Browse Prior Art Database

Triple Tone Multiple Frequency Dialing for Mnemonic Telephone Numbers / ID's

IP.com Disclosure Number: IPCOM000113161D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 8 page(s) / 292K

Publishing Venue

IBM

Related People

Day, PR: AUTHOR [+2]

Abstract

Expand the Dual-Tone Multiple Frequency (DTMF) protocol, used today to map the 12 keys on a touch tone telephone to the numbers 0-9, asterisk, and octathorp, to include the entire alphabet. This new mapping can be accomplished with a Triple-Tone Multiple Frequency (TTMF) protocol proposed herein. This will pave the way to restructure telephone numbers to support meaningful telephone "IDs," and to support more user friendly interfaces to applications like telephone shopping, bank account query/transfer, telephone registrations systems, and so on.

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This is the abbreviated version, containing approximately 26% of the total text.

Triple Tone Multiple Frequency Dialing for Mnemonic Telephone Numbers
/ ID's

      Expand the Dual-Tone Multiple Frequency (DTMF) protocol, used
today to map the 12 keys on a touch tone telephone to the numbers
0-9, asterisk, and octathorp, to include the entire alphabet.  This
new mapping can be accomplished with a Triple-Tone Multiple Frequency
(TTMF) protocol proposed herein.  This will pave the way to
restructure telephone numbers to support meaningful telephone "IDs,"
and to support more user friendly interfaces to applications like
telephone shopping, bank account query/transfer, telephone
registrations systems, and so on.

      With this invention, the telephone will require an expanded
keypad to input alpha characters.  This may either be a calculator
sized keypad built into the telephone base or handset, or a telephone
integrated into a computer keyboard and monitor.  We envision the
multi-media workstation of the future as having a telephone
integrated with the monitor and keyboard, and absorbing the telephone
keypad into the keyboard.  However, this invention only deals with
the tones needed to map to the additional alpha characters not
present on today's telephone keypad.

      The Current DTMF System - The 12 keys on the typical touch tone
phone (the numbers 0 through 9 and the asterisk (*)  and octathorp
(#) are represented in the telephone system by pairs of tones at
seven different frequencies.  An additional frequency is used to
represent the letters "A,"  "B,"  "C," and "D."  The extra letters
are used in the military Autovon system, but not in standard public
telephones.  The current DTMF system is shown below.

      The circuits that carry telephone signals are designed to carry
only certain frequencies.  The range of frequencies (termed the pass
band) goes from 0 to 4000 hertz.  Of those frequencies, the
transmission of speech uses only 300-3000 Hz.

The tones used by DTMF meet the following criteria:

o   The frequencies in adjoining rows and columns are separated by
    intervals of approximately 10%.

o   The low- and high-frequency groups are separated by about 25%.

o   The frequency pairs exhibit the minimum amount of harmonic
    interaction.  This prevents them from generating overtones or
    difference tones (e.g., resultants) that might be mistaken for
    any of the other frequencies in DTMF.

      The DTMF frequencies have been internationally standardized,
but tolerances of equipment varies from country to country.  In North
America the standard is +- 1.5% for the generator and +- 2% for the
receiver.

      According to [1], a DTMF receiver must be able to:

1.  Detect the tone-pair signal properly if frequencies are within +-
    2% of the standard values, and reject them if they differ by more
    than +- 3%.

2.  Make sure that only one tone is present from each group (i.e.
    the high and the low groups), and that it lasts at least 40
 ...