Wideband AGC Signal-Presence Control for Bursty Frames
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Solution Overview
Problem
In Wideband digital signal reception, existing AGC systems lack the ability to differentiate between signal and noise power, leading to undesired gain control and potential saturations, especially in bursty frames applications where power fluctuations are common, causing signal loss when the signal returns.
Innovation Solution
A method for adaptive power control in Wide Band Automatic Gain Control (WB-AGC) that includes determining signal presence through power derivative analysis, enabling gain adaptation only when a signal is present, and disabling adaptation when the signal is not present, using a state machine and power detector to manage gain adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the AGC adapts gain continuously to minimize noise power, then noise power is reduced, but signal power is also reduced when no signal is present causing large gain fluctuations
Solution Approach 1:
The patent applies preliminary action by detecting signal presence before adjusting gain. The power derivative detector computes the derivative of received power to determine if a signal is present before the AGC adapts its gain, preventing premature gain changes that would cause large fluctuations when no signal is present.
Solution Approach 2:
The patent implements feedback through the state machine that continuously monitors power derivative values and adjusts AGC behavior accordingly. When the power derivative indicates signal presence, the system transitions to signal-present state and enables gain adaptation; when no signal is detected, it transitions to signal-absent state and disables adaptation, creating a closed-loop control system.
2Measurement precision
If the AGC increases gain to amplify weak signals, then signal detection capability is improved, but noise power increases causing saturation when signal returns after bursty frames
Solution Approach 1:
The system performs preliminary detection of signal presence using power derivative analysis before increasing gain. This prevents the AGC from amplifying noise during bursty frame intervals and subsequently saturating when a signal returns, as the gain will only be increased after confirmed signal presence is detected.
Solution Approach 2:
The patent applies preliminary anti-action by disabling gain adaptation when no signal is present, thereby preventing the harmful effect of noise amplification that would lead to saturation. The state machine proactively prevents gain increases during signal-absent periods, countering the potential harmful effect before it occurs.
3Power
If the AGC responds to power fluctuations to maintain desired power level, then power control is improved, but differentiation between signal and noise power becomes necessary in VLSNR conditions
Solution Approach 1:
The patent replaces complex signal-noise differentiation mechanisms with a simpler power derivative-based detection system. Instead of analyzing spectral content or using complex filtering to distinguish signal from noise in VLSNR conditions, the system substitutes a mathematical derivative operation on power values, significantly reducing computational complexity while maintaining effectiveness.
Solution Approach 2:
The patent changes the parameter used for signal detection from direct power level analysis to power derivative analysis. By computing the rate of change of power rather than absolute power levels, the system can distinguish signal presence from noise fluctuations more effectively in VLSNR conditions without requiring complex differentiation between signal and noise components.
Data Source
AI summary
A method and system to provide adaptive power control for a Wide Band Automatic Gain Control (WB-AGC) including: determining a signal is present when a power derivative of the signal ramps up; adapting a gain for an Automated Gain Control (AGC) when the signal is present; and disabling the adapting when the signal is not present.