dtmf example

[Mudassar Mehboob]

Hi

I want to decode DTMF from the anlog input acquired by a NI DAQ. can any one help me with an example or with some thing very descriptive and comprehensive because i m new to labview and this would be a great help for me to start.

Regards

Mudassar Mehboob 

[bjorn1985]

I think the first thing you need to do is determine te frequency of the tones.

If you are using the DAQ assistant, this is easy to do by reading a number of samples at a very high frequency. Then, use a Fourier transformation (also a standard block in LV 8.0) on the output waveform.

This should get you started.

[DavidJCrawford]

I suggest doing a search for DTMF on the discussion forum. There are quite a few discussion threads and sample code.

cheers

David

[Mudassar Mehboob]

Hi

Reading the data from DAQ and taking its fourier transform is ok i have got no difficulty up to this step. The problem arises how to pick that data up from the FFT block and display it on something like a seven segment display or to store it in some variable.

Hope you understand and help

Thanks in advance for your help

Regards

Mudassar Mehboob

[bjorn1985]

I don't want to give too much information here but try to convert the Fourier waveform to an array and find the highest signal. Compare the array to the waveform as I have had some difficulties with this conversion. Then, you can compare the frequency you've found to the DTMF frequencies.

[Mudassar Mehboob]

Thanks for your reply

just tell me one thing i have searched the discussion forum with they keyword dtmf. I have found that there is an example vi named as simphone.vi could u please tell me where is it exactly located in the labview directory because i have searched for it  but i could'nt find it out.

hope you wont feel (uuhh! these begginers ask too much questions)

Regards

[DavidJCrawford]

Mudassar Mehboob

Don't worry about that. We were all beginners at some point.

I couldn't find Sim Phone in LV8.0 but it was there in LV7.1 so I bundled it into a .llb for you. I also found DTMF_decode.zip on my PC. I must have picked it up from somewhere. Its for a sound card but you should be able to adapt it to use your DAQ card.

In the end I bought one of these http://209.51.151.50/ASCIItoDTMF.html to handle DTMF comms. Made life much easier for me at the time. Never looked back.

David