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OWON VDS1022I Quick Teardown (versus the Hantek 6022be)

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Gyro:
As this just came up in another post, and I can't find any other pictures on the web (Plenty of the Hantek 6022be) I though it was about time to do a teardown of my Owon VDS1022I. Naturally there will be quite a few comparisons with the similarly targeted Hantek.

A teardown of the Hantek can be found in this thread:
https://www.eevblog.com/forum/testgear/hantek-6022be-20mhz-usb-dso/

I realize that this won't be of much interest to the Rigol DS1054Z crowd, but when a bunch of these came up cheap a couple of years ago on ebay uk I thought it was worth a go. I already have a Picoscope ADC216 16bit for audio use, a Tek475A 250MHz Analogue for high frequency stuff and a decent logic analyzer for long trace digital, so I couldn't justify yet another bench-top, I just needed a 'fill in' for the middle. I also reasoned that the first things to fail on a Chinese bench scope would be SMPS, front panel controls and fan so getting something with non of these would be a bonus!

Anyway, on with the teardown. The VDS1022I is a dual channel 100Msps (per channel) 25MHz. This seems a bit more realistic sampling speed than the 20MHz 48Msps Hantek. The 'I' suffix indicates USB Isolation - you can float the scope ( the front panel BNCs are 'touchproof' style too). There's also a non-isolated version. Other features include more versatile triggering (Edge, variable Slope and Pulse, TV and with variable hold-off - the Hantek only has edge) Alternate triggering is also included (the ability to trigger on two unrelated signals at the same time) and Variable persistence too. There is also a dedicated Trigger connector which can be used as Trigger In, Trigger Out, and Pass/Fail out, using internally set rules.

The one real downside, spec-wise of the Owon is it's 5k samples per channel memory depth, versus a claimed 1M for the Hantek, not an issue for me, but might be for others. The Owon also uses (only needs) USB 1.1 vs the Hantek's USB2. Both of these are side effects of the significant internal architectural difference.

It is in the architecture that I think the Owon wins. Where the Hantek just uses an EzUSB micro for interfacing the ADC to USB, the Owon includes a Silicon Labs SiM3U156 32 bit ARM Cortex-M3 CPU together with a Xilinx Spartan-3 FPGA. There's clearly a lot more happening on-board than in the Hantek. Presumably the triggering is all handled on board (especially as there is a Trigger-out), together with data compression needed to pipe the data via USB1.1 at decent refresh rate. It also results in very low PC overhead with minimal impact on running other applications even on a low-end PC. The 5k memory depth is clearly a less desirable side effect. I'm not sure where the Hantek's triggering is handled, as it's edge only it could either be on-board or in the PC software.

The USB 1.1 interface also allows the USB isolation, which is performed by an ADUM3160. USB power is isolated by a TI DCP020505 2W isolated DC-DC converter. This has the lower isolation voltage of the two devices at 1kV. PCB clearances are very good. There are also un-populated footprints for a non isolated RS-232 interface. Some of the higher end models have LAN too, but there are no footprints on the board for this.

On the Analogue side, the A/D is an AD9288 dual in its 100Msps variant. ADC drive is via a pair of LMH6551 370MHz Differential op-amps and at least part of the gain switching is accomplished by a pair of AD603 90MHz pin selectable variable gain amplifiers, according to the datasheet these are capable of a 42dB gain range at 30MHz.  The only hand mods visible are beefier supply caps on the LMH6551s. The front end, which presumably includes the higher voltage attenuators, AC/DC selection and input amps is heavily screened in cans top and bottom side which I have no intention of trying to remove (another difference from the Hantek). Video triggering is implemented using a dedicated Rohm BA7046 sync separator rather than all in s/w. There are several other packages that I haven't managed to identify in the analogue area, and there is a scattering of supply regulators around the board.

All in all then a fairly large component cost compared to the opposition. It's clearly a more comprehensive design which presumably shares a lot of its acquisition circuitry with the PDS5022 desktop model, which shares the same  bandwidth, sample rate and memory depth. The supplied probes were 60MHz bandwidth X1/X10 which seem pretty good.

In terms of PC software, this is very subjective from user to user. I like the Owon for its lack of pseudo knobs (!) general screen layout and number of useful shortcuts (once you find them) and of course the added functionality. FFT and Maths traces can be selected to come up on a separate grid to the main traces. Persistence can be set from zero to infinity. Note that interpolation is fixed as sinX/X and trace colors, which match the probes and input connectors cannot be changed. The original s/w had a few bugs around single trace but the current s/w seems fine. I did flag one bug in the memory system at the end of last year which their engineers fixed (sending me a couple of test versions to confirm) before releasing, which I think could be described as 'responsive'.

Full disclosure: I have no connection with either company, other than having bought the Owon.

Pictures are attached and questions / comments are welcome. Thank you if you've made it this far!  :=\

rf-loop:
Thank you about this.

Is it possible you make one very tiny test,

If you have 50ohm BNC terminator use these, if not then input connectors open. (not probe, just open input BNC)
Both channels on, coupling DC.
Set vertical sensitivity to lowest voltage where is not BW rejection.
Set channels vertical positions so that other is 2div over center and other 2 div under center.

Set horizontal speed to 1ms/div,  if you can set persistence 1s or more

Scope display image.

Set horizontal to 1us/div, same persistence

Scope display image.

So we can see scope front end internal noise level.
(keep fingers and all far away from inputs for avoid external signal noise, also depending computer look that its (possible) EMI noise do not affect scope open inputs)

If you have 50 ohm terminators then repeat and take pictures with terminators connected
(in some cases if there internal noise levels this test may change displayed noise level (and how it change may also tell something, specially if it rise)

----

There is higher models also, and lets hope some day someone show VDS 2000 or 3000 series some teardown and tests. (10M memory, 500M and 1G samplerate, up to 4 channels etc)

Gyro:
Hi rf-loop,

Yes, happy to help. I do have 50 ohm terminators so these are fitted.

I've attached the two saved images for 1ms/div (sampling at 250kS/s) and 1us/div (Sampling at 100MS/s) as you asked. The input stages are pretty quiet!

Settings were:

- 5mV/div (most sensitive)
- Persistence set to infinite (ran for about 2 mins each time)
- Sampling, Peak detect

I also turned on the measurements for Vp-p and Vrms.

I don't think pc induced noise is an issue due to the USB isolation.

Yes I'd like to see the higher models too! It's a shame the USB isolation only extends up to the 250MSps model.

I hope this gives you what you need. Please ask if you want other measurements.

Gyro:
Sorry, I just re-read your post and realized that you also asked for screenshots with terminators removed (empty sockets, no scope probes). Please find these attached too. All other settings the same, still nice and quiet.  :)

rf-loop:
Thank you. 
 
Result is not bad at all (some amount better what I expect). Of course it need note that analog BW is 25MHz so also analog front end natural noise is less what makes it quite easy.  (Higher analog BW makes it much more complicated and  there also circuit design and component selection is critical and in high role).  Also it is good that terminated inputs result is same or less that unterminated.

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