A mobile radio communication system is provided with a base station apparatus connected to a wire circuit, a mobile radio station apparatus which is connected to the base station apparatus by a radio circuit, a mode designation device for selecting either an analog mode or a digital mode when radio communication...http://www.google.com.hk/patents/US5335355?utm_source=gb-gplus-share專利 US5335355 - Mobile radio communication system utilizing analog and digital modulation
