Study of the latency and the stability of the latency
of the L1A  from when it is generated in the TTC Crate
until it is issued by the FW that decodes the Combined
Data MGT link on an HTM card  (test FEX card).

In top to bottom order of the signals on the scope:

  Ch #4   40.08 MHz Clock from the TTC Crate

  Ch #3   L1A from the TTC Crate,  scope trigger
          rate is 100 Hz random

  Ch #1   the Recovered 40.08 MHz Clock on the HTM card
          via its Access Signal #1

  Ch #2   L1A on the HTM card  via its Access Signal #2


The two cables bringing the TTC Crate signals to the scope
are the same length  (32 nsec)  and terminated.

The two cables bringing the HTM Card's Access Signals
to the scope are about a foot and one half long twisted
pair and at best are "informally" back terminated.

In all cases the scope trigger is the leading edge of
the L1A in the TTC Crate.

The zoomed in  (aka delayed sweep)  persistent picture has
the most information about the stability of the latency of
the L1A on its trip from generation in the TTC crate until
the Combined Data MGT Link Decoder FW issues it on the HTM
card.   This is an infinite persistence scope picture and
integrated the 6000 sweeps or so in about one minute.
You can see a couple of the expected accidental "extra"
L1As that happened to occur.

The thing to look at is the horizontal width of the
vertical sections of the waveform of the L1A as it is
issued by the HTM FW.   We want this to be narrow and it is.