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Our ADC cards

GHz ADCs: SP-Devices ADQ412AC

We have ADQ412AC-4G-MTCA digitizer cards for the experiment crates (Exp1, Exp2 and FL2Exp1):
ADQ412_datasheet.pdf ( new version, sampling rates table)
The cards are connected via Patch panels to the Experimental endstations and can be operated with a jddd panel:

  • NOTE: between ADC and Patch panel we have installed an EMP protector and an additional 1dB attenuator
  • for the influence of the Patch cable and the EMP protector see also this logbook entry

Impedance AC50 OHM
Input voltage range800 mV pp!!!!!!!!!!!!!!!!
Digitizer resolution12 bit


Sampling rate2 *GSPS
Analog bandwidth2GHz


Sampling rate4 *GSPS
Analog bandwidth1.3GHz

 * note that the sample rate is NOT locked to the FLASH repetition rate ! Thus there is a not integer number of samples between FLASH pulses. The sample rate also differs slightly from ADC card  to ADC card. The rough spacing is 1993.846 samples between 2 pulses at 1 MHz for details ask the local contact.


The HDF5 names for the ADC traces are depending on the beamline :

PG Beamline:
/FL1/Experiment/PG/ADQ412 GHz ADC/CH00/TD
/FL1/Experiment/PG/ADQ412 GHz ADC/CH01/TD
/FL1/Experiment/PG/ADQ412 GHz ADC/CH02/TD
/FL1/Experiment/PG/ADQ412 GHz ADC/CH03/TD

BL Beamlines:
/FL1/Experiment/BL1/ADQ412 GHz ADC/CH00/TD
/FL1/Experiment/BL1/ADQ412 GHz ADC/CH01/TD
/FL1/Experiment/BL1/ADQ412 GHz ADC/CH02/TD
/FL1/Experiment/BL1/ADQ412 GHz ADC/CH03/TD

/FL1/Experiment/BL2/ADQ412 GHz ADC/CH00/TD
/FL1/Experiment/BL2/ADQ412 GHz ADC/CH01/TD

/FL1/Experiment/BL3/ADQ412 GHz ADC/CH02/TD
/FL1/Experiment/BL3/ADQ412 GHz ADC/CH03/TD

and at FLASH2

/FL2/Experiment/MTCA-EXP1/ADQ412 GHz ADC/CH00/TD
/FL2/Experiment/MTCA-EXP1/ADQ412 GHz ADC/CH01/TD
/FL2/Experiment/MTCA-EXP1/ADQ412 GHz ADC/CH02/TD
/FL2/Experiment/MTCA-EXP1/ADQ412 GHz ADC/CH03/TD

here the CH00.TD is the full ADC trace as it is sampled ( typically several 100.000 samples per pulse train) while the CH00.DAQ.TD trace only has the number of samples which are sent to the DAQ OR if grouping is activated the CH00.DAQ.TD contains only the grouped spectra. To read the ADC trace with an online analysis program the CH00.DAQ.TD is preferable to use ...

in addition there are also additional parameters saved like:

  • sample frequency (in MHz)
  • error (state)
  • offset

Amplifiers for the GHZ ADCs

108 MHz ADCs:  Struck SIS8300-L2D

There is one in each of the MTCAs in the hall: MTCA-EXP1 at PG/BL1, the other at BL2 and BL3.

They are 16 bit, 10 channel, 125 MS/s ADCs.

50 Ohm input impedance, -1 V,...,+1 V default input range, analog signals can be routed to AC and DC input stage. The coupling is DC via op-amp (switching to AC transformer involves resoldering of SMD solder bridges).

Here is a trace of the first signal, a 1 MHz trigger connected from the x2timer board in the same MTCA:

Pulse energy server: Using the Struck SIS8300-L2D to detect only integrated values of pulses

FS-LA (Falko Peters) programmed a pulse detection server that automatically detects peaks in the signal and integrates the samples around the peak. 

Things to set:

  • Min peak height: threshold fro which on some signal is considered to be a peak. The actual peak is then determined as the maximum of the counts after the threshold
  • pre and post peak integration time: how much ns to be integrated before and after the peak sample that are taken into account for the peak
  • pre and post peak noise time: before and after the samples that are taken for the actual signal these samples are used as background ( they also can be used to define the "deadtime" of the detector before it searches for new peaks.


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Detailed stuff

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