Modified amplitude method for detecting frequency-hopping spread spectrum signals modulation with a low computational cost

DOI: 10.31673/2412-9070.2026.025307

Abstract

A modified amplitude-based method for detecting frequency-hopping spread spectrum (FHSS) signals is presented and evaluated using numerical simulations in the GNU Radio Companion environment. The proposed modification addresses a key limitation of the previously developed non-parametric amplitude method, namely its reduced performance when processing FHSS signals with partial channel occupancy, which is a common characteristic of real-world emitters transmitting telemetry or low-rate control data. To enable controlled testing, an enhanced parametric FHSS signal synthesizer was developed, allowing independent adjustment of channel bandwidth, hopping rate, signal amplitude, and channel occupancy factor. The modified detection algorithm incorporates correlation-based frequency estimation followed by time-accumulated amplitude histogram analysis, enabling stable detection in the presence of packet gaps and over lapping hopping patterns.
Simulation results demonstrate that the proposed method reliably separates multiple FHSS signals with overlapping frequency ranges when the amplitude difference exceeds approximately <1dB. The sensitivity analysis shows that correct amplitude estimation is maintained for channeloccupancy levels down to 15%, with deviations closely matching theoretical expectations. Further more, the algorithm exhibits stable operation across a dynamic input amplitude range of at least 20 dB without significant degradation in detection accuracy.
The use of simple mathematical operations and histogram-based accumulation ensures low computational complexity, making the method suitable for implementation on low-power SDR platforms. The obtained results confirm that the introduced modifications significantly improve the robustness of amplitude-based FHSS signal detection under realistic transmission conditions with intermittent activity.

Keywords: FHSS, signal detection, amplitude-based detection method, amplitude-based signal selection, histogram analysis, SDR.