Frequency-Selective AGC for Jam-Resistant ADC Loading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Communication systems using frequency hopped spread spectrum waveforms face challenges in maintaining optimal gain settings across varying interference and channel conditions, leading to quantization noise and saturation issues in analog-to-digital converters.
Innovation Solution
A frequency selective automatic gain control (AGC) mechanism that dynamically adjusts gain settings on a bin-by-bin basis using a multifrequency bin-based gain profile, implemented in a digital signal processor to maintain optimal aggregate signal power within the analog-to-digital converter's dynamic range, while detecting and adapting to interference and signal faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gain level of the input to the receiver's analog-to-digital converter is set at a mean value, then the receiver can operate across a wide dynamic range, but hopping to the jamming band will result in saturating the ADC, causing data packets to be occasionally lost
Solution Approach 1:
The patent divides the frequency spectrum into multiple frequency bins and creates separate gain settings for each bin. Instead of using a single mean gain value for the entire bandwidth, the system segments the gain control into individual frequency-specific gains, allowing each bin to be optimized independently for its interference conditions.
Solution Approach 2:
The patent applies local quality by assigning different gain values to different frequency bins based on their specific interference characteristics. Each frequency bin receives a tailored gain setting rather than a uniform mean value, allowing the system to adapt locally to jamming conditions in specific frequency regions while maintaining optimal performance in clean frequency regions.
2Reliability
If the gain is set at a value based upon the impact of the jammer in that one band, then when the receiver is hopping to and collecting energy in other bands, the ADC is underloaded, introducing quantization noise and causing unwanted degradation in performance
Solution Approach 1:
The system segments the gain control into multiple frequency-bin-specific gain values stored in a gain profile. Each frequency bin has its own optimized gain setting that prevents ADC saturation in jammed bins while maintaining optimal loading in clean bins, eliminating the need to use a conservative mean gain value that would underload the ADC in interference-free regions.
Solution Approach 2:
The patent dynamically changes the gain parameter for each frequency bin based on detected interference conditions. The gain profile stores different gain values for different frequency bins, allowing the system to adjust the ADC loading factor locally for each bin to achieve optimal performance across the entire frequency spectrum.
3Object-affected harmful factors
If the gain is set to low to avoid saturation, then the ADC will not saturate under jamming conditions, but quantization noise will dominate and the number of effective bits of the analog-to-digital converter will be reduced
Solution Approach 1:
The patent applies local quality by setting different gain levels for different frequency bins based on their specific interference conditions. Frequency bins experiencing jamming receive lower gain settings to prevent saturation, while clean frequency bins receive higher gain settings to maximize the number of effective bits and minimize quantization noise, optimizing performance locally for each bin.
4Measurement precision
If the gain is set to high to maximize signal utilization, then the ADC will be optimally loaded for clean signals, but the analog-to-digital converter will saturate when hopping to jammed frequency bins, distorting the waveform and preventing successful data recovery
Solution Approach 1:
The system segments the gain control into frequency-bin-specific values, allowing each bin to be optimized independently. This enables the ADC to be optimally loaded for clean frequency bins while using lower gain for jammed bins, preventing saturation and waveform distortion in interference-affected regions while maximizing signal utilization in clean regions.
Solution Approach 2:
The patent dynamically changes the gain parameter for each frequency bin based on detected interference conditions and stores these settings in a gain profile. This allows the system to adapt the ADC loading factor locally for each bin, achieving optimal signal utilization in clean regions while preventing saturation in jammed regions.
Data Source
AI summary
A digital signal processing-based receiver architecture performs automatic gain control (AGC) for a frequency hopping spread-spectrum communications receiver that may be subjected to one or more sources of interference or jamming. Rather than set the AGC gain at a fixed, best hoped for value, and then attempt to rely on decoding or interleaving to interpolate lost or degraded data, the present invention, through repeated but aperiodic transitions or hops across a plurality of frequency bins of interest, develops a gain profile for the plurality of frequency bins, and uses the gain profile to adjust, on a hop-by-hop basis, the gain for the channel/bin to which the receiver is listening, so as to maintain the average aggregate input signal power at an optimal ADC loading factor.