Telecommunications Device
for the Deaf Modem
by HotHaus Technologies

Software Overview

The HotHaus Telecommunications Device for the Deaf (TDD) modem software module provides 
demodulation and modulation of 5-bit Baudot-coded TDD characters. HotHaus TDD is compliant with TDD 
Standards Projects PN-1663 EIA TR-41 and utilizes half-duplex FSK at 45.45 baud. It is available 
standalone or as a PSTN line service for HausWare.
A well written and thorough Technical Reference Manual is available describing the 
Telecommunications Device for the Deaf modem 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. TDD has been 
written entirely in assembly. 

Features and Benefits

•	1 MIP, 1K Word of ROM required
•	Fully re-entrant, each extra port requires only small additional RAM space
•	Receives successfully down to -45 dBm

Processor and System Requirements

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

Usage Limitations or Performance Considerations

None

Algorithm Verification

Tested against commercial TDD modems.

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