Methods and system for multi-path mitigation in tracking objects using reduced attenuation RF technology

Abstract

A method and system for a long range Radio Frequency (RF)-based identification, tracking and locating of objects. The method and system use a narrow bandwidth ranging signal(s), including VHF of lower frequency bands, which minimizes propagation loss and loss of accuracy of the RF locating signals. The method and system includes narrow bandwidth ranging signal multi-path mitigations processor, which further improves the track-locate accuracy. The signal is sent from a Master Unit(s) to a Tag. The signal traveling time is recorded and the distance between the Master(s) and the Tag is calculated. The method and system allow achieving a longer distance of the RF narrow bandwidth ranging signal penetration and an increased accuracy by using VHF bands in conjunction with the narrow bandwidth ranging signal multi-path mitigations processor. The techniques of Digital Signal Processing and Software-Defined Radio are used. The actual waveforms transmitted and received by the radios are defined by the software. The roles of the Master Unit(s) and the Tag can be reversed.

Description

technical field [0001] The present invention relates to methods and systems for radio frequency (RF) based identification, tracking and location of objects, including RTLS (Real Time Location Service). Background technique [0002] RF-based identification and location finding systems for determining the relative or geographic location of objects are generally used to track individual objects or groups of objects, as well as to track individuals. Conventional position finding systems have been used for position determination in open outdoor environments. RF-based Global Positioning System (GPS) and Assisted-GPS are commonly used. However, conventional position finding systems have certain inaccuracies in locating objects in closed (ie, indoor) environments as well as outdoors. [0003] Indoor and outdoor location inaccuracies are mainly due to the physics of RF propagation, especially due to loss / attenuation of the RF signal, signal scattering and reflections. Loss / attenua...

AI Technical Summary

Problems solved by technology

Therefore, at VHF and lower frequencies, the size of the antenna array will significantly affect the portability of the unit

[0008] On the other hand, due to the very limited spectrum, narrow-bandwidth ranging signals are not conducive to the multipath mitigation techniques currently used by conventional RF-based identification and position-finding systems

The reason is that the ranging signal distortion (i.e., the change in signal) induced by multipath is too small to be reliably detected / processed in the presence of noise

Also, due to limited bandwidth, narrow bandwidth receivers cannot distinguish between the direct line-of-sight (DLOS) path of the ranging signal and the delayed ranging signal path when these paths are separated by small delays, because narrow bandwidth receivers lack The desired time resolution, which is proportional to the bandwidth of the receiver (e.g. narrow bandwidths have an integral effect on the incoming signal)

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