HF Frequency Selection Algorithm with LUF-MUF Interference Screening
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Solution Overview
Problem
HF communication systems are vulnerable to active denial and intentional/unintentional interference, leading to disrupted long-range communication.
Innovation Solution
A software-defined radio system that determines usable frequencies by discarding those above or below the LUF and MUF, and selects frequencies where the received power from the transmitter is higher than interferers, ensuring robust communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If HF waveforms are used for long-range communication, then communication range is extended, but vulnerability to interference increases
Solution Approach 1:
The system dynamically changes frequency parameters by calculating LUF and MUF boundaries and selecting optimal frequencies within this range. The frequency selection algorithm adjusts the operating frequency based on ionospheric conditions and interference levels, allowing the communication system to maintain long-range capability while avoiding interfered frequencies.
Solution Approach 2:
The frequency selection process is dynamic rather than static. The system continuously monitors signal strength, calculates usable frequency ranges, and adapts frequency selection based on real-time conditions including interference patterns. This dynamic adaptation enables the system to maintain communication resilience while preserving long-range capability.
2Reliability
If frequency selection algorithm is implemented to avoid interference, then communication reliability is improved, but computational complexity increases
Solution Approach 1:
The frequency spectrum is segmented into usable and unusable regions based on LUF and MUF boundaries. By dividing the HF band into distinct frequency ranges with specific propagation characteristics, the algorithm simplifies the selection process - only frequencies within the calculated LUF-MUF range need to be evaluated, reducing the search space while maintaining reliability.
Solution Approach 2:
The system performs preliminary calculations of LUF and MUF boundaries before actual frequency selection. By pre-establishing the usable frequency range based on ionospheric conditions, the algorithm reduces real-time computational requirements during frequency selection, balancing reliability with computational efficiency.
Data Source
AI summary
Techniques for selecting frequencies of operation are described. HF signals may land at the receiver node with power levels dependent upon the transmit frequency. The frequency with the highest power level at the receiver node may be selected when the receiver node is not subject to interfering. The receiver node may be unable to receive a desired signal if an interfering signal has a signal level which is higher than the desired signal. The transmitter node may select a frequency which has a receiver signal level which is higher than the interfering signal for the selected frequency. The receiver node may then receive the transmit signal at the selected frequency even when subject to interfering from the interferer node.