mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-01 16:13:57 -04:00
7f8caca508
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7184 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
45 lines
2.6 KiB
Plaintext
45 lines
2.6 KiB
Plaintext
A text box entitled Astronomical Data provides information needed for
|
|
tracking the sun or moon, moon, compensating for EME Doppler shift,
|
|
and estimating EME Doppler spread and path degradation. Toggle the
|
|
*Astronomical data* on the *View* menu to display or remove this window.
|
|
|
|
image::AstroData_2.png[align="center",alt="Astronomical Data"]
|
|
|
|
Available information includes the current *Date* and *UTC* time; *Az*
|
|
and *El*, azimuth and elevation of the moon at your own location, in
|
|
degrees; *SelfDop*, *Width*, and *Delay*, the Doppler shift, full
|
|
limb-to-limb Doppler spread, and delay of your own EME echoes; and
|
|
*DxAz* and *DxEl*, *DxDop*, and *DxWid*, corresponding parameters for
|
|
a station located at the DX Grid entered on the main window. These
|
|
numbers are followed by *Dec*, the declination of the moon; *SunAz*
|
|
and *SunEl*, the azimuth and elevation of the Sun; *Freq*, your stated
|
|
operating frequency in MHz; *Tsky*, the estimated sky background
|
|
temperature in the direction of the moon, scaled to the operating
|
|
frequency; *Dpol*, the spatial polarization offset in degrees; *MNR*,
|
|
the maximum non-reciprocity of the EME path in dB, owing to spatial
|
|
polarization; and finally *Dgrd*, an estimate of the signal
|
|
degradation in dB, relative to the best possible time with the moon
|
|
at perigee in a cold part of the sky.
|
|
|
|
The state of the art for establishing three-dimensional locations of
|
|
the sun, moon, and planets at a specified time is embodied in a
|
|
numerical model of the solar system maintained at the Jet Propulsion
|
|
Laboratory. The model has been numerically integrated to produce
|
|
tabular data that can be interpolated with very high accuracy. For
|
|
example, the celestial coordinates of the moon or a planet can be
|
|
determined at a specified time to within about 0.0000003 degrees. The
|
|
JPL ephemeris tables and interpolation routines have been incorporated
|
|
into _WSJT-X_. Further details on accuracy, especially concerning
|
|
calculated EME Doppler shifts, are described in
|
|
|
|
The sky background temperatures reported by _WSJT-X_ are derived from
|
|
the all-sky 408 MHz map of Haslam et al. (Astronomy and Astrophysics
|
|
Supplement Series, 47, 1, 1982), scaled by frequency to the (-2.6)
|
|
power. This map has angular resolution of about 1 degree, and of
|
|
course most amateur EME antennas have much broader beamwidths than
|
|
this. Your antenna will therefore smooth out the hot spots
|
|
considerably, and the observed extremes of sky temperature will be
|
|
less. Unless you understand your sidelobes and ground reflections
|
|
extremely well, it is unlikely that more accurate sky temperatures
|
|
would be of much practical use.
|