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Spectral filter

This topic has 4 replies, 2 voices, and was last updated 18 years, 2 months ago by norbert.bakkers@lr.org.

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October 12, 2006 at 9:54 pm #12645

norbert.bakkers@lr.org
Participant

I currently use a VBA programme to perform a spectral filter on data in Flexpro. The procedure involves:
1) Calculate complex FFT
2) Replace non interesting frequencies by zeros
3) Calculate IFFT
The main advantage of this filter is that it has no effect on signal phase at all. I checked the ‘Digital Filters’ and ‘Spectral Analysis’ descriptions, but couldn’t find this option.
Is there an identical ‘ready’ option available in Flexpro or any of the add-on modules?

October 12, 2006 at 9:54 pm #8308

norbert.bakkers@lr.org
Participant

I currently use a VBA programme to perform a spectral filter on data in Flexpro. The procedure involves:
1) Calculate complex FFT
2) Replace non interesting frequencies by zeros
3) Calculate IFFT
The main advantage of this filter is that it has no effect on signal phase at all. I checked the ‘Digital Filters’ and ‘Spectral Analysis’ descriptions, but couldn’t find this option.
Is there an identical ‘ready’ option available in Flexpro or any of the add-on modules?

October 12, 2006 at 10:44 pm #9044

Bernhard Kantz
Participant

There is no FFT-based filter function in FlexPro but the FPScript function Resample() uses the same principle.

You should note however that this procedure does not lead to an ideal filter as well due to the leakage effect of the FFT. Just try signals with different phase angles at the beginning and at the end.

Please try out the new Digital Filters option. The FIR filters, which you can design with this option, always have linear phase. The phase delay can be optionally corrected.

support@weisang.com

October 12, 2006 at 11:10 pm #9045

norbert.bakkers@lr.org
Participant

Is the Resample() function new for version 7?
I have version 6 and couldn’t find it.

Would it be possible to purchase the ‘Digital Filters’ option for Flexpro 6 or is this only available for Flexpro 7?

I am reluctant to switch to Flexpro 7 as I got the impression that a lot of fuction calls have changed in Flexpro 7. This would mean that all my VBA programma’s will have to be rewritten.

October 12, 2006 at 11:47 pm #9046

Bernhard Kantz
Participant

”Norbert” wrote:

Is the Resample() function new for version 7?
I have version 6 and couldn’t find it.

The Resample() function has been introduced in FlexPro 7.

”Norbert” wrote:

Would it be possible to purchase the ‘Digital Filters’ option for Flexpro 6 or is this only available for Flexpro 7?

No, the ‘Digital filters’ option is available only in FlexPro 7.

”Norbert” wrote:

I am reluctant to switch to Flexpro 7 as I got the impression that a lot of fuction calls have changed in Flexpro 7. This would mean that all my VBA programma’s will have to be rewritten.

Of course there are changes in the object model in FlexPro 7. For instance UI automation has been added. Most changes at existing objects are source code compatible, so programs written in VBA won’t be affected at all. A minor part of the changes requires also code changes, but most of them can be done by search and replace.

A detailed list of the changes can be found in the online help of FlexPro 7:
[list]

In the german version search for the topic: Neue Features des Objektmodells von FlexPro 7

In the english version search for the topic: What’s New in FlexPro 7’s Object Model
[/list]We would recommend to open an existing project with the FlexPro 7 demo version and simply run your macros. In case of an error you should search the above mentioned topic for the involved property, method, object or enumeration member and migrate the code.

Support
support@weisang.com

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