Increased ranging capacity using Ultrawideband direct-path pulse signal strength with dynamic recalibration

Abstract

Pulsed-RF (aka. Ultrawideband, or UWB) signaling strategies inherently produce separation of multi path reflections from the earliest Line-of-Sight (LOS) signal. Direct waveform scanning in each UWB transceiver allows coarse estimation of distance through relative signal strength measure of the earliest, most direct path pulse. Even with multi path separation this technique suffers from errors due to channel and antenna pattern changes inherent in distributed dynamic localization systems. This problem can be overcome through occasional, as-needed precise two-way Time-of-Flight (TOF) ranging which can provide periodic dynamic recalibration of the Coarse Range Estimate (CRE). CRE error conditions such as Non-Line-of-Sight (NLOS) and signal saturation can be mitigated through real-time direct sampling and analysis of the pulse waveform. In this investigation a recursive model-based Kalman range filter is used to combine the less accurate CRE with very accurate TOF Precision Range Measurements (PRM). In order to support dynamic recalibration a simple periodic "lout of N" PRM scheduler is compared to a more flexible and capable Range Target Prioritization (RTP) algorithm designed to minimize PRM requirements while maximizing range accuracy in a network environment. The resulting ranging system is much more scalable and suitable for large-scale systems such as distributed ad hoc collision avoidance, safety, and automation networks.

Range validation of UWB and Wi-Fi for integrated indoor positioning

“…Time Domain ® PulseON 410 UWB modules generate three types of range measurements using coarse range estimation (CRE) which is based on relative signal strength of the first received pulse, precise range measurement (PRM) which is the outcome of the TW-ToF range estimation and the filtered range estimate (FRE) which is the outcome of an internal Kalman filter implementation of the P 410 module combining the CRE and PRM ranges (Dewberry and Beeler 2012). For the validation purposes of the current study, the PRM ranges functionality is selected as the most unaffected outcome of the modules in order to avoid possible filter generated impacts on the FRE range and the instability of the CRE ranges.…”

Ultra-wideband based cooperative relative localization algorithm and experiments for multiple unmanned aerial vehicles in GPS denied environments

“…Note that, in this latest research result, the flight tests were conducted only in a small space due to the limitation of Bluetooth signals. By using UWB signals, our proposed system can operate within at least a 100level 20 region.…”