Limitations or Performance Considerations

None

Availability

Immediately on 'C5x. Can easily be ported to 'C2xx and other TI fixed-point DSPs.

Company Background and Contact Information

HotHaus are experts in TI fixed-point DSP software algorithms for telecommunications. HotHaus' 
algorithms are ideally suited for advanced telecommunications products such as feature phones, PBX 
or key systems, and general computer telephony products.
HausWare is the flagship of the company's product line, and it provides a complete DSP software 
system architecture specifically for telecommunications products. HausWare is the key to HotHaus 
providing a cost-effective software system solution to our customers.

Contact:	Dan McCallum
		HotHaus Technologies Inc.
		1B - 7218 Progress Way
		Delta BC Canada
		V4G 1H2
		(604) 946-0060
		fax: (604) 946-5811