lhcb-week june 2005 ot 1 dirk wiedner 1 mhz readout and zero suppression for the outer tracker dirk...
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LHCb-week June 2005 OT 1Dirk Wiedner
1 MHz Readout and Zero Suppression
for the Outer Tracker
Dirk Wiedner, Physikalisches Institut der Universität Heidelberg
LHCb-week June 2005 OT 2Dirk Wiedner
FE-Data Overview
1 optical link/FE-box:
128 channel Data
Data = header+drifttime
1-2 O-RxCards/TELL19
9 optical links per O-Rx
9 (18) x 128 channels
6 % expected occupancy
4 x OTIS TDC Data
GOL-Aux Board
O-RxCard
TELL1
FE-Box
9 x
1 (2) x
LHCb-week June 2005 OT 3Dirk Wiedner
Zero suppression algorithmoutline
A)Hit-Pattern Data Format
One Hit bit for each OT Straw-Channel
Fixed event size: 172 (334) byte per TELL1
B)Zero-suppressed Data Format
Channel Address for valid hits
Variable event size: 172 (334) bytes @ 11.5% occupancy
LHCb-week June 2005 OT 4Dirk Wiedner
Implementation forHit-Pattern Data Format
Extract Bunch-ID, L0-ID, Detector Location from TDC header
Generate Bank header, TELL1 header, GOL header
Parse the incoming OT data stream
for non-zero drift time, set hit-bit
Rearrange Data and output to L1 link-wise:
1 Byte GOL-address, 16 bytes Hit-Pattern
LHCb-week June 2005 OT 5Dirk Wiedner
...
TDC 0 TDC 35
HEADER
DATA
GOL0TDC 3
TDC2
TDC1
TDC0
GOL8TDC35
TDC34
TDC33
TDC32
...
BANK HEADER
TELL1 HEADERGOL HEADER
HIT-PATTERNDATA
Front End
L1 Farm Switch
LHCb-week June 2005 OT 6Dirk Wiedner
Implementation for Zero-suppressed Data Format
Build data headers as for Hit-pattern
Parse incoming OT data stream
Generate an address byte for each non zero drift time (counter from 0 to 127)
Count the number of hits in each link
Output data link-wise:
GOL address and number of hits (2 bytes)
Address of hit channels (1 byte each)
LHCb-week June 2005 OT 7Dirk Wiedner
Expected PerformancePipelined architecture:
Latency for Data sync. and extraction ~40 cycles
Latency for building Header ~10 cycles
Data output 86 (167) cycles for Hit Pattern Data
136 (217) cycles delay between first bit in and last output bit
Event size full OT:
Hit Pattern: 48 (24) TELL1 x 172 (334)= 8256 (8016) [Bytes]
Zero supp.: 48 (24) TELL1 x (28 (46) + occ.[%] x ca.14 (28)) Bytes
8256 (8016) Bytes @ 11.5% occ., 5664 (5424) Bytes @ 6 % occ.
LHCb-week June 2005 OT 8Dirk Wiedner
Impact on data quality
Both schemes (hit-pattern and zero suppression) give up drift times:
Space resolution 2.5/ mm instead of 200 μm
Zero suppression scheme can be upgraded to combine 2 straw tube layers:
Resolution ~300 μm
Solved ambiguities
5664 (5424) Bytes/Event @ 6% occupancy
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LHCb-week June 2005 OT 9Dirk Wiedner
Current status
Current algorithm is used for 4-6 link readout
Full OT data input synchronization and error checking
Reformatting for SDRAM or PCI output
Output format:
TDC 0 header + full TDC 0 data
TDC 1 header + full TDC 1 data
...
LHCb-week June 2005 OT 10Dirk Wiedner
Summary
Output of Hit-pattern or Zero-suppressed Data Format possible @ 1.1 MHz
OT Eventsize ≤ 8256 (8016) Bytes
Single channel resolution 2.5/ mm
Pipelined algorithm
ca. 3.4 (5.5) μs full latency
Current data formatting can be modified to suggested 1 MHz schemes
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