Time%20stamping%20with%20CAEN%20V1290N - PowerPoint PPT Presentation
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Time%20stamping%20with%20CAEN%20V1290N
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We have tested the setup using high stability generators and GPS based 1PPS ... Linux based PC is used to collect measurement results and store them to disk ... – PowerPoint PPT presentation
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Title: Time%20stamping%20with%20CAEN%20V1290N
1
Time stamping with CAEN V1290N
- Bled, 26th 28th March 2008
- Dušan Ponikvar, Dejan Paradiž
- Faculty of Mathematics and Physics
- Ljubljana, Slovenia
2
Present state
- We have connected CAEN V1290N time-tag module
with CAEN V1718 USB-VME interface and can control
both units using Linux based PC - We have prepared the software in C for reading
and evaluation of results - We have tested the setup using high stability
generators and GPS based 1PPS
3
DT for periodic pulses
DT ps
100ps
Sample number
- Input is 20000 Hz from Agilent function generator
HP33250 - Jitter specifications (rms) 100ppm 50ps 5ns
- CAEN 1290N internal clock of 40MHz used
- Measurement duration 1s
- Deviation /- 125ps
4
DT for 1pps pulses from HP33250
DT ps
50ns
Sample number
- Input is 1 Hz from Agilent function generator
HP33250 - Jitter specifications (rms) 100ppm 50ps
100ms - CAEN 1290N internal clock of 40MHz used
- Measurement duration 2 hours
- Deviation /- 50ns
5
DT for 1pps pulses from GPS
DT ps
50ns
Sample number
- Input is 1PPS from GPS
- Jitter specifications (max) /- 150ns
- CAEN 1290N internal clock of 40MHz used
- Measurement duration 1,5 hours
- Deviation /- 100ns after initial warming-up
period
6
Hardware
GPS1pps
Photonpulses
RS232
- Signal sources
- CAEN inputs are connected to signal sources using
home-made TTL to NIM translator - PC is a Linux based machine, disk HD is an
integral part of the PC
SYNC 20kHz
USB-VMECAEN 1718
COUNTERCAEN 1290
TTL-NIMHOME
PC
HD
7
Software
- The software consists of two parts
- Data from CAEN to disk on-line data streaming
- Data from disk to evaluation of-line evaluation
PC
CAEN
HD
PC
HD
USER
8
CAEN V1290N
Counter state
21
2 -1
0
t
- V1290N uses 21 bit counter, clock frequency is
40MHz counter period equals 52ms - Continuous storage mode is used
- Result is the state of the counter at the arrival
time of the electrical pulse 5 bit identifier
(00000) 5 bit channel number 21 bit time-tag - Results are grouped in CAEN internal buffer and
periodically transferred to PC using USB bulk
transfer
9
CAEN V1290N
- Periodic synchronization pulses are applied to
V1290N spare input to identify counter periods - Frequency must be at least 20kHz
- Lots of sync pulses!
- What we expect to time-tag is - few thousands
(up to 10k) pps photon pulses, - 20k
sync pulses and - 1PPS from GPS
--------------------------------------------------
--------------- our system can cope with
it
10
PC
- Linux based PC is used to collect measurement
results and store them to disk - Maximum throughput of the system is about 100.000
pulses per second when our software is running at
high priority - File size is 100MB maximum, therefore results of
the measurement must be stored in several
consecutive files - PC hardware specifications AMD Athlon(tm) XP
1700, 512MB memory
11
Hardware built
- CAEN 1290N requires NIM standard inputs a 4
channel TTL to NIM translator was built, since
this was faster than buying it - CAEN 1290N requires positive differential ECL
inputs for sync clock of 40MHz a logic level
translator was built for the same reason
12
Immediate plans
- We currently have some problems with the GPS 1PPS
output antenna? Old GPS? Warming? - We need to introduce 1PPS sync pulses into CAEN
1290N no problem - We need to include RS232 output from GPS (time
stamp) into streamed file with CAEN 1290N
measurement results to identify absolute time
no problem - Testing with better clock and GPS system
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