psd

[as2717@sussex.ac.uk]

I have a question about this PSD. why does it show only the freq range between 0-0.5? how to correct it? what i am doing wrong?/???

i wanted to see in the freq range 0-100Hz. 

thank u 

[GerdW]

Hi as,

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as2717@sussex.ac.uk wrote:

I have a question about this PSD. why does it show only the freq range between 0-0.5? how to correct it? i wanted to see in the freq range 0-100Hz. 

what i am doing wrong?/???

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• You are using way too many ExpressVIs and DDT wires.
• You don't understand what happens when converting 1D array to DDT wire.
• You only attach images of your VI instead of the real VI.

Suggestion:

Convert the 1D array of samples to a waveform, using the correct dt value. Once you do this the PSD function (there is a non-Express version as well!) will give expected frequency values for the X axis!

[as2717@sussex.ac.uk]

i cant convert 1d array to waveform. what can i use it is a single waveform in converting option. but it doesnt change the result of PSD. it shows wrong value at 10 Hz. while the signal is 50Hz. 

[as2717@sussex.ac.uk]

VI

[GerdW]

Hi as,

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as2717@sussex.ac.uk wrote:

i cant convert 1d array to waveform.

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Once you would get rid of ExpressVIs this task becomes really easy:

Conversion of 1D array of samples to waveform…

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as2717@sussex.ac.uk wrote:

what can i use it is a single waveform in converting option. but it doesnt change the result of PSD. it shows wrong value at 10 Hz. while the signal is 50Hz. 

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Because you forgot about the samplerate!

Did I mention the "correct dt" before?

[as2717@sussex.ac.uk]

it doesnt give proper result either. 

[GerdW]

Hi as,

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as2717@sussex.ac.uk wrote:

it doesnt give proper result either. 

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Your image shows an executable VI with a plot on the graph and no error in the error cluster.

As far as I can tell from your image "your VI is working as programmed". (Maybe "as programmed" is different to "as needed"...)

When you need more help then you should attach your VI!

[JÞB]

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as2717@sussex.ac.uk wrote:

it doesnt give proper result either. 

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Why are you not using the waveform instance of the Analog Input Read?

HINT: When you get the AI channel data AS WFM all the configured timing information is part of the waveform and you don't need to try to stuff the y array into a waveform with the (wrong) dt.

Also, I think your scaling is very wrong.   The PSD output is in dBm so either scale the linear input by x1000 OR just ADD 30 to the output. 

[as2717@sussex.ac.uk]

i am using myrio 1900 device.

this vi is generating sine wave and sending that signal to the ao/0 and attaching it to the antennna, then another sensor reads it and sends signal to the input of myrio, so i confugured AI0/0 as a source for the psd.

it doesnt work properly tbh, and the values in the ai0/0 is only between 0-4 volts yes bcs it is mxp connectors, 

i can use msp connectors if i want proper vision of the signal output and psd, but for the high thr with n samples is only available mxp pin3.

i need n samples for plotting psd which is available only with high thr, or are there any other methods to plod psd without high throughput?

idk, im tired.

[as2717@sussex.ac.uk]

actually my problem is with acqusition of the signal, why does it look like that in grapgh, but in scope was different, like pure sine wave. in some forum ppl mentioend using fifo. do smn know solution? pls help asap.