Radio Receiver Obtruding Signal Detection via Nyquist Translation
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Solution Overview
Problem
Radio receivers face challenges in completely eliminating aliasing effects during analog-to-digital conversion, as anti-aliasing filters do not always suffice, leading to residual issues such as phony or interfering signals due to obtruding signals.
Innovation Solution
A radio receiver system that performs frequency translation operations on an oversampled baseband signal to detect obtruding signals by comparing signal levels before and after translation, allowing for the determination of obtruding signal presence and adjusting receiving parameters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an anti-aliasing filter is applied prior to analog-to-digital conversion, then aliasing effects are reduced, but residual aliasing effects still remain
Solution Approach 1:
The patent divides the aliasing mitigation process into two independent stages: (1) analog anti-aliasing filtering before ADC, and (2) digital aliasing detection and mitigation after ADC. This segmentation allows each stage to address specific aspects of aliasing without compromising the other, thereby achieving more complete elimination of aliasing effects.
Solution Approach 2:
The patent implements a feedback mechanism where the digital baseband signal is frequency-translated to detect aliasing components, and this detection information is used to adjust receiving parameters. This closed-loop feedback enables continuous mitigation of residual aliasing effects that the open-loop analog filter cannot eliminate.
2Measurement precision
If frequency translation operations are performed on oversampled baseband signal to detect obtruding signals, then detection accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent applies frequency translation only to the necessary portion of the signal spectrum for aliasing detection, rather than processing the entire signal. By focusing computational resources on detecting aliasing components at specific frequency locations, the system achieves high detection accuracy while avoiding unnecessary processing complexity.
Solution Approach 2:
The patent introduces frequency translation as an intermediary operation that converts hard-to-detect aliasing components into detectable forms. This intermediary step enables accurate obtruding signal detection without requiring complex direct detection methods, thereby balancing detection accuracy and processing complexity.
3Reliability
If receiving parameters are adjusted based on obtruding signal detection, then reception quality is improved, but system complexity increases
Solution Approach 1:
The patent implements dynamic adjustment of receiving parameters based on real-time obtruding signal detection results. The system adapts filter parameters and processing configurations dynamically according to the detected aliasing conditions, thereby improving reception quality without requiring a completely complex static system design.
Solution Approach 2:
The patent changes receiving parameters (such as filter cutoff frequencies and processing gain) based on the detected obtruding signal characteristics. By adjusting parameters rather than redesigning the entire system, the patent improves reception quality while minimizing the increase in system complexity.
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
Effectively identifies and mitigates aliasing effects by determining the presence and impact of obtruding signals, enabling improved signal processing and reception quality by adjusting filter parameters and reducing unnecessary processing complexity.
Implementation Method 1
a mixer arranged to mix a received signal to an analog baseband signal at or close to zero-frequency
Implementation Method 2
a filter arranged to low-pass filter said analog baseband signal
Implementation Method 3
an analog-to-digital converter arranged to oversample, with an oversampling rate, said filtered analog baseband signal at a sample frequency such that a digital baseband signal is formed
Implementation Method 4
a frequency translator arrangement arranged to translate the digital baseband signal around a Nyquist frequency being based on a nominal sample frequency
Data Source
AI summary
A method of detecting an obtruding signal in a radio receiver, a receiver and a computer program are disclosed. The receiver has a mixer arranged to mix a received signal to an analog baseband signal at or close to zero-frequency, a filter arranged to low-pass filter said analog baseband signal, and an analog-to-digital converter arranged to sample said filtered analog baseband signal at a sample frequency such that a digital baseband signal is formed. The method comprised receiving a radio frequency signal, mixing the radio frequency signal to the analog baseband signal at or close to zero-frequency, low-pass filtering said analog baseband signal, and analog-to-digital converting said filtered analog baseband signal at an over sample frequency such that a digital baseband signal is formed. The method further comprises frequency translating the digital baseband signal around a Nyquist frequency being based on a nominal sample frequency, the nominal sample frequency being a fraction of the oversampling frequency according to the oversampling rate, to form a translated digital baseband signal such that signal content of the digital baseband signal around zero frequency will be translated to around the nominal sample frequency and vice versa in the translated digital baseband signal, determining a first signal level at zero frequency of the digital baseband signal and a second signal level at zero frequency of the translated digital baseband signal, detecting an obtruding signal based on a relation between the first and second signal levels, and outputting an obtruding signal state signal.