Talk:7T11

Random trigger mode

I am confused about this feature of the 7T11, because it further needs a periodic signal to synchronize and predict the next trigger event. So this job can be done in normal sequential mode too.

In the mean time I was able to repair me 7T11 and made some tests therefore.

1. A 100ps pulse train with 30MHz rep. was feed through a S6 head to ext. 50 Ohm. Sequential trigger performed well. But random mode did not work correct, but sometimes a impulse was stable visible with signal portions appearing at "negative" positions, forming loops into the impulse or bend to the left, so risetime has to read as 0pS.

2. A 100ps pulse train completely random (noisy, "full period jitter") was then used. Sequential trigger showed a random pattern in time and amplitude, as predicted. Surprisingly in random mode there was a impulse visible, but verry noisy and no samples outside +-50nS! This is not declearable, because the internal prediction circuit can not foresee the next event!

Someone an idea about the strange behavior?

--GHz 09:24, 31 March 2010 (UTC)