Author Topic: Which scope below $300 has best. FFT function  (Read 2235 times)

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Offline gfmucci

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Which scope below $300 has best. FFT function
« on: May 31, 2020, 08:05:13 pm »
Which scope below $300 has best FFT function?  How important is bit memory/record length to the quality of this function compared to other specs?
« Last Edit: May 31, 2020, 08:09:10 pm by gfmucci »
 

Offline nctnico

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Re: Which scope below $300 has best. FFT function
« Reply #1 on: May 31, 2020, 08:46:55 pm »
That is the Analog discovery.

FFT length is important to get a high frequency resolution. More bits means more dynamic range.
« Last Edit: May 31, 2020, 08:48:38 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Fungus

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Re: Which scope below $300 has best. FFT function
« Reply #2 on: May 31, 2020, 10:47:02 pm »
That is the Analog discovery.

Analog Discovery 2:)



 

Offline egonotto

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Re: Which scope below $300 has best. FFT function
« Reply #3 on: May 31, 2020, 10:56:23 pm »
That is the Analog discovery.

FFT length is important to get a high frequency resolution. More bits means more dynamic range.

Hello,

more FFT length give also more dynamic range.

Best regards
egonotto
 

Offline nctnico

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Re: Which scope below $300 has best. FFT function
« Reply #4 on: May 31, 2020, 11:05:12 pm »
That is the Analog discovery.

FFT length is important to get a high frequency resolution. More bits means more dynamic range.

Hello,

more FFT length give also more dynamic range.

Best regards
egonotto
No. You'll always be limited by the number of bits in order to resolve the signal.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Wolfgang

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Re: Which scope below $300 has best. FFT function
« Reply #5 on: June 01, 2020, 12:05:12 am »
Which scope below $300 has best FFT function?  How important is bit memory/record length to the quality of this function compared to other specs?

The budget scopes like Rigol or Siglent are lousy.
Most important is resolution, because that limits your dynamic range.

What I do is sample the tracks into a PC via SCPI and do the FFT there. MUCH better and flexible.

Expensive scopes with a 16bit resolution mode (oversampling plus averaging) create a good FFT, normally (Keysight Infiniium, e.g.).

 

Offline rsjsouza

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Re: Which scope below $300 has best. FFT function
« Reply #6 on: June 01, 2020, 12:51:11 am »
Which scope below $300 has best FFT function?  How important is bit memory/record length to the quality of this function compared to other specs?
What is the use? If audio, then a soundcard could go a very long way and do a much better job than any real oscilloscope.
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Offline Elasia

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Re: Which scope below $300 has best. FFT function
« Reply #7 on: June 01, 2020, 01:16:34 am »
Which scope below $300 has best FFT function?  How important is bit memory/record length to the quality of this function compared to other specs?

The budget scopes like Rigol or Siglent are lousy.
Most important is resolution, because that limits your dynamic range.

What I do is sample the tracks into a PC via SCPI and do the FFT there. MUCH better and flexible.

Expensive scopes with a 16bit resolution mode (oversampling plus averaging) create a good FFT, normally (Keysight Infiniium, e.g.).

I've been doing this method for years although its usually for just spitting out the occasional fancy graph for an exec lol

Something like matlab will run numbers around most scopes.. it just needs the data
 

Online TK

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Re: Which scope below $300 has best. FFT function
« Reply #8 on: June 01, 2020, 04:23:18 am »
You can get the GW Instek GDS1054B for $310 at tequipment.  I think it has a very decent FFT.  Can be hacked to over 100MHz.
 

Offline egonotto

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Re: Which scope below $300 has best. FFT function
« Reply #9 on: June 01, 2020, 05:10:10 am »
That is the Analog discovery.

FFT length is important to get a high frequency resolution. More bits means more dynamic range.

Hello,

more FFT length give also more dynamic range.

Best regards
egonotto
No. You'll always be limited by the number of bits in order to resolve the signal.

Hello,

but increasing the measurement period and the number of samples by a factor of 10
reduces the bin size with that factor and lowers the noise floor by 10 dB

Best regards

 

Offline _Wim_

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Re: Which scope below $300 has best. FFT function
« Reply #10 on: June 01, 2020, 06:11:51 am »
That is the Analog discovery.

Analog Discovery 2:)

For FFT (and almost every other spec apart from power supplies) the original discovery has the same specs as version 2, but the original one can often be bought on Ebay for less than 100$, which makes it an absolute bargain for the functionality is offers.
 
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Offline tautech

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Re: Which scope below $300 has best. FFT function
« Reply #11 on: June 01, 2020, 09:10:04 am »
Some examples of SDS1202X-E FFT experiments from a few months back:
https://www.eevblog.com/forum/beginners/is-this-oscilloscope-perhaps-the-best-for-the-beginner/msg2985420/#msg2985420

And more earlier in the thread.
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Offline nctnico

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Re: Which scope below $300 has best. FFT function
« Reply #12 on: June 01, 2020, 09:18:45 am »
That is the Analog discovery.

FFT length is important to get a high frequency resolution. More bits means more dynamic range.

Hello,

more FFT length give also more dynamic range.

Best regards
egonotto
No. You'll always be limited by the number of bits in order to resolve the signal.

Hello,

but increasing the measurement period and the number of samples by a factor of 10
reduces the bin size with that factor and lowers the noise floor by 10 dB

Best regards
But you still can't see below the noise floor of the front-end and the dynamic range of the ADC. At some point you are looking at the performance of the analog front-end instead of a signal.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Fungus

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Re: Which scope below $300 has best. FFT function
« Reply #13 on: June 01, 2020, 02:33:34 pm »
Some examples of SDS1202X-E FFT experiments from a few months back:
https://www.eevblog.com/forum/beginners/is-this-oscilloscope-perhaps-the-best-for-the-beginner/msg2985420/#msg2985420

And more earlier in the thread.

