Author Topic: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.  (Read 27001 times)

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Offline Rosendorfer

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Hi Guys

It is my first post so welcome everyone hire...

I'm in situation regarding decision about new scope.. but ..well ..not everyone needs the same one...

I'm mainly analogue audio, stuff guy and I'm looking for jet affordable but quiet and high sensitivity scope with "usable" FFT option.
So there is Hameg HMO1022 with whatever it means "Reference Class" quiet ADC with 1mV/div @ full bandwidth but with just 2000WFMS/S plus Hameg adv.10 bit high precision mode..and FFT at VGA screen
And I almost made my decision on it, well it is rather on expensive side .... but then I have found out on this forum about new Rigiol DS2000, and now I need Your advice...
New Rigol DS2000 comes with "Class Leading"  0,5mV/div and /hire things gets bit blurry as I can't find anything on official Rigol manuals/ but something like 10 (or even 12bit(!!)) "high precision mode"....with nice 800x4800 FFT screen and 50 000WFMS/S.

So my question is if any  of You guys could give me some advice what really can be seen at 10bit mode FFT scope screen at high sensitivity levels..like 1mV/div. I know that high precision mode comes at bandwidth "cost" but at audio frequencies that should be more than OK.
I have made small calculation and this in theory makes possible to "see":
1mV/div x 8 div = 8mV at full screen so with 10 bit ADC we have 8mV/1024=0,0078mV=7,8uV with Hameg and with Rigol 0,5mV/div half of that so about 4uV... OK there is some noise and quantisation errors but still how realistic and "usable/reliable" it can be?

Well I have been looking about this question around, but seems that it is not very popular subject..
So who if not EEVBlog can shine some light at my dilemma..

Rosendorfer
 

Offline PChi

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #1 on: June 19, 2012, 02:06:24 pm »
I am guessing that the 'high precision' modes are just using the 8 bit ADC and relying on oversampling then digitally filtering the result. I guess it depends what the input signal is doing and whether dither is applied to the ADC. Your calculations of resolution assume a 10 bit converter but it probably is just an rather inaccurate 8 bit so not very reliable. The ADC is optimised for bandwidth. I guess that the waveforms per second update rate may or may not reflect on how much of the input data the FFT uses.

I would also add that modern test equipment loves using software to output a pretty picture that isn't always the full truth.

I have some experience of using an old Tektronix TDS 754 Oscilloscope and didn't entirely trust the high resolution mode. I vaguely remember Dave using the high resolution mode on the Agilent and it not being entirely obvious what was going on.
In my opinion the dynamic range of the Oscilloscope high bandwidth ADCs aren't suitable for audio FFT measurements. Unfortunately there is no substitute for a 'Dynamic Signal Analyser' produced by Agilent or SRS with 16 bit ADCs. Or even more expensive Rhode and Scwartz or Audio Precision or something else.

The low cost low bandwidth option is to use a PC Sound Card and something like ARTA software.
 

Offline Rosendorfer

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #2 on: June 19, 2012, 04:07:28 pm »
Hi

Thanks for Your input...
As english is not my native language and it seems, that I like to complicate even simple things things, let my rephrase my question to make it hopefully bit more clear.
Well ..... I'm not at idea of substituting AudioPrecision System2 or R&S Audio System with 1500USD scope../ actually how AP2 cost,  as everybody seems to recommend it.... I need to finally check that.. ;) /
There is no denying that usually scopes ADC are 8bit and 10-12 bit high precisions modes are using kind of multi-sampling that comes at expense of speed on so on....
And finally I'm doing  measurements with 24bit  Audio Sound card and I know they can give pretty impressing results.. but with frequencies higher than 30-40kHz they start to just give up, and this is bit low for many situations and requires Laptop PC Software and some additional work around, so it is not convenient for quick measurements..

My question is how actually high precision scope mode works in real life... and specific in FFT , as this is possibly the only tool that can use it effectively, as seeing difference between 8 and 10 bit in time mode on usual scope screen is questionable.. .this is agreed.

OK..lets try these  way...
My trusted old 8bit scope is able to show FFT down to -70dB but pretty big part is noise, so effectively it can be used to -60-65dB .

So going back to the "high precision" ... with 10 bit in theory we should get into -100dB region and with 12bit mode possible at new Rigols, at speeds lower than 5us, as I recently find out, we should be able to reach -110dB  and this starts to be really interesting.../ well of cause if my dB calculations are OK /
But this is theory and I'm looking for real life info on it ....
Question is what can be REALLY seen at FFT's is there any more useful information, as possibly should be, any influence from memory depth, WFMS/S or any other scope parameters ??

