GB1049406A - Improvements in or relating to tropospheric radio links - Google Patents

Abstract

1,049,406. Radio signalling. CSF. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. June 22, 1964 [June 24, 1963], No. 25669/64. Heading H4L. A radio link comprises a main transmitter and receiver for signal transmission and an auxiliary transmitter and receiver for frequency band exploration and detection of the optimum transmitting frequency, and means for automatically aligning the main transmitter and receiver at predetermined intervals T on the frequency last found to be optimum. As shown in Fig. 4, the transmitting station comprises a main transmitter E 1 , an auxiliary transmitter E 2 , and a clock control unit HE which frequency-sweeps the transmitter E2 through a predetermined band and also retunes the transmitter E 1 to the new optimum frequency found by E 2 in the last exploration in accordance with the information received on the auxiliary receiver R 3 . The signals from transmitters E 1 , E 2 are supplied to a common aerial AE via a directional coupler, Fig. 3 (not shown), the power transmitted by E 1 being much greater than that transmitted by E 2 and the auxiliary signals requiring only a narrow band link. At the receiver a common aerial AR supplies the signal receiver R 1 and the auxiliary superheterodyne receiver R 2 , a clock control unit HR, which is synchronized with HE, regulating the frequency sweep of the local oscillator in R 2 in synchronism with E 2 . R 2 is connected to R 1 to indicate to R 1 which frequency is to be used at the end of an interval T, and also supplies this information to a transmitter E 3 cooperating with receiver R 3 .