Known time desc » History » Version 30
Anonymous, 08/07/2016 12:28 PM
| 1 | 1 | Anonymous | h1. Known time description |
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| 2 | 23 | Anonymous | |
| 3 | |
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| 4 | 24 | Anonymous | |
| 5 | 2 | Anonymous | h2. Double Time ranges : date from 01/01/1970 to 01/01/2100 |
| 6 | 23 | Anonymous | |
| 7 | 22 | Anonymous | |
| 8 | 4 | Anonymous | * seconds from 01/01/1970 00:00:00 : 0 to 4 102 488 000 |
| 9 | * milliseconds from 01/01/1970 00:00:00 : 0 to 4 102 488 000 000 (ambiguity for the first 48days of 1970 with previous time format) |
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| 10 | * seconds from 01/01/0000 00:00:00 : 62 168 472 000 to 66 270 960 000 (no ambiguity) |
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| 11 | * milliseconds from 01/01/0000 00:00:00 : 62 168 472 000 000 to 66 270 960 000 000 (no ambiguity) |
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| 12 | 1 | Anonymous | * seconds from 01/01/2000 00:00:00 : - 946 728 000 to 3 155 760 000 (TT2000) |
| 13 | * milliseconds from 01/01/2000 00:00:00 : - 946 728 000 000 to 3 155 760 000 000 (ambiguity with TT2000 in seconds?) |
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| 14 | 14 | Anonymous | |
| 15 | 25 | Anonymous | µs, ns, ps might also be needed for tt2000 |
| 16 | |||
| 17 | 29 | Anonymous | |
| 18 | Double (IEEE754) |
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| 19 | 64bits |
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| 20 | min value: -1.7977E+308 |
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| 21 | max value :1.7977E+308 |
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| 22 | 30 | Anonymous | |
| 23 | Number of seconds per year = 60*60*24*365.25 = 31 557 600 |
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| 24 | Numbers for 100 years : |
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| 25 | 3 155 760 000 s = 3.15576 e+9 s |
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| 26 | 3 155 760 000 000 ms = 3.15576 e+12 ms |
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| 27 | 3 155 760 000 000 000 µs = 3.15576 e+15 µs |
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| 28 | 3 155 760 000 000 000 000 ns = 3.15576 e+18 ns |
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| 29 | 3 155 760 000 000 000 000 000 ps = 3.15576 e+21 ps |
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| 30 | |||
| 31 | Typical dynamics for a double seems to be 15 digits, after that we might experiment precision loss. |
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| 32 | Recommendation is to store time in QLop as microseconds since Epoch (01-01-1970 00:00:00) |
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| 33 | 29 | Anonymous | |
| 34 | 23 | Anonymous | |
| 35 | |
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| 36 | 5 | Anonymous | |
| 37 | 1 | Anonymous | h2. Known time description |
| 38 | 23 | Anonymous | |
| 39 | 22 | Anonymous | |
| 40 | 14 | Anonymous | |_.Mission Name |_.time var name |_. units |_.DEPEND |_.LABLAXIS|_.FIELDNAM |_.CATDESC |_.Type |_.VIRTUAL|_.nb of records|_.VAR_NOTES| |
| 41 | |Cluster FGM |time_tags__CDFNAME |ms |0 |UT |Universal Time |Interval centred time tag |CDF_EPOCH | |normal |field missing| |
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| 42 | |Cluster HIA |time_tags__CDFNAME |ms |0 |UT |Center Time |Interval centred time tag |CDF_EPOCH | |normal |field missing| |
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| 43 | |||||||||||| |
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| 44 | |Themis Efi,SCM |VARNAME_time |sec |TIME |UT |Same as time var name|UTC, in seconds sinc 01-Jan-1970 00:00:00|CDF_DOUBLE | |normal |Unleaped seconds| |
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| 45 | |Themis Efi,SCM |VARNAME_epoch |field missing|0 |UT |Same as time var name|Unrelated |CDF_EPOCH |true |0 |field missing| |
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| 46 | |Themis Efi,SCM |VARNAME_dot0_epoch0|msec |EPOCH0 |UT |Same as time var name|EPOCH of THEMIS time base |CDF_EPOCH | |1 |EPOCH of 01-Jan-1970 00:00:00| |
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| 47 | |Themis Esa |VARNAME_time |sec |TIME |UT |Same as time var name|UTC, in seconds sinc 01-Jan-1970 00:00:00|CDF_REAL8 | |normal |Unleaped seconds| |
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| 48 | |Themis Esa |VARNAME_epoch |field missing|0 |UT |Same as time var name|Unrelated |CDF_EPOCH |true |0 |field missing| |
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| 49 | |Themis Esa |VARNAME_dot0_epoch0|msec |EPOCH0 |UT |Same as time var name|EPOCH of THEMIS time base |CDF_EPOCH | |1 |EPOCH of 01-Jan-1970 00:00:00| |
