Charge indicator for hand-held transmitter of remotely operated vehicle security system

摘要

The transmitter is supplied from an integrated energy store. The charge in the energy store is monitored and an indication given when it is depleted. The remaining charge in the store is checked after each operation of the transmitter. When the charge is depleted the transmission power is reduced from a maximum (107) to a minimum value (106), so that a definitely reduced range of transmission power can be detected by the user whilst maintaining the minimum distance from which the vehicle security system must able to be remotely operated.