Adaptive Off-Channel Detector for Receiver Interferer Rejection
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Solution Overview
Problem
Direct Conversion Receivers (DCRs) are sensitive to interferers, leading to noise and distortion due to their direct conversion to baseband, which affects the rejection of constant and non-constant envelope interferers, resulting in suboptimal performance.
Innovation Solution
An adaptive system is implemented in the receiver to adjust parameters such as peak detector decay time, threshold, and hysteresis based on the peak-to-average ratio of the signal, using a lookup table to determine the type of interferer and select appropriate settings for the off-channel detector, thereby minimizing distortion and improving interferer rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Direct Conversion Receiver (DCR) topology is used for low cost and small size, then receiver sensitivity to interferers increases, causing noise and distortion
Solution Approach 1:
The patent implements dynamic adjustment of receiver parameters (IF bandwidth, gain, filter settings) based on real-time detection of interferer characteristics. The system transitions from static DCR configuration to adaptive configuration that modifies operating parameters according to the detected signal environment, thereby maintaining low cost while reducing interferer sensitivity.
Solution Approach 2:
The system changes physical parameters (bandwidth, gain, filter coefficients) of the receiver based on detected interferer types. By dynamically adjusting these parameters, the receiver maintains the simplicity of DCR topology while adapting its performance characteristics to reject specific interferer categories such as constant envelope or non-constant envelope signals.
2Device complexity
If fixed receiver parameters are used to simplify design, then performance across various interferer types deteriorates
Solution Approach 1:
The receiver incorporates an automatic interferer detection and classification system that autonomously identifies interferer types and adjusts receiver parameters without manual intervention. This self-service mechanism allows the system to maintain simple fixed design parameters while achieving adaptive performance through automated parameter selection based on detected signal characteristics.
Solution Approach 2:
The system implements a feedback loop where the receiver continuously monitors incoming signals, detects interferer presence and type, and uses this information to adjust receiver parameters. This closed-loop control enables the receiver to maintain optimal performance across different interferer scenarios without increasing fundamental design complexity.
Data Source
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AI summary
Receivers (500) and methods of adaptively adjusting the receivers based on a received interferer are described. The peak-to-average ratio of a received signal is used to determine the type of interferer. The ratio and interferer type, in addition to the type of on-channel signal, are used to select parameters to adjust the decay time of a peak detector (516), and the threshold and hysteresis of a comparator (518). The peak detector (516) and comparator (518) are used to generate an off-channel flag that indicates the presence of a relatively strong interferer to other modules in the receiver (500). If valid data is not present a default set of parameters is provided. The ratio is determined by dividing the maximum peak over the average or a range of ratios is determined by comparing a scaled value of the average to different scaled values of the peak.