How can I get smooth Envelope waves..? Plz help me.

[simpson67]

Hello, everyone.

I wanna get above red waves that is the Evnvelope wave of some input signals.

But I don't know what it can.

Now, I am using DAQ(NI USB-6259BNC ) and Labview 2010 evaluate ver.

Exactly I am wondering that getting above red envelope is possible smoothly.

Now, I can be getting the difference frequency waveform. And I am trying to get a Envelope waveform Using Fast Hilbert transform Block but It isn't working..

I will attach soem pictures those I want to get and VI file. Plz help me.



Have a nice day.

[simpson67]

Attached files

[johnsold]

Two things:

1. Multiply your sine signal (with different frequencies), not subtract. That will produce a non-constant envelope.

2. Use Re/Im to Complex, not Polar to Complex.

Lynn

[johnsold]

Some additional discussion there. Since the question is not DAQ-related, let's keep the discussion here.

Lynn

[simpson67]

Oh.. Thank you for reply.

Could I get your VI file? 

Have a nice weekend

[simpson67]

I couldn't understand those pictures without VI file, sorry..

[johnsold]

I used the Diagram Disable structure to disable the DAQ VIs so that I could test the mathematics. If you wnat to run with your hardware, you will need to remove the Diagram Disable structures.

I also have some extra code to verify that Absolute Value correctly calculates with complex inputs. That is how I discovered that you had the wrong conversion to  complex. I changed some captions to make identification of graphs readable in English.

Lynn