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| REVIEW - Rigol DS2072 - First Impressions of the DS2000 series from Rigol |
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| EV:
Traces when using type as dots or vectors look quite different. Why? Time base 1 ns, Ch1 and Ch2 both on, HW 1, BW 300 MHz. |
| marmad:
--- Quote from: Teneyes on December 26, 2013, 06:53:05 pm ---from Tek 3032B Manual Separate Digitizers. Ensure accurate timing measurements with separate digitizers for each channel. Each digitizer can sample at up to the maximum sample rate (2.5GSa/s); acquisition on all channels is always concurrent to provide full single-shot bandwidth on each channel. So IMO, Tek is combining samples from 2 channels, if so Let's deleted all this dicussion, Please --- End quote --- This didn't really solve the mystery - since EV had posted an image with both channels on and samples displayed every 200ps. There is no way the scope could combine samples to do that; it's impossible (it could do it for 1 channel - but not for both). Anyway, we don't necessarily need to discuss it further here - but if I was EV, I'd probably do some tests to figure out exactly what my real max. sample rate was. |
| Hydrawerk:
--- Quote from: EV on December 27, 2013, 12:52:48 pm ---Traces when using type as dots or vectors look quite different. Why? Time base 1 ns, Ch1 and Ch2 both on, HW 1, BW 300 MHz. --- End quote --- It looks like a sinx/x interpolation, but it is weird. |
| EV:
I noticed it already here: https://www.eevblog.com/forum/testgear/first-impressions-and-review-of-the-rigol-ds2072-ds2000-series-dso/1785/ There time base is 2 ns. Wim13 explained then: "There is always something like cross talk between channels. To the book Rigol claims cross talk between ch1 and 2 better then 40 dB" I however now noticed that there is not this trasition in the Dots picture. The trace there looks same as if Ch2 is not on. --- Quote from: Hydrawerk on December 27, 2013, 04:14:42 pm --- --- Quote from: EV on December 27, 2013, 12:52:48 pm ---Traces when using type as dots or vectors look quite different. Why? Time base 1 ns, Ch1 and Ch2 both on, HW 1, BW 300 MHz. --- End quote --- It looks like a sinx/x interpolation, but it is weird. --- End quote --- |
| JDubU:
--- Quote from: EV on December 27, 2013, 04:58:25 pm ---I noticed it already here: https://www.eevblog.com/forum/testgear/first-impressions-and-review-of-the-rigol-ds2072-ds2000-series-dso/1785/ There time base is 2 ns. Wim13 explained then: "There is always something like cross talk between channels. To the book Rigol claims cross talk between ch1 and 2 better then 40 dB" I however now noticed that there is not this trasition in the Dots picture. The trace there looks same as if Ch2 is not on. --- Quote from: Hydrawerk on December 27, 2013, 04:14:42 pm --- --- Quote from: EV on December 27, 2013, 12:52:48 pm ---Traces when using type as dots or vectors look quite different. Why? Time base 1 ns, Ch1 and Ch2 both on, HW 1, BW 300 MHz. --- End quote --- It looks like a sinx/x interpolation, but it is weird. --- End quote --- --- End quote --- There seems to be a problem with the sample-to-display interpolation algorithm (sin(x)/x) when the horizontal time base is faster than about 20ns/div. The dots display looks reasonable but the vector display introduces interpolation artifacts when the distance between sample points spans a larger number of pixels on the display. This can be seen more easily in single sweep mode. The dots reliably form a smooth curve but the vectors tend to "zig zag" between adjacent sample points with multiple 2 or 3 pixel steps in opposite directions as the trace moves from one sample point to the next. On a free running sweep, these display artifacts appear as a noisier trace. This also partially explains why enabling CH2 increases the apparent noise on CH1. The sampling rate is cut in half causing the distance between sample points to double (producing more display artifacts) for a given time base setting. |
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