Is that "below $300"?
 

Offline khutch004

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Re: Which scope below $300 has best. FFT function
« Reply #14 on: June 01, 2020, 04:21:13 pm »
Is that "below $300"?

No, it's $379 and less than $360 with a well known discount. The question is, which is more important to you, $60 or good FFT performance? Your answer may legitimately be different than mine but when I considered everything I went with the $499 (before discount) member of that family and FFT performance was one of the big factors in choosing that series.
 

Offline Wolfgang

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Re: Which scope below $300 has best. FFT function
« Reply #15 on: June 01, 2020, 05:26:58 pm »
Which scope below $300 has best FFT function?  How important is bit memory/record length to the quality of this function compared to other specs?

The budget scopes like Rigol or Siglent are lousy.
Most important is resolution, because that limits your dynamic range.

What I do is sample the tracks into a PC via SCPI and do the FFT there. MUCH better and flexible.

Expensive scopes with a 16bit resolution mode (oversampling plus averaging) create a good FFT, normally (Keysight Infiniium, e.g.).

I've been doing this method for years although its usually for just spitting out the occasional fancy graph for an exec lol

Something like matlab will run numbers around most scopes.. it just needs the data

... even a simple Python script can do that if no MATLAB is available
 

Offline Fungus

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Re: Which scope below $300 has best. FFT function
« Reply #16 on: June 02, 2020, 05:36:09 am »
The question is, which is more important to you, $60 or good FFT performance? Your answer may legitimately be different than mine but when I considered everything I went with the $499 (before discount) member of that family and FFT performance was one of the big factors in choosing that series.

Feel free to upload evidence to the contrary but I'm not convinced that Siglents have good FFT performance. See this thread from the other day:

https://www.eevblog.com/forum/testgear/fnirsi-1013d-100mhz-tablet-oscilloscope/msg3084923/#msg3084923

"Better than a Rigol DS1054Z" isn't much of a yardstick when looking at FFTs.

The GW-Instek is similarly priced to your Siglent but does a much better job. The Micsigs are also better,
 

Online TK

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Re: Which scope below $300 has best. FFT function
« Reply #17 on: June 02, 2020, 05:59:39 am »
The question is, which is more important to you, $60 or good FFT performance? Your answer may legitimately be different than mine but when I considered everything I went with the $499 (before discount) member of that family and FFT performance was one of the big factors in choosing that series.

Feel free to upload evidence to the contrary but I'm not convinced that Siglents have good FFT performance. See this thread from the other day:

https://www.eevblog.com/forum/testgear/fnirsi-1013d-100mhz-tablet-oscilloscope/msg3084923/#msg3084923

"Better than a Rigol DS1054Z" isn't much of a yardstick when looking at FFTs.

The GW-Instek is similarly priced to your Siglent but does a much better job. The Micsigs are also better,
The GW-Instek GDS1054B is priced at $310 at tequipment
 
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Offline Fungus

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Re: Which scope below $300 has best. FFT function
« Reply #18 on: June 02, 2020, 07:33:20 am »
The GW-Instek GDS1054B is priced at $310 at tequipment

Anybody on the market for an entry level scope should be grabbing one, it's a complete bargain at that price!

 

Offline jjoonathan

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Re: Which scope below $300 has best. FFT function
« Reply #19 on: June 02, 2020, 02:17:03 pm »
Ooh, good catch! The GW Instek is in a completely different FFT league from the rigol and siglent.
 

Offline tautech

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Re: Which scope below $300 has best. FFT function
« Reply #20 on: June 02, 2020, 02:36:44 pm »
Ooh, good catch! The GW Instek is in a completely different FFT league from the rigol and siglent.
:-DD
Yep, Dave hated it.

Really, Fungus links a 4 year old video on FFT shootout and thinks it's relevant to todays offerings ?  ::)  :horse:
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Offline nctnico

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Re: Which scope below $300 has best. FFT function
« Reply #21 on: June 02, 2020, 02:43:09 pm »
Ooh, good catch! The GW Instek is in a completely different FFT league from the rigol and siglent.
:-DD
Yep, Dave hated it.

Really, Fungus links a 4 year old video on FFT shootout and thinks it's relevant to todays offerings ?  ::)  :horse:
Correct. Meanwhile GW Instek has added a spectrum analysis mode as well. But even the normal FFT mode works just fine; it is just that Dave doesn't like GW Instek for some reason. In reality the GW Instek and Siglent in the same price class are on par which isn't a surprise because the basic components are the same.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online TK

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Re: Which scope below $300 has best. FFT function
« Reply #22 on: June 02, 2020, 03:01:52 pm »
Ooh, good catch! The GW Instek is in a completely different FFT league from the rigol and siglent.
:-DD
Yep, Dave hated it.

Really, Fungus links a 4 year old video on FFT shootout and thinks it's relevant to todays offerings ?  ::)  :horse:
It has not changed a lot in 4 years, has it?
 

Online TK

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Re: Which scope below $300 has best. FFT function
« Reply #23 on: June 02, 2020, 03:03:31 pm »
There is another video from Dave where he tests a Near Field Probe and if I remember correctly, he gets a very nice match from a GW Instek FFT, compared to the Rigol Spectrum Analyzer that he uses as the model.
 

Offline Gandalf_Sr

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Re: Which scope below $300 has best. FFT function
« Reply #24 on: June 02, 2020, 03:11:56 pm »
Does the GDS1054B have serial decode and triggering?
If at first you don't succeed, get a bigger hammer
 


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