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Author Topic: DS1054Z FFT Example  (Read 3465 times)

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Offline DykesC

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DS1054Z FFT Example
« on: March 12, 2016, 05:24:35 PM »
Hi to all. New Rigol DS1054Z owner.

Below is an FFT example. My Kenwood TS-2000 transceiver was transmitting on a carrier frequency of 7.2 MHz. Between the two vertical cursors is the third harmonic spur at 21.6 MHz. It is -58.6 dbV down from the carrier. Liking this scope.

« Last Edit: March 12, 2016, 05:27:07 PM by DykesC »
 

Offline Mechatrommer

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Re: DS1054Z FFT Example
« Reply #1 on: March 12, 2016, 06:45:18 PM »
this is what possibility you can make out of your 24Mpts Rigol...
(nitpickers section: there are still some bugs lingering around the SW... many bugs)


if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline Athanasis

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Re: DS1054Z FFT Example
« Reply #2 on: April 26, 2016, 10:15:18 PM »
Guys sorry for bringing this up again. This scope is in my future budget. Anyone tried it with audio signals? I am looking into testing the fidelity of small audio amplifiers.

Thanks

 

Offline ebastler

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Re: DS1054Z FFT Example
« Reply #3 on: April 27, 2016, 01:36:42 AM »
Hi Athanasis, this has been discussed a couple of times here. For audio analysis, you are much better off with a decent quality sound card and free audio analyser software. 24 bit resolution is regularly available, and will give you much better data to work with than what an 8-bit ADC in a scope can provide. (Of course, sound cards are limited to 192 kHz sampling frequency or so, while your scope will do 1 GHz sampling rate - but you don't need that for audio signals.)
 

Offline 2x2l

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Re: DS1054Z FFT Example
« Reply #4 on: April 27, 2016, 01:59:50 AM »
this is what possibility you can make out of your 24Mpts Rigol...
(nitpickers section: there are still some bugs lingering around the SW... many bugs)


Has anyone tried to swap out (presumably (one or more of the) ADC(s)?) to get a higher sample rate to increase the resolution (VWB?) The bottleneck is in the ADC sampling rate so one channel with a better ADC should get you a bit of performance boost. Send in a sawtooth to sweep and you should be golden?

(In case you can tell, basically I'm doing everything I can to avoid having to buy a spectrum analyzer for 'casual' use. How 'bad' is the out-of-the-box FFT on the 1504z compared to say, the entry level MSO3000s?)
 

Offline Fungus

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Re: DS1054Z FFT Example
« Reply #5 on: April 27, 2016, 04:16:20 AM »
(In case you can tell, basically I'm doing everything I can to avoid having to buy a spectrum analyzer for 'casual' use. How 'bad' is the out-of-the-box FFT on the 1504z compared to say, the entry level MSO3000s?)

If FFT is your main thing then maybe the R&S1002 is a better fit. It has a better FFT than the DS1054Z and it's a lot cheaper than the MSO3000s.

It's also small, silent, and cute.
 

Online _Wim_

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Re: DS1054Z FFT Example
« Reply #6 on: April 27, 2016, 06:42:18 AM »
If FFT is your main thing then maybe the R&S1002 is a better fit. It has a better FFT than the DS1054Z and it's a lot cheaper than the MSO3000s.
It's also small, silent, and cute.

The HMO1002 also has an 8bit DAC, which is insufficient for audio use. As other have commented, use a sound card together with one of the many audio software packages available for free.
 

Offline pxl

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Re: DS1054Z FFT Example
« Reply #7 on: April 27, 2016, 08:58:50 AM »
If FFT is your main thing then maybe the R&S1002 is a better fit. It has a better FFT than the DS1054Z and it's a lot cheaper than the MSO3000s.
It's also small, silent, and cute.

The HMO1002 also has an 8bit DAC, which is insufficient for audio use. As other have commented, use a sound card together with one of the many audio software packages available for free.

