Satellite RF Geolocation Using Ground-Based Goniometry
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Solution Overview
Problem
Existing satellite communication systems face challenges in accurately locating radiofrequency transmitters causing interference due to high development and integration costs, and the need for specific onboard equipment and processing, which are not compatible with co-frequency transmissions.
Innovation Solution
A satellite system with an analogue device that frequency-multiplexes RF signals from multiple radiating elements and transmits them to the ground for goniometry processing, eliminating the need for onboard digital processing and allowing calibration to correct for system imperfections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radio goniometry processing operations are implemented on board the satellite with frequency transposition and digitization, then the location accuracy of interfering transmitters is improved, but the device complexity and development cost increase significantly
Solution Approach 1:
The patent extracts the complex digital processing functions (frequency transposition, digitization, and goniometry calculations) from the satellite and relocates them to ground-based equipment. The satellite retains only the essential RF reception and analog processing functions, while the computationally intensive tasks are performed on the ground, thereby reducing onboard device complexity while maintaining location accuracy.
Solution Approach 2:
The patent introduces an intermediary analog processing stage that converts RF signals to baseband signals before transmission to the ground. This analog intermediary simplifies the satellite's onboard requirements by performing initial signal conditioning, allowing the complex digital processing to be deferred to ground equipment while preserving measurement precision.
2Adaptability or versatility
If a dedicated onboard computer and signal conversion chains are implemented, then goniometry processing capability is improved, but the development time and integration validation time increase
Solution Approach 1:
The patent removes the dedicated onboard computer and complex signal conversion chains from the satellite, extracting only the essential RF reception and analog processing functions. This significantly reduces the development and integration time required for the satellite while maintaining full goniometry processing capability through ground-based equipment.
Solution Approach 2:
The patent makes the satellite's analog processing equipment multi-functional, enabling it to handle both communication signals and RF interference signals. This universal approach allows the same hardware to serve multiple purposes without requiring dedicated goniometry-specific equipment, thereby reducing development time.
3Ease of manufacture
If conventional satellite equipment is used without specific locating function equipment, then development cost and integration time are reduced, but the location functionality is lost
Solution Approach 1:
The patent enhances conventional satellite equipment with multi-functional analog processing capabilities that enable both communication and locating functions. By making the existing RF reception and processing equipment universal, the satellite can perform location determination without requiring dedicated locating hardware, thus maintaining ease of manufacture while gaining locating functionality.
Solution Approach 2:
The patent introduces an analog processing intermediary that bridges the gap between conventional satellite equipment and goniometry requirements. This intermediary performs necessary signal conversions in the analog domain, allowing conventional equipment to be used while still enabling location functionality through ground-based processing.
4Measurement precision
If angle error measurement method with three beams is used, then location accuracy is improved, but the angular coverage is limited to a few tenths of a degree
Solution Approach 1:
The patent transitions from angular domain processing to frequency domain processing by implementing frequency multiplexing. Instead of using multiple narrow angular beams, the system multiplexes signals from multiple antennas in the frequency domain, allowing wide angular coverage while maintaining location accuracy through ground-based goniometry processing.
Solution Approach 2:
The patent changes the processing parameter from angular beamforming to frequency multiplication factor. By varying the frequency multiplication factor in the analog processing stage, the system can accommodate different angular coverage requirements while maintaining measurement precision, overcoming the fixed angular coverage limitation of traditional beamforming.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces development and integration costs, enables accurate location of interfering transmitters, and is compatible with co-frequency transmissions, while maintaining flexibility and reducing satellite payload overhead.
Implementation Method 1
a reception antenna comprising a plurality N of radiating elements configured to receive an RF signal
Implementation Method 2
analogue means for frequency multiplexing the N RF signals received on the N radiating elements, configured to transpose said N RF signals received on the N radiating elements around distinct centre frequencies
Data Source
AI summary
A satellite configured to operate radiofrequency communications from one or more antenna systems. The satellite further comprises a device dedicated to locating RF equipments comprising: a reception antenna comprising a plurality N of radiating elements configured to receive an RF signal, analogue means for frequency multiplexing the signals received on the N radiating elements, means for transmitting the multiplexed signals to a satellite station on the ground. A complete satellite system further comprising a satellite station and computation means configured to receive the multiplexed signals, demultiplex them and implement goniometry processing operations to determine the position of the RF equipment to be located, and to the associated locating method.