Moon tracking
The Moon tracking is lauched with the menu Group, sub-menu Moon.
In this chapter, the word "Visibility" always refers to a radioelectrical visibility.
The relevant window opens after a few seconds of calculation. This window displays the followings datas :
- The current time in local time or UTC time according to the choice of the user.
- The Ephemerids table of the Moon for the current visibility period or, if the Moon is not visible, for the next visisbility period.
- The date and time of the next moonrise if it is not visible and the date of time of the next moonset.
- The elevation and azimuth angles pointing to the Moon in the sky from the location of the user.
The display has a green background if the Moon is visible and a red background if the Moon is NOT visible.
The display is given with two decimal figures (0.01 degree) to be compliant with the EGIS antenna system.
These angles are sent to command the antenna system chosen by the user when the Moon is visible.
- The Tracking button to start and stop the tracking of the Moon by the antenna system of the user.
This button, when depressed, will stop any current tracking on an artificial satellite or on the Sun.
This button is disabled when the Moon is not visible.
- The current EME coverage of the Moon. It allows the user to know which countries of the Earth actually see the Moon at the same time and can contact themselves by using EME traffic.
This coverage map is updated every 2 minutes. The geometrical center of the map is the vertical projection of the Moon on the Earth. The relevant coordinates of this center are displayed at the bottom of the map.
- The current value of the Self-Doppler in Hz for the uplink frequency of the user (see later).
- The current value of the DX-Doppler in Hz for the uplink frequency of a distant station (DX) received by the user (see later).

Menu

- Menu File :
- Sub-menu Copy the Ephemerids table : A click on this sub-menu will copy the Ephemerids table in the clipboard. The user can then paste it into any text document with the Ctrl+V command of Windows.
- Sub-menu Close : To close the Moon tracking and return to the main window of Sat-Explorer.
- Menu Time :
- UTC time : To display date and time in UTC time.
- Local time : To display date and time in local time.
- Menu EME Settings : This menu opens a panel to enter several parameters mandatory for EME traffic :
- The transmitting frequency of the user (Ft). This frequency is necessary to compute the Self-Doppler (see later the Self-Doppler section)
- The grid square (or locator) of a distant station (or DX station) chosen by the user to compute common visibility of the Moon between the user's station and the DX station.
This locator may be input directly by the user (example: AA11bb) or it may be computed from a list of DXCC prefixes.
This DXCC list is the same as the one used to define a DX station in the satellite tracking process.
The field separator of the items of this list may be changed in using the DX button of a specific satellite window.
The user must be aware that the grid square computed from a DXCC country applies to the geographical center of this country.
If this country is quite large, the computed grid square may differ significantly from the "real" grid square of a DX station located far from the center of his country.
- The transmitting frequency (Fx) of the distant station (DX station) for computing the DX-Doppler (see later the DX-Doppler section).
Ephemerids table

This table includes the following datas for each round minute of the current visibility or next visibility if the Moon is not currently visisble :
- Date and time of each round minute in UTC or local time
- Elevation and azimuth angles of the Moon in the sky (0.1 degree display).
Note that these angles are given with 0.01° accuracy per second for antenna tracking and DDE/TCP-IP exchange.
- Lattitude and longitude of the Moon (round values).
Note that these values are displayed on the EME coverage with a 0.1° per second accuracy
- Altitude of the Moon from the surface of the Earth in kilometers.
- Self-Doppler and DX-Doppler frequency shifts in Herz to tune on its own signals (Self-Doppler) or on the signals of a DX station (DX-Doppler). See the Doppler section.
Please note : the first line of the table refers to the first round minute of the visibility. This round minute is normally the current minute BUT, when lauching the Moon tracking process, you will probably notice that the Moon is already visible (or will become visible) during the previous minute. Elevation and azimut angles will be computed at that time but Doppler calculations will start at the next round minute. So it could last a maximum of 60 seconds before Doppler shifts are available.
When the Moon is visible, the top line of the table is always the one of the current minute (but when starting the process). The former lines are deleted as the time goes.
EME coverage

This azimuthal map show the Earth as it would be seen by an observer on the Moon if the Earth was always in the sun.
This coverage allows the user to know currently which countries of the Earth see the Moon at the same time and are able to contact themselves in EME traffic i.e. by reflection of radioelectrical signals on the Moon. EME=Earth-Moon-Earth.
This map is updated every 2 minutes. It is always displayed, either the user sees the Moon or not.
At the bottom of the map are displayed the vertical geographical coordinates of the Moon, longitude on the left side, lattitude on the right side.
These coordinates are the center of the map.
Note that generating this map requires a lot of ressources of the CPU. If your computer is not powerfull, this generation may take a few seconds that will "blocked" your computer. A bargarph on the right of the map tells you about the progress of the process.

