Mobile Receiver Positioning Using Multi-Frequency Carrier Phases
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Solution Overview
Problem
Existing positioning systems struggle to accurately determine the location of mobile receivers in both indoor and outdoor environments with a large range, are costly due to wide frequency transmission bandwidths, and are affected by multi-path signals, leading to sensitivity issues and lengthy determination processes.
Innovation Solution
A system using synchronized stationary transmitter bases transmitting unmodulated pure carrier signals, allowing the mobile receiver to calculate time-of-flight differences through Fourier transforms on measured phases, distinguishing direct and bounced signals, and determining its position autonomously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If modulated radio frequency signals with wide frequency bandwidth are used for positioning, then positioning precision can be achieved, but system cost increases significantly
Solution Approach 1:
The patent extracts only the essential carrier signal transmission function, removing the complex modulation and wide bandwidth requirements. By using simple unmodulated continuous wave carrier signals, the system achieves positioning functionality without the costly wideband transmission infrastructure, directly resolving the contradiction between precision and cost.
Solution Approach 2:
The patent changes the signal transmission parameters from wideband modulated signals to narrowband unmodulated carrier waves. This parameter change maintains positioning capability through phase measurement while dramatically reducing the required transmission bandwidth and associated system costs.
2Measurement precision
If phase interferometry with super-resolution algorithms is used to avoid multi-path disturbances, then measurement accuracy improves, but noise band increases and sensitivity decreases
Solution Approach 1:
The patent segments the received signal analysis by measuring phase at multiple distinct frequency points and processing them separately through Fourier transform. This segmentation approach allows the system to identify and isolate direct path signals from multi-path signals in the frequency domain, achieving accurate measurement without requiring super-resolution algorithms that increase noise band.
Solution Approach 2:
The patent converts the potential harm of multi-path signals into a benefit by using the frequency diversity of multi-frequency carrier signals. The multi-path signals arrive with different time delays and thus different phase shifts at each frequency, allowing the system to distinguish and eliminate them through Fourier transform processing, while the direct path signal remains consistent across frequencies.
3Measurement precision
If the mobile receiver successively determines the position of multiple transmitter bases, then positioning can be achieved, but the determination process becomes lengthy and expensive
Solution Approach 1:
The patent implements preliminary action by having the mobile receiver simultaneously measure the phase of carrier signals from multiple transmitter bases in parallel rather than successively. The receiver equipped with multiple antennas can perform phase measurements on all visible bases concurrently, and the Fourier transform processing simultaneously determines distances to all bases, dramatically reducing the overall positioning determination time.
Solution Approach 2:
The patent merges the positioning determination process by combining phase measurements from multiple transmitter bases into a single integrated Fourier transform operation. Instead of separately determining position for each base and then cross-referencing, the system processes all measurements together to directly compute the mobile receiver's position, reducing computational steps and time.
4Loss of information
If wide frequency transmission bandwidth is used for radiolocating systems, then positioning data can be transmitted, but spectrum occupancy increases and cost increases
Solution Approach 1:
The patent extracts only the minimum necessary transmission bandwidth by using unmodulated carrier signals. Since positioning information is derived from phase measurement of simple continuous waves rather than modulated data, the system transmits only the essential carrier frequency without requiring wide bandwidth for data modulation, thereby minimizing spectrum occupancy while maintaining positioning functionality.
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 system achieves accurate positioning with sub-meter precision, low cost, and high sensitivity, operating over 10 km range in both indoor and outdoor environments without GPS, while minimizing spectrum occupancy and noise band.
Implementation Method 1
the mobile receiver comprises: means for measuring, for each given signal frequency and for each respective transmitter base, the phase of the signal consisting of the various signals coming from said base and having said frequency; and computing means connected to the measuring means and to the storage means, and configured to: apply, for each transmitter base, a Fourier transform to a signal consisting of the various measured phases of the radio frequency signals coming from said base; determine, for each transmitter base, from the Fourier transform computed for said base, a time-of-flight between the mobile receiver and said base
Implementation Method 2
each transmitter base being configured to transmit a sum of at least two unmodulated pure carrier signals of different frequencies, each pure carrier signal being in the form of an unmodulated continuous wave
Data Source
AI summary
The invention relates to a system (1) for positioning at least one mobile receiver (2), comprising at least two stationary transmitter bases (4, 4A, 4B). Each transmitter base (4, 4A, 4B) is configured to transmit radio frequency signals (S1A, S1B, sdA, sdB, srA, srB) and to transmit a sum (S1A, S1B) of at least two unmodulated pure carrier signals of different frequencies; and the mobile receiver (2) further comprises: means for measuring phases of the signals; and computing means configured to: apply a Fourier transform to a signal consisting of the various measured phases of the radio frequency signals; determine a time-of-flight between the mobile receiver (2) and each base (4A, 4B); calculate at least one time-of-flight difference between the mobile (2) and two transmitter bases (4A, 4B); determine the position of the mobile receiver (2) from the calculated time-of-flight difference(s).