Output variable string or number consecutively

[LD_PVL]

Hello,

I have an input signal of telephone digits and I am trying to output the digits on a string or number indicator one by one as they come out so that at the end I would have a full telephone number. I understand the logic to program it but I can't quite get a way to do it visually in LabVIEW. Can you help?

Thanks,

LD

[hecmar.arreola]

Where is the input signal coming from?  How is this input signal attached to the computer?

[Dennis_Knutson]

Sounds like all that you need is a shift register and the concantanate string function.

I know that in an earlier post, you were given the links to the basic tutorials. Have you taken them yet?

[LD_PVL]

I'm trying to detect an 11-digit telephone number coming from a cable. I'm using an NI USB 6008 unit to get the signal in and then work out the numbers. What I have right now is LEDs flashing up for each number from 0 to 9.

I've attached my file for reference.

I have two side questions I'd like to ask. First one is about DAQ Assistant: you know when you're setting up the DAQ Assistant, there's sampling rate, acquisition mode and samples to read parameters, what exactly is the samples to read parameter? The help information said that it's the number of samples specified to read for N Samples acquisition mode or the buffer size for Continuous sampling acquisition mode.

I've got a bit confused about this samples to read parameter because when I tried putting it at high values like 10k, the output of the signal on the graph indicator was going really slow, like it would take snap shots at long intervals. And when putting the parameter at lower values, the signal becomes more continuous. The same actually goes for the sampling rate which is even stranger.

The second question is actually related to the above question. Every digit is dialed (automatically) every 40ms - on the oscilloscope it's like 40ms of waves and then 40ms rest and then 40ms of waves again, so that's like a pulse going at 12.5 Hz. But the waveforms have frequency components within the range of 0.5k to 2k. So my question is what determines the values I'd want to use for the above parameters (if any)?

Sorry for the shabby drawing 😛

[LD_PVL]

I did read the tutorial, it's just that I've not reached that far. But I've looked at it again and found the section for shift registers. I've another small question though.

For the problem that I had, I surely would like a feed back going back to the concantenate string function. I did that and it was working however if I stop the program and re run it, new strings would be added into the old string, no matter how many times i stop the program and re run it, it just keeps adding, instead of going back to the default value of an empty string. What am I doing wrong? I tried using the feedback node as well but it gave the same thing.

Thanks,

LD

Message Edited by LD_PVL on 02-17-2010 07:34 PM

[GovBob]

For this latest problem you need to initialize your shift register. Right click on your left shift register and create an empty constant.

Also there is a library available someone made for DTMF here.

Message Edited by GovBob on 02-17-2010 08:05 PM