White Rabbit Fine-Delay time-stamp testing

I'm testing the White Rabbit Fine-Delay FMC. It has an ACAM TDC-GXP time-to-digital converter that time-stamps the leading edge of an input trigger signal with ~30 ps resolution.

Recent work by Alessandro Rubini introduced a raw_tdc=1 driver mode which on my computer is able to collect time-stamps at a maximum rate of ca 150 kHz. Each time-stamp is 24-bytes, so this corresponds to a data-stream of roughly 4 Mb/s.

The video shows two graphs that update in real-time on the machine that collects time-stamps. The first is simply a (reciprocal) frequency counter where we count how many time-stamps arrive within a certain gate/window.

The second part of the video shows a modulo(tau) histogram where we bin time-stamps modulo tau into a histogram. The histogram was calculated for tau=100 us and an input frequency of 1 kHz was used. This results in the central peak in the histogram. I then slightly increased the frequency to 1.000010 kHz which makes the peak wander to the right. The peak on the right was produced by again tuning the input frequency to exactly 1 kHz. Similarly a lower input frequency of 999.970 Hz makes the peak wander to the left, and the peak around 20us was produced after tuning back to 1 kHz.

This hardware/software combination will be useful for collecting statistics and correlations in any experiments where a pulse type detector is used to measure something - provided the pulse-rate is below 150 kHz or so.

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