FAX Relay 
Control Software
by ILLICO!

Software Overview

Voice communication systems using advanced voice compression techniques require on-line FAX signal 
handling to pass FAX traffic in the available channel bandwidth, typically 16 kbps or 8 kbps. FAX 
relay systems automatically recognize and demodulate the FAX signal to recover the "baseband" image 
data stream, ranging from 2.4 kbps to 14.4 kbps. This data is then formatted and passed though the 
link for re-modulation at the remote end. ILLICO's FAX relay control software provides modem 
control, data formatting, and end-to-end communications control for FAX relay links. This software 
is written in C-language for compilation to either floating point (TMS320C3x) or fixed-point 
(TMS320C5x/'C25) assembly language. Combined with ILLICO's assembly language Group 3 FAX modems, 
FAX relay software creates a complete FAX relay capability in a single Digital Signal Processor. As 
an option to FAX relay, ILLICO also supports data relay for BELL and CCITT data modem standards. 
Please contact ILLICO for details on data relay.

Features and Benefits

•	Relay software is written in `C' for ease of support and customization.
•	Optional forcing of the FAX transaction to a lower bit rate for low bandwidth systems.
•	Support for rates up to 14.4 kbps  (V.17/V.33).
•	PCM interface with fixed 8-kHz sampling rates.
•	Group 3 signal classification by protocol analysis (the relevant T.30 control bits are extracted 
to learn the data rate and modem standard used for image transmission).
•	Direct interface with ILLICO assembly language FAX modem modules (V.21, V.27ter, V.29, and 
V.17/V.33).

Processor and System Requirements

The following example shows the resource loads for the `C' language Fax Relay code compiled for the 
TMS320C5x family. The figures apply to a V.17 single

channel implementation and include the loads for the ILLICO assembly language TMS320C5x Fax modems.

•	Data RAM per channel
1.5 kwords external RAM
256 words internal DARAM 
•	 Program memory
12 kwords
•	Per channel MIPs loading (Million Instructions per Second, zero-wait state)
12  MIPs

Algorithm Verification

ILLICO's FAX relay control software is qualified using two Genoa Technology FaxLab™ fax terminal 
emulators. Each station is capable of emulating the characterisitcs of over 60 commercial FAX 
machines and cards. Network emulation is provided by the T.A.S. Model 182 equipment which provides 
a full range of U.S. and international line conditions.

Availability

FAX relay control code is available now under a royalty-free licensing arrangement which includes a 
source code option. Demonstrations are available at ILLICO's offices in Santa Clara, California.

Company Background and Contact Information

ILLICO is a software development and licensing firm specializing in the application of digital 
signal processing to telecommunications product development. We have been active for over seven 
years with U.S. and international clients, principally in the area of voice band modem design. All 
ILLICO products were created by ILLICO's staff and are typically modified to meet special client 
requirements.

Contact:    Lien Nguyen
		ILLICO!
		2700 Augustine Drive
		Suite 145
		Santa Clara, California  95054
		(408) 980-8179
		Fax: (408) 980-9327