Hantek IDSO1070 noise on channel 2

[bevangg]

Has anybody else on the forum got one of these and do you have the same issue? Noise on channel 2 looks to be 10x channel 1.
Hantek advised me that the channels are different and to use 64x average acquisition, which seems to remove the noise with no signal to some degree but hooked up to a dds 5mhz function generator there is significant difference again.
And then changing the average does not make any difference.
This is looking like a hardware or firmware fault to me.

[CustomEngineerer]

This is looking like a hardware or firmware fault to me.

It is a Hantek.

[bevangg]

Yes, it is definitely a Hantek

[gf]

According to the photos on this page https://sigrok.org/wiki/Hantek_iDSO1070, I would be surprised if the two channels were constructed differently. Are you using the same vertical settings (Volt/div, probe attenuation) for both channels? Otherwise noise levels of the channels are certainly not comparable.

Can you quantify the noise amount? Is the magnitude reasonable or unreasonable? All wide-band low-cost scopes have a fair amount of noise. For instance, the noise floor of my Hantek 6074BD is about 300~400µV RMS at 2mV/div 1:1 setting (which implies 3-4mV RMS at 20mV/div with 10:1 probe). That's only  about 25dB SNR wrt. a full-scale sine wave signal. At higher V/div settings the SNR becomes better, but still not more than guesstimated 40~50dB.

[gf]

Hantek advised me that the channels are different and to use 64x average acquisition, which seems to remove the noise with no signal to some degree but hooked up to a dds 5mhz function generator there is significant difference again. And then changing the average does not make any difference.

If averaging does not make a difference, this is an indication that what you see is not random noise, but rather a systematic component in the signal.

How can you be sure that you need to blame the scope and not the DDS generator? Are you aware of all your DDS generator's limitations?  Do you have the opportunity to check the signal on a different (better, low-noise) scope? And finally, how is your generator connected to the scope? BNC cable with 50Ohm termination at the scope? Probe? Or just some arbitary test cables?

(For instance, the built-in DDS generator of my 6074BD suffers from clock feedthough which is evident at low signal levels, and it took me a indeed while to figure out that the presumed "noise" in the signal was actually the 200MHz DDS clock, leaking into the output of the signal generator - I was simply too blue-eyed and had not expected such flaws beforehand.)

[bevangg]

Hi gf

Thanks for the comments. Since I posted I have seen the EEVBlog video on connecting scopes to signal generators and ordered some proper connectors.

I have done a video of the noise without leads connected and measured the voltages.

https://youtu.be/JqX7sm3b26Y

Does this look right?

Regards

[gf]

The quantization steps in the displayed noise signal make me assume that the scope's "true" capability is just 100 mV/div with roughly +/- 1 bits of noise (which may be well acceptable), while the settings below, down to 10 mV/div, are likely just implemented by digital amplification/zoom of the signal captured at 100 mV/div (w/o spending any extra ADC resolution and low-noise pre-amps). So IMO this does per se not look like a bug, but rather a (cost-driven) design limitation of this model (at the bottom line, my 6074BD seems to be significantly better in this regard - just wondering btw, what's actually the price of the IDSO1070?).

I'd consider the difference betwen the two channels within tolerances (it's obviously not factor 10). There is also a small noticeable DC offset on channel 2 (maybe you get rid of it when invoking "calibrate", but I would not be sure).

[bevangg]

Thanks for the analysis. Makes sense. When my connectors arrive I will try it with the sig gen.

I am sure your 6074BD is far better, the IDSO1070 has same 70mhz bandwidth but is only 250msps. It cost £120 so much cheaper.

Seems like a reasonable basic 'scope, especially for field use. Also being wifi connected means you can work with high voltage without risking nuking your pc.

Regards

[gf]

The major feature of the iDSO series is indeed the battery-powered wireless operation. Btw, my 6074BD was actually not significantly pricier (I got it for 138 EUR at AliExpress, incl. shipping), but I can't use it w/o PC, and it has its limitations either.

[Nounours18200]

Although it is an old post, I post a reply:

I own a Hantek DSO8060 and the channel 2 is also noisy.

I have not found any post giving any solution to fix it, but found many posts saying that the channel 2 is often noisy.

So this problem seems to be a regular issue with Handek