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| 50 | |Themis Peer |VARNAME_time |sec |TIME |UT |Same as time var name|UTC, in seconds sinc 01-Jan-1970 00:00:00|CDF_DOUBLE | |> data |Unleaped seconds| |
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| 51 | |Themis Peer |VARNAME_epoch |field missing |0 |UT |Same as time var name|VARNAME |CDF_EPOCH | |normal |field missing| |
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| 52 | |Themis Peer |VARNAME_epoch0 |msec |EPOCH0 |timebase |Same as time var name|EPOCH of THEMIS time base |CDF_EPOCH | |1 |EPOCH of 01-Jan-1970 00:00:00| |
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| 53 | 15 | Anonymous | |||||||||||| |
| 54 | 14 | Anonymous | |MMS fpi |Epoch (absent, Epoch_minus_var is present) |s |0 |Field missing | VARNAME|VARNAME |CDF_UINT1 | |1 |VARNAME| |
| 55 | |MMS scm |epoch_timetag |ns |0 |VARNAME |Same as time var name|Packet time time |CDF_TIME_TT2000| |normal |field missing| |
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| 56 | |MMS scm |Epoch (other var time) |ns |0 |VARNAME |Same as time var name|Time |CDF_TIME_TT2000| |normal |field missing| |
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| 57 | 16 | Anonymous | |||||||||||| |
| 58 | |ACE mfi |Epoch |ms |0 |VARNAME |Time |Time ,beginning of interval |CDF_EPOCH | |normal |field missing| |
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| 59 | |||||||||||| |
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| 60 | |Helios nessmag |Epoch |ms |0 |field missing |Epoch |Default Time |CDF_EPOCH | |normal |field missing| |
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| 61 | 1 | Anonymous | |||||||||||| |
| 62 | |Ulysses hft |Epoch |ms |0 |Time |Epoch |Time in NSSDC Epoch format |CDF_EPOCH | |normal |field missing| |
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| 63 | 17 | Anonymous | |||||||||||| |
| 64 | 18 | Anonymous | |SOHO cst |Epoch |ms |0 |Epoch |Time Line |Time |CDF_EPOCH | |normal |field missing| |
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| 66 | |||
| 67 | 23 | Anonymous | |
| 68 | |
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| 69 | 24 | Anonymous | |
| 70 | 18 | Anonymous | h2. Algorithm Proposition |
| 71 | 23 | Anonymous | |
| 72 | 18 | Anonymous | |
| 73 | VariableThatNeedsTime |
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| 74 | depend0 = get(VariableThatNeedsTime.DEPEND_0 variable) |
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| 75 | |||
| 76 | if(depend0.nbOfRec == VariableThatNeedsTime.nbOfRec) |
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| 77 | 21 | Anonymous | * test depend0.firstValue for different double range mentionned above (this part might include CDF_TYPE for TT2000) |
| 78 | * if(ambiguity) |
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| 79 | ** look at depend0.units |
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| 80 | 26 | Anonymous | ** if field is missing, look at VariableThatNeedsTime.depend_epoch0.units field |
| 81 | //ATM, these lines are written, epoch0 units are useless since that variable only appears when matching time is DEPEND_TIME variable |
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| 82 | 18 | Anonymous | |
| 83 | else |
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| 84 | dependTime = get(VariableThatNeedsTime.DEPEND_TIME variable) |
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| 85 | if(dependTime.nbOfRec == VariableThatNeedsTime.nbOfRec) |
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| 86 | 21 | Anonymous | * test dependTime.firstValue for different double range mentionned above (this part might include CDF_TYPE for TT2000) |
| 87 | * if(ambiguity) |
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| 88 | ** look at dependTime.units |
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| 89 | 27 | Anonymous | |
| 90 | |
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| 91 | |
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| 92 | |||
| 93 | h2. Useful links |
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| 94 | |
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| 95 | |||
| 96 | |||
| 97 | http://spdf.gsfc.nasa.gov/CDFconversion/time_formats.html |
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| 98 | http://cdf.gsfc.nasa.gov/html/leapseconds_requirements.html |
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| 99 | 28 | Anonymous | |
| 100 | how autoplot is processing cdf files : |
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| 101 | http://autoplot.org/help#Reading_CDF |