In this article, we study the behaviour of an Ultra- Wide Band (UWB) physical layer when executing our protocol Parallel Symmetric Double-Sided Two-Way Ranging. We com- pare it to the reference protocol introduced in IEEE 802.15.4a, Symmetric Double-Sided Two-Way Ranging, in terms of precision of the obtained estimates and to other existing protocols such as SDS-TWR-MA and D-TWR in terms of overhead. These samples were obtained using a testbed made of IEEE 802.15.4a UWB nodes. From these first experiments, we derive a simple correction mechanism which enhances the convergence rate of the localisation algorithm and reduces the localisation error compared to the case where no dynamic correction takes place. The location error reduction varies between 36 and 60% while the algorithm manages to estimate 98.6% of the positions with the addition of the correction.