1. Data acquisition at GEO600
Martin Hewitson

2. Schematic overview (Ruthe)
coch
32f/64s chans 1 MB/s
DCU
(alchemist)
central
Data
collector
To Hannover
(< 1 MB/s)
vDCU
(control)
Raw data
server
1000us 5 kB/s
f = fast (16 kHz)
S = slow (512 Hz)
Us = ultra-slow (1 Hz)
DCU
(pandora)
east
DCU
(thot)
north
16f 500 kB/s
16f 500 kB/s
GEO meeting Sept 2004

3. DCU
Fast channels
Slow channels
GEO meeting Sept 2004

4. On Coch… Data collecting software Raw data server
Writes data to disk in proprietary format
Uses GEO directory structure
Raw data server
Accessible from Ruthe
1 sec latency
GEO meeting Sept 2004

5. Schematic overview (Hannover)
bute
client
frame maker
h(t)
maker
fserv 9000
From Ruthe
(< 1 MB/s)
RAID array (3 TB)
hour trend
maker
day trend
maker
client
fserv 9008
Charlie (Archival)
GEO meeting Sept 2004

6. A summary of file types Raw data files (1 second duration)
fs <= Hz
One file per DCU per second
Frame files (1 minute duration)
60 frames per file, one second per frame
All channels in one file
+ calibration information
Hour trends files (1 hour duration)
fs = 1 Hz
60 frames per file, 60 seconds/samples per frame
Min, max, av
Day trend files (1 day duration)
fs = 1/60 Hz
24 frames per file, 60 minutes/samples per frame
GEO meeting Sept 2004

7. Current DAQ system - summary
Commercial solution (mostly)
Has evolved into quite a stable solution
99% reliability
improvements mostly due to software
Some problems remain
Easily damaged input stage
Sometimes high level of cross-talk is observed
Some parts are obsolete
Main drawbacks
Costly repairs and replacement parts
No user-serviceable parts
GEO meeting Sept 2004

8. Moving forward Continue with the current system?
Need to repair ADC boards once per year
Spare processor boards no longer available
Problems still exist with signal sizes and channel overload protection
This needs more investigation
Cross-talk is difficult to predict and control
Move to a new DAQ system
GEO meeting Sept 2004

9. A new DAQ system
Aims:
Replace existing system with something we can control
More exactly meet the needs of GEO
Make something cheap (comparatively), expandable and versatile
A flexible system that can also be used in lab environments
Extends the current software model of parallel data streams
GEO meeting Sept 2004

10. General approach Make a modular system
Each channel is an independent module
Each module collects data and sends it over ethernet
Modules can be placed anywhere (near signal source)
Cost per module ~€300 + infrastructure
GEO meeting Sept 2004

11. System overview
GEO meeting Sept 2004

12. A channel module
Single channel board designed to fit into its own enclosure
Each module connects directly to a data collecting computer via TCP/IP
GEO meeting Sept 2004

13. Advantages over current system
Each channel is independent of all the others
Cross-talk is minimised
Effect of failures is minimised
Only the required number of channels is used
Individual channels can have independent acquisition rates
Individual channels are easy to repair/replace
Channels can be placed close to signal source
Reduces pick-up of noise
GEO meeting Sept 2004

14. Open questions
What is the required operational time of the current DAQs?
Should we be looking beyond GEO?
GEOHF needs
Are we happy to continue with the (costly) repairs?
Should we move to a new DAQs?
Manpower?
GEO meeting Sept 2004