We give a short description of the "Mars-96" experiment and scientific problems which will be studied on board the spacecraft by the plasma wave complex ELISMA. The multichannel ULF wave analyser ULF-W developed at the Special Design Division of the Physical Mechanical Institute, National Academy of Sciences, is one of the main components in this complex. A special structure of this device includes high-stability ULF-filters, with identical phase-frequency parameters, amplifiers with controlled amplification coefficients, sample-and-hold blocks, and a variety of processing algorithms for data collection, compression and decompression. All this provides wide possibilities for a multicomponent analysis of electromagnetic fields. We discuss the methodology and results of onground tests of the ULF-W analyser as a component of the ELISMA complex under conditions approaching such of the outer space.