An Electronic Road Pricing (ERP) system was introduced in 1998 in Singapore to reduce the traffic congestion in the city area, almost all vehicles in Singapore are equipped with onboard equipment called in-vehicle unit (IU). Using these in-vehicle units and the technologies based on the ERP system, Mitsubishi Heavy Industries, Ltd. (MHI) has developed an Electronic Parking System (EPS) that enables settlement of parking fees without parking tickets and cash. In order to keep the compatibilities of current car park system, antennas were made smaller and compact, processing systems were integrated and devices for calculating the fees were developed, the device for calculating the fee was called charging unit (CHU). In order to meet the various needs of the car park owners and to allow free setting of the parking fee, the devices are designed. The introduction of EPS in Singapore has brought about an unprecedented realization of the application using the same onboard equipment in both EPS and ERP systems (application fields).