How to perform AM-DSB Modulation/Demodulation using Modulation toolkit

[Kamranmu]

Hi to All

I am new to Labview, I have tried to perform AM-DSB Modulation using Modulation Toolkit, but the result is very strange, When I change the Modulationg Signal Frequency, the caries frequency changes, and when I change the Amplitude of Modulating Signal the result is very strange, Maybe I am doing some mistake, so please guide me. Also problem like this when demodulating the signal. I have attached my vi, please check it.

thanks

[Aaron_W.]

Kamranmu,

Thanks for posting on the NI Forums. The reason you are getting this behavior is because you are using a dynamic data type (blue wire from the Simulate Signal2 Express VI) and the Modulation Toolkit Upconvert Baseband VI is expecting a double value instead of a dynamic data type. Since you are basically inserting a sine wave in where a single double value is expected the conversion of the data is causing the problem. Whenever you change the amplitude of the signal, the conversion interprets this as changing the frequency as well. 

I was able to open up a NI-FGEN example (which includes hardware) and take out the hardware portion of the code out. I have attached this example saved back  for LV 8.2. If you have any version after that you should be able to open the example. This example should show you how to use the Modulation toolkit to generate an AM signal like you want. 

[o4enPro]

Dear Kamranmu, 

 i was doing an AM modulation demodulation telecom project using labview.
your uploaded files helped me so mush in modulation. but i am wondering how to apply it on my message signal (which is a function generation- in attachment) as a message signal in order to be modulated.
thank you for your help.moreover i will be thankfull if u have somehting similar for AM demodulation.

thanks again

[o4enPro]

Dear 

 i was doing an AM modulation demodulation telecom project using labview.
your uploaded files helped me so mush in modulation. but i am wondering how to apply it on my message signal (which is a function generation- in attachment) as a message signal in order to be modulated.
thank you for your help.moreover i will be thankfull if u have somehting similar for AM demodulation.

thanks again

[o4enPro]

Dear 

 i was doing an AM modulation demodulation telecom project using labview.
your uploaded files helped me so mush in modulation. but i am wondering how to apply it on my message signal (which is a function generation- in attachment) as a message signal in order to be modulated.
thank you for your help.moreover i will be thankfull if u have somehting similar for AM demodulation.

thanks again

[Timothy_S]

o4enPro,

If you wanted to use your own message signal in the VIs that were attached in previous posts, you would simply need to integrate the waveform output of your Function-generator.vi as being the "message signal" input on the MT Modulate AM.vi. This is where the modulating VI is getting the message information, so you simply need to provide it with a different source instead of the VIs that are generating a message in the above examples.

The Modulation Toolkit does have several functions for demodulations (Functions>> RF Communications>> Modulation>> Analog>> Demodulations) that would be used in similar fashions to the VIs that are used in previous posts.