GPS Receiver Parallel Synchronization Reduces Time to First Fix
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Solution Overview
Problem
Conventional GPS receivers experience prolonged time-to-first-fix (TTFF) due to time-consuming bit synchronization, frame synchronization, and demodulating the hand-over word processes, which are sensitive to signal strength and interference, and inefficient use of channel resources.
Innovation Solution
A GPS receiver with a correlator having multiple demodulator channels and a processor that performs parallel synchronization, allowing all channels to track a satellite's signal with different timing hypotheses, retaining only the correct one, and eliminating the need for bit synchronization and HOW demodulation for subsequent satellites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sequential bit synchronization, frame synchronization, and HOW demodulation processes are used for each satellite, then synchronization accuracy is achieved, but time-to-first-fix is prolonged
Solution Approach 1:
The patent performs bit synchronization, frame synchronization, and HOW demodulation in parallel before satellite tracking begins. By completing these synchronization tasks preliminarily using multiple demodulator channels, the system eliminates the need to perform these steps sequentially for each satellite, thereby reducing time-to-first-fix while maintaining synchronization accuracy
Solution Approach 2:
The patent divides the synchronization process into separate parallel tasks that can be executed simultaneously by different demodulator channels. Each channel handles specific synchronization functions independently, allowing the system to process multiple satellites' synchronization requirements concurrently rather than sequentially, thus reducing overall processing time
2Reliability
If one demodulator channel is allocated per satellite for independent parallel processing, then synchronization reliability is maintained, but channel resource efficiency deteriorates
Solution Approach 1:
The patent makes demodulator channels universal by allowing them to perform multiple functions: initial signal acquisition, bit synchronization, frame synchronization, and HOW demodulation. Instead of dedicating one channel per satellite, the same pool of channels can be dynamically allocated to different satellites at different stages, improving resource efficiency while maintaining reliability through proper channel management
Solution Approach 2:
The patent implements dynamic channel allocation where demodulator channels are not statically assigned to specific satellites but are dynamically allocated based on current processing needs. Channels can be reassigned between satellites as synchronization progresses, allowing the system to optimize resource utilization while maintaining the reliability needed for accurate synchronization
Data Source
AI summary
A global positioning system receiver with a system and method for parallel synchronization. The novel receiver includes a correlator having plural demodulator channels for receiving a signal from a first satellite, and a processor for processing the signal from the first satellite using a plurality of the channels. The processor includes a parallel synchronization process for synchronizing the receiver with the signal. In an illustrative embodiment, the processor is adapted to instruct the plurality of channels to track the signal from the first satellite in parallel, each channel using a different timing hypothesis. Only the channel determined to have the correct timing is retained for tracking the satellite. For the first satellite only, the processor also demodulates the hand-over word and determines a GPS transmit time. The parallel synchronization process is then repeated for subsequent satellites in turn.