GNSS Signal Processing Using Frequency Domain Filtering
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Solution Overview
Problem
Existing satellite positioning systems face challenges in efficiently processing GNSS signals due to interference, which requires significant digital resources for filtering and conversion, leading to resource overconsumption, especially in limited FPGA components.
Innovation Solution
The process involves converting the GNSS signal to the frequency domain using a Fourier transform, treating interferential components, filtering using a Bande-Bande filter, transposing in frequency, and then converting back to the time domain, all while reducing the computational resources needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional time-domain filtering and baseband conversion methods are used, then interference suppression is achieved, but digital resource consumption increases excessively
Solution Approach 1:
The patent transitions from time-domain processing to frequency-domain processing by applying Fourier transforms. This dimensional change allows interference filtering to be performed more efficiently in the frequency domain, where selective attenuation of interfering frequency components can be achieved with fewer computational resources than time-domain FIR filters requiring 64 or more coefficients
Solution Approach 2:
The patent changes the domain parameter from time to frequency, enabling the use of frequency-selective filtering. By transforming the signal to the frequency domain, the system can target and attenuate specific interfering frequency components more efficiently, reducing the overall computational burden compared to broadband time-domain filtering approaches
2Object-affected harmful factors
If multi-coefficient FIR filters are used for interference filtering, then filtering performance is improved, but device complexity increases
Solution Approach 1:
The patent moves filtering operations from the time domain to the frequency domain using Fourier transforms. In the frequency domain, filtering is achieved by simple multiplication with a frequency response function, which is computationally simpler than convolving with long FIR filter coefficients in the time domain, thereby reducing device complexity while maintaining filtering performance
3Ease of operation
If frequency transposition is performed in the time domain, then baseband conversion is achieved, but computing resources are significantly consumed
Solution Approach 1:
The patent performs frequency transposition and baseband conversion in the frequency domain rather than the time domain. By applying Fourier transforms, the system can efficiently shift frequency components and perform baseband conversion through simple frequency offset operations in the spectral domain, which requires fewer computational resources than time-domain mixing and filtering operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies digital operations, improves signal processing performance, and reduces the consumption of digital resources, allowing for more efficient use of FPGA components and enabling additional functions without resizing existing FPGAs.
Implementation Method 1
conversion of the radionavigation signal in the frequency domain by means of a Fourier transform so as to obtain a frequency radionavigation signal comprising several frequency components
Implementation Method 2
filtering of the digital frequency signal thus processed by means of a band-stop filter to obtain a filtered frequency radionavigation signal
Implementation Method 3
conversion of the baseband frequency radionavigation signal by means of an inverse Fourier transform in order to obtain a time baseband radionavigation signal in which interference has been attenuated/suppressed
Data Source
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AI summary
The invention relates to a method for processing a radionavigation signal from at least one satellite, said method comprising the following steps implemented in a processing unit (2) of a radionavigation receiver (1): - conversion (102) of the radionavigation signal in the frequency domain by means of a Fourier transform so as to obtain a frequency radionavigation signal comprising several frequency components; - processing (103) of the frequency radionavigation signal so as to process at least one frequency component called the interfering component, said component thus processed having been either attenuated or canceled; - filtering (104) of the digital frequency signal thus processed by means of a band-stop filter to obtain a filtered frequency radionavigation signal;- frequency transposition (105) of the filtered frequency radionavigation signal in order to obtain a baseband frequency radionavigation signal; - conversion (106) of the baseband frequency radionavigation signal by means of an inverse Fourier transform in order to obtain a time baseband radionavigation signal in which interference has been attenuated/suppressed.