So well any of You guys have any first hand experience regarding that nice looking features...from scopes marketing brochures....???
Maybe Dave, could have a deep(!!) look at it with one of his scope reviews...??

Rosendorfer
 

Offline jahonen

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #3 on: June 19, 2012, 04:59:15 pm »
I think it boils down to SFDR specification, spurious free dynamic range. While averaging tricks improve the noise floor, they don't improve nonlinearities or dynamic range. So you can't reliably measure low level distortion using a scope, at least without using some kind of prefiltering.

If you want to measure just low-level signals without need of wide dynamic range, then just get a preamplifier. With such thing, you can see µV-levels with a DSO. Something like 80 dB of low-noise gain works wonders there.

Regards,
Janne
 

Offline Rosendorfer

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #4 on: June 19, 2012, 05:21:18 pm »
Hi Jahonen

Actually I'm just trying to find out what is possible/real .....
But well, pre-amplifier with some notch filters have been planed as next step... ;)

But my point is.... from theory all of that 10-12 bit FFT's  on new scopes seems to be pretty interesting, I wonder where is the "problem" that nobody is going in that way.

I just found out /how can I miss that !!! / wonderfull program from dexter2048  Topic: "Using Rigol DS1052E for spectrum analysis" and well it starts to be really interesting.. I can get away from "build in" scope screen and get some really interesting data out of that pretty quick ...

It seems that finally I will have to get my hands on one of Rigol DS4000/2000 scopes and see for myself what is coming out of that...

Rosendorfer
 

Offline Gunb

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #5 on: June 19, 2012, 08:53:36 pm »
Hi,

as far as I know there are two common methods of increasing resolution: ERES and HiRes. First was introduced by LeCroy, second by Tektronix. Both methods are using filter algorithms for calculating a higher resolution.

You should not only consider the wfm/s. This value depends always on the timebase and is usually NOT constant but decreasing.

I obtain the Rigol DS4012 as well as the Hameg HMO2524. You should know, that the number of samples for FFT of the HMO can be adjusted between 2048 and 65535, the DS4000-series from Rigol is fixed to 700pts constantly only. I assume, the DS2000 uses the same no. of samples cause it's a downgraded DS4000.

From my point of view the HMO offers better FFT analysis.

The low cost low bandwidth option is to use a PC Sound Card and something like ARTA software.

Yes, that's what I've done also for audio measurement. I recommend a soundcard with a good SNR.

Kind regards
Gunb
« Last Edit: June 19, 2012, 08:57:27 pm by Gunb »
 

Offline Rosendorfer

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #6 on: June 19, 2012, 09:50:02 pm »
Hi Gunb

This is kind of info I was looking for. Thank You ...!!!

Any chances You could send some photos/screens of FFT measurments from Your scope's ..
What is the dB scale of Hameg FFT at normal and high precision mode and what about scope noise...??
Any chance to compare the same with DS4000..???
Well just any info You could share on my dilemma.

Thanks in advance..!!!

Best regards
Rosendorfer   
 

Offline anotherlin

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #7 on: June 19, 2012, 09:52:08 pm »
Hi,

I do have an Hameg HMO0722, it's the 70MHz model. So far, I'm pretty happy with it.
If you have specific questions, I'll be happy to help you. I can run some test for you if you want.

You may want to check :

http://jeelabs.org/2011/12/02/new-oscilloscope/

The guy of the blog bought an HMO, not sure if it's a HMO0722 or a HMO1022 though.
There's also a video review of the HMO1022 on youtube if you search.

Now regarding the 1mv precision, the scope can only display 8mv peak-peak on its screen (it may acquires more than 8mv).

Unless you want to analyze a signal directly from a guitar pickup (a few mV) or microphone, what would be the point ? A "line signal" would be around 1V, right ?

I'm no expert in signal processing, but for a FFT you're more interested in the frequency content rather than amplitude ?


Best regards,
"Lots of people have made $100K or more mistakes and didn't get the boot. It's called training, why fire them after such an expensive lesson?" -- EEVblog Electronics Community Forum
 

Offline EEVblog

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #8 on: June 19, 2012, 10:34:55 pm »
If you want to measure just low-level signals without need of wide dynamic range, then just get a preamplifier. With such thing, you can see µV-levels with a DSO. Something like 80 dB of low-noise gain works wonders there.

