Urgent!!please help!

[MichaelHo856]

Hello,

anyone can help me out of my school labview assignment?

here is the procedure:

1.Simulate and display a square signal on a graph square with Amplitude=3, 50Hz, Samples rate=10000Hz, Sample number=1000, others remain default.

2. Adding uniform white noise into the signal. You may need “uniform white noise waveform.vi” and “formula”. Display it on another graph. Find and display the error (standard deviation) of the signal including noise.  For a periodic signal assumed constant frequency and phase. The only error is from the amplitude. For the error of amplitude, we only consider the error of the peak value. 

[Blokk]

If you want to get help in this forum, show some real attempt doing your home work. We are not here to do other peoples's homework for free. But if you show a VI, and explain what your goal is, what you tried and what is not clear, then people will start to help you.

[altenbach]

I am sure all you need was covered in class, so go over your notes once more. Also, you definitely don't need "formula", whatever that is.

What have you tried?

[MichaelHo856]

Hi, I am new in labview. Recently I have an assignment work of using labview.  Here is the procedure:

1. Simulate and display a square signal on a graph square with

Amplitude=3, 50Hz, Samples rate=10000Hz, Sample number=1000,

others remain default.

2. Adding uniform white noise into the signal.

(You may need “uniform white noise waveform.vi” and “formula”)

(Display it on another graph.)

3. Find and display the error (standard deviation) of the signal

including noise.

I have finished step 1 and 2, but I Don't kknow how to Find and display the error (standard deviation) of the signal, can anyone help me?

[altenbach]

If you don't have sufficient course notes (I am sure all this was covered), try some of the LabVIEW tutorials.

Instead of simulating two different signals, you probably should simulate only a single noiseless signal, then add noise to it, then do the rest of the processing.

[0Forest0]

press ctrl+space in block diagram. Type: "Std Deviation and variance". This VI may help.

[MichaelHo856]

Here is my project requirement, I have almost finished the whole VI, but I still can not run the VI, the error still exist, can anyone tell me?

1.Simulate and display a square signal on a graph square with

Amplitude=3, 50Hz, Samples rate=10000Hz, Sample number=1000,

others remain default.

2. Adding uniform white noise into the signal.

(You may need “uniform white noise waveform.vi” and “formula”)

(Display it on another graph.)

(Find and display the error (standard deviation) of the signal

including noise.)

3. Adding the 2nd noise, “Gaussian White noise” , into the noise signal.

You may need “Gaussian White noise Waveform.vi”

Display it on a graph.

Find and display the error (standard deviation) of the signal

[LV_Pro]

Ok, what is the problem you are seeing with your program? We will point you in the right direction, but won't do a homework assignment. You need to show what you have done and what your specific question regarding what you have done.

Running the vi you attached gives a pretty definitive message.

[GerdW]

Hi MichaelHo,

- Why do you need to start the next thread for the very same topic? Why don't you stick with your discussion to keep all relevant information in one place?

- Why do you still not provide a meaningful thread title? All the threads in the forum are about "needing help"!

- We will not do your homework even when you name your thread as "urgent" - it's urgent just for you…

[arteitle]

Did you read the error message? "Waveforms have different dt values." To add two waveforms they have to have the same values for dt, which is the sampling interval, the reciprocal of the sampling frequency. Your square wave has a sampling frequency of 10000 Hz (10 kHz), which means a dt of 1/10000 = 0.0001 sec. But then you're taking the waveform produced by "Uniform White Noise Waveform.vi" and repackaging it into a new waveform with dt = 10000 seconds, which means a frequency of just 1/10000 = 0.0001 Hz. So the two waveforms have very different dt (and therefore very different sampling rates). Hint: "Uniform White Noise Waveform.vi" generates a waveform already, you don't need to repackage the output into another waveform. Read the documentation about the "sampling info" input to this subVI.