Reconfigurable Code Space Search for Fast GPS Signal Acquisition
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Solution Overview
Problem
Current GPS systems require a lengthy initial signal acquisition phase, taking 5 to 10 minutes for a cold start, which limits the response time in emergency communication situations due to the need to search a two-dimensional code-phase delay and Doppler frequency shift space.
Innovation Solution
A dynamically reconfigurable code space search system that performs coherent integration tasks, using a searcher and accelerator to generate energy values and non-coherent energy summations, allowing for flexible search space dimensions and reduced acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional sequential search method is used to search the two-dimensional code-phase delay and Doppler frequency shift space, then the search is thorough and reliable, but the acquisition time is long (5 to 10 minutes for cold start)
Solution Approach 1:
The patent divides the code space search into multiple independent tasks that can be executed in parallel. The search space is segmented into different code-phase delay ranges and Doppler frequency shift ranges, with each task handling a specific segment. This segmentation allows simultaneous processing of multiple search regions, dramatically reducing the total acquisition time while maintaining thorough coverage of the entire search space.
Solution Approach 2:
The patent implements dynamic task configuration where the number and parameters of search tasks can be adjusted based on signal conditions. The system dynamically configures coherent integration hypotheses and task parameters to optimize the balance between search speed and reliability. This dynamic adaptation allows the system to maintain reliable acquisition performance while minimizing acquisition time under varying operational conditions.
2Measurement precision
If the search space dimensions are increased to improve search accuracy, then the measurement precision is improved, but the device complexity and processing requirements increase
Solution Approach 1:
The patent segments the large search space into multiple smaller, manageable task regions. Each task operates on a subset of the total search space with reduced complexity, while the collective set of tasks provides comprehensive coverage. This segmentation allows the system to achieve high measurement precision through fine-grained searching in each segment without requiring a single overly complex processing unit.
Solution Approach 2:
The patent creates a universal task structure that can handle multiple search configurations through programmable parameters. The same basic task template can search different code-phase delay ranges, Doppler frequency shift ranges, and integration time periods by simply changing configuration parameters. This multi-functionality reduces device complexity by avoiding the need for separate dedicated hardware for each search dimension while maintaining full search capability.
Data Source
AI summary
Apparatus and methods of implementing code space search of received signals are described herein. A code space search is implemented as a searcher that perform a subtask that is dynamically reconfigurable at each boundary of an initial integration time. Each particular subtask sets forth a programmable configuration of coherent integration hypothesis that are performed during the initial integration time. The searcher stores the results of the coherent integration hypothesis in a first portion of memory. A search accelerator operates on the initial integration results. The search accelerator can perform coherent integration of various frequency bins of different timing hypothesis, can generate energy values of the coherent integration results, and can generate a non-coherent energy summation. The energy values of the coherent integrations and non-coherent energy summations are stored in a second portion of memory. The ability to reconfigure the subtasks and accelerator operation provides flexibility in search space dimensions.