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A prototype ultra-wideband (UWB) precision asset location (PAL) system was developed and tested aboard the SS Curtiss in Port Hueneme, California. The PAL system was developed to assess the capability of UWB geolocation to operate in severe multipath shipboard environments. The PAL system was based on an earlier UWB relative-time-of-arrival (RTOA) transceiver location system and was extended to a differential-time-of-arrival (DTOA) beacon architecture required for longer tag battery life. Testing was performed in open cargo spaces (worst-case multipath) and partially loaded cargo spaces (blockage). A reference laser surveying system was installed for comparison and accuracy tests were conducted over a cargo space. The PAL system performed to the estimated accuracy of a few feet in open cargo holds. UWB appeared to penetrate large cracks between containers, maintaining localization capability during blockage tests. This paper describes the UWB PAL system and the shipboard testing.
Fontana et al. (2003) studied this question.