Dual Tone Multiple-Frequency (DTMF)

What is a Mobile controlled DTMF ?

Ans :
DTMF Mobile is a machine that can be controlled with a mobile . In this project, the robot is controlled by a mobile phone that makes a call to the mobile phone attached to the robot. In the course of a call, if any button is pressed, a tone corresponding to the button pressed is heard at the other end of the call. This tone is called “Dual Tone Multiple-Frequency” (DTMF) tone. The robot perceives this DTMF tone with the help of the phone stacked on the robot. The received tone is processed by the micro controller with the help of DTMF decoder. The micro controller then transmits the signal to the motor driver ICs to operate the motors & our robot starts moving

DTMF Tone : 
The DTMF technique outputs distinct representation of 16 common alphanumeric characters (0-9, A-D, *, #) on the telephone. The lowest frequency used is 697Hz and the highest frequency used is 1633Hz, as shown in Table 1. The DTMF keypad is arranged such that each row will have its own unique tone frequency and also each column will have its own unique tone frequency. Above is a representation of the typical DTMF keypad and the associated row/column frequencies. By pressing a key, for example 5, will generate a dual tone consisting of 770 Hz for the low group and 1336 Hz for the high group.

Digit Low frequency High frequency
1             697                 1209 Hz
2             697                 1336
3             697                 1477
4             770                 1209
5             770                 1336
6             770                 1477
7             852                 1209
8             852                 1336
9             852                 1477
0             941                 1336
*              941                 1209
#             941                 1477

DTMF (dual tone multi frequency) is the signal to the phone company that you generate when you press an ordinary telephone’s touch keys. In the United States and perhaps  elsewhere, it’s known as “Touchstone” phone (formerly a registered trademark of AT&T). DTMF has generally replaced loop disconnect (“pulse”) dialling. With DTMF, each key  you press on your phone generates two tones of specific frequencies. So that a voice can’t imitate the tones,one tone is generated from a high-frequency group of tones and the other from a low frequency group. Here are the signals you send when you press your Touchstone phone keys:

DTMF and Tone Generation (+VTS)
This command allows the transmission of DTMF tones and arbitrary tones. These tones
may be used e.g. when announcing the start of a recording period. In GSM this operates
only in voice mode. If the optional parameter <duration> is left out, the tone duration is
given by the setting +VTD (see +VTD description).

For AT command
=============
AT+VTS=As described above OK
OR
CME ERROR: <error>
<DTMF>:
is a single ASCII character in the set 0-9, #, , A-D.
==========================

3G Call Flow for DTMF ( Dual Tone Multiple-Frequency) 
======================
Initial Condition : UE is attached to 3G network

>>>>>MO call is triggered 
atd011992906049;
>>>>>we can see CM service request for the same.
CM SERVICE REQUEST
RB0: UL_CCCH: RRC CONNECTION REQUEST (originatingConversationalCall )
RB0: DL_CCCH: RRC CONNECTION SETUP;
RB2: UL_DCCH: RRC CONNECTION SETUP COMPLETE
RB3: UL_DCCH: INITIAL DIRECT TRANSFER CM Service Request
RB2: DL_DCCH: SECURITY MODE COMMAND
RB2: UL_DCCH: SECURITY MODE COMPLETE
Setup (mobile originating call establishment)
RB3: UL_DCCH: UPLINK DIRECT TRANSFER Setup
RB3: DL_DCCH: DOWNLINK DIRECT TRANSFER Call Proceeding
RB2: DL_DCCH: RADIO BEARER SETUP
RB2: UL_DCCH: RADIO BEARER SETUP COMPLETE
RB2: DL_DCCH: RADIO BEARER RECONFIGURATION
RB2: UL_DCCH: RADIO BEARER RECONFIGURATION COMPLETE
RB3: DL_DCCH: DOWNLINK DIRECT TRANSFER Alerting
ALERTING (NETWORK TO MOBILE STATION DIRECTION)
RB3: DL_DCCH: DOWNLINK DIRECT TRANSFER Connect
Connect Acknowledge
>>>>>Here Call is successfully connected in UMTS
RB3: UL_DCCH: UPLINK DIRECT TRANSFER Connect Acknowledge

>>>>Now START DTMF is sent in the UL direct Transfer when MO call was established
at+vts=1
Start DTMF
RB3: UL_DCCH: UPLINK DIRECT TRANSFER Start DTMF
>>>>acknowledgement is received
RB3: DL_DCCH: DOWNLINK DIRECT TRANSFER Start DTMF Acknowledge
>>>>Stop DTMF and STOP DTMF ACKNOWLEDGE
RB3: UL_DCCH: UPLINK DIRECT TRANSFER Stop DTMF
RB3: DL_DCCH: DOWNLINK DIRECT TRANSFER Stop DTMF Acknowledge

>>>>Later call is disconnected
ATH
Disconnect (mobile station to NETWORK direction); Cause: Normal call clearing
Release Complete (mobile station direction to network); Cause: Normal call clearing
RB1: DL_DCCH: RRC CONNECTION RELEASE No state match
STATE_IND: –> IDLE

Start DTMF
=================

RB3: UL_DCCH: UPLINK DIRECT TRANSFER Start DTMF
Pointer_0 : ASN1 Message ——– ASN1 3GPP 25.331
value UL_DCCH_Message ::= {
integrityCheckInfo {
messageAuthenticationCode ‘11101000100000011010101011111100’B — ‘E881AAFC’H –,
rrc_MessageSequenceNumber 4
},
message uplinkDirectTransfer : {
cn_DomainIdentity cs_domain — 0 –,
nas_Message ‘03352C31’H
}
}
Start DTMF Acknowledge
======================
RB3: DL_DCCH: DOWNLINK DIRECT TRANSFER Start DTMF Acknowledge
Pointer_0 : ASN1 Message ——– ASN1 3GPP 25.331 R11
value DL_DCCH_Message ::= {
integrityCheckInfo {
messageAuthenticationCode ‘11010111111011111001010011110011’B — ‘D7EF94F3’H –,
rrc_MessageSequenceNumber 7
},
message downlinkDirectTransfer : r3 : {
downlinkDirectTransfer_r3 {
rrc_TransactionIdentifier 2,
cn_DomainIdentity cs_domain — 0 –,
nas_Message ‘83362C31’H
}
Stop DTMF
===================
RB3: UL_DCCH: UPLINK DIRECT TRANSFER Stop DTMF
Pointer_0 : ASN1 Message ——– ASN1 3GPP 25.331 R11 December
value UL_DCCH_Message ::= {
integrityCheckInfo {
messageAuthenticationCode ‘11010101111101110010101111001001’B — ‘D5F72BC9’H –,
rrc_MessageSequenceNumber 5
},
message uplinkDirectTransfer : {
cn_DomainIdentity cs_domain — 0 –,
nas_Message ‘0371’H
}
}

Stop DTMF Acknowledge
===========================
RB3: DL_DCCH: DOWNLINK DIRECT TRANSFER Stop DTMF Acknowledge
Pointer_0 : ASN1 Message ——– ASN1 3GPP 25.331
value DL_DCCH_Message ::= {
integrityCheckInfo {
messageAuthenticationCode ‘00000000001110111010100011011000’B — ‘003BA8D8’H –,
rrc_MessageSequenceNumber 8
},
message downlinkDirectTransfer : r3 : {
downlinkDirectTransfer_r3 {
rrc_TransactionIdentifier 3,
cn_DomainIdentity cs_domain — 0 –,
nas_Message ‘8332’H
}
}