Measurements of frequency-dependent variations of amplitude and group delay in digital radio links

During multipath fading on line-of-sight microwave radio paths, errors can occur as result of intersymbol interference, caused by frequency-dependent variation of amplitude and group delay within the radio channel. Such variation is usually referred to as dispersion of amplitude and distortion of group delay response. Measurements of group delay and amplitude dispersions, induced by propagation path, over a 40 MHz band have been made on two adjacent 43 km, 6 GHz, digital radio channels. The data were collected using a particular measuring and recording set-up. The set-up is basically a recorder of amplitude and group delay variations due to selective fadings. Associated to this information, data of error presence (single error, error burst, BER, etc.) are collected to determine, by successive elaborations, relationships between error occurrence and critical values of amplitude and group delay distortions.<
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