Launching the tracking

The image of the Moon in the upper left corner of the window includes the datas necessary for the Moon tracking by your EME antenna system :
- The current date and time in UTC or local time
- The date and time of the next moonrise if it is not visible and the date of time of the next moonset.
- Elevation and azimuth angles with a 0.01° accuracy. The display appears on a green background if the Moon is currently visible and on a red background if not visible.
- The button to activate or to stop the Moon tracking by your antenna system.
The angular values are updated every second.
The activation of the antenna interface is enabled when the Moon is visible and if an antenna interface has been chosen by the user.
This button is :
- white when inhibited (no antenna interface or Moon invisible),
- green when enabled (an antenna interface is chosen and the Moon is visible)
- sky blue when depressed (the antenna system is commanded).
Please note that if your antenna interface is already in use to track a satellite, it will be automatically pointed to the Moon and the tracking of the satellite will be given up !
At moonset, the tracking will be automatically disabled. In the meantime, the tracking may be stopped manually in releasing the button.

EME Doppler

The Doppler shift is the difference of frequency between the uplink frequency of a distant station and the dowlink frequency of the same signals as received at your own station. This shift is due the relative movement of the Moon w.r.t the DX location and the user's location. If the path length between the DX station and the user's station, after reflection on the Moon, decreases then the Doppler shift is positive. If this path increases, it is negative. It is about null when the path length reverses.
Please note that the Doppler shift calculation starts at the first round minute of theEphemerids table. See above.

Sat-Explorer computes two types of Doppler shift : the Self-Doppler and the DX-Doppler.

- SELF-DOPPLER : Also called Home-Doppler or Echo-Doppler in reference to the medical examination, the Self-Doppler is the frequency shift which appears on the own signals of the user after reflection on the Moon (echo). The Self-Doppler is available during the whole visibility period of the Moon. It depends on the transmitting frequency (Ft) ofthe user. This frequency must be set through the menu EME Settings. By default, this setting is 1GHz. The Self-Doppler is mainly used by the user to verify the feasability of an EME contact with other stations (accuracy of the Moon pointing, acceptable link budget).
The user must be aware that the echo of his own signals will be received about 2.5 seconds after transmission, due the round trip to the Moon (about 750000 km).

- DX-DOPPLER : The DX-Doppler is the frequency shift which appears between the signals of a DX station when emitted and the signals of the same DX station as they will be received at the user's station. The DX-Doppler is available only during common visibility of the Moon at the DX and the user's stations. The DX-Doppler is depends on the geographical location of the DX station and on its transmitting frequency. These datas must be set through the menu EME Settings. The DX location is defined by its grid square (DX Locator). This locator may be input directly by the user (example: AA11bb) or it may be computed from a list of DXCC prefixes.
This DXCC list is the same as the one used to define a DX station in the satellite tracking process.
If the DX location is not defined, the DX-Doppler is not computed (N/A). If the DX station and the user's station do not see the Moon simultaneously, the DX-Doppler is not computed (N/A).
Remember that the DX signals will be received about 2.5 seconds after transmission, due the round trip to the Moon (about 750000 km).

DDE & TCP-IP

As for an artificial satellite, Sat-Explorer may exchange frames with third-party softwares which want to treat its computed EME datas (TRX-Manager for example). These frames are a little bit different from those attached to an artificial satellite.
For the Moon, the structure is as follows :

'MOON AZ:xxx.xx EL:yyy.yy RR:z.zzzzzzzz RS:u.uuuuuuuu AH:Y/N'

AZ: and EL: are the identifiers of the elevation and azimuth angles with an accuracy of 0.01°. If the Moon is currently not visible, the values are those of the beginning of the next visibility period.
RR: is the identifier of the corrective factor of the light speed to compute the DX-Doppler. It has no dimension unit. To compute the relevant frequency shift, the 3rd-party software must use the following formula : DX-D oppler(Hz) = -Frequence(Hz) * RR * (1 / 299792.458). If RR is not available, Sat-Explorer sends the value RR:0.00000000 .
RS: is the identifier of the corrective factor of the light speed to compute the Self-Doppler. It has no dimension unit. To compute the relevant frequency shift, the 3rd-party software uses the same formula as above : Self-D oppler(Hz) = -Frequence(Hz) * RS * (1 / 299792.458). If the Moon is not visible, Sat-Explorer sends the value of the beginning of the next visibility period.
AH:Y if the Moon isvisible, AH:N if the Moon is NOT visible. AH is the short for "Above Horizon".
Field separator is the space. Numerical values are not fixed format.

For more informations, please read chapters DDE and TCP-IP.