Code Phase Signalling Module for Direct Sequence Spread Spectrum Signal Acquisition
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Solution Overview
Problem
In satellite navigation systems like GPS and Galileo, the acquisition of direct sequence spread spectrum signals can be hindered by low signal levels and multipath propagation, leading to challenges in synchronizing with satellite signals, especially in portable devices and urban areas where signal strength is impaired.
Innovation Solution
A code phase signalling module provides assistance to synchronize the phase of a synchronization code with the modulation code of direct spread spectrum signals, using code phase time signalling that is independent of code length, allowing synchronization with past, present, or future received portions of the code sequence, and can be transmitted via a cellular air interface to aid in signal acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct sequence spread spectrum transmission is used in satellite navigation systems, then multi-user access and immunity to interference are improved, but signal acquisition becomes more difficult due to low signal levels and multipath propagation
Solution Approach 1:
The system performs preliminary actions by generating acquisition assistance data that contains code phase information and Doppler frequency offset data before the actual signal acquisition process. This preliminary data preparation enables the receiver to start the correlation process with reduced search space, directly addressing the difficulty of detecting weak satellite signals in the presence of multipath interference
2Measurement precision
If code phase time signalling is provided to assist signal acquisition, then synchronization accuracy is improved, but device complexity increases due to additional signalling requirements
Solution Approach 1:
The acquisition assistance data structure is designed to serve multiple functions simultaneously: it provides code phase alignment information, Doppler frequency offset compensation, and signal acquisition timing. By making the signalling system multi-functional, the patent reduces the need for separate dedicated systems for each function, thereby managing complexity while maintaining high measurement precision
3Device complexity
If the receiver searches for satellite signals without assistance data, then device complexity is reduced, but acquisition time increases significantly
Solution Approach 1:
The system applies partial action by providing acquisition assistance data that covers only the essential parameters needed for initial signal acquisition (code phase and Doppler frequency), rather than providing complete navigation data. This partial provision of information is sufficient to dramatically reduce acquisition time while keeping the receiver structure relatively simple
Data Source
AI summary
A code phase signalling module arranged to provide code phase signalling to assist in signal acquisition of direct sequence spread spectrum signalling received by a receiver module from a transmitter module. The code phase signalling is arranged to be used by the receiver module to synchronise the phase of a synchronisation code provided from within the receiver module with the phase of a modulation code of the direct spread spectrum sequence signalling received by the receiver module. The synchronisation code sequence corresponds to the modulation code sequence. The code phase signalling module is arranged to provide code phase time signalling representing the offset time of the synchronisation code from a reference time. The reference time is associated with the time of transmission of a particular reference portion of the modulation code of the direct spread spectrum signaling.