Satellite Receiver Demodulation Using Early Correlation Sums
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Solution Overview
Problem
Existing satellite receiver technologies require a significant amount of time to start data demodulation, which delays the determination of a mobile device's position, particularly in emergency situations where quick location determination is critical.
Innovation Solution
The method involves correlating wireless signals with a local reference signal and storing initial correlation results without knowing the data bit's edge, allowing for early data collection and demodulation once the bit's location is determined, thereby reducing the time to initiate data demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data collection is performed sequentially after bit edge detection, then data demodulation can be performed with accurate bit synchronization, but the time required to start data demodulation is delayed
Solution Approach 1:
The patent performs data collection and correlation operations before bit edge detection is complete. Integration sums are accumulated in advance during the bit edge detection period, and data demodulation is then performed using these pre-collected sums. This preliminary action eliminates the sequential delay while maintaining synchronization accuracy through post-detection grouping of the collected data.
Solution Approach 2:
The patent enables continuous data collection and integration throughout the entire signal acquisition process, rather than pausing for bit edge detection. The correlation and integration operations continue uninterrupted, accumulating useful data sums that can be immediately processed for demodulation once detection is complete, maximizing the utilization of available signal data.
2Measurement precision
If bit edge detection is performed before data demodulation, then data can be accurately synchronized to bit transitions, but the overall processing time is increased
Solution Approach 1:
The patent performs data collection and integration in advance during the bit edge detection phase. Integration sums are accumulated continuously before and during detection, so that when bit edge detection completes, the data is already prepared and synchronized for immediate demodulation. This eliminates the sequential processing delay while maintaining accuracy.
Solution Approach 2:
The patent merges the data collection phase with the bit edge detection phase by performing correlation and integration operations simultaneously throughout the detection process. Instead of separate sequential steps, both functions operate concurrently, combining their useful actions into a single integrated processing flow that improves productivity without sacrificing synchronization accuracy.
Data Source
AI summary
An apparatus and method begin creation and storage of correlation sums to be demodulated (“early-collected sums”) prior to determination of a location of a bit of data in a wireless signal relative to a local clock. Such early storage allows demodulation of these early-collected sums at a later time, specifically on determination of the data's location in the wireless signal, thereby to yield early-collected data bits. Additionally, after determination of the data bit's location in the wireless signal, additional data bits are further generated in the normal manner, by demodulating the wireless signal, thereby to yield normally-collected data bits. Use of early-collected data bits in generating navigation data reduces the time to start data demodulation, and enables fewer normally-collected data bits to be used to generate navigation data, in several aspects of the invention.