Dynamic RF Filter for Co-site Interference Reduction
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Solution Overview
Problem
In aircraft communication systems, co-site interference between transmitter and receiver antennas leads to receiver desensitization due to low-level broadband noise, which existing solutions like increased spatial separation or large, heavy RF filters cannot effectively address, especially in space-constrained platforms.
Innovation Solution
A method and apparatus that involve determining a second frequency based on a first frequency of a transmitted signal, tuning filters to this second frequency, and using these filters to remove components outside this frequency range from received signals, thereby reducing noise and improving RF isolation without the need for large, bespoke filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spatial separation of transmitting and receiving antennas is increased to reduce co-site interference, then RF isolation is improved, but device complexity and space requirements increase
Solution Approach 1:
An RF filter is introduced as an intermediary component between the transmitting and receiving antennas to reduce co-site interference. The filter blocks unwanted frequency components from the transmitted signal before they reach the receiver, thereby improving RF isolation without requiring increased spatial separation between antennas.
Solution Approach 2:
The harmful broadband noise and sideband components are extracted and removed from the transmitted signal path using the RF filter. By taking out these interfering frequency components, the system achieves better RF isolation while maintaining compact antenna spacing.
2Reliability
If traditional RF filters are used to reduce broadband noise, then receiver desensitisation is reduced, but weight, size, and power consumption increase
Solution Approach 1:
The RF filter is designed with adjustable frequency parameters that can be dynamically tuned based on the transmitted frequency. By changing the filter parameters (center frequency, bandwidth, attenuation characteristics) to match the operating conditions, the filter achieves effective noise reduction with a lighter, more adaptable design rather than requiring heavy fixed-frequency filters.
Solution Approach 2:
The filter system incorporates dynamic tuning capability where the filter characteristics are adjusted in real-time according to the transmitted signal frequency. This dynamic adaptation allows a single lighter filter unit to replace multiple heavy fixed-frequency filters, reducing overall system weight while maintaining receiver sensitivity.
3Reliability
If traditional RF filters are used to eliminate interference, then signal quality is improved, but the system loses adaptability to frequency changes and requires bespoke installations
Solution Approach 1:
The RF filter incorporates dynamic frequency tuning capability through voltage-controlled oscillators and variable capacitors that allow the filter center frequency to be adjusted electronically. This enables the same filter hardware to adapt to different frequency bands and communication protocols, providing both high signal quality and frequency versatility without requiring bespoke installations.
Solution Approach 2:
The filter system is designed as a universal module that can operate across multiple frequency bands and with different radio systems. By integrating frequency tuning control and using standardized interfaces, the single filter unit replaces multiple dedicated filters, achieving both superior signal quality and broad adaptability to various communication standards and frequency ranges.
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 effectively reduces receiver desensitization, enhances RF isolation, and is modular, lightweight, and power-efficient, allowing for use in various platforms, including aircraft, without the need for extensive redesign or hardware upgrades.
Implementation Method 1
filtering, by the one or more filters, the received second signal to remove, from the second signal, components having a frequency greater than the second frequency, and remove, from the second signal, components having a frequency less than the second frequency
Data Source
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AI summary
Apparatus for and method of processing radio frequency signals, the method comprising: obtaining a signal indicative of a first frequency (e.g. by obtaining a sample of a transmitted signal), the first frequency being a frequency of the transmitted signal; and using the signal indicative of a first frequency, establishing a second frequency depending on the first frequency, the second frequency being a frequency to which to tune a filter (28, 32) for filtering a received signal (10).An antenna (4) for receiving and/or transmitting a signal may be a co-site antenna with respect to at least one other antenna.