Wireless sensor networks have received a lot of attention in recent years both in the research community and in standards organizations. The emphasis of most sensor network research activities has been on the development of low cost and low power technologies for low bit rate applications. In this paper, we describe our work on ultra-wideband (UWB) sensor network technology targeted for video surveillance applications that require high immunity to noise, interference and jamming, high bit rate, and quality of service support. Such sensor networks are expected to find primary applications in the public safety and military fields. Our emphasis in this paper is on the design of the physical layer that can support such requirements and provide high end-to-end throughput when multi-hopping is used.