## 1 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 Radiotherapy (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 IoT-over-Satellite systems [5, 6, 3, 7] to improve their real performance and help to design interference mitigation techniques. Spectrum monitoring can help to solve some of the challenges of future satellite systems, such as efficient spectral usage and interference mitigation capabilities [8]. The UHF amateur radio band (430-440 MHz) is a popular frequency band for Telemetry, Tracking and Command (TT&C) of small satellites [9]. Several operators of small satellites have experienced poor uplink performance in this band and have performed interference measurements to analyse the problem [10; 11; 12; 13]. In 2014, the University of Vigo carried out a set of preliminary measurements with the HumSat-D satellite, where pulsed interference was detected [10]. In the same year, the University of Wurzburg registered high interference levels over central Europe in certain frequencies within the UHF amateur radio band (430-440 MHz) with the UWE-3 satellite [11]. Additional measurements were performed by the University of Vigo using the SERPENS satellite in 2015 and 2016. Strong, consistent uplink interference was detected over North America, Europe, the north of Africa, and the Middle East. Low levels were measured over South America and some regions of Africa [12]. Moreover, Technische Universitat Berlin (TU Berlin) has worked on spectrum monitoring in the same band (in addition to VHF, L-band, and S-band) and detected high power interference over North America and Europe using a Software-Defined Radio (SDR) on the International Space Station (ISS) in 2018 [13]. In 2020, TU Berlin launched the SALSAT, a CubeSat to continue their spectrum monitoring activities without the ISS constraints [14], but no results have been published yet. There are also companies, such as Hawk Eye 360 and Aurora Insight, that have started to monitor the spectrum in the last years and are building a constellation to provide frequency spectrum data services, such as geolocation of interference sources [15; 16; 17]. Most of the published results focus on the average interference power over a certain measurement duration [10; 11; 13], omitting the time structure of the interference. In addition, the sub-satellite points of some measurements are limited between \(-51.6^{\circ}\) and \(+51.6^{\circ}\) latitude, specifically, the measurements performed by TU Berlin from the ISS [13] and the SERPENS measurements [18]. Satellite orbits with higher inclination can extend sub-satellite points further north as in Reference [10; 11; 19]. Heatmaps have been the traditional way of showing the average power of interference [11; 13], but they do not show the variability. The temporal characteristics of the noise/interference impact what type of error correction coding is needed. For example, turbo-codes have a good performance in the presence of Additive White Gaussian Noise (AWGN), but they are weak codes for burst-noise channels [1]. Reed-Solomon error correction coding performs better in burst-noise channels than in AWGN [1].