Satellite Terminal Geolocation via Doppler Shift Analysis
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Solution Overview
Problem
Existing methods for geolocating satellite telecommunications terminals using non-geostationary, transparent moving satellites are complex and require multiple antennas, making them inefficient for simple and accurate positioning.
Innovation Solution
A method that uses temporal evolutions of radio frequency parameters, such as Doppler shift and transit time, to determine the position of a satellite terminal without explicit position exchange or waveform change, utilizing a single antenna and analyzing signals exchanged with a known terminal to passively locate the terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direction finding methods are deployed at the satellite level using multiple antennas, then the emission source can be located, but the device complexity increases and multiple antennas are required
Solution Approach 1:
The patent introduces a second terminal with known position as an intermediary element. Instead of using multiple antennas at the satellite, the system uses signals exchanged between the first terminal (to be located) and the second terminal (known position) via the satellite. This intermediary terminal enables geolocation through temporal evolution analysis of radiofrequency parameters, eliminating the need for complex multi-antenna direction finding at satellite level.
2Loss of information
If explicit position exchange messages are used, then the position can be obtained, but the communication protocol complexity increases and waveform changes are required
Solution Approach 1:
The system enables the first terminal to be located passively without requiring it to send explicit position information. The terminal simply exchanges normal communication signals with the second terminal, and the geolocation is derived from the temporal evolution of radiofrequency parameters of these signals. This self-service approach eliminates the need for additional position reporting messages or waveform modifications.
3Measurement precision
If GNSS-type solutions are used, then the position can be obtained, but the solution is not always available or broadcastable by radio
Solution Approach 1:
The patent uses the satellite communication infrastructure itself as an intermediary to enable passive geolocation. By analyzing the temporal evolution of radiofrequency parameters in signals already exchanged through the satellite, the system provides position information without relying on external GNSS signals. This makes the solution available in environments where GNSS may not be accessible or reliable.
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
Enables accurate and efficient geolocation of satellite terminals using signals from a transparent moving satellite, eliminating the need for GNSS and multiple antennas, allowing for precise positioning without initial terminal position knowledge.
Implementation Method 1
The present invention exploits the temporal evolutions of one or more radiofrequency parameters of the link generated by the transparent scrolling constellations dependent on the position of the first terminal
Implementation Method 2
The present invention exploits the temporal evolutions of one or more radiofrequency parameters of the link generated by the transparent scrolling constellations dependent on the position of the first terminal
Data Source
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AI summary
Method of geolocating a first satellite telecommunications terminal (20) via a transparent orbiting satellite (10), comprising, for N signals received from said first terminal at successive times t by the second terminal (30): calculating each successive value TT(t) of the signal transit time at each of the N successive times t and considering that in addition TT(t) satisfies the following theoretical formula considered at each of said times t: TTt=1cXTxt−XSatt2+YTxt−YSatt2+ZTxt−ZSatt2=XRxt−XSatt2+YRxt−YSatt2+ZRxt−ZSatt2 with: (XSat(t);YSat(t),ZSat(t)) : the known coordinates of the satellite at time t; (XTx(t),YTx(t),ZTx(t)): the unknown coordinates of the first terminal at time t; (XRx(t);YRx(t);ZRx(t)): the known coordinates of reception at time t. Determine the geolocation of the first terminal at at least one of said times t.