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  • how do we time-in the detector
    • proposal: we run a low-rate beam, see a "prompt" signal (high energy, lower TOF electrons), move the timing to be close to that prompt signal
    • other possibility: use a diode with accelerator at the experiment and use the simulator box to "calibrate" extra delays in the system.  one cable goes to photodiode, other goes to the simulator (either start signal, or output signal)
  • do electron hits cross pulse id boundaries
    • yes, this can happen
    • analysis software can't tell if an electron really belongs to this pulse (not complicated algorithm to assign electrons to other pulse-ids)
    • try to configure voltages so this possibility is minimized
  • how do we know what the pulse id boundaries are (e.g. is there one udp packet per pulse)
    • happens naturally 
  • clarify interface between daq and surface-concepts ack'd-udp code
    • this scTDC code is provided by surface concepts
    • need the "simulator box" and the "TDC box" (maybe received at SLAC sometime in July?)
  • ami plots needed

TDC box needs a second ethernet interface for DHCP and configuring the delay (start pulse to the detector).  ethernet interface to AXI4 registers.  also registers for configuring the pause threshold to the DAQ.  Python software exists for this.

SC software is a special version with support for the timestamp.  Yves will provide.  Closed source.  Will receive binaries and headers.  We're currently using GCC11.   GUI to play around with it.  Dependencies? QT5, sqlite.

Dedicated network interface for the bulk data (e.g. static IP).

Additional software for a GUI for the simulator (over USB, from linux).  Python software exists for this.

Potential issue: we may need both timestamp and pulse-id.  Yves only sends surface concepts FPGA all bits of the pulse-id and they send full pulse-id once per ms and include lower bits with every electron.  But LCLS receives a "reconstructed" full pulse-id with every electron.  The smaller number of bits (17 bits) used for pulse-id internally by SC could perhaps break if we go "dead" for a long time.  We would get incorrect pulse-id's for a while, but would fix itself after about a millisecond.  We will need to get the timestamp in the DAQ. in another way, probably with a KCU1500 receiving the timing system.  Need to match the SC data with the KCU timestamp using the pulse-id.