The measurement of baseband frequency range for military satellite terminals

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VSAT stations (Very Small Aperture Terminals) are small, cheap terrestrial satellite stations, which are equipped with small antennas (typically from 1 m to 2 m), low power RF transmitters (typically from 0.5 W to 2 W) and in modems and signal converters, forming a compact structure. Stations can be very easily installed on the roof, wall or car park in front of the user's office, where the end devices are placed. Stations can be used in a very convenient and economical way to connect end users devices to the main computer located in a remote data center. VSAT stations are usually used to transmit digital data.VSAT stations often work in a star network. VSAT stations communicate with a large ground station, called the central station. In this case, the type of modulation, transmission rate, coding and access methods for the outgoing channel (from the central station to the VSAT station) and for the incoming channel (from the VSAT station to the central station) are usually differentiated, in order to use the satellite channel effectively, using methods multiplied access. In this type of VSAT networks, user data is usually processed by VSAT stations and the central station, so as to effectively support various computer network protocols.The article concerns problems related to electromagnetic compatibility of military satellite terminal with small VSAT antennas (Very Small Aperture Terminals). The article focuses on the measurement of the frequency range of military satellite terminal work in the basic band for VSAT satellite terminals intended for data transmission. The article presents a laboratory stand and a method for measuring the operating frequency in the basic band for VSAT satellite terminals, which was developed on the basis of European civil standards and a military standard containing requirements on the operating frequency in the basic band for VSAT. In the case of measuring the operating frequency in the basic band for satellite terminals of the tested device, we must remember to estimate the uncertainty of the measurement. The extended value of the uncertainty of measurement for individual frequency ranges is determined from the f0± 2*10^-7 relationship.