Hantek2d42 bugs report

gf1

@OASJ2YSeeEhBQo1:

To demonstrate how sinc interpolation can screw-up the displayed waveform (when the bandwidth of the captured signal did violate the sampling theorem) I have captured a 7.8125 MHz square wave signal from the 2D72 AWG with my 6074BD, a) with sinc interpolation and b) with linear interpolation. In order to force a reduced sampling rate of 250MSPS (in order that the result is better comparable to the 2D72), I have turned on all 4 channels.

6074BD - sinc interpolation:



6074BD - linear interpolation:



The "linear" result is likely closer to the  true waveform (square wave). And the sinc result looks almost like the waveform displayed on my 2D72 (in single channel mode) at the same sampling rate and timebase. Unfortunately, sinc interpolation is the default on the 2D72 and can't be turned off - in cases where it is undesired.

EDIT: Added the 2D72 screenshot for comparison (also 250MSPS, 50ns/div) - looks almost the same as 6074BD with sinc.




@Amy: Feature Requests:

• Do you think it is possible to implement linear interpolation in next firmware/FPGA version, as a user-selectable alternative to sinc?
• Dou you think it would be possible to implement an "average" acquisition mode, like in other models? This would enable smoothing of noisys signals. Since the display is only 320 pixels wide, and since the capture buffer is 3k samples (6k in single channel mode), I guess that averaging up to 8x (or 16x in single-channel model) might be feasible.
• Alternatively to (2) - or additionally - a phosphor emulation would be nice as well. I miss this feature in the PC software as well (also in the PC software for the 6004BD models).
  

OASJ2YSeeEhBQo1

Hi Amy,

I have a few more observations, if you allow me. Please, don't get me wrong, I really like this device and I think it has a great potential, it just need some polishing.

1- With the last FW in Scope mode, Measure window was changed from amplitude to max/min, but the values for MAX and MIN are computed with reference to the center of the screen, not to the channel cursor. So if I move the channel trace, the values changes. Fixed (in FW 2019030201)
Regarding the Measure windows I have two suggestion:
a- Add the option to choose a different parameter to measure, like Vpeak-peak, Vrms, Max/Min, amplitude, frequency, duty cycle and period. It don't need to have all types of measurement, I understand that you want to keep it simple, but having just one type is very limiting.
b- Display the values only for the channel that is active. The screen is small and there is no reason to keep showing a banner with only "????" on top of the signal I'm trying to see.

2- Connecting the USB cable to the scope adds a small DC offset to the waveform;
3- This one is very annoying: Every time the device is connected to the PC software, its settings are reset to default. The software also do not keep the last configuration used nor reads the actual settings on the device.
4- The PC software uses only 1200 data points to trace the waveform when we could have up to 6k;
5- The PC software is very slow and barely usable;
6- The AutoUpdate feature is very nice to have, but the related window need to be translated to English; Fixed (in Software version 1.1.10)

7- When using the device connected to the PC software, the configurations are not synced in both ways. If I set a parameter in the software the corresponding function in the handheld is updated but it does not work the other way around causing some problems. For exemple:

8- The PC software in DMM mode keeps logging values even while the hold or "stop collecting data" button is pressed.
9- Just a minor detail: in AWG mode setting a negative offset and then using the arrow keys "^" to increase the value will show "-0.00V" when it gets to 0V.
10- One last suggestion: add the ability for the button "Menu" to toggle the menu on and off. So when I press the button the menu is shown on the display, pressing it again will close it, this way I don't have to wait a delay time for the menu to disapear. Same for Channel, Time and Trig buttons.

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.

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.

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).

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

OASJ2YSeeEhBQo1

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

amy

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

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

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.