20201009
========

We have looked at the scope on what happens at the time of the trigger.
On the SRU is a NIM pulse output on lemo PX10, correlated at a fixed time
relative the L1 trigger sent by the SRU to the CPLD.
This is used to trigger the scope. We then looked at the voltages
below.

The NIM pulse width is set to be 200*DTC clock = 200*25ns = 5 microsec.
The delay from sending L1 to the CPLD and the NIM pulse is 200*DTC clock = 200*25ns = 5 microsec.
L1 arrives at the SALTRO after have been sent on DTC control line and decoded by the CPLD,
unknown time (order microsecond). I have to check when the sampling starts relative L1.

We only tried the delay of 200, should have tried other delay to check correlation with
what is seen below.

after = between resistor and SALTRO
before = between opamp and resistor

refN:
after 100 ohm resistor: 20201010_145038.jpg
before 100 ohm resistor: 20201010_155915.jpg

On the plot after the resistor is a slight increase (bump) in refN seen,
which is not seen on the voltage before the resistor.

refP:
after 100 ohm resistor: 20201010_153606.jpg
before 100 ohm resistor: 20201010_154834.jpg

On the plot after the resistor is a slight decrease (valley) in refP seen,
which is not seen on the voltage before the resistor.


2.5V: 20201010_151229.jpg measured on capacitor
1.5V: 20201010_152336.jpg measured on capacitor
Some sign of a bump?

Remember the currents and voltage changes as measured on
the protomcm:
100 ohm -> spänningsfall på 20 mV = 0.2mA på refP
100 ohm -> spänningsfall på 0mV = 0.0 mA på cmin,cmout
100 ohm -> spänningsfall på -20 mV = -0.2 mA på refN

If the currents changes slightly, e.g. +(-)0.2 mA -> +(-)0.22 mA
would change the span refP - refN with 4 mV, i.e. 3-4 ADC counts.
This could explain the bump seen in the time sweeps.