convert digital to analog

[nolsqn]

hey hi

how can i convert an array of complex no into a analog signal that i can use to send out using a daq card????

[S_Hong]

Hi nolsqn,

Since you can only output real signals, I suppose you simply want to truncate your complex number and retain simply the real part or take its magnitude. To do this you can use one of our function nodes from our Complex palette by opening up the Functions palette. We can use the "Complex to Polar" or the "Complex to Re/Im" function node under Programming » Numeric » Complex to get your data and pass this data to your DAQ assistant or your DAQmx Write VI.

Please let me know if I have not answered your question.

[altenbach]

Of course you might want to output it in two channels, one for the real and one for the imaginary part of the signal.

Can you give us a few more details?

What is your main problems (converting from complex, outputting an analog signal, etc.)

[nolsqn]

hey

well i know that i need to saperate real and complex parts ...but i am not sure is that how to get analog output because arnt these real and img parts whd be digital ..........so my problem is how to get the analog output from a daq card since i have an array of complex numbers ..........................i know how to get an analog signal out of the daq card what i cannot understand is that how a bunch of real and img part be taken out of the daq card as an analog value?????

[altenbach]

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nolsqn wrote:

... know how to get an analog signal out of the daq card what i cannot understand is that how a bunch of real and img part be taken out of the daq card as an analog value?????

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Well, you need a DAQ card with a minimum of two channels, use one for the RE component and one for the IMG component of the complex data.

Sorry, it is difficult to fully understand what you actually want.

[Dennis_Knutson]

What 'digital' are you talking about and what does that have to do with complex numbers? I also don't think you understand at all how to output a signal from a DAQ board. To output the real and imaginary components on two separate channels, you use the Complex to Re/Im, you get two arrays out and you just have to use a Build Array and the appropriate DAQmx Write.

Message Edited by Dennis Knutson on 08-18-2008 08:51 PM

Message Edited by Dennis Knutson on 08-18-2008 08:52 PM

[nolsqn]

to Dennis Kn… I am using a keithley 3116 DAQ card and when i give it a the data as u have shown it gives error "invalid number of channels in the data array"

[Dennis_Knutson]

The message is pretty clear but I have no experience with the Keithley so you will have to contact Keithely, read the manual, or hope someone else has knowledge on how to correctly setup for a multi-channel generation.

[S_Hong]

Hi nolsqn,

Is it possible that you didn't specify 2 channels in your DAQmx physical channels? For example, for a 2 channel output (ao0 & ao1), you would have to define the channels in either of two ways:

Dev1/ao0:1

or

Dev1/ao0, Dev1/ao1

Perhaps you could post your code so we could have a look at the problem.

[nolsqn]

to S_Hong

i was using single channel multiple samples. as a was using only an array ... i also tried with mutiples channel  multiples sample  it was giving the same error even when i specified two channels....attached is the progromme that i want to get the data out from the daq... on the next post i have attached the VI that i am using to get dataout from keithley

Message Edited by nolsqn on 08-25-2008 09:20 PM