how to read resolution, video BW of spectrum analyzer using labview?

[Jiri_Kominek]

@Pallavi: you've read the document so now you know you don't have to play with SCPI commands and question marks, do you? Just drop the 'crazy' express VI into your diagram, select the parameter you want, set its operation to Read and click Ok. That's it. No need to study helps and creating SCPI commands.

[Sim5]

@Jiri,

Ya right but which vi to use for calculating PSD,Resolution BW, Video BW....I tried with many options but i am unable to get correct values... Sorry for disturbing but i tried with differnt vi's ... So can u help me in that...I will be very Thankful...

Pallavi 

[juergenstraub]

Dear pals,

as stated in my Email the PSDs can be read via the noise marker as shown in the example attached. The return value is the PSD in dBm per 1 Hz.

If another bandwidth is required, the value can be corrected with 10 log (BW).

Regards Juergen Straub

[Sim5 · Accepted solution]

Hello All,

Thanks a lot... I will try out all your suggestion will let u know the results...

Once again Thanks to all....

Pallavi 

[Albert.Geven]

Thanks Juergen

I knew it should have been easy, but it was too long ago.

And really that express VI is not the way to program in LabVIEW.

Express vi's can indeed hide complexity but using such express vi as a look up for programming strings is not what they were inteded for.

In fact I admire the way this vi is programmed but a splitting it up in more manageble pieces would be much nicer.

Or use a real string database to form the scpi commands.

But anyway, thanks for helping

[Sim5]

@All,

Thanks so much once again...

Pallavi 

[juergenstraub]

Dear Albert,

please let me do some remarks on your comment:

>using such express vi as a look up for programming strings

This Express VI doesn't act as search engine. This is more an type-safe interface to the low-level part of the driver. For browsing the so called "attributes" (see similiarties to the IVI-C Spec) a chm help file is shipped with the driver.

Furthermore the driver provides a well defined "high-level"-APIwhich is intended to be used for "regular" users. Anyway for "full" instrument control the attributes allows to modify the instrument in a more defined/percise way.

>Or use a real string database to form the scpi commands.

I do not know what your are talking about, might you please more concrete on tha?

So long, Juergen

Message Edited by juergenstraub on 11-19-2009 06:00 PM

[Albert.Geven]

Thanks Juergen for trying to explain.

Indeed it is a typesafe interface but with such a lot of functions combined in one vi, that takes a lot of load time. In fact about 38 seconds on my dell D620 with a 7200rpm disk.

And I guess this all points to the almost 5M data in a global with constants.

Instead of having these strings in a vi stored in a (1733 elements) big constant, you could put thes constants in e.g. a SQLite string database. Also the specific features (window 1, 2 etc) could be stored along such a string. If you want I could send you the SQLite LabVIEW interface we developed with Philips Research.

Allthough I'm very glad that R&S builds such beautiful spectrum anaylyzers, and supplies us with a so complete and working driver I would like a bit better structuring of the of the driver and  something like the projectstyle approach for the menu's.

It is a bit too early for moving to an object oriented approach but LabVIEW is ready for it.