Radio Receiver BOC Signal Processing Architecture
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Solution Overview
Problem
Current GNSS receivers face challenges in accurately processing dual sideband BOC signals due to their multi-lobed autocorrelation function, particularly when the ratio of the sub-carrier frequency to the chip rate is two or more, leading to difficulties in obtaining accurate timing information and navigational positions.
Innovation Solution
A receiver architecture that uses a single downconverter for each sideband, shared across all channels, with chip matched filters and nearest-neighbour sampling, simplifying hardware and reducing power requirements, while processing both sidebands separately to enhance tracking accuracy and reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a chip matched filter followed by nearest-neighbour sampling is used to process BOC signals, then computational efficiency is improved, but signal-to-noise ratio loss increases
Solution Approach 1:
The patent applies preliminary action by implementing the chip matched filter and nearest-neighbour sampling before the correlation process. This pre-processing step transforms the BOC signal into a form that is more suitable for correlation, converting the multi-lobed autocorrelation function into a single-lobed function that is easier to process while maintaining computational efficiency and minimizing signal-to-noise ratio loss.
2Measurement precision
If separate downconverters are used for each channel in BOC signal processing, then processing accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent applies universality by designing a single downconverter that serves multiple channels simultaneously. This downconverter processes signals from multiple satellites across different frequency bands (upper and lower sidebands) using a unified architecture, thereby reducing hardware complexity and power consumption while maintaining tracking accuracy through shared processing resources.
Solution Approach 2:
The patent merges the downconversion functionality into a single shared component that handles all channels. By combining the downconversion operations for multiple satellites and frequency bands into one unified downconverter, the system reduces the number of separate hardware components while preserving the accuracy needed for signal tracking and navigation.
3Device complexity
If a single downconverter is shared across all channels, then device complexity and power consumption are reduced, but processing capability for multiple signals is limited
Solution Approach 1:
The patent applies segmentation by dividing the frequency spectrum into distinct upper and lower sidebands, each handled by separate processing paths within the shared downconverter. This segmentation allows the single downconverter to simultaneously process multiple satellite signals across different frequency bands without interference, maintaining high processing capability while using simplified shared hardware.
Data Source
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AI summary
The disclosed radio receiver comprises a downconverter for downconverting dual sideband signals such as Binary Offset Carrier (BOC)signals from multiple sources to produce an upper and a lower sideband signal, and chip-matched filters for filtering each of the sideband signals. The output of each filter is provided to a series of separate channels, one for each source, where there are at least Early, Prompt and Late gates. Each gate has a nearest-neighbour sampler and a multiplier for multiplying with an appropriate part of a spreading code, a mixer for removing Doppler or other frequency offsets and an integrator. The invention provides a means for demodulating signals such as BOC modulated satellite navigation signals in an efficient manner by using a single downconverter for the received signals of interest from the multiple sources.