What commercial ones are there?
I've been thinking of rolling my own.
Have used a Tek ADA400 in the past, but not really aware of any others.

Dave.
 

Offline jahonen

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #9 on: June 20, 2012, 09:34:40 am »
If you want to measure just low-level signals without need of wide dynamic range, then just get a preamplifier. With such thing, you can see µV-levels with a DSO. Something like 80 dB of low-noise gain works wonders there.

What commercial ones are there?
I've been thinking of rolling my own.
Have used a Tek ADA400 in the past, but not really aware of any others.

Dave.

I can't name any others. But indeed, I have built one (more for AC applications) myself, at work I put it parasitically on one customer project panel, as there were empty space on the panel (actual board was U-shaped) and I needed the preamplifier anyway to characterize the power supply noise so I designed it to fit to the unused space. I knew that first revision is going to be changed anyway so I can remove the preamplifier from subsequent revisions. Not nice outline and capacitors were too big but it got the job done I had to do:



Schematic

I was a bit surprised that it was not actually necessary to put any shielding on top of the PCB (although shown in the schematic), at least in typical lab environment. Probably partly because of heavy ground planes and low-impedance wide traces, surprisingly little noise couples to the PCB, considering the gain.

Residual noise with inputs shorted.

10 µVp-p signal measured with full bandwidth (around 1 MHz).

Output of a 7805 regulator, loaded with a LED and a resistor.

All voltages shown in those screenshots should be divided by 10000, to get input referred values.

Regards,
Janne
 

alm

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #10 on: June 20, 2012, 11:12:20 am »
What commercial ones are there?
I've been thinking of rolling my own.
Have used a Tek ADA400 in the past, but not really aware of any others.
There is the discontinued Tek AM502, which shares the design with the 7A22/5A22N scope plugins, and is essentially the predecessor to the ADA400. It needs a TM500 mainframe, but it is sometimes available on eBay for well under $100. I think it went down to something like 10 uV/div. Bandwidth was 1 MHz, with selectable low and high pass filters. I seem to recall there is also a differential pre-amp available from Preamble Labs, also sold by Lecroy, but I don't recall the noise floor or gain.
 

Offline robrenz

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #11 on: June 20, 2012, 11:51:12 am »
I've been thinking of rolling my own.

Dave.

Dave, please do, I would buy a "Micro pre amp" in a second. I think many others would also.

Offline Rosendorfer

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #12 on: June 20, 2012, 01:04:04 pm »

I do have an Hameg HMO0722, it's the 70MHz model. So far, I'm pretty happy with it.
If you have specific questions, I'll be happy to help you. I can run some test for you if you want.

You may want to check :

http://jeelabs.org/2011/12/02/new-oscilloscope/

Best regards,

Hi anotherlin

I have gone thought Your Hameg HMO review/impresions and it is absolutely great job, if You ask me..
And again very interesting blog You have there...

As for my  high precisions dilema I would be very interested in few simple tests if you could run on Your very nice Hameg :)

At Hameg HMO manual ther is something they call High precision mode and they claim then scope runs in 10bit mode. In time mode it is probably hard to see if scope runs 8 bit or 10 bit well maybe at HAMEG VGA screen You could see something worth to try, but that probably would need bit special wawe... rather not simple sine .. but again 8 bit or 10 bit mode  should in theory be pretty nice reflected on FFT screens.
So if You can run some simple sinwawe out of Your lets say CD player.. :), You can burn it on CD ...:)  or from Sound Card possibly in "decent" laptop ...about 10 kHz and maybe second at 20kHz and made FFT analysis of that sine in normal mode and in high precision mode with markers activated in dBV not in VRMS and positioned at top and bottom of the screen so we could see scope claimed dB range and share with us the screens of that that, I'm very interested if there is any new valuable information or not.
If You could go one step further.. :) Very interesting would be to have simple VR resistor about 25-50kOhm set up between CD or Sound Card and scope input and in that way change signall amplitude and try to go pretty low. Lets say if You could do tests with 200mV/div; 20mv/div and 2mV/div and even try to get to 1mV/div and then we possibly could see the scope noise at FFT screen start to get into the picture... Important is to do not change the signal level at CD or sound card but leave that fixed at some standard usually about  2-3 Vp-p and do the changes at VR.
Well last thing is that with tests it is important to run signal in "full scale" on the scope, means that measured sine should have full screen amplitude typically 8div, but not more, so we are using full range of ADC...
Hope it is OK.. And You could find some time to run that tests ...
In any questions please let ma know...
Well and of cause if other knowledgeable guys hire do have some other ideas or see faults in that tests please let us know..

