Use sampled waveform to generate analog signal

[young grasshopper]

I have no experience using analog outputs in LabVIEW, and I'm just trying to determine whether this would be possible, so I don't kill myself trying to do something which can't be done...

If I acquired a sample of an analog waveform (somewhat resembling a 1V 80 Hz pulse), would there be any way to turn around and use that sample as the basis for a new signal being generated on the analog output line of a DAQ board? What I would like to be able to do is reproduce the original waveform, but change the frequency and amplitude as desired.

I haven't looked into this that much, so I'm sorry if this is a dumb question, but from what I've read it seems like signals are mostly generated in LabVIEW through either an equation, or using generic signal types like a sine wave.

Thanks for any advice!

[Neville D]

QUOTE(young grasshopper @ May 7 2007, 08:03 AM)

I have no experience using analog outputs in LabVIEW, and I'm just trying to determine whether this would be possible, so I don't kill myself trying to do something which can't be done...

If I acquired a sample of an analog waveform (somewhat resembling a 1V 80 Hz pulse), would there be any way to turn around and use that sample as the basis for a new signal being generated on the analog output line of a DAQ board? What I would like to be able to do is reproduce the original waveform, but change the frequency and amplitude as desired.

I haven't looked into this that much, so I'm sorry if this is a dumb question, but from what I've read it seems like signals are mostly generated in LabVIEW through either an equation, or using generic signal types like a sine wave.

Thanks for any advice!

Your question isn't very clear.. do you want simultanous analog input and analog output? Or is the AO calculated off-line?

The frequencies seem fairly low (80Hz?) so you should be able to get away with software-timed analog output. This will allow you to change the frequency. You should be able to use hardware time Analog Input.

I'm not sure if you can do hardware timed AI and AO simultanously while changing the frequency of the AO; most probably not. DAQ cards usual have only one on-board FIFO, which limits you to only one of the above.

Using a more expensive DAQ card (for example M-Series as opposed to the cheaper E-Series) will allow you more DMA channels for simultanous AI/AO (but still won't allow changing the AO frequency on the fly).

Speak to your local NI rep or call NI for more in-depth info.

Neville.

[young grasshopper]

QUOTE(Neville D @ May 7 2007, 03:54 PM)

Your question isn't very clear.. do you want simultanous analog input and analog output? Or is the AO calculated off-line?

The frequencies seem fairly low (80Hz?) so you should be able to get away with software-timed analog output. This will allow you to change the frequency. You should be able to use hardware time Analog Input.

I'm not sure if you can do hardware timed AI and AO simultanously while changing the frequency of the AO; most probably not. DAQ cards usual have only one on-board FIFO, which limits you to only one of the above.

Using a more expensive DAQ card (for example M-Series as opposed to the cheaper E-Series) will allow you more DMA channels for simultanous AI/AO (but still won't allow changing the AO frequency on the fly).

Speak to your local NI rep or call NI for more in-depth info.

Neville.

Nope I wouldn't need simultaneous AI & AO, the signal would be based on the one sample and should never change in form. The frequency is low because this is a waveform associated with a human heartbeat - the application is a patient simulator for testing pulse oximeters.

Thanks

[Neville D]

QUOTE(young grasshopper @ May 7 2007, 09:07 AM)

Nope I wouldn't need simultaneous AI & AO, the signal would be based on the one sample and should never change in form. The frequency is low because this is a waveform associated with a human heartbeat - the application is a patient simulator for testing pulse oximeters.

Thanks

I think hardware or softwared timed AO should work fine. Take a look at the DAQmx examples; you should see one that matches your needs.

N.

[Dirk J.]

hey grasshopper

(you're going to regret choosing that name.... )

in principle re-sampling of your data, horizontally and vertically, shouldn't be that much of a problem.

can you share some of your code, so we can see to what point you got?

-sensei