Multichannel Radar Gain Control for Precise Noise Leveling
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Solution Overview
Problem
Radar systems with multiple channels face challenges in maintaining a constant noise level due to variations in tilt, interfering signals, and component changes, making it difficult to control noise levels across all channels efficiently, especially in systems like the RDR-4000 radar which requires a 0.1dB noise level control across a 40MHz bandwidth.
Innovation Solution
An automatic gain control method that includes determining coarse and fine gain corrections, as well as frequency vs. gain curve corrections during inactive scan modes, using a digital signal processor and attenuator to adjust gain in each channel based on noise power measurements and a mathematical model, ensuring precise noise level control across the bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channelized solutions are used to control noise level in each channel, then individual channel control is achieved, but system complexity and processing time increase significantly for large number of channels
Solution Approach 1:
The patent segments the noise control problem into three distinct components: coarse gain correction (addressing large variations), fine gain correction (addressing residual errors), and frequency vs. gain curve correction (addressing systematic frequency-dependent variations). This segmentation allows each component to be optimized independently, reducing overall system complexity while maintaining precise control across all channels.
Solution Approach 2:
The patent performs preliminary measurements and corrections during inactive scan modes before actual radar operation. By pre-determining coarse gain correction, fine gain correction, and frequency vs. gain curve correction during inactive periods, the system avoids real-time computational complexity while ensuring precise noise level control is ready for immediate application during active scanning.
2Reliability
If traditional feedback control is applied to all channels, then noise level stabilization is achieved, but processing time and computational load increase for real-time operation
Solution Approach 1:
The patent implements periodic action by performing gain corrections during inactive scan modes in a cyclic manner. The system alternates between active scanning (signal detection) and inactive modes (noise measurement and correction). This periodic approach allows comprehensive noise level stabilization without continuous processing, significantly reducing computational load and processing time while maintaining reliable noise control.
Solution Approach 2:
The patent performs all necessary noise measurements and gain corrections during inactive scan modes before they are needed for active operation. By completing coarse gain correction, fine gain correction, and frequency vs. gain curve correction in advance during inactive periods, the system eliminates real-time processing delays and ensures noise stability is already established when active scanning begins.
3Measurement precision
If gain control is adjusted for each channel individually in real-time, then precise noise control is achieved, but system response time and processing speed decrease
Solution Approach 1:
The patent performs all gain control calculations and corrections during inactive scan modes before they are needed for active radar operation. By pre-determining coarse gain correction, fine gain correction, and frequency vs. gain curve correction values during inactive periods, the system prepares precise noise control parameters in advance, eliminating real-time computational delays and ensuring rapid response during active scanning.
Solution Approach 2:
The patent segments the gain control into three hierarchical levels: coarse gain correction (handling large-scale variations), fine gain correction (handling residual precision requirements), and frequency vs. gain curve correction (handling systematic frequency-dependent variations). This segmentation allows the most time-consuming measurements to be performed once during inactive modes, with faster application during active operation, thereby maintaining precision while improving response speed.
Data Source
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AI summary
Apparatus and methods for performing automatic gain control in a radar system (20). One embodiment of the system includes an attenuator that controls gain of signals received from a radar receiver (24). A digital signal processor (44) determines coarse gain correction based on digitized noise data for a plurality of channels, dstemimes fine gain correction based on the residual error after the coarse gain, and determines frequency vs. gain curve correction based on the digitized noise data for a plurality of channels and a mathematical model of frequency gain across a noise spectrum for the radar system. The result of the processor is a gain control signal that is sent to the attenuator to perform hardware gain control and a channel specific scale factor for software gain control. In one embodiment, the processor generates the gain contra signal during an inactive scan mode of the radar system.