Enhance resolution of signal

[marimuthu]

Hi

 I am acquiring a signal using PCI 5112 Scope card. The rate is 50MS/s and record length is 10Lakhs. I want to perform the Enhance resolution by 1.5 bits on the signal. In the LeCroy scope that is available in math function. Is the same option available in LabVIEW? How I can achieve the same operation available in LeCroy? Any VI's Please!

[Paul_C.]

Hi Marimuthu,

From my searches, It looks like the LeCroy Scope enhance resolution function basically just performs a low-pass filter on the resulting signal.  You might want to double check that this is the case.  If this is true, we have many vi's available in LabVIEW that will filter signals.  I would suggest taking a look at the filter express vi.  This can be found by right-clicking on the block diagram in LabVIEW and navigating to Express » Signal Analysis » Filter.  You might also want to look at the signal processing filter palette by right-clicking on the block diagram again and going to Signal Processing » Filters.  Both the express vi and the lower level filter vi's should give you all the filtering required to perform the "Enhance resolution" feature you are looking for.

I hope this helps,
Paul C.

[alanjb]

Hi Marimuthu,

LeCroy Tech Support here.. The ERES function is described in an application note found here: http://www.lecroy.com/tm/library/AppNotes/EnhancedRes/AN_006a.pdf

Here's part of the first paragraph:

"The Enhanced Resolution function applies a Finite Impulse Response (FIR) filter which, is similar to smoothing the signal with a simple moving average filter, except that it is more efficient in terms of bandwidth, and has better pass-band characteristics. "

I don't know LabVIEW's filter selections too well;  hopefully the above information can help you find the right VI based on what Paul C. suggested in his post.

Best Regards,
Alan

[marimuthu]

Hi Alan and Paul

          Thank you. Can you help me how to enter or map the following enhanced filter parameters in our filter vi's.

bits- 1.5

-3db BW- 0.121

filter length- 11

Eff. dynamic range- 724:1

Marimuthu M

Apna technologies.

[Paul_C.]

Hi Marimuthu,

I'm still not exactly sure from that document which filters are being used with what order, type, settings, etc.  From the way the article reads it looks like they are using a combination of more than one FIR and lowpass filters.  If we could get some more specifics regarding which filters (specifically which type of FIR filter and what characteristics, ie. coeficients etc.) are being used, we might be able to find find the correct counterpart in LabVIEW.  I would also like to mention that if we don't currently have the correct filter it may be possible to design the correct filter using the Digital Filter Design Toolkit.  This product page can be found here.  There is also a great document for designing a digital FIR filter here. 

I hope this helps,
Paul C.

Message Edited by Paul C. on 12-13-2007 03:49 PM