Reduced complexity software AM radio

Despite the fact that the AM receiver is nearly a century old, software implementations have been cost prohibitive. Currently, AM receivers are implemented in hardware (HW), employing AM/FM low cost chips. However, in a multiprotocol communication handheld device, the HW implementation becomes less attractive due to extra chip costs and the PC board area. The most attractive alternative for multiprotocol communication devices is provided by software defined radios (SDR). SDR is able to execute multiple communication protocols on the same processor, provided RF front ends are available to receive the transmission bands. As processor capabilities evolve to higher performance, the border between analog and digital components moves closer to the antenna, reducing the number of analog chip components. We present a low complexity implementation of an AM receiver using few HW components. The radio is based on a software defined communications baseband processor designed by Sandbridge Technologies. The device is intended to be used for handheld applications such as in mobile phones and PDAs. In our implementation, all functions associated with the AM receiver, including most of the filtering and demodulation, are executed in SW using two threads of the Sandbridge Technologies SB9600 multithreaded processor.