GNSS Overlay Sequence Synchronization for Time Ambiguity Resolution
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Solution Overview
Problem
Current radio navigation systems, such as Global Navigation Satellite Systems (GNSS), face challenges in achieving fast and sensitive synchronization between the GNSS time scale and the terrestrial network time scale, leading to significant synchronization errors, especially in snapshot positioning and Assisted GNSS scenarios, which impact positioning accuracy and power consumption.
Innovation Solution
The method involves generating an overlay sequence with a M-ary De Bruijn sequence, modulated onto the radio signal, allowing for efficient time ambiguity resolution by capturing a snapshot of the signal and determining the relative position of the implicit time marker within the time ambiguity interval, thereby synchronizing the receiver's time scale with the GNSS time scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current radio navigation signals are used for snapshot positioning, then positioning service can be provided, but synchronization accuracy deteriorates due to time ambiguity between GNSS time scale and receiver time scale
Solution Approach 1:
The patent introduces an intermediary sequence (e.g., De Bruijn sequence) as a mediator between the GNSS time scale and the receiver time scale. This sequence is embedded in the navigation signal and serves as a reference marker that allows the receiver to accurately determine its position within the time ambiguity interval, thereby resolving the time ambiguity without requiring perfect synchronization between the two time scales.
Solution Approach 2:
The patent applies preliminary action by pre-embedding the intermediary sequence with known properties (such as unique word sequences) into the navigation signal before transmission. This allows the receiver to perform snapshot positioning by simply capturing and correlating the received signal with the known sequence, enabling fast synchronization without requiring prolonged signal processing or prior synchronization.
2Measurement precision
If longer signal processing is used to resolve time ambiguity, then synchronization accuracy improves, but power consumption increases
Solution Approach 1:
The patent applies partial action by using only a portion of the navigation signal (a snapshot) containing the intermediary sequence for time ambiguity resolution, rather than processing the entire signal over an extended period. The intermediary sequence is designed to be detectable within a short time window, allowing the receiver to achieve synchronization accuracy without prolonged signal processing, thus reducing power consumption while maintaining synchronization performance.
3Use of energy by moving object
If fast snapshot positioning is implemented, then power consumption is reduced, but synchronization accuracy deteriorates due to limited signal processing time
Solution Approach 1:
The patent applies local quality by concentrating the synchronization information into a specific local region of the navigation signal - the intermediary sequence. This sequence is designed with unique properties (such as being a De Bruijn sequence or containing a unique word) that make it highly detectable and unambiguous within the snapshot. By focusing the synchronization function into this specific local region rather than distributing it throughout the entire signal, the receiver can achieve accurate synchronization from a short snapshot, enabling fast positioning with low power consumption.
Data Source
AI summary
Embodiment of the invention relate to a Method and related devices for resolving time ambiguity between a radio transmitter of a plurality of transmitters having a first time scale and a radio receiver of a plurality of radio receivers having a second time scale, said radio transmitter being coupled to said radio receiver, said radio transmitter transmitting a radio signal to said radio receiver wherein said method comprising the steps of generating, by said radio transmitter an overlay sequence comprising a set of symbols per time ambiguity interval, said set of symbols having a predetermined length, said overlay sequence satisfying a condition of single occurrence of a subset of symbols within said set of symbols of said time ambiguity interval, each said time ambiguity interval comprising an implicit time marker and transmitting said radio signal, by said radio transmitter to said radio receiver said radio signal comprising said overlay sequence modulated onto a carrier of said radio signal and receiving said radio signal by said radio receiver and capturing a snapshot of said radio signal by said radio receiver (RX1), said snapshot comprising a subset of symbols of said overlay sequence comprising N symbols, processing said snapshot, by said radio receiver to determine a relative position of said implicit time marker of said radio signal based on the position of said subset of symbols included in said snapshot within said set of symbols of said time ambiguity interval and resolving said Time Ambiguity between said first time scale and said second time scale by evaluating a delay between said implicit time marker expressed in said first time scale and based on said processing of said snapshot and said implicit time marker within said overlay sequence generated based on the second time scale wherein said overlay sequence consists of a M-ary sequence which is based on M-ary De Bruijn sequence.