Spectrum Analyzer using Swept Frequency

[Dave Korpi]

Using the AWESOM example foundhere:
http://zone.ni.com/devzone/explprog.nsf/6c163603265406328625682a006ed37d/433c2cbc5a1c4a49862569500035f715?OpenDocument

Give the person who wrote that an A+. I want to replace the FIR filter with a REAL device. I want to send a swept sin wave (just like the original) and then read the response from the Analog Input channel. I put a vi in place of the vi called :IIR Filter for 1 Chan.vi. Go to the NI ftp site to ge t the file named ZZDMKSin.zip (I could not get the file attachment to work within this post) The symptom is the Frequency Response does not get any data that can be seen...

In the end I simply want to put a REAL UUT in place of the FIR filter. This would turn the VI into an equi
v of a $30,000 spectrum analyzer! Sooooo cool!

Any help would be greatly appreciated. My e-mail is korpi@starband.net

Thanks,

Dave

[Filipe A.]

Dave;

I'm not quite sure if I understood your application, but by my understanding you want to replace one of the Filter VIs by a VI that does data acquisition from a real external device.

The first thing you might want to double check is the data acquisition VI by itself. Set up the system with the external device and with the data acquisition VI only. Make sure the VI is acquiring data as expected.

After that done, make sure that the data acquisition VI output is outputing the same data type that is expected at the output of the IIR Filter.vi.

I believe that either one of the previous issues might be the answer.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments

[Dave Korpi]

The solution to make use of this VI with real devices is two fold. First: Connect the error indicator from the Divide Waveforms.vi to merge errors.vi so that when an error happens we can see it. To properly use this system in a REAL mode you need to make sure that the dt's are correct or the frequency will not indicate. My solution was to change the 25000 to 10000 on Fs outside the while loop. Carlos gets all the credit for figuring that out! Great job Carlos!

Thanks,

Dave Korpi
korpi@starband.net

Case closed for me!

[Dave Korpi]

The solution to make use of this VI with real devices is two fold. First: Connect the error indicator from the Divide Waveforms.vi to merge errors.vi so that when an error happens we can see it. To properly use this system in a REAL mode you need to make sure that the dt's are correct or the frequency will not indicate. My solution was to change the 25000 to 10000 on Fs outside the while loop. Carlos gets all the credit for figuring that out! Great job Carlos!

Thanks,

Dave Korpi
korpi@starband.net

Case closed for me!