Telettra Telefonia Elettronica E Radio Spa

Luigi Vismara

Maurizio Nannicini

Umberto Casiraghi

The automatic transmit power level control in multiline radio links using a multilevel QAM modulation is basically comprised of:

Automatic transmit power level control in radio links

A system for stabilization of the coupling value between the transmitted radio signals resulting from cross polar discrimination, using the transmit power level control in radio link systems formed of several radio channels using multilevel QAM modulation. A first control signal is derived for each RF channel and a second control signal is derived for the adjacent channels. The first and second control signal are then combined to derive threshold signals. The threshold signals are multiplexed with station identification signals and this multiplexed signal is multiplexed with other service signals. The twice multiplexed signal is then inserted in the frame of a main information signal. The signal is demultiplexed to derive a remote transmit power control signal. The atmospheric precipitation condition is evaluated through statistical control of the bit error rate. A local transmit power control signal is derived. The local and remote transmit power control signals are then applied the predistortion circuits of the power amplifiers.

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Vimercate, Italy

Luigi Vismara