There is a transmitter in France also that uses TDF at 162Khz
(w. receiver schematic)
It seems like a Phasemodulation on a "standard" 162Khz longwave transmitter signal.
Seems like coverage is better (in Greece) , but i don't know about availability of receivers.
Btw: All threads i have seen says that Pollin DCF77 is not as good as the two you have.
If this is only for 1 or 2 i'd get some cheap GPS'es like this one
RoyalTek RGM-2000 Sapphire GPShttp://cgi.ebay.de/GPS-MAUS-ROYALTEK-RGM2000-MD95000-MD40600-MD41600-/120619570508?pt=DE_PDA_Zubeh%C3%B6r_KM&hash=item1c157c954c
They have serial nmea TTL out (runs off 5v) ,and i have used them with AVR'shttp://www.tobias-schlegel.de/?page_id=51&lang=en