Analysing and generating a signal

[GoviRe]

Hello,

I am using NI Multisim 13.0.I want to generate a signal similar to the one shown in the attachments acquired using labview which is the output of a phototransistor.The output image contains 10 signals each contaning each acquired by using 1k samples and below freq images shows freq components only 1 signal of 1k sample.From the images it can be analysed that it has DC volatge of 2.6V but I am confused as it contains different frequenices and most(very high number) of the frequencies are lying below around 1Hz and some are lying at  around 135 and others at 275 to 300 and very less number of other frequency components.

What all things to be taken to generate these kind of freq's and How to add these different kind of frequencies to the DC component so as to generate the signal that will be same as in the shown image.

I want to genearte this signal in multisim as this will used as a input for designing the filtering stage in multisim.

Thanks.

[Tien_P · Accepted solution]

Hi Patangova,

 Save your acquired data as an .lvm file in LabVIEW.  In Multisim, select Place>>component, go to the "Sources" group, select the "Signal Voltage sources" family, there should be a LVM Voltage source.  Drop this part on the work area, double-click on it then click the Browse button to load you .lvm file.

[GoviRe]

Hello Tien P,Great its working.

And can I know how to generate the signal from this lvm file containing values for only 1 sec interval , as the signal is being generated from the .lvm file for only 1 sec and after a second it is showing some constant value.Can I make this generate this signal of 1 sec interval continuously.The signal generated from .lvm file is attached.

Thanks.

[Tien_P]

Double click the LVM source, there is a "repeat" check box.

[GoviRe]

Hello Tien P,

Can I know how to check and analyse the different frequency components present in a signal.

Thanks.

[Tien_P]

You have to use the Fourier analysis from Simulate>>Analyses>>Fourier Analysis.

You can find more information about the Fourier analysis from here:

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YHDjCAO&l=en-US

[GoviRe]

Hi Tien P,

I am trying to read the samples in .LVM (that are saved using 'one header only while' writing into .LVM file) that has samples for more than 1 sec duration since 1sec duration has 1k samples so more samples will be there for more than 1 sec as shown in the attached file.But When I am trying to read this into the multisim uisng LVM voltage source it only showing 1 sec samples waveform (as shown it the attached image)and after that it is not plotting anything but it is supposed to plot the as many samples that are in the .LVM file.

Can I know how to read all the samples form the .LVM file.

Thanks.

[Tien_P]

Hi,

I am not sure why the signal stopped a 1 sec; I will let the developer look into it.

You can use the Piece Wise Linear Source (PWL) source instead; it's in the same family as the LVM source.  You do have to change the data by adding a time column.