6404D time differencies between channels in ETS mode

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6404D time differencies between channels in ETS mode

Post by korzo » Mon Sep 18, 2017 12:42 pm

I use a 6404D scope with the PicoScope SDK for digitizing 4 repetitive signals with maximum ETS rate (50 GS/s). Have a few questions about time differencies present in the captured data.

1. Let's take first the real-time sampling mode. Maximum sampling rate is 1.25 GS/s for the four channels, but it is obvious that the sampling clock runs with 5 GHz and 4 successive clock pulses are always used for sampling different input channels. What is the exact sampling sequence of the channels? My guess would be A-C-B-D, but I need a confirmation about it. In this mode there is always a time difference of 200, 400 or 600 ps between the channel data series, depending on how close the channels are to each other in the sampling sequence. This cannot be eliminated or decreased (we simply do not have measurement points on one channel closer than 800 ps). So if the guessed sequence is correct, then e.g. all points in the captured data array for channel C belong to time values 200 ps later than the points in data array for channel A.
2. In ETS mode the time interval between two real-time sampling events (in this case 800ps) is subdivided and the subintervals are filled with converted data from successive captures of the repetitive signal. With maximum ETS rate the time slots are just 20 ps wide. My question is if the time differences between channels are still the same (as in real-time mode) in the captured data arrays or have they been corrected by the much finer time resolution. I have checked two approximately simultaneous signals with the PicoScope 6 program in ETS mode and I could not see time difference between them in the magnitude of 200 ps. So it is obviously corrected, but I do not know where: only in the PicoScope 6 program or is it already done in the driver?


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Re: 6404D time differencies between channels in ETS mode

Post by Martyn » Tue Sep 26, 2017 10:40 am

The question has been answered through your Support Desk ticket.

To answer the thread, the scope samples simultaneously on all four channels.
Technical Support Manager

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