Wideband Receiver Filtering for Interferer Rejection Before AGC
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Solution Overview
Problem
Wideband receivers are susceptible to interference signals, which can cause automatic gain control circuitry to attenuate desired signals, degrading the signal-to-noise ratio and suppressing the desired signal.
Innovation Solution
A wideband receiver system with a dual receiver architecture, comprising a primary receiver and an auxiliary receiver, where the auxiliary receiver identifies interferer signals and tunes tunable filters based on their characteristics to maintain a sufficient signal-to-noise ratio for desired signal recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the wideband receiver is open to the entire wide band signal spectrum, then the receiver can receive desired signals across a wide frequency range, but the receiver becomes more susceptible to interference signals such as jammer signals
Solution Approach 1:
The patent divides the wideband receiver into two separate functional units: a first receiver that performs spectrum monitoring and interferer detection, and a second receiver that performs desired signal reception and processing. This segmentation allows the monitoring function to identify interferers without degrading the performance of the signal reception function, resolving the contradiction between wideband coverage and interference susceptibility.
2Reliability
If automatic gain control circuitry attenuates strong interference signals, then the ADC is prevented from reaching full scale, but the desired signal power is also reduced, degrading the signal-to-noise ratio
Solution Approach 1:
The patent extracts and removes the harmful interferer signals from the received wideband signal before the automatic gain control stage. By using the first receiver to identify interferer frequencies and characteristics, and then filtering these interferers out in the second receiver, the system prevents the interferers from triggering unnecessary AGC attenuation, thereby maintaining the SNR of desired signals while still protecting the ADC from overload.
3Measurement precision
If a dual receiver architecture is used with separate monitoring and reception functions, then interferer detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent implements multi-functionality within each receiver unit. The first receiver performs spectrum monitoring, interferer detection, and interferer characterization functions. The second receiver performs desired signal reception, filtering, and processing functions. This universal design within each unit reduces the need for additional specialized components, thereby limiting the increase in overall system complexity while maintaining high interferer detection accuracy.
Data Source
AI summary
A receiver system has at least one antenna that receives a plurality of signals, including a desired signal, across a wide band of frequencies. At least one tunable filter is in signal communication with the at least one antenna, and filters the plurality of signals to produce a plurality of filtered signals. Gain control circuitry is in signal communication with the at least one tunable filter, and produces a gain adjusted version of the filtered signals. A processing unit processes received signals in a portion of the wide band to extract signal characteristics of at least one undesired signal in the portion of the wide band. The at least one tunable filter is tuned based at least in part on the signal characteristics of the at least one undesired signal to maintain the SNR of the desired signal above a threshold level at the output of the gain control circuitry.