But if you simply use it with a notebook only on its battery, unplugged from the wall, it's also effectively isolated, no? (though not wireless
)
Yes that would isolate the scope and PC from earth ground. But c'mon now, where's the unneeded complexity in that !
![Wink ;)](https://www.eevblog.com/forum/Smileys/default/wink.gif)
I got my VDS1022 delivered today. Thumbs up to Saelig, I put the order in on Fri and it came (free shipping) 5 days later.
![ThumbsUp :-+](https://www.eevblog.com/forum/Smileys/default/icon_smile_thumbsup.gif)
I wanted to put up a somewhat obvious chart of sampling rate vs horizontal time setting in case some people didn't realize that they're tied in a DSO. In particular with only 5k samples/chan of storage, there's only so long it can collect data before that memory is full. And so to "see" a longer display means a slower Sa/s rate. And that means less than the full bandwidth is available as those rates.
5ns/div 100MS/s
...
2us/div 100 MS/s
5us/div 50MS/s
10us/div 25MS/s
20us/div 12.5MS/s
50us/div 5MS/s
100us/div 2.5MS/s
200us/div 1.25MS/s
500us/div 0.5MS/s
1ms/div 250kS/s
2ms/div 125kS/s
5ms/div 50kS/s
10ms/div 25kS/s
20ms/div 12.5kS/s
50ms/div 5kS/s
................. trigger to auto mode, no single shot available
100ms/div 2.5kS/s
200ms/div 1.25kS/s
500ms/div 0.5kS/s
1s/div 250S/s
2s/div 125S/s
5s/div 50S/s
10s/div 25S/s
20s/div 12.5S/s
![Huh? ???](https://www.eevblog.com/forum/Smileys/default/huh.gif)
?
50s/div 5S/s
100s/div 2.5S/s
![Huh? ???](https://www.eevblog.com/forum/Smileys/default/huh.gif)
?
I wonder how Owon splits those half samples ?
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/grin.gif)
I had a brief chance to sniff the USB link and what I've seen so far is (I think) that the program on the PC sends a set of 3 commands to the scope HW. Each of these gets a 5 byte response except for the last one. If the HW is not "ready" (buffer not full ?) then a "busy" response is sent. IF the HW is ready then there's a 5216 byte message. The 1'st hundred or so bytes seem to be some header of some sort, the remainder appears to be the sampled data.
In this case I had only a single channel on, digitizing the 1kHz test signal. The scope was autoset to some ?? V/div vertically, near zero offset and 50kSa/s. One period of that data looks like ;
3C 3D 3C 3C 3C 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3E 3D
00 01 01 00 00 00 00 00 00 00 00 00 FF FF FF 00 00 FF 00 00 FF 00 00 FF 00
I interpret those 50 bytes as 25 samples of 0 or -1, 25 samples of 61 (+/- 1). The numbers make sense if the scope sends a 2's complement number, -127 to +128 for it's 8 bit sample. The 50 samples make sense for a 1 msec period sampled at 50kSa/s (-> 50 Sa/ms). The 50% DC of the test waveform is obvious.
So sometime this weekend I'll vary the sample rate and turn on the other channel just to see what I can see via the sniffed USB. I'll post my results and thoughts here, if anyone is interested and the OP doesn't mind the "hijack" of his thread. And if I can how to get the multiport to output, I'll measure the waveforms/sec update rate vs horz time setting, which should be good for a laugh. From the USB timestamps for the above, it was ~ 14 ms between 2 full data packets or ~71 wvfrms/s.