Creating complex data waveform

[JanVerwilligen]

Hi,

I have a 2 channel audio file that contains both the real and complex parts of an I/Q wave. I am trying to demodulate this using the MSK block from the modulation toolkit but I have trouble getting the I/Q stream in the right type. The MSK block asks for a complex waveform as input but after building this complex waveform I found out that it really needed a 'Complex Data Waveform.ctl'.

How can I get my data in the right format? I can't find a block that generates this 'Complex Data Waveform.ctl'.

I have attached a picture of the situation.

Best regards,

Jan

[johnsold]

The standard waveform does not support complex data.

Try creating a control by popping up on the input to the MSK VI. To see the datatype of the wire hover the wiring tool over the wire connecting the control to the VI. The context help window will show the datatype of the wire.

I do not have the modulation toolkit so I cannot try it on your code.

Lynn

[JanVerwilligen]

Well, it is possible to put complex data in a waveform type. Problem is that the MSK block demands a 'Complex Data Waveform.ctl' (the pink wires) of which I can't find how one should compose it.

[GovBob · Accepted solution]

Try this

 Right click on the input complex waveform node of that MT Demodulate MSK subvi. Click 'Create' >>'Constant'. Now delete the wire between the newly created constant and that subvi. Add a bundle by name cluster. Wire the constant into the top of the bundle by name cluster. Left click and  Pull down on the bottom of the bundle by name cluster until 3 inputs appear. Right click each input and use the select item to get the inputs you require.

[JanVerwilligen]

Okay, what you suggested allowed me to wire up the complex signals to the MSK block without, but I don't think the complex data is transferred correctly to the Complex Data Waveform.ctl. Running this leads to an error message (21837, not found in the explain error help page) stating a possible reason: 'Waveform contains no values'.

I've put an image with the setup in the attachment.

Thanks for all your help

Jan 

[RavensFan]

Do you have data in both of those Y arrays?  And data in the array coming out of the Real/Imaginary to Complex function?

You are wiring a 1 and a 2 into the Index Waveform function.  Should you be wiring a 0 and a 1?

Also, the Index Waveform function is kind of overblown.  A simple Index Array would work, then you could expand the bottom border down and get both waveforms from a single function.

[JanVerwilligen]

Thanks! It got that problem solved.

Kind regards,

Jan

[chahatb]

I am getting the same problem..Could u xplain how u got it??

[ThiCop]

Hellon Chahatb,

What does your code look like?

Where are you gettingg issues?

[chahatb]

Hello

Here is my code. The constellation diagram is not displaying anything.

Thanks