Hi!
Since recently I also own a DS2000 series scope (the 200MHz version) and I have some questions and comments too.
Overall it's a quite nice device, the UI is mostly intuitive and other than for the Owon scopes, you can look at the screen without getting eye cancer from the bad color choices. For what I tested it matches the promised specifications. The startup time is reasonably fast. The fan is sort of loud but its pitch is not annoying; I can easily live with that. The USB/LAN programming API is very powerful anyways (I just played with it a little bit). The overall build quality feels solid. The pushable knobs are a bit annoying at first since you often accidentially rotate them a bit while pushing, but I'm very sure that that will not happen any more once you've used them for a few weeks, it's just about practice. I'm already getting better at it.
I think there is no point in writing down all the things which are cool, most of that has been said already.
Instead here's some more questions and toughts.
Here's the frequency response of the DS2202 scope (sorry, it's in relative units, the actual values on the y axis mean nothing; it's probably kind of inaccurate too). The four or five little "spikes" are measurement errors. You can see that the -3dB point is a bit above 200MHz. The trigger works okay for up to ~650MHz to 700MHz, above that it's getting very difficult to see anything except blur on the screen in non-singleshot mode. Maybe the big waves in the diagram are due to impedance mismatch, I'm not sure. I'll try again with different matching later.
This is not a professional measurement, don't rely on it or anything, it's just a nice image for illustration.
This was measured by pluging a frequency generator into the scope and making it sweep, reading Vpp via TMC after every sweep step.
Even at 1GHz there's still something visible, but only sharp in Single mode and it's kind of wobbly.
Then, some things that confuse me.
In the drawings, the probes that come with the scope have two adjustment screws, for LF / HF or so, one on the plug and one on the probe itself. Mine only have a screw on the plug and the hole on the probe is filled with plastic stuff (but the hole can be seen clearly). Is that normal?
Also about the probes, the hooktip accessoires don't stick to the probes well, they very easily slip off a bit and then you're confused why you don't measure anything. Am I just too stupid to mount them (you just need to push them over the probe front, right?) or is this really a problem?
About the trigger, can I somehow trigger Ch1 and Ch2 seperately? Isn't that a sort of common feature? My old 1970 scope could do that, anyways
It's not a big problem because the memory depth is so huge, but it would still be nice in some situations.
Then, a general technical question about how the trigger and dead time works. I figured that the DSO works by sampling the input and writing this to a ring buffer with size specified by memory depth. If a trigger event happens, the ring buffer is frozen (no new data is written to it) and the contents are what you call a "captured waveform" and will be displayed on the screen. After the buffer readout is complete, sampling continues. Is this correct so far?
How does the trigger work: is it done on the sampled data, or in an analog circuit? For the edge trigger, I guess the former, but I can't imagine that it holds true for the I2C trigger.
From the above, I would conclude that dead times only happen after trigger events. So, if there's a one-time event you set the edge trigger up for, and iff (sic) you set the trigger to Normal mode (not Auto), you'll capture it for sure. Is that correct?
Oh also, the DS2202 seems to display more than one captured waveform per screen update, even with Min persistence time set. "Min" apparently means "all waveforms captured since the last screen refresh"... which is just fine. It implies, however, that pressing STOP while the scope is in T'D or AUTO state will not have the same result as pressing SINGLE, then FORCE (or waiting for a trigger event), since the former might display more than one waveform on the screen.
Then, why did Rigol decide not to have a 50 Ohm input on the scope? I found that many of the scopes on the market don't have it. Is it because it's a bit easy to destroy with high-power input?
Anyways, if I plug a BNC T piece directly into the scope input, and terminate one end with a 50 ohm load, and plug my 50 ohm signal into the other, that will basically be a 50 ohm input with still accurate voltage measurements; correct?
At some places, the scope feels quite sluggish when moving or resizing curves. For example, in FFT mode, it seems to recalculate the FFT each time you move the reference level, making it feel quite sluggish to change that. It would be really great if Rigol fixed this, it wouldn't be very difficult
It's not a big deal anyways, it just feels a bit slow in some situations (not that it would be any faster if they'd just move the curves, but it would *feel* faster).
Thanks for the nice amount of information collected in this thread anyways, very useful!
Greetings,
Sven
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P.S.:
marmad, I sent you a private message.
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