GNSS Relay Code Carrier Phase Synchronization
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Solution Overview
Problem
In Global Navigation Satellite Systems (GNSS), synchronizing a spreading code with a carrier becomes challenging when signals are generated at a ground-based device and relayed via an intermediary device, such as a communication satellite, rather than being directly transmitted from a satellite.
Innovation Solution
The techniques involve synchronizing the phase of a spreading code with the phase of a relayed carrier signal, ensuring that at the relaying device, the phase of a code modulated by a carrier signal is aligned with the phase of the carrier signal. This is achieved by determining the downlink carrier frequency and code signal, adjusting the phase of the code signal, and initiating the transmission through the relaying device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If signals are generated at a ground-based device and relayed via an intermediary device, then flexibility to alter signal parameters is improved, but phase synchronization between code and carrier deteriorates
Solution Approach 1:
The patent introduces a phase synchronization mechanism that acts as an intermediary between the ground-based signal generator and the relayed carrier signal. This mechanism measures and adjusts the phase difference between the code and carrier, ensuring they remain synchronized despite the signal relay process through the intermediary device.
Solution Approach 2:
The patent implements a feedback loop that continuously measures the phase difference between the spreading code and the carrier signal after relaying. Based on this measurement, the system adjusts the phase of one signal relative to the other to maintain synchronization, creating a closed-loop control system that compensates for phase shifts introduced by the relay process.
2Area of stationary object
If signals are relayed via high-altitude satellites, then coverage area is improved, but signal power at receiver deteriorates
Solution Approach 1:
The patent employs parameter changes by adjusting the phase relationship between the code and carrier signals to optimize their combined amplitude. By synchronizing the phases, the signals constructively interfere, maximizing the received signal power and improving the signal-to-noise ratio, which compensates for the path loss from high-altitude relaying.
3Measurement precision
If code and carrier phases are not synchronized, then time of flight measurement accuracy deteriorates, but signal generation complexity is reduced
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the phase of the spreading code with the carrier signal before transmission and relaying. This preliminary phase alignment ensures that when the signals arrive at the receiver, they remain synchronized, enabling accurate time of flight measurements without requiring complex post-reception processing.
Solution Approach 2:
The patent introduces a phase measurement and adjustment mechanism that serves as an intermediary between signal generation and reception. This intermediary component measures the phase difference and applies corrections to maintain synchronization, thereby enabling precise ToF measurements while managing the complexity through a dedicated synchronization subsystem.
Data Source
AI summary
According to one or more of the embodiments herein, systems and techniques are provided for synchronizing a spreading code with a carrier, such as for Global Navigation Satellite Systems (GNSS) and associated codes which incorporate a navigation message modulated by a spreading code with a carrier, e.g., for facilitating precise measurement of time of flight (ToF) of received weak signals which are relayed via an intermediary device. Specifically, the techniques herein provide for synchronizing the phase of a spreading code with the phase of the relayed carrier signal. The techniques herein ensure that at a relaying device, the phase of a code modulated by a downlink carrier signal is aligned with the phase of the downlink carrier signal.