In-Orbit Measurements and Analysis of Radio Interference in the UHF Amateur Radio Band from the LUME-1 Satellite

Gara Quintana-Diaz,Torbjörn Ekman,Diego Hurtado De Mendoza,Fernando Aguado Agelet,Alberto González Muíño,José Miguel Lago Agra

doi:10.3390/rs13163252

Abstract

Radio interference in the uplink makes communication to satellites in the UHF amateur radio band (430–440 MHz) challenging for any satellite application. Interference measurements and characterisation can improve the robustness and reliability of the communication system design. Most published results focus on average power spectrum measurements and heatmaps. We apply a low complexity estimator on an SDR (Software-Defined Radio) to study the interference’s dispersion and temporal variation on-board a small satellite as an alternative. Measuring the Local Mean Envelope (LME) variability with different averaging window lengths enables the estimation of time variability of the interference. The coefficient of variation for the LME indicates how much the signals vary in time and the spread in magnitudes. In this article, theoretical analysis, simulations, and laboratory results were used to validate this measurement method. In-orbit measurements were performed on-board the LUME-1 satellite. Band-limited interference with pulsed temporal behaviour and a high coefficient of variation was detected over North America, Europe, and the Arctic, where space-tracking radars are located. Wide-band pulsed interference with high time variability was also detected over Europe. These measurements show why operators that use a communication system designed for Additive White Gaussian Noise (AWGN) at power levels obtained from heatmaps struggle to command their satellites.

Highlights

Communication with satellites is required to operate any spacecraft and offer the service planned, no matter what type of service (telecommunication, Internet of Things (IoT), remote sensing, etc.)
Spectrum monitoring is especially important for IoT-over-Satellite networks and for small satellite communication, where uplink interference levels will rise due to the increasing number of IoT devices deployments [3] and small satellites launched [4]
5 s long, repetition period of 16.67 ms, and 300 kHz bandwidth are shown in Figures 3–5, respectively

Summary

Introduction

Communication with satellites is required to operate any spacecraft and offer the service planned, no matter what type of service (telecommunication, Internet of Things (IoT), remote sensing, etc.). The choice of communication parameters should be based on the communication channel properties and the actual interference and noise environment [1]. For Radiofrequency (RF) communication, the radio environment can be measured on-board satellites and provide information to improve the design of the communication system and increase the data throughput. In-orbit spectrum monitoring is paramount for satellite communication systems and has been supported by the European Space Agency (ESA) [2]. Spectrum monitoring is especially important for IoT-over-Satellite networks and for small satellite communication, where uplink interference levels will rise due to the increasing number of IoT devices deployments [3] and small satellites launched [4]. Actual in-orbit interference measurements can complement existing system models for

Results

Discussion

Conclusion