Author Topic: Oscilloscope with the fastest FFT display below $400?  (Read 936 times)

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Offline daslolo

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Oscilloscope with the fastest FFT display below $400?
« on: April 23, 2018, 06:59:47 am »
I'd like an oscillo with a very fast FFT with good navigation. Below 10 Mhz is ok, portable or USB ok as well. In fact portable would be great, I looked at the miniDS212 but it doesn't have FFT.
Thank you.
« Last Edit: April 23, 2018, 07:56:45 am by daslolo »
 

Offline Performa01

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Offline Mechatrommer

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Re: Oscilloscope with the fastest FFT display below $400?
« Reply #2 on: April 23, 2018, 07:19:18 am »
how many bit depth? is this for audio? how long fft we are talking about?
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline daslolo

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Re: Oscilloscope with the fastest FFT display below $400?
« Reply #3 on: April 23, 2018, 07:42:37 am »
how many bit depth? is this for audio? how long fft we are talking about?
Bit depth, I don't know, by length you mean #bins? I don't know either, I'm tinkering with an idea.
I'll process audio signal but also electric signal, the idea is to make some device that can recognize a machine by its EMF signature and audio signature, if that's even possible.
 

Online BravoV

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Re: Oscilloscope with the fastest FFT display below $400?
« Reply #4 on: April 23, 2018, 07:44:10 am »
As you don't completely know what you want, start with the easiest one, what is your budget ?

Offline daslolo

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Offline Performa01

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Re: Oscilloscope with the fastest FFT display below $400?
« Reply #6 on: April 23, 2018, 08:16:08 am »
Are you using one? Experience?

Not a 2000 series, but the software is the same for all models and you just need to pick one with deep memory to make use of the >1Mpts FFT even though this cannot be fast anymore once the resolution bandwidth drops down to a few Hz. But down to some 100Hz bin width you get a quasi real-time display.

I do have 3000 and 4000 series PicoScopes and I'm very pleased with them.

A Siglent SDS1202X-E also has a very nice and fast FFT up to 1Mpts and would be within your budget, yet I've recommended the PicoScope for several reasons:

1. You've asked for the absolutely fastest. That's the PicoScopes, even though the difference to decent & fast benchtop scopes like the SDS1000X-E isn't huge, especially on narrow RBWs.
2. For more sophisticated applications, the Pico SDK together with the continuous streaming capability might be a bonus.
3. The user interface of the Pico FFT is pretty much like a spectrum analyzer, so it's certainly the easiest to use.
4. The PicoScope provides automatic measurements like THD, SFDR, SINAD and more.

Here's an example what a 16bit Pico 4262 can do in analyzing a 19.9kHz sine wave from an AWG and its harmonics up to 1MHz at 1Hz bin width:


Pico4262_2M_19900Hz_Span1M_avg

 

Offline Mechatrommer

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Re: Oscilloscope with the fastest FFT display below $400?
« Reply #7 on: April 23, 2018, 08:32:13 am »
how many bit depth? is this for audio? how long fft we are talking about?
Bit depth, I don't know, by length you mean #bins? I don't know either, I'm tinkering with an idea.
I'll process audio signal but also electric signal, the idea is to make some device that can recognize a machine by its EMF signature and audio signature, if that's even possible.
so i guess this is for general purpose. although usb scope may cost you 5X cheaper, but when you get advanced, you'll find it limiting, and then you are going to buy another dedicated DSO. so you can choose between:

1) buy USB-DSO now and real-DSO later, or...
2) buy real-DSO now and done...

the real-DSO i'm talking about for hobby is Rigol DS1054Z 100MHz (not crippled to 10MHz only) 1GSps (max, can be set to lower sample rate according to your flavor), although its built-in FFT is a crap, but it has 24Mpts that we can download to PC for serious FFT business. there is low end DSO that can do FFT built in better, Siglent iirc, but it just 1Mpts FFT, not sure if longer points is downloadable to PC nobody have done that afaik. with Rigol 24Mpts, DC - 500MHz, 50Hz RBW FFT can be calculated in less than 10 seconds, and for your purpose (10MHz span 1Hz RBW), lower than -100dB noise floor is achievable esp if average FFT is computed.

you may refer to other thread here regarding DSO FFT such as...
https://www.eevblog.com/forum/testgear/oscilloscope-for-fft-functions/

you also may give a try VisaDSO, that can download and compute the FFT for 24Mpts from DS1054Z, there are few sample files to get you some idea of what can be achieved...
http://www.soasystem.com/download/visadso/

« Last Edit: April 23, 2018, 08:34:52 am by Mechatrommer »
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 


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