Electromagnetic compatibility (EMC) is an important requirement for spacecrafts due to the limitation of their volume and the possibilities of the layout of individual subsystems. Interference from satellite service systems are the main problem in conducting high-sensitivity measurements of magnetic fields when studying wave processes in plasma in the range of low frequencies. This is especially true for the becoming recently popular very small satellites — CubeSats (CS) with sensitive equipment for measuring electric and magnetic fields in the range from direct current to low frequencies. In order to minimize the mutual influence of the payload and service systems, it is necessary to determine the frequency and amplitude of the main spectral components of the emitted magnetic field of each satellite subsystem to reduce the level of the interference or, if not possible, to take into account when processing data.

           A special measuring system, created for registration and estimation of magnetic interference in the ULF range, is described in the article. This system consists of two identical three-component induction magnetometers, data acquisition unit, power supply unit, and control computer with a corresponding set of programs. With this system, the level of the AC magnetic field, generated by each of the subsystems of the CS, was measured and digital processing was performed. For the separation of the studied and background signals, data obtained from two identical three-component induction magnetometers of the system were used with the following solution of the inverse problem — the determination of the parameters of the radiation source using the measured magnetic field generated by this source at two points. The results of the EMC tests for the CS developed under the SEAM project, the values and locations of the equivalent magnetic dipoles of the radiation of the separate subsystems, which are the sources of radiation in the CS, are given.