Satellite Transponder AGC Using PID Control Under AWGN Jamming
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Solution Overview
Problem
Conventional automatic gain control (AGC) schemes in satellite transponder systems struggle to effectively manage signal amplitude fluctuations under partial-time partial-band additive white Gaussian noise (AWGN) jamming, leading to increased inter-modulation levels and degraded link performance.
Innovation Solution
A PID-based automatic gain control method is introduced, which involves receiving sample signals, determining different block sizes, and computing signal-amplitude-ratio (SAR)-based gain values. The method calculates gain control values using a combination of SAR values, tracking errors, and derivative terms to anticipate and respond to amplitude fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AGC scheme using predefined LUT is used, then the system performs well in specified environments with small fluctuations, but it cannot handle large amplitude variations caused by frequency hopping and jamming signals
Solution Approach 1:
The patent implements a dynamic AGC scheme that adapts its block size based on signal conditions. When large amplitude variations are detected (indicating frequency hopping or jamming), the system automatically switches to a smaller block size to respond faster. This dynamic adaptation allows the AGC to maintain reliability in normal conditions while gaining versatility to handle extreme amplitude variations, directly resolving the contradiction between stable performance and adaptability.
2Speed
If SAR-based AGC computes gain control value based on tracking errors at previous time instant, then the system responds to significant changes, but it cannot anticipate future events and provide satisfied control performance
Solution Approach 1:
The patent applies preliminary action by using derivative terms in the PID controller to predict future tracking errors based on current error trends. Instead of merely reacting to past errors, the derivative component anticipates where the error is heading and pre-adjusts the gain control value accordingly. This allows the system to maintain fast response while improving control precision by acting before the full error manifests, resolving the contradiction between speed and accuracy.
3Object-affected harmful factors
If frequency hopping algorithm is applied for anti-jamming, then the system resists AWGN jamming, but it increases uncertainty of amplitude fluctuations caused by jamming signals and channel noise
Solution Approach 1:
The patent segments the signal processing into variable block sizes to handle different signal conditions. By dividing the continuous signal stream into manageable blocks of adaptive size, the system can process frequency-hopped signals more effectively. Smaller blocks capture rapid amplitude changes from frequency hopping, while larger blocks provide stability during normal operation. This segmentation approach maintains anti-jamming capability while reducing amplitude fluctuation uncertainty, resolving the contradiction between resistance and stability.
Data Source
AI summary
The present disclosure provides a method, a system and a storage medium of PID-based automatic gain control for a satellite transponder system. The method includes receiving a sequence of sample signals; determining two different block sizes where a block size of a first block is greater than a block size of a second block; using the block size of the first block to compute a first signal-amplitude-ratio (SAR)-based gain value and using the block size of the second block to compute a second signal-amplitude-ratio (SAR)-based gain value by the AGC processor through the sequence of sample signals; calculating a to-be-applied gain control value of an m-th transmitted symbol at a n-th time step; and calculating a new AGC gain at the n-th time step according to the to-be-applied gain control value at the n-th time step and a corresponding AGC gain at the (n−1)-th time step.