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This module shows the implementation of a DTMF detector using the DSK6713. The detector is desgined using Simulink.


The Dual-tone multi-frequency (DTMF) signaling method was developed originally to replace pulse (Dial Pulse or DP in the U.S. ) and loop disconnect (LD) signaling methods to dial numbers, in order to shorten the holding time of the switch during dialing , specially for long distance calls.

DTMF signaling uses two tones to represent each key on the touch pad. There are 12 distinct tones The DTMF method defines four additional digits: “A”, “B”,”C”&“D”. Most of the systems today do not use those digits. (Please refer to Table 1). When any key is pressed the tone of the column and the tone of the row are generated. As an example, pressing the '5' button generates the tones 770 Hz and 1336 Hz. The frequencies were chosen to avoid harmonics: no frequency is a multiple of another, the difference between any two frequencies does not equal any of the frequencies, and the sum of any two frequencies does not equal any of the frequencies.

DTMF Frequencies
. 1209 Hz 1336 Hz 1477 Hz
697 Hz 1 2 3
770 Hz 4 5 6
852 Hz 7 8 9
941 Hz * 0 #

Table 1- DTMF frequencies

The low frequencies are referred as rows, The higher frequencies are referred as columns.

This example will show the implementation of a DTMF receiver using the DSK6713. The DTMF receiver will be based on the simulation model used in the Simulink demo. A graphic user interface (GUI) will also be created to activate the DSK6713. DTMF digits will be sent from the PC sound card.


The simulation model

Figure 1 shows the model used to simulate DTMF detection and generation.

DTMF Simulation

The DTMF generator is composed by 7 sine wave generators, corresponding to the 7 DTMF frequencies. The oscillators are grouped as described in Table 1. The oscillators’’ outputs are multiplexed and summed (Please refer to Figure 2). Upon selection of a digit to be transmitted, the correspondent oscillators are activated.

DTMF Generation

The DTMF detection comprises two processes, the frequency detection algorithm itself, and a leading edge detection subsystem.

The frequency detection subsystem measures the energy present at the seven frequencies, and calculates the digit by taking the component of maximum energy in the lower and upper frequency groups. The process is shown in Figure 3. This process runs continuously; however the calculated digit is reported only if its energy is above a threshold as determined by the leading edge detection subsystem. The DTMF detection process is shown in Figure 4.

Frequency Detection
DTMF Detection

Running the simulation

  • Open the simulation model “DTMF.mdl”
  • In order to select the digit double click the DTMF generator subsystem and enter the digits to be sent as follows:
"Dialing" DTMF Digits
  • Activate the simulation, the detected digits will be displayed as shown:

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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