The clocks controlled by the radio are automatically set on the basis of signal DCF 77, broadcasted from the broadcaster near German Frankfurt in area about 1500 – 2000 km. The products JVD with this labeling set themselves right time and date automatically with no needs for further operating. Includes setting of summer or, if you like, winter time. The signal is approachable on major parts of Czech, Slovakia and Poland. The advantage is absolutely exact time that is constantly synchronized. If you lose the signal or if it changes to a different broadcaster, the system will still go on on a principal of the usual system quartz. After you buy a clock JVD controlled by the signal DCF 77 it is necessary to place it on a good spot because the monitors, television receiver, fluorescent tube etc. create electromagnetic field and the field disturbs every other signals around including the signal DCF 77. If you want to have absolutely exact time on your table, the radio controlled clock JVD is the right choice for you.