I've been "getting to grips" with the USB interface and Regen - as the Regen will be a competitors product I'll have to be careful so as not to appear critical - I'll have to claim the 5th amendment if some question might force me into being too harsh about its design.
As a USB source I'm using a small Sony Pocket PC (VGN-UX380) and the USB connected via its docking station - running WinXP SP3.
Early days, so I'm just performing simple tests - but I can already see on a fast Analogue scope that the USB Packet it jitter visually effected by what the PC is processing - with eye pattern Jitter increasing from 320pS to 400ps simply by running a Youtube video.
The Screen is a mess and I'm just getting the feel of whats going on - while its easy to see the jitter modulation on the Analogue scope screen, I'm not sure how to post it here.... the screen is a mess....
You can see via the jitter modulation on the scope when the PC is performing other tasks - with big "apparently" random jumps in jitter, I suspect that these jumps are caused by other "hidden" operations being performed by the Windows OS.
I'm not in anyway endorsing the idea behind "optimized" media players (as the are trying to resolve an issue that should not effect the analogue domain in the first instance - IMO they are an indirect poor and dubious bodge fix) - but seeing the OS / CPU "Process" modulation comes as no surprise and opens a whole bag of hurt...
This observations are with the Upstream USB input to the Regen, it will be interesting to see if the USB hub is able to reformat the data packets and thus attenuate the OS / CPU process related jitter modulation.
Hi john,
How is the scope triggering?