Composite Signal Receiver Tracking Without False Zero Crossings
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Solution Overview
Problem
Navigation satellite receivers face synchronization errors and reduced reliability in decoding composite signals, particularly due to false zero crossing points in discriminator functions, leading to instability in demodulation.
Innovation Solution
A method and receiver system that combines received composite signals with local replicas to extract BOC and QBOC components, using amplitude-driven selection to eliminate false zero-crossing points by choosing between BOC and QBOC correlations based on primary and secondary amplitudes for unambiguous code and carrier tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a receiver locks on a false zero crossing point of a discriminator function to track a BOC signal, then carrier tracking can be achieved, but synchronization error occurs and reliability in decoding is reduced
Solution Approach 1:
The patent segments the correlation function evaluation into multiple discrete zero-crossing point checks. Instead of relying on a single discriminator function that may have false zero-crossings, the method evaluates multiple potential zero-crossing points and selects the correct one by checking which point satisfies the unambiguous correlation criteria, thereby resolving the contradiction between achieving tracking and avoiding synchronization errors
Solution Approach 2:
The patent introduces an intermediary verification step between signal correlation and final locking. The method uses an unambiguous correlation function as an intermediary check that validates whether a detected zero-crossing point is correct before final locking occurs. This intermediary layer prevents false locks while maintaining reliable decoding
2Ease of operation
If a receiver uses a discriminator function with false zero crossing points to detect carrier phase, then carrier tracking is possible, but demodulator stability is reduced
Solution Approach 1:
The patent applies preliminary action by performing unambiguous correlation verification before final carrier phase locking. The method预先 checks multiple potential zero-crossing points using the unambiguous correlation function to identify the correct phase point before the demodulator locks, preventing instability caused by false locking while maintaining ease of carrier tracking
3Measurement precision
If a receiver uses BOC correlation alone for signal processing, then in-phase component detection is achieved, but false zero crossing points cause synchronization errors
Solution Approach 1:
The patent merges BOC correlation and QBOC correlation into a unified processing framework. By combining both correlation functions and using the unambiguous correlation verification to select between them, the method achieves accurate signal component detection while eliminating false zero-crossing errors that plague either method when used alone
Data Source
AI summary
A data processor selects a set of BOC correlations in accordance with a BOC correlation function for the sampling period if the primary amplitude exceeds or equals the secondary amplitude for the sampling period. An electronic data processor determines whether the receiver is operating in a steady-state mode by evaluating the detected primary amplitude. The data processor selects and/or processes a set of BOC correlations for the sampling period to track a carrier of the received composite signal if the receiver is operating in the steady-state mode. In one embodiment, the data processor forms a first code error using the selected BOC correlations with a first chip spacing to drive the code tracking.