Best Regards
Rosendorfer


 

Offline Rosendorfer

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #13 on: June 20, 2012, 01:45:09 pm »
@ jahonen

Regarding Active Probe with Gain Project let me put my 2 cents.... as I have been thinking about it already...
It should aim at possibly 20MHz bandwidth and LiPo battery powered ..;).
I wonder about 40dB, 60dB, 80dB gain, probably not variable but different probes...
Well just my 2 cents...
But agreed it is pretty interesting project...
 ;D.... Specially for Agilent DSOX2000 owners... Sorry guys, but I just could not resist..;)  8)..

!!! Rigol wfm viewer program from dexter2048 .. it is absolutely amazing toy....!!!....

Rosendorfer

 

Offline anotherlin

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #14 on: June 20, 2012, 03:59:12 pm »
I have gone thought Your Hameg HMO review/impresions and it is absolutely great job, if You ask me..
And again very interesting blog You have there...

jeelabs.org is not my blog. It is the blog of some guy in netherland.

Regarding the precision of the ADC for full scale and lowest voltage, keep in mind that it may not operate at the same voltage as input :

For a mV, signal from probes may be amplified by a preamp before going to ADC.
And for a full scale (10V per division), the input may go through an attenuator before ADC.

So it's not just a question about the ADC precision, but the full system.

For testing, my signal generator is not working currently. However I should be able to do a capture of a low-level signal with my guitar. I'll do that tonight, after work.
"Lots of people have made $100K or more mistakes and didn't get the boot. It's called training, why fire them after such an expensive lesson?" -- EEVblog Electronics Community Forum
 

alm

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #15 on: June 20, 2012, 06:45:53 pm »
Remember that thermal noise is proportional with the square root of the bandwidth, so higher bandwidth means more noise. For 20 MHz of bandwidth and 1 Mohm input impedance, Johnson noise would be about 0.5 mV. Multiply this by 80 dB of gain and you're in trouble. This is why for example the Tek AM502 or ADA400 have a much more limited bandwidth.
 

Offline DaveW

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #16 on: June 20, 2012, 06:54:35 pm »
Looking through some pictures I took when I got my scope, there is one that might be useful to you. The first photo is a 2mV p-p sin signal being fed into the scope from an HP3325A signal generator. I believe the connection was a straight BNC cable, and I can't remember whether I set the input to be hi Z or 50 ohm. The settings were as default, so no high resolution mode or similar. The second photo is the FFT of this signal, so this should give you some idea of noise floor and low level performance
 
I'm part way through moving, so I don't have access to the scope at the moment, but if haven't had any luck in a couple of weeks, I'll get it set up and run some tests for you!



 

Offline larry42

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #17 on: June 20, 2012, 10:22:59 pm »
Hi, I'm afriad I dont have time to really read the whole thread - but I recently needed to do some measurements using my HMO 1524.

Using 1:20 diff probe (you know the cheapo 25MHz type), I was able to confirm that a signal was attenuated down to -70dBm.

A client was amazed that I was basically using this ultra-compact scope as a spectrum analyzer.

I can easily measure down to -90dBm with this scope - I dont have enough attenuation at the moment to measure lower. The peaks of the noise - the noise floor looks to be around -105dBm or so (Peak detect off, HR on, no averaging). If you average, say 8 times, then I see the noise floor down at -120dBm

There is a bit of 1/f noise, and a spur at 10kHz (not sure if internal or external - it's at -97dBm)

The SFDR is not great though - I was doing some MTPR testing, and couldn't get better than about 40-50dB MTPR when I looked at the multitone spectrum on the scope (the sig gen was > 60dB MTPR)

My old work has some DSOX3000 series - they are faster in terms of UI and much faster waveforms/s* etc - but I think that the HMO is great value for money - especially as i got mine with the serial decode options. I was considering a Rigol briefly. But I wanted to support Hameg, for what I think is a unique product.

PS the HMO is *really* quiet acoustically.


*unless you are doing digital, I don't think that wfms/s is that important. 
« Last Edit: June 20, 2012, 10:30:04 pm by larry42 »
If you have an animated GIF in your avatar or signature then I reserve the right to think you're a dolt.
 

