Offline raw data format of SVD2.0

1
Offline raw data format of SVD2.0
H.Ishino (2002/7/25)

• The offline raw data format of SVD2.0 is almost
  same as that of SVD1.0 which was developed by
  Krakow people.
• The big difference is that the offline raw data
  are generated with a C program which sparsifys
  and encodes the FADC data, while an assembler
  program is doing it for SVD1, so it is much
  easier to modify the code.

2
The offline raw data format
A data set of one hybrid. i.e. data of 512 strips
Header
6 words
256 words (max)
Data of each strip
Pedestal and CMS noise of each strip
9 words (changeable)
1 word
Tail
32 bits 1 word
3
Header format
Data Format Version (4bit)
AA55 (start marker)
Data length (12bit)
Hybrid ID (8bit)
Event number (8bit)
Tag for data format specification (8bit)
Empty (4bit)
Number of chips (4)
Error flag (16bit)
Reserve (16 bit)
CM level of chip 1 (8bit)
CM level of chip 2 (8bit)
Average of CMS noise of chip 1 (8bit)
Average of CMS noise of chip 2 (8bit)
CM level of chip 3 (8bit)
CM level of chip 4 (8bit)
Average of CMS noise of chip 4 (8bit)
Average of CMS noise of chip 3 (8bit)
Trigger bit (for L2 or L3 trigger)
P Pedestal subtraction if 1
Tag for data format specification
C CM subtraction if 1
xxTU csCP
s data suppression if 1
Each character corresponds to 1bit
c data compress if 1
U Pedestal and CMS noise update
T trigger bit on if 1
4
Data format (1)
I prepared 5 versions of data format. But it is
too much detail to present all specifications
here (the all specifications will be explained in
a Belle note.). Two major specifications are
shown.
csCP 0000 (transparent data)
10 bit
10 bit
0000 00AA AAAA AAAA 0000 00AA AAAA AAAA

1284/2256 words

5
Data format (2)
csCP 11x1 (suppressed and compressed )
Basically a datum of each strip has 1byte
(8bits). However some data would have 2bytes.
0eee eeee
If the first bit is 0, this datum indicates eee
eeee (0127) channels are empty.
10Ss ss.ss
If the fist bit is 1 and the second bit is 0,
this datum means small signal (-8.00 7.75).
S is the sign.
11Ss ssss ssss ss.ss
If both the first and second bit are on, this
datum has 2bytes, covering large signal (-2048.00
2047.75)
6
Data format 3
csCP 11x1
For example,
088F C103 BF11 81EF 35
08 8 empty channels
8F 15/4 3.75 ADC counts
C103 259/4 64.75 ADC counts
BF 1011 11.11 ¼ -0.25 ADC counts
11 17 channels are empty
81 0.25 ADC counts
EF 35 1110 1111 0011 01.01 -1074.75 ADC counts
7
Pedestal and CMS noise of each strip
In order to reduce data size, a part of pedestal
and CMS noise data of all strips is taken.
Different event has different strip data, so
after some events are acquired we can know all of
pedestal and CMS noise values. By default, 16
strips of data are taken.
Nominal is 0xf
c3c3 (start marker of this section
Strip number of the first data (0511)
Number of channels
CMS noise
pedestal
CMS noise
pedestal
16/2 8 words
CMS noise covers the range of 063.75.
We will fill pedestal value divided by 4. So
precision is lost, but we need not so much
precision.
8
tail
Check sum
A5A5 (strop marker)
16 bits
16 bits
Check sum is calculated with the same method as
used by the DSP on Halny. The detail of algorithm
calculating check sum is slightly complicated for
explanation here (sorry). It will be shown in
the Belle note.