The present invention relates to a method 400 and a system 100 for controlling a robotic garden tool 202 around a working area 204 in a boundary wire aided system. With the aforesaid lamp fixture, not only glare can be prevented, but also uniformity of the lamp fixture is improved. The information may be encrypted with synchronized encryption keys. The action of the modulation correlator trims the modulation and the PLL bandwidth without disturbing the normal operation of the transmitter, and allows the use of modulation bandwidths greater than the PLL bandwidth. Thus, the armature is a dual-hinged armature, providing at least two degrees of freedom, one translational and one rotational, for the sealing member to be properly seated against the valve seat. When the switching circuits switch between the plurality of electronic endoscope and switch video signals and synchronizing signals to that of a newly selected electronic endoscope, the output of video signals are suspended during a predetermined period, by the timer.