UWB Pulse Shaping With Precursor Phase Shift for Multipath Ranging
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Solution Overview
Problem
Ultra-wideband pulse measurements in multipath environments suffer from precision loss due to interference from multipath components, especially when the receiver filter alters the shape of direct and multipath signals, affecting the accuracy of time of arrival measurements.
Innovation Solution
Generate ultra-wideband pulses with a main pulse and a shorter, lower-amplitude precursor pulse, phase-shifted relative to the main pulse, to create a steeper leading edge that is less affected by multipath interference and filter smoothing, enhancing measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a short ultra-wideband pulse with steeper rise time is used, then time of arrival measurement precision is improved, but the pulse is more susceptible to multipath component interference
Solution Approach 1:
The pulse is segmented into two distinct parts: a precursor pulse and a main pulse. The precursor pulse is positioned before the main pulse in time and has a different amplitude level. This segmentation allows the leading edge of the main pulse to be used for time of arrival measurement while the precursor provides reference information for multipath mitigation through algorithms like precision time of flight.
Solution Approach 2:
The pulse parameters are changed by introducing a precursor pulse with specific amplitude and timing relationships. The precursor pulse amplitude is controlled relative to the main pulse amplitude, and its position is adjusted to optimize the measurement process. This parameter modification enables the system to distinguish between direct path and multipath components.
2Reliability
If the receiver filter is applied to process the signal, then noise is reduced, but the shape of the direct path signal and multipath signal is altered, slowing the leading edge
Solution Approach 1:
The precursor pulse is transmitted before the main pulse, providing preliminary information to the receiver. This preliminary action allows the receiver to prepare for the arrival of the main pulse and to use the precursor as a reference for compensating filter effects. The precursor-main pulse structure enables the system to maintain measurement precision even after filtering by providing a reference point for time of arrival calculation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method improves measurement accuracy by ensuring a steeper leading edge for the main pulse, reducing the impact of multipath components and filter distortion, thereby enhancing ranging and sensing performance in noisy conditions.
Implementation Method 1
The term 'downward energy' can be understood from the effect of having signal energy for the precursor pulse out of phase with that of the main pulse, which may destructively interfere with the beginning of the main pulse, e.g., in the receiver filter, thereby resulting in the steeper rise time of the main pulse.
Data Source
AI summary
A method for generating an ultra-wideband signal is provided. The method comprises the steps of generating at least one ultra-wideband pulse envelope comprising a main pulse and a precursor pulse, the precursor pulse being shorter in length and lower in amplitude compared to the main pulse, and modulating a carrier signal in amplitude such that the envelope corresponds to the at least one ultra-wideband pulse envelope and such that the carrier signal within the main pulse is phase-shifted with respect to the carrier signal within the precursor pulse.