Per Jeff Kissel's request Betsy and I (Xavi) looked at several SYS subsystem channels to perform timing checks on the IO chassis.

These checks were in slides by Shivaraj and the slides should be added to this alog and references to the slides added. 

The channels we looked at (shown in the attached green medm screen shot) are:

H1:SYS-TIMING_C_MA_A_PORT_2_SLAVE_CFC_TIMEDIFF_1 (Master1)
H1:SYS-TIMING_C_MA_A_PORT_2_SLAVE_CFC_TIMEDIFF_2 (Master2)
H1:SYS-TIMING_Y_FO_A_PORT_9_SLAVE_CFC_TIMEDIFF_1 (Y-arm)
H1:SYS-TIMING_X_FO_A_PORT_9_SLAVE_CFC_TIMEDIFF_1 (X-arm)

Two of them are in the Master, one in the y-arm, and the third in the x-arm. It does not appear that any other channels are active at this time.

We took a week of data (in the past of today) for each of these channels and attach figures that show the time series (to check for trends) as well as histograms.  

All in all these plots look reassuring. Notable features:

1) The timing differences between adjacent points are integer multiples of 7.45ns. Mostly the integer is 1 (see Master1TimeseriesDiff.jpg, only posted it for Master 1, others look the same).

2) There do not appear to be significant drifts (e.g. < 50ns for 1 week in Master 1)

3) The spread is about 50ns (shown in figures labeled Histograms)

4) there is ~1 day periodicity in the time series for Master 2

5)  There seem to be common glitches (small ones at the level of ~0.25 us, e.g. see all time series toward the end)

Betsy and Xavi