Utvärdering av försvarsspecifika radiovågformer

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To be able to evaluate different radio waveforms in a laboratory environment FOI in Linköping has developed an experimental system for radio communication called Rasmus. The system consists of a transmitter, a channel emulator and a receiver. The transmitter modulates a digital signal to a desired analogue waveform. The channel emulator is used to simulate a real radio channel. The channel emulator distorts the signal by splitting it up in several propagation paths. Each path has its own statistical distribution, delay and so on. The receiver digitises the signal and saves it in a memory. Analysis of the signal is performed in non-real time. The system has some limitations concerning signal bandwidths and channel models. This Master Thesis deals with the problem of scaling the radio channel (with respect to noise, Doppler shift and fading) in order to examine signals that have properties outside the normal operation of the Rasmus system. The radio channel studied is a Rayleigh fading channel with two independent propagation paths. A differentially modulated QPSK signal is used as input to the channel. The signal is filtered through root-raised-cosine filter in the transmitter and receiver to reduce the effect of inter-symbol interference. Theoretical calculations result in a metho...