high frequency

[Mystogan]

Hi everyone, im pretty new with Labview, and I need a help. I would like to simulate square wave with high frequency (40MHz).

1. Can anyone help me, how can I simulate the signal (test2.vi) in a moving (time) axis?

2. I would like to catch the datas and write it into .txt or excel. I found this example (0807-LVM_Beispiel.vi). Can I get the datas like this from my 40Mhz frequency generator?

A little help would be nice. Thanks.

[Mystogan]

help anyone?

[smercurio_fc]

Patience, my young padawan. Patience. This is a forum made up of mostly volunteers, and most (if not all) have full-time jobs.

Now, as to your question. The "test2" example actually generates 3 square waves, so you only need 1/3 of it since you said you wanted one square wave. If you want a moving axis you'd want a chart. You'd also want a loop if you want to see if generate over time. Or are you just looking for a single shot of data over a certain amount of time?

As for the writing, what exactly do you want to write out and how much? At 40MHz you're going to have a lot of points to save.

[Mystogan]

thanks for replying. The 3 signals are needed just for simulation, not 1 (I forgot to mention that).

For the loop, Im not sure how to make my signal moving on the loop with such high frequency. I mean, I've searched the trick how to simulate a moving signal, with using while loop and using the i as a counter. Ive tried to modify (like in the file test.vi), but I dont have idea how to make it work with 40MHz frequency.

As for the writing, I think to get as much as possible points. If im not mistaken, its like about 65000 points with excel, right?

[Mystogan]

I've tried to put my signals into chart now, but somehow it reacts so slowly, compares to the example I got from other forum (Chart_with_Timestamp.vi). Because my signal is 40MHz? I've tried to change the delay, but doesn't work. And I was thinking to get the data samples as much as I want (by changing the samples number #s). The problem is, I cant get the time data in my .txt.

[smercurio_fc]

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@Mystogan wrote:

thanks for replying. The 3 signals are needed just for simulation, not 1 (I forgot to mention that).

For the loop, Im not sure how to make my signal moving on the loop with such high frequency. I mean, I've searched the trick how to simulate a moving signal, with using while loop and using the i as a counter. Ive tried to modify (like in the file test.vi), but I dont have idea how to make it work with 40MHz frequency.

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You will never be able to do this that way, since you cannot run the loop that fast in software.

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As for the writing, I think to get as much as possible points. If im not mistaken, its like about 65000 points with excel, right?

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"As much as possible" is meaningless. You need to decide how many periods you want to save. You are generating a 40MHz waveform with a certain sampling rate, and specifying a total number of samples. That number of samples refers to many periods. If you save all of them, then you will have multiple periods. This may or may not be what you need.

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I've tried to put my signals into chart now, but somehow it reacts so slowly, compares to the example I got from other forum (Chart_with_Timestamp.vi). Because my signal is 40MHz? I've tried to change the delay, but doesn't work. And I was thinking to get the data samples as much as I want (by changing the samples number #s). The problem is, I cant get the time data in my .txt.

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Time is relative. You can't expect to see a fast moving signal if your timescale is set too large. All you'd see is a sea of white (assuming your plot line was white). You have to reduce your timescale so you can see one or two periods. If you look at the attached VI you will see the chart's timescale is set so you can see a couple of periods, and the time increases as the waveforms are generated.

[Mystogan]

thanks for your help.

Ive been searching, and now I've changed my test2.vi into test CIC.vi and modified it. If you may see it, im trying to simulate the signal with frequency 40MHz and, with sampling frq. 800MHz and sample rate 1000samples or max. ~300.000samples (and save it in a txt.file). Actually, my task is, that im gonna need to make a labview program that can take as many points as possible, that might be not periodic. I mean, we gonna use NI card (in near future, not bought yet) to take some input datas, and to get all the data-samples in high frequency range. Is it possible to make such a program (capture the data) without knowing in the first place which NI card that we are going to use. But i believe, we gonna buy a digitizer, digital I/O and might also mxi controller (I've looked at the offered device list) from NI. Thanks a bunch. Is it much easier after buying the devices? (like getting the device's driver and maybe program that support it).

One other question, in my test CIC.vi, im saving my points into .txt file (only the amplitude). How is the trick to take also the x-axis points (time axis) and save it in the same .txt file.

[Mystogan]

I've got the trick to take the x-axis points (time axis):smileyhappy:, but still my biggest problem at the moment: I cant get like 1million samples in 1 sec (which means samples from 1MHz frequency?)