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/* SPU HLSW V5.7 - WHAT'S NEW !!

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/* Project: 		HSO/PACS, SPU HLSW

/* Originator: 		Ahmed Nabil Belbachir

/* Contact:		spuhlsw@prip.tuwien.ac.at 

/* User Manual issue:   5.7

/* Date:		29-07-2003

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SPU HLSW 5.7 is positioned as an upgrade of SPU HLSW 5.6, containing the following 

new features:

 

  - Predefined values are accepted as sub-ramp length (Write detector constant in Spectroscopy)

  - The size of data which may be compressed lossless is limited

  - Bug in Raw channel data compression for photometry corrected







This will be explained in the specific sections that follow.





The SPU HLSW Development Team.





Predefined values are accepted as sub-ramp length (Write det. const. Spectr.)

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The HLSW Version 5.7 has a default value of 32 for sub-ramp length. This parameter could be updated via the Write detectors constant in spectroscopy command. The allowed values for this parameter are 1,2,4,8,16,32,64,128,256 and 512. All other values will be rejected with a negative acknowledgment "Invalid Parameter". In this case, the parameter sub-ramp length will keep then the previous written correct value.



The size of data which may be compressed lossless is limited

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SPU HLSW 5.6 crashes whenever compression is started for all detectors selected in lossless compression mode. This is due to the high CPU workload which is required to compress data lossless from all detectors selected. In HLSW 5.7, the software checks the size of the data to be compressed lossless. If this size is greater than 120 Kbytes (considering a reduction of factor 4 of the data), then a DEC/MEC header error is flagged in the SPU HK and the first 120 Kbytes of the available data will be compressed lossless and downlinked.



Bug in Raw channel data compression for photometry corrected

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Using the RZip algorithm for raw channel data compression, the compression SW (also decompression SW) needs to set the redundancy cycle to have a higher compression rate. In spectroscopy, the redundancy cycle chosen was the reset interval. in SPU HLSW 5.6, the reducndancy cycle was also the reset interval in photometry which is wrong as in this mode there is no reset. In HLSW 5.7, we set the redundancy cycle to 8 (5Hz chopping (40Hz/5Hz))



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