The European Space Agency in cooperation with Inmarsat launched the Alphasat communication satellite in 2013, which hosts four technology demonstration payloads. One of them is the Aldo Paraboni payload composed of the Q/V band communication and Ka/Q band propagation experiments. The payload and the communication experiment are funded by the Italian Space Agency. Budapest University of Technology, Hungary in cooperation with Joanneum Research, Austria built a receiver station to conduct site diversity and adaptive coding and modulation experiments over the Q/V band satellite channel. The transmitter/receiver station in Austria and the receiver station in Hungary form a long-distance diversity system that is used to investigate the capabilities of the adaptive technique under various propagation conditions controlled by the local signal quality at the receiver site in Budapest. This paper provides a detailed overview of the diversity station in Budapest. The operation of the adaptive coding and modulation experiment is illustrated with measurements performed in 2017. KEYWORDS Alphasat, Q/V band communication experiment, site diversity, adaptive coding, and modulation 1 | INTRODUCTIONAlphasat is the largest European telecommunications satellite ever built with a total mass of greater than 6.6 tonnes at launch in July 2013. This satellite supplements Inmarsat's existing I-4 series, providing coverage over Europe, the Middle East, and Africa from its in-orbit geosynchronous location at 24.9°East with an inclination above the Equatorial plane not exceeding 3°. 1,2 The new high-power satellite platform, called Alphabus, was developed by Astrium and Thales Alenia Space under a joint contract with the European Space Agency (ESA) and Centre National d'ÉtudesSpatiales.In addition to the commercial payload, approximately 20% of the spacecraft's resources are dedicated to four hosted payloads, also called technology demonstration payloads, which were provided by ESA. One of these payloads is the Aldo Paraboni payload that is composed of the communication experiment (COMEX) payload in the Q/V band and the "scientific" (propagation) experiment (SCIEX) payload in the Q and Ka bands, which cover all of Europe. 1 The payload development was supported by the Italian Space Agency (ASI) as an in-kind contribution to the Alphasat project, which is executed by the ESA in the framework of the ARTES 8 Telecom program. 3,4 The Department of Broadband Infocommunications and Electromagnetic Theory at Budapest University of Technology and Economics (BME-HVT) participates in both experiments by operating the receive-only stations. However, this article concentrates on the COMEX station, and the following short introduction of the SCIEX experiment may be advantageous for a complete overview of the Aldo Paraboni payload. The Aldo Paraboni propagation payload consists of two coherent beacons at 19.701 GHz with a linear vertical polarization and 39.402 GHz with a linear tilted 45°polarization. The coverage areas plotted in Figure 1 show that the...