The low sample rate makes it look like all noise anywhere over 50 MHz or so.
But now you've lost me. The maximum (real-time) sample rates on the 1000C are 200 MSa/400 MSa, for 2 and 1 channel respectively. The sample rates on the 1000E are 250 MSa/500 MSa under the same conditions. The oft-quoted 1 GSa/sec sampling rate is limited to single-channel operation, capturing into the smaller ShortMemory only. That's because there's not enough channel bandwidth to transfer acquistions at 1 GSa into the larger ISSI memory. ShortMemory is retained internal to one of the VLSI chips, possibly the Cyclone, though probably the BlackFin, since that's where all the processing is done. I'm sure someone here would know for certain.
So you're saying that a 20% slower (maximum) sampling rate makes a huge difference in performance on the 1000C scopes?
- Mark
You're saying it's 20% slower maximum, but that's actually the minimum. The maximum would be 600 MS/s slower with both scopes in single channel operation, and 300 MS/s with both scopes in dual channel operation. That's 50% and 50% maximum difference. The minimum difference would be 20% with the DS1052E in dual-channel operation and the C model in single channel operation.. I do say this makes a huge difference in performance, I operated them side by side to test my modifications and the noise in the C model made the readings far worse than even my 50 MHz unmodified channel.
...according to Dave, 1/10 of sampling rate is about the best a real-time readout can do.
I'm surprised to hear that Dave made that claim. Especially since it's not true. ...
It is true. I said "real-time" and you're talking about equivalent-time sampling.
Thanks for all of your posts at the RC forum Mark, the amount of information in the Rigol post there is overwhelming and if you hadn't mentioned the serial commands being cracked by mxmxmx I would have never seen them!
Dave has taken a break, he posted a note in the "Announcements" forum saying he's going walkabout for a while. I'm sure the deluge of e-mails and consistent output of quality video blogs has been taxing his time for a while now!
For those reading this without the proper serial cable, when I get off of spring break I'll make it a priority to write a simple program to send VISA commands via USB. I tried to find all of the proper connectors at school one day and just gave up, serial ports are everywhere, but practically antiques now, so it's understandable most people won't have them.
The really interesting thing here for me is that they can go ahead and change the firmware, but the hardware mod will live on until they re-design the analog section, after which it will still be a trivial matter to modify now that we know what they're up to! The new schem from Mr. JimBeam illustrates that I can still just remove a single resistor and effectively cancel the 50 MHz bandwidth limit.