Scope Pictures Comparing 470 nFd and 12 nFd Coupling Capacitors
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                                             Original Date:  24-JUNE-2002
                                              Current Date:   2-JULY-2002


The first 2 scope pictures (scope_1.pdf and scope_2.pdf) are looking
directly into the cable from the BLS card.  There is no active
electronics at the receiving scope end of the cable, just the
terminator circuit.   These are with 470 nFd capacitors at the sending
and terminating ends of the cable.  These show the noise bump from
the Precision Cal readout.

   Violet  shows where the L1_Accept took place (the "T")
   Yellow  is the the non-inverted side of the differential cable
   Blue    is the inverted side of the differential cable
   Red     is the sum of the above two trigger pick off signals with a
             scaler of about 30 mV per GeV Et.


All scope pictures in the range scope_3.pdf to scope_10.pdf show the
trigger pick off signal right as it is applied to the ADC input.  That
is, these pictures include the analog signal processing of the trigger
pick off signal that takes place in the L1 Cal Trig.


Pictures  scope_3.pdf and scope_4.pdf  show real calorimeter energy
deposits from the Tevatron.  These are both with 470 nFd coupling
capacitors.  The traces in these pictures are the following:

   Blue    not used
   Yellow  location of the beam crossings in D-Zero
   Violet  falling edge is when the ADC samples (don't worry about
             the wave form)
   Green   ADC input about 30 mV per GeV Et.


Pictures scope_5.pdf and scope_6.pdf show the noise from the Precision
Calorimeter readout.  These are both with 470 nFd coupling capacitors.
The traces in these pictures are the following:

   Blue    shows where the L1_Accept took place (the "T")
   Yellow  location of the beam crossings in D-Zero
   Violet  falling edge is when the ADC samples
   Green   ADC input about 30 mV per GeV Et.


Pictures 7, 8, 9, 10 are with 12 nFd coupling capacitors at each end.

Pictures scope_7.pdf and scope_8.pdf show a real calorimeter energy
deposit.  Compare this to pictures 3 and 4.  Note the undershoot after
the bump from the energy deposit.  Scope_8.pdf is with a longer
time scale to show more of the undershoot.

   Yellow  location of the beam crossings in D-Zero
   Blue    falling edge is when the ADC samples
   Green   ADC input about 30 mV per GeV Et.


Pictures  scope_9.pdf and scope_10.pdf  show the noise from the
Precision Calorimeter readout.  These should be compared to pictures 5
and 6.  You can see where the L1_Acpt was issued and then look at the
appropriate location on the ADC input trace to see the effect of the
Precision Cal readout.  I don't see anything much but this whole thing
needs to be studied.  Dean and I tried to make pictures 9 and 10 a 
"typical" and a "worst case" scope shots of this effect.

   Blue    shows where the L1_Accept took place (the "T")
   Yellow  location of the beam crossings in D-Zero
   Green   ADC input about 30 mV per GeV Et.