Frequency-Selective AGC for Multi-Channel Receiver Interference
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Solution Overview
Problem
Current receivers for cellular and land-mobile radios face challenges in demodulating information signals due to interference from stronger signals, which can overwhelm amplifier dynamic range and cause noise floor issues, leading to degraded signal quality and Signal-to-Noise Ratio (SNR) in multi-channel reception scenarios.
Innovation Solution
A dual-watch simultaneous receiver system (DW-SRS) employing a wideband phase detector and attenuators to identify and attenuate stronger information signals, ensuring that both signals are processed within acceptable noise levels by adjusting attenuation based on the relative magnitudes and phase information of the signals, thereby maintaining signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a receiver processes multiple information signals simultaneously across different channels, then the receiver can receive diverse information, but stronger signals consume the dynamic range of amplifiers and ADCs, degrading the quality of weaker signals
Solution Approach 1:
The system dynamically adjusts the gain of amplifier stages and attenuation levels in real-time based on the relative strengths of simultaneous signals detected in different channels. This dynamic adaptation allows the receiver to maintain optimal signal quality for both strong and weak signals by continuously reconfiguring the RF signal path parameters.
Solution Approach 2:
The invention applies different gain and attenuation settings to different signal paths corresponding to different channels. Each channel's signal processing chain is independently optimized based on the detected signal strength, allowing localized adjustment of signal quality parameters for each channel while maintaining multi-channel operation.
2Adaptability or versatility
If a receiver processes multiple information signals simultaneously, then multi-channel reception is enabled, but nonlinearities in mixers and ADCs generate spurs that cause interference between channels
Solution Approach 1:
The system performs preliminary detection of signal strengths in multiple channels before the signals undergo mixing and ADC conversion. Based on this preliminary information, it pre-adjusts gain and attenuation levels to prevent the generation of excessive intermodulation products and spurs, thereby proactively eliminating the source of inter-channel interference before it occurs.
Solution Approach 2:
The invention changes operating parameters (gain levels, attenuation settings) of the RF signal processing chain based on the detected signal conditions. By adjusting these parameters dynamically, the system optimizes the operating point of nonlinear components like mixers and ADCs to minimize spur generation and inter-channel interference while maintaining multi-channel reception capability.
Data Source
AI summary
A wideband phase detector configured to receive an intermediate frequency (IF) signal having a plurality of information signals at predetermined carrier frequencies and to generate a carrier indication signal used to control one or more attenuators to equalize the signal levels of the information signals thereby enabling a multichannel receiver to process the two information signals in a parallel fashion using a common analog front-end and analog to digital conversion circuit. The circuit may include an attenuation controller configured to provide control signals to the one or more attenuators to attenuate one or more corresponding information signals based on an average of the carrier indication signal.