This page (revision-34) was last changed on 07-Dec-2016 14:14 by JianSun

This page was created on 06-Jun-2008 14:21 by JianSun

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Difference between version and

At line 1 added 2 lines
[{ALLOW edit EISMainUsers}]
[{ALLOW view Anonymous}]
At line 74 changed 9 lines
|DPCM |2.19|2.19 (2.38)|2.19|2.19|2.54|2.46|2.19|2.18
|JPEG98|2.33|2.46|2.22|3.15|2.85 (avg)|2.31|2.28 (2.32)|
|JPEG95|3.26|3.64|3.26| |6.12|6.38 (6.54)|3.26|
|JPEG92|3.63|3.31 (avg)|6.65 (avg)|2.74 (avg)|6.53 (avg)|2.74 (avg)|3.63 (avg)|
|JPEG90|3.82|3.82|4.34|3.73|4.67 (avg)| |3.84|3.78
|JPEG85|4.51|4.82|4.51|4.91|3.9 (avg)| |4.51|
|JPEG75|6.20| |6.2| |18.88 (avg)| |6.2|7.52
|JPEG65|7.33| |19.94 (avg)| |25.97 (avg)| |7.33 (avg)|
|JPEG50|17.72|20.98|17.72| |35.37 (avg)| |17.72|
|DPCM |2.12|2.19 (2.38)|2.19|2.19|2.54|2.46|2.19|2.18
|JPEG98|2.60|2.46|2.22|3.15|2.85 (avg)|2.31|2.28 (2.32)|
|JPEG95|3.02|3.64|3.26| |6.12|6.38 (6.54)|3.26|
|JPEG92|3.45|3.31 (avg)|6.65 (avg)|2.74 (avg)|6.53 (avg)|2.74 (avg)|3.63 (avg)|
|JPEG90|4.01|3.82|4.34|3.73|4.67 (avg)| |3.84|3.78
|JPEG85|4.79|4.82|4.51|4.91|3.9 (avg)| |4.51|
|JPEG75|5.89| |6.2| |18.88 (avg)| |6.2|7.52
|JPEG65|7.38| |19.94 (avg)| |25.97 (avg)| |7.33 (avg)|
|JPEG50|9.39|20.98|17.72| |35.37 (avg)| |17.72|
At line 104 added 3 lines
For full history of EIS compression factor, see: [this page|fullHistoryOfDcFactor]
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!!Some comments:
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%%information
The nubers are quite different from the ones showned during EIS science meeting in MAY. Basically, there are two reasons for this:
* we got much more data points to cover all compression schemes (see [datasets|../images/dcgifs/datasets_list.txt] used in this calculation.
* the start-time & end-time in some fits headers are not corresponding to the time on MDP data packet curve
** For example, from eis_l0_20080501_054833.fits.gz header:
strat: 2008-05-01T05:48:33\\
end: 2008-05-01T05:50:03
[{Image src='images/dcgifs/eis_l0_20080501_054833.fits.gz.gif}]
''It's clear that: if using start-time & end-time in fits header, then the calculated MDP data volume is 0; if using raster duration to get end-time, only partial MDP data packets will be counted; using study duration seems fine to get completed data volume.''
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Another example: eis_l0_20080501_190013.fits.gz:
start: 2008-05-01T19:00:13\\
end: 2008-05-01T19:01:35
[{Image src='images/dcgifs/eis_l0_20080501_190013.fits.gz.gif}]
''For this fits file, if using start-time & end-time in fits header, then only half MDP data packets are counted, which making compression factor double; if using raster duration and study duration to get end-time, both will get completed data volume and generate reasonable compression factor.''
%%
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%%information
However, at this stage, not sure which one is not correct: time in fits header or time in MDP packet curve?
This mismatch, ie. the data coming is slower than the expection, might explain MDP data recorder full on-board, for example, in the case that EIS data packets for previous and current studies are coming very close in time!
%%
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%%information
There is a structure array to store all related information for the EIS data investigated here. The array has element with the following format:
{{{
compFactor={compression_factor, $
study_ACR :'', $ ;string
study_id :'', $ ;string
rast_ACR :'', $ ;string
rast_id :'', $ ;string
ll_ACR :'',$ ;string
ll_id :'',$ ;string
start_time :'', $ ;string
end_time :'', $ ;string
fitsname :'',$ ;string
target :'',$ ;string
sci_obj :'',$ ;string
slit :'',$ ;string
def_volume :0LL,$ ;long64 int, unit: bits
mdp_volume :0.0,$ ;float, unit: kbits
comp_scheme :0,$ ;int
nexp :0,$ ;int
rast_req :0,$ ;int
exposures :fltarr(8) $ ;float, unit: sec
}
}}}
I attached an [IDL sav file |../images/dcgifs/str1_fitsheader_endtime_fixed.sav.tar.gz]. You may download and play it, for example, I use:
{{{if (str1[i].SCI_OBJ eq 'QS') && (str1[i].COMP_SCHEME eq 1) && (str1[i].MDP_VOLUME gt 0.) then ind[i]=1}}}
to extract records associated with 'QS' SCI_OBJ and using DPCM compression scheme.
%%
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JianSun (MSSL) - 2008-06-09
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[{InsertPage page=EisCompressionTest}]
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JianSun (MSSL) - 2008-07-07
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This page (revision-34) was last changed on 07-Dec-2016 14:14 by JianSunTop