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Offline raw data format of SVD2.0

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.

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Offline raw data format of SVD2.0

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  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) Event number (8bit) Hybrid ID (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 …………………………………………………………… 128×4/2=256 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 (0~127) 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 (0~511) Number of channels 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.

  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.

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