Spectral overlay of spread spectrum system on analog FM system

The spectrum sharing capability of a spread spectrum system overlaid on an analog FM system is investigated. This overlay may cause two types of interference: (i) interference from the overlaid wideband SS system on the FM receivers; (ii) interference from the FM stations to the SS system. The comparison of the RF protection ratio of the FM receivers in case of several kinds of interference is presented through quite a lot of experiments. The derivation of the FM spectrum is also derived through laboratory measurements in a closed-form mathematical expression, in order to have a good approximation of the interference on the SS system.