Dual Tone Multi-Frequency (DTMF)

DTMF signaling is a means of transferring information from a user to the telephone network through the use of in-band audio tones. Each digit of information is assigned a simultaneous combination of one of a lower group of frequencies and one of a higher group of frequencies to represent each digit or character. There are 8 tones that are capable of producing 16 combinations; 0-9, *, #, A-D. The letters A-D are normally used for non-traditional systems (such as the military telephone systems).

This diagram shows how DTMF tones are created. This example shows that DTMF tones consist of two frequencies that are combined. These frequencies are selected from a matrix of 4 (low group) by 4 (high group) frequencies. Each button on a telephone is assigned one frequency from a high group and one from a low group. This diagram shows that DTMF signals are used to represent numbers, characters and extended digits on a telephone keypad.

Digital Subscriber Line - DSL Diagram

Dual Tone Multi-Frequency (DTMF) Diagram

Related Digital Subscribe Lines - DSL Terms

Quadrature Phase Shift Keying (QPSK)
Carrierless Amplitude and Phase Modulation - CAP
Discrete Multitone Transmission -DMT
Copper Wire Frequency Response
Coaxial Cable Frequency Response
Crosstalk
Bridge Tap Reflections
Audio Loading Coils
Line Splice Attenuation
ISDN Digital Subscriber Line - IDSL
High bit rate Digital Subscriber Line - HDSL
High Bit Rate Digital Subscriber Line 2nd Generation - HDSL2
Symmetric Digital Subscriber Line -SDSL
Asymmetric Digital Subscriber Line - ADSL
Asymetric Digital Subscriber Line Lite - ADSL-Lite
Asymetric Digital Subscriber Line 2nd Generation - ADSL2
Asymmetric Digital Subscriber Line 2nd Generation + - ADSL2+
Reach Extended ADSL - RE-ADSL
Bonded Asymmetric Digital Subscriber Line - Bonded ADSL
Very high bit-rate Digital Subscriber Line - VDSL
Bridged DSL
DSL Modem
DSL Splitter
DSL Microfilters

Digital Subscriber Lines - DSL Books

Introduction to Cable Television (CATV) Book

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Introduction to Digital Subscriber Lines - DSL

This book covers the different types of DSL systems, why DSL is so important to telephone operators, and what services it can offer. It explains how DSL technology allows a standard twisted copper wire to provide broadband (1 Mbps+) and ULTRA broadband (10 Mbps+) data and high quality broadband data, digital telephone and IPTV television services.

$14.99 Printed, $11.99 eBook


Fundamentals Of Dsl Technology	DSL For Dummies	Understanding Digital Subscriber Line Technology
Fundamentals Of Dsl Technology Philip Golden,Hardcover - New Edition, English-language edition,Pub by AUERBACH	DSL For Dummies David Angell,Paperback - REV, Edition: 2,Series: For Dummies Series, English-language edition,Pub by Wiley, John & Sons, Incorporated	Understanding Digital Subscriber Line Technology Thomas Starr, John M. Cioffi, Peter J. Silverman,Other Format - New Edition,Series: Prentice Hall Communications Engineering Series, English-language edition,Pub by Prentice Hall

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