Mean Method Algorithm

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Mean Method Algorithm

• For the 128 channels of each APV
• Finds third lowest value
• Adds user-definable Noise Threshold (NT)
• Common Mode Noise is the mean of all values below
  (3rd lowest value NT)
• Can divide 128 APV channels into blocks of 64 or
  32
• Algorithm takes 270 clks, so calculation can
  begin after reordering (unlike Median method)

Disabled channels ignored
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Mean Method FPGA Utilisation
One fibre pair
Resource Used Utilisation
Function Generators 1151 5.35
CLB Slices 576 5.36
Dffs or Latches 750 3.28
Complete FE design
Resource Used Utilisation
Function Generators 16060 74.68
CLB Slices 8030 74.68
Dffs or Latches 10576 46.24
Block RAMs 24 42.86
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Mean Method Results 1
4
Mean Method Results 2
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Mean Method Results 3
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Mean Method Results 4
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Mean Method Results 5
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Mean Method Results 6
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Mean Method Results 7
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Mean Method Results 8
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Mean Method Results 9
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Mean Method Results 10
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New Cluster Finding Algorithm

• Cluster finding algorithm show in LabVIEW at last
  meeting has been converted to VHDL (test system
  for 1 APV)
• FPGA utilisation

Resource Used Utilisation
Function Generators 431 2.00
CLB Slices 216 2.01
Dffs or Latches 284 1.24
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Cluster Finding Example
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Cluster Finding Issues

• Iterative process, requiring 131 clks per step
• Can fit in 6 iterations at 100 kHz
• Very bad frames may require more, leading to
  reduction in trigger rate
• or apply a limit to number of steps and readout
  potentially unfinished results
• Variable processing time for each APV
  incompatible with current throttle system
• Would require significant additional firmware
  modifications in order to implement it in the FED
• Will leave as a working prototype for now

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TOTEM Tests

• TOTEM intend to run with an average occupancy
  of 8
• Too high for a fully populated FED, but what if
  half of the channels are disabled?

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TOTEM Results 1
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TOTEM Results 2
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TOTEM Evaluation

• FED can cope with 8 occupancy when half of the
  inputs are disabled, but
• Assumes that TOTEM can sustain a 400 MB/s readout
  rate
• 200 MB/s reduces maximum occupancy to 5.4
• Assumes that cluster width distribution matches
  CMS
• e.g. single strip clusters would significantly
  reduce maximum occupancy