Direct RF Digitization Receiver for Phase Coherent Geo-Location
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Solution Overview
Problem
Conventional radio frequency receivers with multiple mixing stages are complex and difficult to synchronize for geo-location applications, leading to accuracy issues due to phase mismatch and costly calibration processes.
Innovation Solution
A receiver system using ultra-high-speed data converters that directly digitize RF signals at multiple GHz rates, eliminating the need for down converters and mixing stages, with synchronized clocks and electronically switched RF filters for simplified and remote processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional super heterodyne receivers with multiple mixing stages are used, then signal processing capability is achieved, but device complexity increases and synchronization becomes difficult
Solution Approach 1:
The patent extracts and removes the complex down-conversion and mixing stages from the receiver architecture, keeping only the essential RF-to-DC conversion function. This extraction of unnecessary components directly reduces device complexity while maintaining the core signal processing capability needed for geo-location applications.
Solution Approach 2:
Instead of the conventional approach of converting RF signals through multiple mixing stages to intermediate frequencies before digitization, the patent inverts the architecture by directly converting RF signals to digital form using high-speed ADCs. This inversion eliminates the need for complex RF circuitry and makes synchronization between multiple receivers significantly easier.
2Ease of operation
If multiple mixing stages with oscillators are used, then signal processing is achieved, but ease of operation deteriorates due to calibration requirements
Solution Approach 1:
The simplified receiver architecture with direct RF-to-digital conversion inherently maintains better phase coherence and requires less external calibration and adjustment. The system essentially calibrates itself through the simplicity of its design, eliminating the need for extensive manual calibration procedures that would otherwise be required to maintain synchronization accuracy.
3Loss of time
If GPS or reference clock sources are used for periodic disciplining, then clock synchronization is achieved, but loss of time increases due to periodic disciplining requirements
Solution Approach 1:
The patent performs clock synchronization once when all receivers are co-located, establishing a common time reference before the receivers are deployed to remote locations. This preliminary synchronization action eliminates the need for periodic disciplining operations, saving time while maintaining measurement precision through the use of high-speed ADCs that preserve phase coherence.
Data Source
AI summary
A receiver system using commercially available super high-speed data converters that are able to directly digitize at multiple GHz sampling rates with sufficient accuracy to fit many radio applications. Unlike conventional receivers, no down converters or mixing stages are required. Instead it uses a bank of RF filters from which the desired RF filter, based on the frequency band of interest, is switched in. The frequency spectrum scan rate is very fast as the settling time for the simple RF front-end is small and the speed of RF switching is high. The filtered output is digitized at a multiple GHz sampling rate and all signal processing is done by FPGA or a combination of FPGA and/or a general-purpose processor.