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ni myDAQ oscilloscope bandwitdth

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hi guys i´m planning to purchase the ni myDAQ but i have some questions about the oscilloscope function i´m checking the specs but i can´t find anithing about its bandwitdth, thanks

yes i´m new to this forum

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Hi Rivera25081:

 

The specs you are looking for are in the product MyDAQ User Guide and Specifications, page 20

 

Have a great day

Juan Arguello Director Support Services @NI
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Thank you for your answer it solved other doubts about mydaq but it doesn´t mention its bandwidth 

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Hi Rivera25081:

 

What do you mean with bandwith maybe we are thinking about different things??

Juan Arguello Director Support Services @NI
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for example here at college we have some analog oscilloscopes and their bandwidth is about 10MHz so i was wondering if i could use the oscilloscope function of mydaq to measure a waveform (sin) that has a frecuency of 3MHz

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Accepted by topic author Rivera25081

Hi Rivera25081:

 

I believe that what you need is the MyDAQ Sample Rate in order to know if you can measure the 3MHz sine wave. The max sample rate of the Oscilloscope is 200KHz this means by Nyquist Theorem that you can detect the frecuency of a sine wave of 100KHz. If you want a more accurate representation of a sine wave this signal must be about 10KHz. The signal you are trying to measure has a hi frecuency (Radio Frecuency) It is necesary a faster and more robust equipment to measure this type of signals.

 

Check this equipment:

http://www.ni.com/digitizers/

Juan Arguello Director Support Services @NI
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Hello Rivera25081,

 

The analog bandwidth for the myDAQ AI channels is given in the specifications (http://www.ni.com/pdf/manuals/373060e.pdf) on page 36 as "Passband (-3dB) Analog Input ... DC to 400 kHz". There is not an anti-alias filter in the signal chain, so it does pass frequencies higher than Nyquist -- they will just alias back to lower frequencies, depending on your sample rate.

 

myDAQ was designed to interact with signals up to about 10-20 kHz for teaching data acquisition and circuits concepts. As JuDa pointed out, NI has other devices with higher analog bandwidth and sample rates if you need something more specialized.

 

I hope this helps,

 

Charles Y.

National Instruments

 

 

 

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I just tested with the NI myDAQ.... i find that up to 20 kHz.. you get a reasonable sine curve on the oscilloscope VI. You need to adjust the time base.. it can go up to about 70 kHz.. but the curve is zig zag at that point and beyond this.. the frequency is very unstable and unaccurate..

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Hi krakzz42,

You are correct, based on Nyquist Theorem you'll be able to measure accurately the frequency of your sine waveform up to half the sampling rate (if the myDAQ sampling rate is 200kHz you can detect up to 100kHz). Now if what you care about is that you don't distort the shape of the waveform you have to sample it at least 10 times the frequency of the waveform you are reading. Here are some great resources that talk more in-depth about it.

 

Sampling Theorem

Acquiring an Analog Signal

 

Juan Arguello Director Support Services @NI
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