standard data format of a digitizer

[Dimitri MALSAM]

Hello,

I'm using a NI PCI-5122 digitizer together with LabWindows/CVI 8.0 to acquuire a QPSK modulated signal. It contains IQ-data. In order to proceed with my analysis I have to be sure which format the acquired data has. Is it already a complex data array or is it a real waveform and I have to convert the data first into IQ format?

If it is the first case and the acquired dat is already IQ, how is the format? Is it 'I1Q1I2Q2I3Q3...' or 'I1I2I3...Q1Q2Q3...'?

If the data is real how can I convert it into IQ data with the means of Labwindows/CVI?

Thank you for your help!

Dimitri

[Dimitri MALSAM]

Hello,

I'm sure now that the data acquired is real and not complex. So to transform it into IQ format I need to know the phase of the signal.

Can anybody please tell me how I can do it in LabWindows/CVI?

Or does anybody knows an algorith how to get IQ data aout of a sampled waveform signal?

Thanks,  Dimitri

Message Edited by Dimitri MALSAM on 04-07-2006 02:32 PM

[Benjamin_M]

Hello,

The National Instruments Spectral Measurement Toolkit provides a set of flexible spectral measurements in LabWindows/CVI. The Spectral Measurements Toolkit contains functions for performing modulation-domain operations such as passband to baseband (I-Q) conversion and generation/analysis of analog modulated signals.

Here is a link where you'll find informations about it :
https://www.ni.com/en/support/downloads/software-products/download.spectral-measurements-toolkit.htm...

Hope I answer the question,

Regards,

Benjamin M
NIF

[Dimitri MALSAM]

Thank you Benjamin! To be honest, the project I'm working on is a prototype and we don't want to spend to much money in order to see if one calculation is working properly together with the NI PCI-5122 high speed digitizer. I'm still looking for alternative ideas, so if anyone can help, please do so.

Thank you, Dimitri