Receiver AGC Using Sample Threshold Counts Against Jammer Signals
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Solution Overview
Problem
Conventional communication systems face reduced performance due to jammer signals with high peak-to-average power ratios (PAPRs) in Ultra-Wide Band (UWB) systems, which affect the receiver's ability to optimize signal reception.
Innovation Solution
An automatic gain controller (AGC) in the communication system adjusts the gain of the analog front end by counting in-phase and quadrature phase digital samples above and below dynamic thresholds, dynamically changing gain to optimize signal-to-noise ratio (SNR) and prevent saturation, using a gain table to select appropriate gain values based on count window thresholds and programmable settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AGC uses analog level detectors to control amplifier gain, then the system can maintain basic signal amplitude within dynamic range, but the receiver performance degrades in the presence of jammer signals with high PAPR
Solution Approach 1:
The patent replaces the conventional analog level detector with a digital signal processing approach. The AGC controller uses a digital processor to receive I and Q samples from the ADC, calculate signal power, and generate gain control signals. This substitution of digital processing for analog detection improves reliability by providing more precise control and better immunity to jammer signals with high PAPR.
Solution Approach 2:
The patent dynamically adjusts the gain control parameters based on the detected signal conditions. The AGC controller calculates the power of the received signal and adjusts the gain of the LNA and/or mixer accordingly. This parameter change approach allows the system to adapt to varying jammer conditions and maintain optimal receiver performance.
2Measurement precision
If the AGC increases gain to capture weak desired signals, then signal sensitivity improves, but the receiver saturates when strong jammer signals are present
Solution Approach 1:
The patent implements a dynamic gain control system where the AGC controller continuously monitors the power of received signals and adjusts the gain of the LNA and/or mixer in real-time. The controller receives I and Q samples, calculates signal power, and dynamically modifies gain parameters to prevent saturation while maintaining sensitivity for weak signals. This dynamic adaptation allows the system to handle both weak desired signals and strong jammer signals effectively.
3Reliability
If the AGC decreases gain to prevent saturation from jammer signals, then dynamic range is preserved, but the sensitivity for detecting weak desired signals is reduced
Solution Approach 1:
The patent applies different gain control strategies to different signal components. The AGC controller separately processes I and Q samples, calculates their individual powers, and combines them to determine the total signal power. This local quality approach allows the system to apply precise gain control to each signal component, maintaining stability while preserving the ability to detect weak signals that might otherwise be lost.
Data Source
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AI summary
A communication system including an analog front end and an automatic gain controller. The analog front end includes at least one amplifier for amplifying a received analog signal and an analog to digital converter that converts the analog signal to digital samples. The automatic gain controller includes comparator circuitry, counter circuitry, and a gain controller. The comparator circuitry compares each of the digital samples with an upper threshold and a lower threshold. The counter circuitry counts a high-count number of the digital samples having magnitudes that are greater than the upper threshold during each count window and counts a low count number of the digital samples having magnitudes that are less than the lower threshold during the count window. The gain controller adjusts a gain of the at least one amplifier by an amount based on the high-count number and the low count number.