Radionavigation Receiver AGC Control Against Pulsed Interference
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Solution Overview
Problem
Existing digital radionavigation reception systems face divergence issues due to pulsed interference, which affects the automatic gain control (AGC) loop and prevents accurate signal demodulation, as the loop reacts to frequent interference pulses by increasing gain, leading to excessive cancellation of signals.
Innovation Solution
A power inversion module is introduced to estimate and filter the digitized signal's power, inverting it to determine an adaptive gain that is applied to the signal, compensating for filtering delays and modifying the AGC loop's input, thereby reducing interference impact without requiring a prior cancellation threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If temporary signal cancellation technique is used to suppress pulsed interference, then interference suppression is improved, but AGC loop stability deteriorates due to artificial decrease in average power measurement
Solution Approach 1:
The patent applies inversion by switching from conventional cancellation (zeroing signal during interference) to reinforcement (amplifying signal during interference). The adaptive gain controller applies a gain greater than 1 during detected interference pulses, inverting the conventional approach. This prevents the artificial power decrease that causes AGC divergence while still suppressing interference through subsequent processing stages.
Solution Approach 2:
The patent converts the harmful interference pulses into a beneficial effect by using them to trigger adaptive gain reinforcement. The interference detection mechanism identifies pulses and the adaptive controller uses this information to apply compensating gain, effectively converting the harmful interference event into an opportunity for signal reinforcement and AGC stabilization.
2Object-affected harmful factors
If fixed threshold cancellation is applied, then interference suppression is improved, but signal quality deteriorates due to excessive signal zeroing
Solution Approach 1:
The patent replaces the static fixed threshold approach with a dynamic adaptive gain controller that adjusts the gain factor in real-time based on interference detection. Instead of always cancelling signals above a fixed threshold, the system dynamically applies reinforcement gain only during detected interference events, adapting to varying signal and interference conditions to maintain signal quality.
Solution Approach 2:
The patent changes the parameter being controlled from binary cancellation (zero or full signal) to continuous adaptive gain reinforcement. The gain factor becomes a variable parameter that is adjusted based on interference detection, allowing fine-grained control that preserves signal quality while suppressing interference, rather than the all-or-nothing fixed threshold approach.
Data Source
AI summary
A system for receiving an analogue signal e includes amplifying and digitizing the signal in order to obtain a digitized signal en, a power inversion module, the module determining an inversion gain g2, this gain being applied to the digitized signal en, an automatic gain control AGC loop adapting the power of the signal e before digitization, the input signal of the AGC loop being a function of the inversion gain g2.