RF Receiver AGC Sequencing for Secure Ranging Under Multipath
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Solution Overview
Problem
RF ranging systems face accuracy degradation due to interference from strong reflected pulses, which cause receivers to lose sensitivity to weak line-of-sight pulses, leading to incorrect distance measurements.
Innovation Solution
An RF receiver with an automatic gain control (AGC) controller that initializes in a low gain state, increases gain to detect weak signals before strong signals, and maintains high gain to prevent clipping, allowing detection of weak line-of-sight pulses even in the presence of strong reflected pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver gain is increased to detect weak line-of-sight pulses, then the sensitivity to weak signals is improved, but the strong reflected pulses cause clipping and distortion
Solution Approach 1:
The receiver initializes in a low gain state before signal arrival to avoid clipping from strong reflected pulses, then transitions to high gain state after detecting the leading edge of the weak line-of-sight pulse. This preliminary low-gain operation prevents distortion before the harmful strong signals arrive.
Solution Approach 2:
The receiver dynamically switches between low gain and high gain states based on signal detection. The gain control mechanism adjusts the receiver sensitivity in real-time, transitioning from low gain (to avoid clipping) to high gain (to detect weak pulses) based on the presence and timing of detected signals.
2Object-affected harmful factors
If the receiver gain is decreased to avoid clipping from strong reflected pulses, then the harmful effects are reduced, but the sensitivity to detect weak line-of-sight pulses deteriorates
Solution Approach 1:
The receiver operates in low gain state as a preliminary measure to avoid clipping from strong reflected pulses. After detecting the leading edge of a weak pulse, it transitions to high gain state to maintain sensitivity for detecting the weak line-of-sight signal without suffering from initial clipping.
Solution Approach 2:
The gain control system dynamically adjusts between low and high gain states based on signal conditions. The receiver transitions from low gain (protecting against clipping) to high gain (enhancing weak signal detection) based on real-time signal presence detection.
3Object-affected harmful factors
If the receiver uses conventional AGC to maintain optimal gain for strong signals, then the handling of strong reflected pulses is improved, but the detection of weak line-of-sight pulses is lost
Solution Approach 1:
Instead of using conventional AGC that maintains optimal gain for strong signals, the receiver preliminarily operates in low gain state to avoid clipping. After detecting the leading edge of a weak pulse, it transitions to high gain state, inverting the conventional AGC approach to prioritize weak signal detection over strong signal handling.
Solution Approach 2:
The invention inverts the conventional AGC philosophy by initially using low gain (opposite of conventional high gain for strong signals) to detect weak pulses, then switching to high gain after detection. This inverted approach prioritizes weak signal detection before strong signals arrive, rather than optimizing for strong signal handling as conventional AGC does.
Data Source
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AI summary
A receiver, including: a tuner receiving an input signal; a signal processor configured to process the input signal; an automatic gain control (AGC) controller configured to: initialize the receiver in a low gain state; determine the presence of a signal; and increase the receiver gain to determine if a weak signal is present prior to a strong signal.