AGC Peak Detection Using Block Maxima in Digital Radio Receivers
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Solution Overview
Problem
Existing digital radio receivers face challenges in efficiently managing signal amplitude variations across a wide dynamic range, requiring complex gain control mechanisms that can be computationally intensive and affect signal-to-noise ratios.
Innovation Solution
The proposed AGC implementation reduces computational requirements by dividing the input frame into blocks and finding the maximum value within each block, using a peak detector that decays based on a time constant, thereby simplifying the peak detection process and reducing the number of multiplications needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a variable attenuator is used for gain control, then the signal level can be reduced, but the signal-to-noise ratio is also reduced
Solution Approach 1:
The patent divides the continuous gain control function into discrete gain steps (e.g., 0 dB, -3 dB, -6 dB, -9 dB). Instead of using a variable attenuator that continuously reduces signal level, the system selects from predefined gain reduction steps, thereby maintaining signal-to-noise ratio while still providing gain control capability.
2Object-affected harmful factors
If gain control is distributed over multiple stages, then signal-to-noise ratio is maintained, but device complexity increases
Solution Approach 1:
The patent implements a universal gain control mechanism that can be applied across multiple signal processing stages (RF, first IF, second IF) using the same architectural approach. The gain control circuit selectively adjusts gain in different stages based on signal conditions, providing multi-functional capability without proportionally increasing complexity.
Solution Approach 2:
The system performs preliminary gain control in earlier stages (RF and first IF) when signal levels are high, before signals are processed through subsequent stages. This preliminary action prevents overload and intermodulation in later stages, maintaining signal-to-noise ratio throughout the chain without requiring complex coordination between all stages.
3Measurement precision
If peak detector computes maximum value of all IF samples, then accurate signal level measurement is achieved, but computational load increases
Solution Approach 1:
The patent segments the set of all IF samples into smaller groups or blocks. Instead of computing the maximum value across all samples, the system computes maximum values within each block and then determines the overall signal level from these block maxima. This segmentation significantly reduces the number of comparisons required while maintaining adequate measurement precision for AGC control.
Solution Approach 2:
The system performs partial peak detection by examining only a representative subset of samples or using simplified maximum detection algorithms that do not require processing every single IF sample. This partial action provides sufficient signal level information for AGC purposes without the full computational burden of exhaustive peak detection.
Data Source
AI summary
A method of peak detection applicable to complex in-phase and quadrature phase signals in a digital radio receiver where the incoming signal is divided into a plurality of frames. Each frame is then further divided into a plurality of smaller blocks, and the signal peak is determined in each block individually followed by selecting the peak signal value from the said blocks.