Datacasting employs the excess bandwidth from digital television signals for use in one-way data transmission, and it is being used successfully for high-speed downloads at fixed locations. There is considerable interest in extending datacast usage to mobile users, although there are reception challenges in the mobile environment that can significantly impact system performance. To explore the feasibility of using datacasting in this environment, datacasting receivers and data logging equipment were installed in emergency vehicles to record performance characteristics over a wide range of operational conditions. Summary conclusions from that study are described in this paper along with details about the network infrastructure and equipment used. Although datacasting provides only a downlink channel, it can be interfaced with other channels so as to form a twoway link. In the work reported here, datacasting was coupled with a broadband cellular channel to successfully provide a two-way ...