Offline raw data format of SVD2.0

• 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.

H.Ishino (2002/7/25)

The offline raw data format

Header

Data of each strip

Pedestal and CMS noise of each strip

Tail

A data set of one hybrid. i.e. data

of 512 strips

32 bits = 1 word

6 words

256 words (max)

9 words (changeable)

1 word

Header format

AA55 (start marker) Data Format Version (4bit) Data length (12bit)

Hybrid ID (8bit)

Event number (8bit)

Tag for data format specification (8bit)

Number of chips (4)

Empty (4bit)

Error flag (16bit) Reserve (16 bit)

CM level of chip 1 (8bit)

Average of CMS noise of chip 1 (8bit)

CM level of chip 2 (8bit)

Average of CMS noise of chip 2 (8bit)

CM level of chip 3 (8bit)

Average of CMS noise of chip 3 (8bit)

CM level of chip 4 (8bit)

Average of CMS noise of chip 4 (8bit)

Trigger bit (for L2 or L3 trigger)

Tag for data format specificationxxTU csCP

Each character corresponds to 1bit

P: Pedestal subtraction if 1C: CM subtraction if 1s: data suppression if 1c: data compress if 1U: Pedestal and CMS noise updateT: trigger bit on if 1

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)

0000 00AA AAAA AAAA 0000 00AA AAAA AAAA

10 bit 10 bit

……………………………………………………………

128×4/2=256 words

……………………………………………………………

Data format (2)

csCP = 11x1 (suppressed and compressed )

0eee eeeeIf the first bit is 0, this datum indicates eee eeee (0~127) channels are empty.

Basically a datum of each strip has 1byte (8bits). However some data would have 2bytes.

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)

Data format 3

csCP = 11x1

For example,

088F C103 BF11 81EF 35………

08: 8 empty channels8F: 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

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.

c3c3 (start marker of this section

Number of channels

Nominal is 0xfStrip number of the first

data (0~511)

CMS noise pedestal CMS noise pedestal

16/2= 8 words

CMS noise covers the range of 0~63.75.

We will fill pedestal value divided by 4. So precision is lost, but we need not so much precision.

tail

A5A5 (strop marker)Check sum

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.