linrad support: The eme window.
(June 28 2002)

The EME databases

The 144MHz eme community supports databases with call signs and geographical locations for EME stations. These databases can be downloaded from the Internet. Linrad currently reads dir.skd, eme.dta and allcalls.dta These files have to be placed in the /home/emedir directory and the file names must be in lower case letters.

When the eme init function, M on the main menu, is run, the files are scanned for call signs and geographical locations. Errors are reported in location_errors.txt in the same directory and all call signs and locations are stored in Linrad's own format in linrad_dxdata also in /home/emedir.

Searching a call sign

The eme window is shown in fig. 1 together with the polarisation graph. The call signs in red are the first four hits when searching for the call fragment ZC The colour is red because there are more hits which are not shown in the window.

Fig. 1. The EME window after searching for *ZC*

To search for a call sign, enter the known characters in the long box with * or ? to indicate missing information.

The search in fig.1 is *ZC* which means all call signs containing Z followed by C. If more information is known a possible search string would be *ZC*HA* which is equivalent to *HA*ZC* and will give HA1ZCG as the only hit. Had there been a call ZC4AHA it would have been a hit too. If the initial star is omitted only call signs that start with the first fragment will give a hit and if the last star is omitted the call sign has to end in the last string to give a hit.

It is also possible to insert one ? for each unknown character and *2?C* is a perfectly legal search string which will give 4N2CCY, DF2ZC and several others.

If the search gives one hit only - or if a complete call sign is entered into the box, the station is accepted as the current dx station.

Moon and DX data

If the dx location is known or if a ww locator is entered in the smaller box, linrad will show the relevant information for the dx station in green as can be seen in fig.2.

Fig. 1. The EME window with data for JL1ZCG

The dx data is the ww locator, the azimuth and elevation at the dx location and possibly the call sign. At the left side of the locator the azimuth for terrestrial communication is shown and the terrestrial distance in km is at the right side of the locator.

Data for the own location is in white. It is the current moon position and the optimum transmit polarisation. In fig. 2 the incoming signal has a polarisation angle of 151 degrees and the optimum transmit polarisation is close to vertical.

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