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--- en:data-outputs [2017/01/05 17:04] – created fluktuacia
+++ en:data-outputs [2019/04/25 15:33] (current) – [Spectral records description] fluktuacia
@@ Line 1: / Line 1: @@
-FIXME **This page is not fully translated, yet. Please help completing the translation.**\\ //(remove this paragraph once the translation is finished)//
 ====== Bolidozor data outputs ======
-The data produced by the detection stations are sent to the [[en:servers|main data server]] running a [[http://space.astro.cz/bolidozor/support/js9browser/#/bolidozor/|JS9browser]] tool. It enables to view the visual portion of the data. Statistical data are available on [[http://rt.bolidozor.cz/|Bolidozor RealTime web]].
+Data produced by detection stations are sent to the [[en:servers|main data server]] running a [[http://space.astro.cz/bolidozor/support/js9browser/#/bolidozor/|JS9browser]] tool, which enables to view the visual portion of the data. Statistical data are available on [[http://rt.bolidozor.cz/|Bolidozor RealTime web]].
-There are several types of files among data records:
+There are several types of files among the data records:
   * Periodic previews (XXXXX_snap.fits)
@@ Line 13: / Line 11: @@
-JS9 web viewer enables viewing only the first two records. A specialised application is required to see the rest of the records. The description of how the data files are sorted can be found on [[en:convention|directory convenctions]] webpage. All the time records are stored either as [[https://en.wikipedia.org/wiki/Unix_time|Unix time]] or [[https://en.wikipedia.org/wiki/Coordinated_Universal_Time|UTC]].
+JS9 web viewer enables viewing only the first two types of records. A specialised application is required to see the rest of the records. The description of how the data files are sorted can be found at [[en:convention|directory convenctions]] webpage. All the time records are stored either as [[https://en.wikipedia.org/wiki/Unix_time|Unix time]] or [[https://en.wikipedia.org/wiki/Coordinated_Universal_Time|UTC]].
 ===== Records generation =====
-The records are generated by a software running on the detection stations. Majority of data are produced by [[en:radio-observer|Radio-observer]] software. Other auxiliary meta-data outputs are generated by a software maintaining an integrity of data flow from the stations.
+The records are generated by a software running on detection stations. Majority of data are produced by [[en:radio-observer|Radio-observer]] software. Other auxiliary meta-data outputs are generated by a software maintaining an integrity of data flow from the stations.
 ===== Spectral records description =====
-Visual records, viewable by [[http://space.astro.cz/bolidozor/support/js9browser/|JS9browser]], have a form of a so-called [[https://en.wikipedia.org/wiki/Spectrogram|spectrograms]], showing frequency on one and time on the other axis.
+Visual records, viewable by [[http://space.astro.cz/bolidozor/support/js9browser/|JS9browser]], have a form of so-called [[https://en.wikipedia.org/wiki/Spectrogram|spectrograms]], showing frequency on one and time on the other axis.
 In our case:
@@ Line 29: / Line 27: @@
-The radar emitting frequency corresponds to the vertical line
+The radar emitting frequency corresponds to the vertical line intersected with the average positions of the meteor trails. This signal is static and thus has almost entirely zero [[https://en.wikipedia.org/wiki/Doppler_effect|Doppler shift]].
-Frekvence na které vysílá radar odpovídá svislici proložené průměrnými pozicemi stop meteorů. Což je signál, který je statický a proto má téměř nulový [[https://cs.wikipedia.org/wiki/Doppler%C5%AFv_jev|Dopplerův frekvenční posuv]].
+{{:cs:outputs:js9browser_meteor.png?600|A typical picture of meteor generated by JS9Browser programme.}}
+The lower portion of the record shows a head-echo - a signal, always beginning at higher frequencies than the meteor trail. Head-echo is a signal formed by the reflection from an ionised plasma at the front of the meteor during its fly-by. It is a moving object whose signal (due to a considerable speed - up to tens of km/s) has a large doppler shift that passes through zero (at the point of the shortest sum of distances transmitter -> meteor -> receiver). Some meteors lack a head-echo signal as a geometry of their fly-by does not allow reflection towards the receiver station. On the other side, other meteors have a head-echo extending even behind the point of the zero doppler shift.
+Following the area of a head-echo signal there is an area of a static reflection from the meteor trail. Its intensity varies in time. The change in intensity is caused by a progressive recombination of a plasma trail of the meteor and periodic changes in intensity are caused by a spatial modulation of the radar signal.
+==== FITS header content ====
+  SIMPLE  =                    T / file does conform to FITS standard
+  BITPIX  =                  -32 / number of bits per data pixel
+  NAXIS   =                    2 / number of data axes
+  NAXIS1  =                    2 / length of data axis 1
+  NAXIS2  =               460800 / length of data axis 2
+  EXTEND  =                    T / FITS dataset may contain extensions
+  ORIGIN  = 'SVAKOV-R12'
+  DATE    = '2017-09-23T05:00:57' / system time of file creation (filled in by FITS library)
+  DATE-OBS= '2017-09-23T05:00:47' / time of observing the event derived from sampling
+  CTYPE2  = 'TIME    '           / in seconds
+  CRPIX2  =                    1
+  CRVAL2  =        1506142847730 / time of first sample derived from sampling
+  CDELT2  =           0.01041667 / time difference between two IQ samples in ms
+  CTYPE1  = 'CHAN    '           / in Hz
+  CRPIX1  =                   1.
+  CRVAL1  =                    0
+  CDELT1  =                    1
+  END
-{{:cs:outputs:js9browser_meteor.png?600|Typický obrázek meteoru vytvořený v programu JS9Browser.}}
-Ve spodní části záznamu vidíme head-echo, což je signál, který vždy začíná na vyšších frekvencích než stopa meteoru. Head-echo je signál vznikající odrazem od ionizované plazmy před meteoroidem během jeho průletu. Jde proto o pohybující se objekt. A jeho signál má proto v důsledku značné rychlosti (až desítky km/s) velký dopplerovský posuv, který během průletu prochází nulou (v místě nejkratšího součtu vzdáleností vysílač -> meteor -> přijímač).
-Některé meteory head-echo signál nemají, protože geometrie průletu nedovoluje odraz do přijímací stanice. Jiné meteory naopak mají head-echo, které pokračuje i za bodem nulového dopplerovského posuvu.
-Na oblast signálu head-echa navazuje oblast statického odrazu od stopy meteoru. Která mění svojí intenzitu v čase. Změna intenzity je jednak způsobena postupnou rekombinací plazmové stopy meteoru a periodické změny intenzity jsou způsobeny prostorovou modulací signálu radaru.