Digital modulation

[fil-leep]

how do i multiply random digital pattern waveform with sine wave form in order to obtain ask modulation scheme

[Samuel_S · Accepted solution]

fil-leep

You may want to look at these:

http://labview.ni.com/docs/proposals/6.1/HTMLHelpProposal/HTML%20Conference/WebHelp/LvwaveMultiply_Waveforms.htm 

You could also convert from DDT and then multiply directly with the multiplication VI using the same number of samples. Also recall that the waveform multiplication needs to have same `dt? this means that with simulated signals and different frequency will not work. I hope this gets you going 🙂

[fil-leep]

thanks for the previous solution.how do i generate a random binary pattern waveform of speed of 10kbps and a sine wave of 30khz

[Samuel_S]

fil-leep 

These should get you going 🙂

https://forums.ni.com/t5/Example-Code/Write-a-Digital-Waveform-With-a-Specific-Pulse-Width-and-Digit...

https://forums.ni.com/t5/Example-Code/Sine-Wave-Addition/ta-p/3495204

I hope this helps!

[fil-leep]

the link you have given me it does not open

[fil-leep]

i have two sine waves of different frequencies,and i want to do fsk modulation i have tried to use select signal vi but it is difficult for me to obtain the fsk modulated wave.i need your help

[Deborah_B]

Hello fil-leep,

Were you unable to open all three links? They came through okay on my end. There is a shipping example in LabVIEW example finder (Select Signals.VI) that can help with modulated signal selection and the select signal.vi. 

Thank you,

Deborah Y.

[fil-leep]

okey i will let you know if it doesn't work.Also how do i shift the level of digital waveform from 0 to -1 and 1 to stay 1?which vi i have to use?

[Deborah_B]

Hi fil-leep,

Here's another, more involved example: https://forums.ni.com/t5/Example-Code/Frequency-Shift-Keying-Digital-Modulation-with-LabVIEW/ta-p/35.... In regards to setting the level, are you using the DWDT Boolean Array to Digital VI to generate that waveform like the example from Sam showed?  Looking at the Context Help on the Mode input for that VI, "mode specifies whether the conversion is performed on the data with the least significant bit (LSB) first or most significant bit (MSB) first. The order of the digital data in digital waveform reflects the selection made in mode". You can change the input level to be 1 here. Let us know how your progress is coming.

Thank you,

Deborah Y.

[fil-leep]

hellow i am having nine signals to display,one at a time by using only one graph.for the signal to be selected user should press the respectivelly switch.i have tried to use select signal vi but i cant make it.please i need your help