Abstract: A data transmission system which is particularly useful for a remote control apparatus for an electric fence. The apparatus includes a portable hand held housing with a contact 16 which in use can contact a conductor of an electric fence line. The output of the apparatus includes a resonating circuit comprising inductor L, transformer 14 and a small high voltage capacitor C2. The apparatus can thus generate information embedded within a series of short signal bursts of a frequency within a predetermined frequency range. A receiver coupled to or forming part of an electric fence energiser can receive a signal from the apparatus to control operation of the energiser.

Abstract: An electric fence energiser for coupling to an electric fence line. The energiser includes a sensor to sense the load on the fence line, at least one storage capacitor, and a charge circuit to charge the storage capacitor(s). A control circuit provides an output pulse with energy appropriate to the sensed load and determines whether the current pulse will exceed a predetermined limit adjustment and adjust the output pulse to send out an output pulse with voltage and/or energy below the predetermined limit if the current pulse will exceed said limit.