Radio Signal Overlay Codes for Fast Time Ambiguity Resolution
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Solution Overview
Problem
Current Global Navigation Satellite Systems (GNSS) require several seconds to receive time markers, such as Time of Week (TOW) information, leading to slow time ambiguity resolution.
Innovation Solution
A radio signal device and method utilizing two signal components with specific overlay codes and phase offsets to enable fast time ambiguity resolution, allowing accurate time retrieval within hundreds of milliseconds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time markers such as Time of Week (TOW) information are transmitted in navigation messages, then time information is provided to receivers, but the acquisition time takes several seconds
Solution Approach 1:
The navigation message is segmented into multiple components: a primary code providing coarse time information and overlay codes providing fine time information. The time acquisition process is divided into two stages: first acquiring the primary code for rough time estimation, then using overlay codes for precise time measurement, thereby reducing total acquisition time while maintaining accuracy
Solution Approach 2:
The primary code is designed to provide preliminary time information before the complete navigation message is received. This preliminary time estimate allows the receiver to prepare for the arrival of overlay codes, enabling faster overall time acquisition by performing initial time synchronization in advance
2Speed
If overlay codes with different durations are used in signal components, then fast time ambiguity resolution is enabled, but the device complexity increases
Solution Approach 1:
Overlay codes with different periodicities are used in different signal components. The first overlay code has a duration that is a non-integer multiple of the second overlay code duration, creating a beat frequency effect. This periodic mismatch allows the receiver to determine time ambiguity by measuring the phase relationship between the two codes, enabling fast resolution without complex processing
Solution Approach 2:
The overlay codes act as intermediaries between the primary code and the final time solution. By introducing these intermediate signaling layers with specific duration relationships, the system translates the time ambiguity problem into a measurable phase difference, simplifying the resolution process while maintaining speed
Data Source
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AI summary
The invention concerns a method of resolving a time ambiguity in a receiver based on a received radio signal. The radio signal comprises a first signal component and a second signal component. The first signal component comprises a first code of X1 code symbols, the first code having a duration of C1 units of time, wherein each of the code symbols has a duration of St units of time. Likewise, the second signal component comprises a second code of X2 code symbols, the second code having a duration of C2 units of time, wherein each of the code symbols has a duration of S2 units of time. Either, the code duration C1 of the first signal component and the code duration C2 of the second signal component are chosen such that the start or the end of the first code and the second code have a reference code phase offset of D units of time every 2 N units of time, wherein 2N is equivalent to the least common multiple of C1 and C2. Or, the code duration C1 of the first signal component and the code symbol duration S2 of the second signal component are chosen such that the start or the end of the first code and the second code symbol have a reference code phase offset of D units of time every 2N units of time, wherein 2N is equivalent to the least common multiple of C1and S2. The method comprises acquiring each of the first and second signal components, and performing code symbol synchronization and/or code synchronization for each of the first code and the second code. The method further comprises estimating a code phase offset between the synchronized first code and the synchronized second code, or a code-symbol phase offset between the synchronized first code and the synchronized second code symbol. Finally, the method comprises resolving the time ambiguity of the receiver within a ±N units of time period based on the time-dependent code phase offset or the time-dependent code- symbol phase offset. The invention further concerns radio signal devices.