GAO DTMF Detector/
Generator/Remover
by GAO Research & Consulting Ltd.

Software Overview

GAO DTMF Generator/Decoder is an implementation of a Dual-Tone Multi-Frequency (DTMF) generator and 
decoder.  DTMF is an international signaling standard for pushbutton telephone digits. The DTMF 
generator generates standard telephone digits as the sum of sinusoids corresponding to a frequency 
table for each digit. The DTMF decoder will take digital signal as input and produce the decoded 
digit. The DTMF software generates and decodes 8-kHz linear 16-bit PCM samples. It also provides 
rapid detection so that all DTMF tones are removed within about 13 ms of tone onset. DTMF has a 
variety of uses in telephone systems. It is widely used in interactive-control applications, such 
as telephone banking, electronic mail system, and many other menu-driven operations that respond to 
digits entered from a telephone.

Features and Benefits

•	Decoder receives high scores on Mitel CM7291 test tape (results available)
•	Implemented in the assembly
•	Highly-efficient decoder
•	Low data and program memory requirements

Processor and System Requirements

•	Devices supported: TMS320C3x, TMS320C5x, TMS320C54x
•	Algorithm category: Telecommunications
•	Required:
Function
Average MIPS
Data Memory
Program Memory
Generator
0.8
180
150
Remove
0.4
30
80
Decoder
0.8
390
550

Algorithm Verification

•	Tested against Mitel CM7291 Test Tape for DTMF detection and obtained excellent scores.

Availability

•	The software is available now and demonstration is available at GAO's offices in Toronto, Canada.

Company Background and Contact Information

GAO Research & Consulting Ltd. is an established international supplier of DSP algorithms, 
software, and systems for the telecommunications market. It provides a complete line of telephony, 
fax, and modem solutions. Its products have been widely reported by over 30 leading publications in 
the industry.
GAO currently employs about 20 DSP engineers. It was founded in 1991 and has been managed by Dr. 
Frank X.Y. Gao.
Contact:	Dr. Frank X.Y. GAO, CEO
		GAO Research & Consulting Ltd.
		55 Nugget Avenue, Unit 204
		Scarborough,  Toronto
			Ontario, Canada M1S 3L1
		(416) 292-0038
		Fax: (416) 292-2364
		e-mail: gao@io.org
		www: http://www.io.org/~gao