Fractional Chip Correlation Device for Spread Spectrum Receiver
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Solution Overview
Problem
Conventional spread spectrum signal receivers face high power consumption due to the need for high operation speed in fractional chip correlation, which is necessary for accurate satellite acquisition and tracking in systems like GPS, leading to increased energy expenditure.
Innovation Solution
The fractional chip correlation device and method reduce power consumption by down-sampling signals with different delays and correlating them with local code replicas at a lower sampling rate, allowing correlators to operate at a reduced speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sampling rate correlation is used to maintain accurate signal processing, then measurement precision is improved, but use of energy by moving object increases
Solution Approach 1:
The patent segments the correlation process into two distinct stages: a coarse correlation stage that operates at low sampling rate to identify approximate signal presence, and a fine correlation stage that operates at high sampling rate only when needed to confirm detection and measure precise signal parameters. This segmentation allows the system to maintain measurement precision when necessary while dramatically reducing average power consumption by limiting high-speed operations to brief intervals rather than continuous operation.
Solution Approach 2:
The patent implements periodic switching between low sampling rate correlation and high sampling rate correlation based on detection needs. The system periodically performs coarse correlation at low rate, and only transitions to high-rate fine correlation when the coarse stage indicates potential signal presence. This periodic action pattern ensures measurement precision is maintained through occasional high-precision operations while minimizing energy consumption through predominant low-power operation.
2Measurement precision
If high operation speed is used for fractional chip correlation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the correlator functionality into two operational modes: a coarse correlation mode that uses simplified processing at low sampling rate to perform initial satellite acquisition, and a fine correlation mode that employs full-precision processing at high sampling rate only for confirmed signal detection and precise tracking. This segmentation reduces device complexity by avoiding the need for continuous high-speed operation while maintaining measurement precision when required.
Solution Approach 2:
The patent dynamically changes the sampling rate parameter based on the operational stage: using low sampling rate for coarse correlation to reduce complexity, and switching to high sampling rate for fine correlation to maintain precision. This parameter change strategy allows the system to adapt its complexity level to the actual processing needs, avoiding unnecessary computational burden during acquisition while ensuring accuracy during tracking and measurement phases.
Data Source
AI summary
A fraction chip correlation device for a spread spectrum receiver for receiving signals modulated with spread spectrum codes and a method for operating fractional chip correlation to spread spectrum signals received by the spread spectrum receiver are disclosed. In the present invention, at least one delayed version of an input signal is generated to be correlated with a local code replica to accomplish fractional chip correlation. By doing so, correlators can operate at a low speed, so that power consumption of the receiver can be significantly reduced.