Offline Gunb

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #18 on: June 21, 2012, 07:36:20 am »
Looking through some pictures I took when I got my scope, there is one that might be useful to you. The first photo is a 2mV p-p sin signal being fed into the scope from an HP3325A signal generator.

As far as I can see you've set the scope to "Veff". It should be considered, that you get quite another trace if switching to "dBm", which is used usually on most analyzers. Then the noise floor becomes higher.

My old work has some DSOX3000 series - they are faster in terms of UI and much faster waveforms/s* etc - but I think that the HMO is great value for money - especially as i got mine with the serial decode options. I was considering a Rigol briefly. But I wanted to support Hameg, for what I think is a unique product.

PS the HMO is *really* quiet acoustically.


*unless you are doing digital, I don't think that wfms/s is that important. 


I agree with you concerning the HMO. Related to the Rigol DS series I've done a few tests yesterday and I come to the conclusion that Hameg offers much more features for measuring the spectrum. The HMO offers dBV, dBm and Veff for the amplitude, the user can also setup the number of samples for the FFT calculation, the Rigol doesn't. With the HMO you can choose between mode "Normal", "Envelope" and "Average" and with search functionality you can jump automatically from peak to peak. I find that the whole adjustment of the range of the part of the signal to be measured is much more comfortable than on the Rigol.

Most of these features are not offered by Rigol. I've found on a server that they use 700 samples for FFT constantly - that's not much and leads more to an approximate spectrum without the option to go into more details.

Besides I'm not sure if a scope is the right tool analyzing an audio spectrum. Signals in the range of a few kHz lead usually to slower timebases and that delays the update rate of the spectrum. Of course, it can be done, but when I look at special PC applications they might be faster and better suited for audio purposes.


Kind regards
Gunb
 

Offline Rosendorfer

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #19 on: June 22, 2012, 12:29:20 am »

Looking through some pictures I took when I got my scope, there is one that might be useful to you. The first photo is a 2mV p-p sin signal being fed into the scope from an HP3325A signal generator. I believe the connection was a straight BNC cable, and I can't remember whether I set the input to be hi Z or 50 ohm. The settings were as default, so no high resolution mode or similar. The second photo is the FFT of this signal, so this should give you some idea of noise floor and low level performance
 

Hi DaveW

Thanks for the photos, let me just say that Your pictures  makes me envy of that scope   8) ... All I can say is more!!! Please... ;D


The peaks of the noise - the noise floor looks to be around -105dBm or so (Peak detect off, HR on, no averaging). If you average, say 8 times, then I see the noise floor down at -120dBm

There is a bit of 1/f noise, and a spur at 10kHz (not sure if internal or external - it's at -97dBm)

The SFDR is not great though - I was doing some MTPR testing, and couldn't get better than about 40-50dB MTPR when I looked at the multitone spectrum on the scope (the sig gen was > 60dB MTPR)

*unless you are doing digital, I don't think that wfms/s is that important. 


Hi larry42

Thanks for Your input,
Very interesting information and absolutely amazing numbers as for noise floor... being able to see down to -120dB !!! well seems that that is worth to have very close look at ...
Any chances You could post some HR=on , FFT pictures..?? This is still thing I miss... And If You could please show some of SFDR limitation, You have mentioned as that is the thing that start to bother me.
Anyway seems that HAMEG is way to go ....


I agree with you concerning the HMO. Related to the Rigol DS series I've done a few tests yesterday and I come to the conclusion that Hameg offers much more features for measuring the spectrum. The HMO offers dBV, dBm and Veff for the amplitude, the user can also setup the number of samples for the FFT calculation, the Rigol doesn't. With the HMO you can choose between mode "Normal", "Envelope" and "Average" and with search functionality you can jump automatically from peak to peak. I find that the whole adjustment of the range of the part of the signal to be measured is much more comfortable than on the Rigol.

Kind regards
Gunb


Hi Gunb

Thank You for information  ... It looks like "Hameg team" is wining ..again....  ;D

If I just could ask  You to check if DS4000 wfm files can be open with program from dexter2048  Topic: "Using Rigol DS1052E for spectrum analysis"; specialy wfm with Rigol's 12bit mode.. that possibly could be very interesting if we could have access to  "12bit raw scope data", then possibly FFT could be done "externally"..
And of cause I very much would like, if possible, to see some screens comparing Rigol and Hameg FFT's with both HR modes on, that would be absolutely great info....

