Hantek2d42 bugs report

gf1

I noticed yet another noise pattern of the scope, caused by the AWG, and affecting both scope channels.

• This one is particularly pronounced at low AWG frequencies.
• AWG is set to square wave, 500 Hz, 2V amplitude.
• AWG output is connected to a 50 Ohm load resistor.
• CH1 and CH2 inputs are 50 Ohm terminated, i.e. no signal applied to the scope inputs (all you see below is noise).
• If the load is removed from the AWG ouput, then the noise amplitude decreases as well. So I guess this particular noise is primarily
  caused by the ouput current of the AWG's EL5166 amp (or the corresponding current drawn from the power supply rails).
  

This noise has maximum amplitude at 10mV/div and 500mv/div, and progressively decreases at 20, 50, 100 and 200 mV/div. So I think it is already present at the output of the frontend's buffer amplifier (at the input of the the resistor ladder attenuator).

The AWG output waveform itself looks OK (when displayed on my 6074BD).

EDIT: The ringing component of this noise signal also shows up on the negative power supply rail of the AWG's EL5166, in an amount of about 40 mV pp. The positive rail is not perfectly clean either, but there is more high-frequency noise.

gf1

gf1

amy replied at 2019-3-12 15:20
Sir, about the AWG burr, there is a solution to deal with.
1. Replace the resistance to 1.5KΩ in th ...

Dear Amy,

thanks for your efforts to get this issue resolved.

Do I understand correctly that the idea is to increase the full-scale DAC current by about 20% and to compensate this by sending a smaller digital count range to the DAC? Then re-calibrate the AWG, using the scope to measure the AWG output. I'm wondering whether the scope is accurate enough to act as calibration reference? Wouldn't the DMM have a significantly better accuracy?

Is it possible to save my current AWG calibration (which happens to pretty accurate, btw. ) and to restore it later if the AWG burr fix procedure does not give the desired results and if I need to fall back?

[ EDIT: re-phrased questions ]


Thank you,
gf1

amy

Sir, about the AWG burr, there is a solution to deal with.
1. Replace the resistance to 1.5KΩ in the following picture.
   

2. Use the firmware to update.
   

3. Connect "Gen out" to "CH1".
4. Open the oscilloscope and press "AWG".
5. Set the waveform type to "Sine", enter the second page and press "Calibrate(F3)" to calibrate.

gf1

Dear Amy,

yet another issue with the AWG:

• Set AWG to square wave, frequency=7.8125MHz, duty cycle=0.5
• Everything fine, signal as expected, duty cycle = 50%
• Turn off the 2D72
• Turn the 2D72 on again, and turn signal generator on again
• The same settings as previously show up in the display (display still shows duty=0.5)
• But the generated signal has now a duty cycle of 53:47 and no longer 50:50
• Even if I enter a duty cycle of 0.5 again via keypad, the generated duty cycle still remains at  53:47
  

Thanks,
gf1

amy

Sorry to reply you that the software and firmware modifications have not yet been completed.
The engineer will finish next week.

OASJ2YSeeEhBQo1

Thx for keeping us informed. I will test the last firmware while I wait for news about the other issues.

gf1

Dear Amy,

that's not a problem, but a remark:

I find the "Hello" boot logo useless, and I see no need that the user can turn it on or off.
If I were you, I would generally display the Hantek company logo and the Sys Info for a couple of seconds during boot (and remove the "Boot Logo" menu entry on page 5/5)

gf1

gf1

But about CH2 noise, our engineer has not come up with a good idea yet.

There seem to be multiple sources of noise.

I'm pretty confident that one of them is related to the AGW.

AWG turned on (nothing connected to the device):


AWG turned off:


EDIT:

When the AWG is turned on, the device also radiates some EMI noise, which I can pick up with a small wire loop "antenna" in the proximity (a few centimeters) of the device. The waveform and spectrum of this noise varies, depending on the selected AWG parameters (frequency, waveform and amplitude). When I set the AWG to square wave, then I can see a clear correlation between the radiated  noise bursts and the generated signal (yellow = picked-up noise radiated by the 2D72, blue = AWG output):



The same, zoomed-in:



Even more zoom (noise only - w/o AWG signal) - CW frequency of the burst circa 250 MHz:



I guess that this noise is not only radiated as EMI, but also coupled into the frontents and/or the signal path between frontent and ADC (where CH2 happens to be affected stronger than CH1).

amy

OASJ2YSeeEhBQo1 replied at 2019-2-25 14:55
Hi Amy,

I have a few more observations, if you allow me. Please, don't get me wrong, I really like  ...

Sir, the  values for MAX and MIN have been modified. Please download the latest firmware to update.
Due to the choice of hardware components, the transmission speed, operation speed and storage depth will be limited. Can not increase sampling number on PC software.
The update software has not been added English language.
About other usage and communication issues, I will feed back to the Engineer to modify.
I will reply you before next Friday.

amy

gf1 replied at 2019-2-25 00:27
@OASJ2YSeeEhBQo1:

To demonstrate how sinc interpolation can screw-up the displayed waveform (when t ...

Sir, sorry, the default interpolation mode is sinusoidal interpolation. No longer add other interpolation modes.
In fact, the choice of hardware components determines the transmission speed, operation speed and storage depth. Can not increase sampling number and add average sampling.
About the AWG burr, we will come up with a solution next week.
But about CH2 noise, our engineer has not come up with a good idea yet.
Please wait for some days.