Sure, yet the HiRes mode helps a bit:

« Last Edit: April 27, 2016, 09:01:19 AM by pxl »
 

Online _Wim_

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Re: DS1054Z FFT Example
« Reply #8 on: April 27, 2016, 04:32:17 PM »
But compare that what you could achieve with a sound card (THD+N = 0.00083%), and that inclusive the generated test signal also with the sound card... Sound card used was an EMU 1212 PCIe
 

Online borjam

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Re: DS1054Z FFT Example
« Reply #9 on: April 27, 2016, 04:58:14 PM »
But compare that what you could achieve with a sound card (THD+N = 0.00083%), and that inclusive the generated test signal also with the sound card... Sound card used was an EMU 1212 PCIe
Although not cheap at all, Metric Halo sells excellent 24 bit audio interfaces and a measurement program called SpectraFoo that, among other goodies, does excellent spectrum analysis.


http://mhsecure.com/metric_halo/products/software/spectrafoo.html
 

Offline pxl

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Re: DS1054Z FFT Example
« Reply #10 on: April 27, 2016, 05:42:39 PM »
But compare that what you could achieve with a sound card (THD+N = 0.00083%), and that inclusive the generated test signal also with the sound card... Sound card used was an EMU 1212 PCIe

Well, it depends. This scope is not well suited for measuring audio, indeed, e.g no logarithmic freq scale, but for developing, the 100 dB S/N with HiRes is a way better than you get usually from 8 bit scopes.
 

Offline Athanasis

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Re: DS1054Z FFT Example
« Reply #11 on: April 27, 2016, 06:07:38 PM »
Hi Athanasis, this has been discussed a couple of times here. For audio analysis, you are much better off with a decent quality sound card and free audio analyser software. ........

Thank you ebastler. I was always wary to use audio cards as analysers and I still can't get it how you can it measure a true and fair low and high frequency when they filter what you pass in them. An audio card (with input analogue circuity etc) will lose its sensitivity at frequencies lets say below 50hz or above 16khz

Thanks for your reply
 

Online borjam

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Re: DS1054Z FFT Example
« Reply #12 on: April 27, 2016, 06:32:06 PM »
Thank you ebastler. I was always wary to use audio cards as analysers and I still can't get it how you can it measure a true and fair low and high frequency when they filter what you pass in them. An audio card (with input analogue circuity etc) will lose its sensitivity at frequencies lets say below 50hz or above 16khz
A professional audio interface (I hesitate to say "card" because, well, these are outside boxes connected through Firewire or USB) should give you a more than enough flat response from 20 Hz (or a bit less) to 40 KHz if you are sampling at 96 KHz. Always check the specs and verify with the manufacturer. Good brands are Metric Halo (my favourite), Apogee, RME, MOTU...

Most of them nowadays can sample at 192 KHz as well, and the frequency response should reach 80 KHz. A friend who was working on some ultrasound stuff actually used a not expensive audio interface (around 100 euro, maybe) sampling at 96 KHz and it produced perfectly valid 30 Khz signals.
 

Offline JPortici

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Re: DS1054Z FFT Example
« Reply #13 on: April 27, 2016, 09:10:21 PM »
get a motu or rme audio interface, they have dc coupled i/os
 

Online _Wim_

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Re: DS1054Z FFT Example
« Reply #14 on: April 29, 2016, 05:33:31 AM »
Thank you ebastler. I was always wary to use audio cards as analysers and I still can't get it how you can it measure a true and fair low and high frequency when they filter what you pass in them. An audio card (with input analogue circuity etc) will lose its sensitivity at frequencies lets say below 50hz or above 16khz
Thanks for your reply

Thats not quite true I think nowadays. Attached the frequency reponce of both channel (measured @ 192kHz sampling with rightmark audio analyzer software)
 

Offline Loboscope

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Re: DS1054Z FFT Example
« Reply #15 on: May 01, 2016, 02:41:54 AM »
Indeed, I can fully confirm @_Wim_ that nowadays nearly all reasonably good audio-interfaces will work more than satisfying for audio measurements. With 192 KHz samplerate, today you should go flat from at least 10 Hz to 95 KHz.
I use the (professional) analysis-software "hpw-works" [http://hpw-works.com/] together with several RME-Intefaces. RME is generally known to deliver a superior quality (and not to be the cheapest manufacturer). With equipment like this you can really make absolutely reliable and professional measurements and trustworthy tests of your audio equipment.

Greetings, J├╝rgen
 


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