1. Beam Charge Measurement &Injection efficiency
The signals from the 4 striplines are connected to the 4 inputs of the libera electron via
1% bandwidth RF filters (centred at 352.2MHz, the acceleration frequency).
These filters allow ‘smearing’ of the RF signal over time so as to correctly determine the amplitude with undersampling at 108MHz single electron bunches.
The smearing of the signal reduces problems due to aliasing.
Benoit Joly, Jean Marc Koch, Graham Naylor, Eric Plouviez

2. Beam Charge Measurement &Injection efficiency
Signal processing
Signal processing: the whole description is done within “System Generator“

3. Beam Charge Measurement &Injection efficiency
Signal processing
The signal from the stripline in the storage ring is mixed with the signals I & Q from the N.C.O..
It is then accumulated for 3 turns and I & Q are sent to a “Cordic” algorithm to compute the amplitude.
This amplitude corresponding to the charge of the beam is accumulated over a time as large as possible
starting a few ms after an injection when the beam become stable (see next slides).

4. Beam Charge Measurement &Injection efficiency
Signal processing
DSP Engine: the signal from a channel is mixed with a signal from an N.C.O. (I&Q)
the result is integrated over a time defined by the user and stored in a register.

5. Beam Charge Measurement &Injection efficiency
Signal processing
Sequencer: data transfer & timing are managed by an embedded processor

6. Beam Charge Measurement &Injection efficiency
Measurement in the Storage Ring
ΔI SR
Integration time:
69ms at 10Hz
or 552ms at 1Hz
simulation
The demodulation of the signal coming from the stripline in SR is performed synchronously with the injection inside an appropriate time slot. The difference ΔI is computed inside the server.