Stable Downlinks for Wideband Radio Frequencies in Distributed Noncooperative System

A stable downlink transmission scheme for wideband anonymous microwave signals in distributed noncooperative system has been proposed and experimentally demonstrated based on an optical switch (OS) scanning. With the round-trip transmission of a pilot carrier, the delay variation of fiber induced by environment is obtained continuously, and can be canceled by controlling variable optical delay line. Furthermore, assisted by an OS, four stable optical downlinks can be realized by employing only one phase drift correction unit, leading to the significant reduction of the system cost increment. Experimental results show that target signals at frequencies of 2 and 18 GHz have been downlink transferred from four different remote ends with the phase fluctuation of only 3.6° and 8.4° at 2 hours through 0.5-km fiber. In addition, the stable phase value for channel can be adjusted from −150° to 150° individually.