Staggered Coherent Integration for GPS Glonass Acquisition Sensitivity
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Solution Overview
Problem
GPS and Glonass satellite acquisition sensitivity is limited by the longest coherent integration period, especially when bit boundaries are unknown, leading to sensitivity losses due to bit-edge transitions and periodic flips in Manchester coding, which restricts the duration of coherent integration and affects Doppler searches.
Innovation Solution
The implementation of an integrated circuit and receiver processes that perform staggered coherent integrations and non-coherent combinations of correlation results across multiple sample windows, allowing for improved sensitivity without requiring knowledge of bit edges, and specifically for Glonass, using offset hypothesis frequencies to enhance detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent integration period is extended to improve sensitivity, then acquisition sensitivity is improved, but bit-edge transitions and periodic flips cause sensitivity losses
Solution Approach 1:
The patent divides the coherent integration period into multiple non-overlapping sample windows (e.g., first sample window, second sample window, third sample window) that are staggered relative to each other. Each window performs correlation and coherent integration independently, avoiding the sensitivity losses caused by bit-edge transitions that affect the entire integration period when using a single continuous window.
Solution Approach 2:
The patent employs periodic staggered sample windows that are systematically shifted in time relative to each other. The first sample window starts at a reference time, the second sample window is staggered by a first time offset, and the third sample window is staggered by a second time offset. This periodic staggering ensures that not all windows simultaneously encounter bit-edge transitions, allowing the system to average out the sensitivity losses across multiple windows.
2Measurement precision
If coherent integration period is lengthened to improve detection performance, then signal detection sensitivity is enhanced, but unknown bit boundaries restrict the maximum integration duration
Solution Approach 1:
The patent segments the total coherent integration period into multiple smaller non-overlapping sample windows. By distributing the integration across several staggered windows rather than using one continuous long window, the system achieves an effective longer integration period while each individual window remains short enough to avoid complete signal loss from bit-edge transitions.
Solution Approach 2:
The patent maintains continuous signal detection by using multiple staggered sample windows that collectively cover a longer time period. The staggered timing ensures continuous monitoring of the signal, and the results from all windows are combined to produce the final detection decision, effectively extending the useful integration period beyond what a single window could achieve.
3Measurement precision
If multiple staggered sample windows are used to improve sensitivity, then acquisition sensitivity is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the results from multiple staggered sample windows by non-coherently combining their correlation outputs. This combining process integrates the information from all windows to improve sensitivity while using a systematic approach that manages the complexity through structured signal processing rather than requiring complex hardware for each individual window.
Data Source
AI summary
An integrated circuit for facilitating spread spectrum reception of data having a data bit period includes an hypothesis search circuit (120, 210, 220) operable to correlate a pseudorandom code with a signal input based on a received signal to produce correlation results, and a processor circuit (320) operable to coherently integrate the correlation results over plural sample windows (PreD1, PreD2) staggered relative to each other in the coherent integration interval and to non-coherently combine the coherently integrated results corresponding to the plural sample windows (PreD1, PreD2) to produce a received signal output, whereby enhancing performance. Other circuits, receivers and processes are also disclosed.