Once more thanks for Your infos guys !!!

All the best
Rosendorfer
 

Offline larry42

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #20 on: June 23, 2012, 06:14:34 pm »
Hi larry42

Thanks for Your input,
Very interesting information and absolutely amazing numbers as for noise floor... being able to see down to -120dB !!! well seems that that is worth to have very close look at ...
Any chances You could post some HR=on , FFT pictures..?? This is still thing I miss... And If You could please show some of SFDR limitation, You have mentioned as that is the thing that start to bother me.
Anyway seems that HAMEG is way to go ....


To the OP - if you are measuring things involving dynamic range in the audio frequency range then a scope - any scope - is not the way to go. The front-ends are not built to provide more than 50-60dB DR, AFAIK.

You can can oversample and do lots of digital tricks and this works well in theory - as long as your ADC is completely linear. I don't think that the oscilloscope ones are (else, why not offer 14, 16, 24 bit sampling modes ;) ?)

For low cost audio analysis I would recommend some external USB 24bit 192kHz soundcard. The better ones will have >90dB SFDR.




If you have an animated GIF in your avatar or signature then I reserve the right to think you're a dolt.
 

Offline T4P

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #21 on: June 23, 2012, 07:18:30 pm »
my laptop's Realtek ALC269 does 90.9db SFDR ... 16bit 96KHz recording but the playback quality on this laptop is phenomenal by any mark
You've got to really see what's the recording max sampling rate
Even the Creative SoundBlaster X-Fi Elite Pro that is about 89SGD does 114.1 ...
 

Offline anotherlin

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #22 on: June 25, 2012, 08:54:03 am »
Hi Rosendorfer,

I didn't have much time at the end of last week.
But here are some captures of my guitar, which features Suhr passive humbucker.
It is the output through a jack cable, with my scope probe at the other end.

As it is a passive pickup, It can reach only 500mV pp by strumming real hard.
With the volume knob at very low setting, I can go to the mV range (first picture).
You may notice that the signal is noisy. I don't it's due to the HMO.
If you short the probe, noise are much less than 1mV, probably around 0,5mV pp.
When volume is up, noise is not visible (second picture) .

So scope seems to work pretty well. Hope it helps you make your decision.

Best regards,
"Lots of people have made $100K or more mistakes and didn't get the boot. It's called training, why fire them after such an expensive lesson?" -- EEVblog Electronics Community Forum
 

Offline Rosendorfer

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Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #23 on: June 25, 2012, 06:21:17 pm »
Hi Rosendorfer,

But here are some captures of my guitar, which features Suhr passive humbucker.
It is the output through a jack cable, with my scope probe at the other end.

So scope seems to work pretty well. Hope it helps you make your decision.

Best regards,

Hi anotherlin

Thanks for Your pictures...
Well I thing we also can assume that Your guitar sounds really nice. ;D
As pointed hire many times Hameg HMO are extremely!!! good scopes and as the low noise goes they are probably the best, at that price level.

Nobody seems to be willing post anything from Rigol scopes, so I take it as the reason to assume that they are not that good.

But as I've try to point few times, I'm really interested in 10bit mode FFT screens, means that if You could turn in Your Hameg HMO scope-- HighPrecision mode ON  and run FFT measurement would be very nice.

Rosendorfer
 

Offline anotherlin

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  • Posts: 216
  • Country: fr
Re: FFT @ high precision mode with HAMEG HMO vs Rigol DS2000 scopes.
« Reply #24 on: June 26, 2012, 11:52:33 am »
Nobody seems to be willing post anything from Rigol scopes, so I take it as the reason to assume that they are not that good.

I don't think Rigol scopes are bad, they have good reviews. Seems that people having Rigol scopes may be just busy and don't want to go into comparison with Hameg.

But as I've try to point few times, I'm really interested in 10bit mode FFT screens, means that if You could turn in Your Hameg HMO scope-- HighPrecision mode ON  and run FFT measurement would be very nice.

I'll try to find some time to do you an FFT. Note that you have no control over the number of bits used by the ADC. And as I say before, the ADC is probably just part of the system. For such low-level signal, you may have a preamp before the actual ADC.
"Lots of people have made $100K or more mistakes and didn't get the boot. It's called training, why fire them after such an expensive lesson?" -- EEVblog Electronics Community Forum
 


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