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Wow! $123 Hanmatek DOS1102 initial comments

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ebastler:
I'm not sure I understand the settings you chose for many of those screenshots. If you modulate with 50 kHz, what does an FFT with 5 or 6 MHz/div tell you? I think you want to choose a much longer record and hence finer spectral resolution to properly show the sideband peaks.

Overall it is not an ambitious test -- due to the 100% modulation depth the sidebands are very clearly seen. Only scopes which are limited to a very short FFT length, and hence poor spectral resolution, should struggle. I have attached another example for the venerable DS1054Z, with settings I would choose. (You can't see the carrier and modulation frequencies in the time domain anymore if you want a record length with decent spectral resolution.)

rhb:
Now try it with a 10 MHz carrier.  The Hanmatek is aliased like mad.  I was quite surprised at the result.  The only way I can see it is possible when the DS1102E fails is the clock and trigger are more stable.

However, my main point was the DOS1102 really is a 100 MHz DSO under $200.  That's half of what my DS1102E cost.

My current focus is getting amy shop lighted and wired, building an 11' x 16' Faraday cage built for my lab and building a 2nd 6 bay 6' rack to hold all the stuff.  I have a 40 year history with DSP and an insane (~$1 million ca 1995) lab suite.   I plan to have some fun dissecting what the various models are doing.

Have Fun!
Reg

ebastler:

--- Quote from: rhb on December 03, 2023, 08:01:56 pm ---Now try it with a 10 MHz carrier. 

--- End quote ---

That still works alright, but it's pushing the capabilities of the DS1054Z. And a lot of knob-twiddling and stabbing in the dark are involved, since it is not transparent at all how many points are actually used in which setting.

I don't mean to brag about the 1054Z; it's not a very braggable piece of kit... ;) Just wanted to point out that the FFT test does not tell that much about the scopes' capabilities.

On a related note: Has intensity grading reached those low-end scopes yet? That would be a deciding factor for me whether I would recommend a model to a beginner. And for digital/embedded projects: Can they decode and trigger on the basic serial protocols -- RS-232, I²C and SPI?

rhb:
Interestingly, my DS1202-ZE can't reproduce your plot.  I'm about to check for software updates.  I can't set the center frequency at 10 MSa/s above 8 kHz.

More after an update.  BTW the Hanmatek required a self-cal to produce an accurate FFT.

ebastler:
I think I'm on the latest firmware. It identifies as 04.05 SP2 in the system info.

You are running the FFT in "memory" mode, right -- not from the trace (screen) buffer only? If I recall correctly, the scope always falls back to "trace" mode upon power-on, which is rather useless.

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