Data-via-spread-quadrature radio

In this paper, we propose an alternative digital simulcasting AM radio, which uses spread spectrum technology to carry the digital data on the quadrature carrier. Because the modulation process is simple, compared to OFDM technology used in existing digital radio systems, the transmitter and receiver equipments can be economically implemented. Also, because the original analog audio (the in-phase component) remains intact during the modulation process, listeners with traditional AM tuner can still receive the same audio-only radio program. The simulation results have shown that the data rate of up to 8 kbps is achievable at SNR=10dB and the power required for the digital broadcast can be as low as -25 dB below the power of the unmodulated carrier.