Well, since I've finished my first video, I've had much more time to run various tests on the Siglent. And one thing I have to say is that I get more and more impressed with the sampling/processing engine of the Siglent. Not only is it very fast, it actually TRULY does 256 levels of intensity grading (when wfrm/s are high enough, as noted below) - unlike the Rigol which, as I've pointed out before in the past, only seems to do 64 level grading (even though they advertise it as 256). The intensity grading of the Siglent is often very nice - so I'm making a new short video to try to demonstrate how good it can look when running. As far as I know, it's the only DSO doing
real 256 level grading that costs less than several thousand bucks.
The only problems with the SDS2000's engine at the moment are it's drop-off in speeds at the faster timebases (1ns, 2ns, etc), and perhaps the need for a slightly more elegant (or switchable) method of dealing with large sample lengths with low wfrm/s - which is what I wanted to clarify here before posting the second video; i.e. the way that the intensity grading differs from the intensity grading that the Rigol is doing:
The Rigol seems to do intensity grading BEFORE downsampling (at least at slower timebases with large memory depths), the Siglent does it after. That means, on the Rigol, the sample memory length can affect the intensity grading - on the Siglent it does not. The Siglent grading is based purely on wfrm/s, with a ratio of something similar to the following table (this is not precise since I haven't tested the exact boundaries - just an indication):
>= 1024 wfrms/s = 256 levels / 128 color temp.
1023 - 512 wfrm/s = 192 levels / 64 color temp.
512 - 256 wfrm/s = 32 levels / 32 color temp.
255 - 128 wfrm/s = 16 levels / 16 color temp.
127 - 64 wfrm/s = 8 levels / 8 color temp.
<= 63 wfrm/s = 4 levels / 4 color temp.
Each method has it's advantages at slower timebases (Rigol = more grading information with larger sample sizes but less wfrm/s / Siglent = more wfrm/s) so I'm not proposing one way is necessarily better than the other - it's just interesting to note the difference. Of course, the best would be to have the ability to use EITHER method as desired.
First, two examples of the same waveform at 50ns - with the difference in grading levels noted - show the Siglent with more than 3x more levels:
Second:
And here, demonstrating the difference made by grading before downsampling at 2ms - note that with memory length set to 140k on the Rigol, the waveform image is similar to the 28M length on the Siglent (but not quite as detailed), but when the Rigol is set to 14M, the grading changes to reflect the downsampled data from the larger memory depth waveform:
Siglent intensity-grading demonstration video to follow in the next day or so....