A system utilizes a single receiver to simultaneously receive and demodulate both amplitude shift keying (ASK) messages and frequency shift keying (FSK) messages. The single receiver is used to demodulate the FSK modulated message and the single receiver provides a received signal strength indicator (RSSI) signal that provides an indication of a combined strength of the FSK and ASK messages. The RSSI signal is filtered and then data sliced to provide a digital message that corresponds to a demodulated version of the ASK modulated message.