GB850110A - Improvements in or relating to radio communication systems - Google Patents

Abstract

850,110. Radio signalling; radio receiving systems. MARCONI'S WIRELESS TELEGRAPH CO. Ltd. Oct. 20, 1958 [Feb. 12, 1958], No. 4596/58. Class 40(5). In a diversity radio communication system, one transmitting and receiving station A comprises two geographically spaced, horizontally polarized transmitting aerials H 1 , H 2 each fed by a transmitter Ti, T 2 respectively each transmitter operating on one of two different carrier frequencies F 1 , F 2 but modulated with the same intelligence, two vertically polarized receiving aerials V 1 , V 2 feeding respective receiving equipments R 1 , R 2 each adapted to accept both of two further modulated carrier frequencies F 3 , F 4 different from F 1 , F 2 . Station B is similar and comprises vertically polarized transmitting aerials V 3 , V 4 fed by transmitters T 3 , T 4 operating on carrier frequencies F 3 , F 4 and horizontally polarized receiving aerials H 3 , H 4 feeding receiving equipments R 3 , R 4 each adapted to accept both carrier frequencies F 1 , F 2 . A single modulator M 1 at station A or M 2 at station B is provided for both transmitters T 1 , T 2 or T 3 , T 4 and means are provided for combining the four outputs of the two receiving equipments at each station. The two frequencies in each pair of carriers may be adjacent e.g. with a separation of 4 mc/s. or they may be more widely separated to provide frequency diversity. The receiving equipments may each be a single receiver having an acceptance band wide enough to cover both frequencies F 3 , F 4 or F 1 , F 2 , or may comprise a branching filter and two receivers, each accepting a different one of the two carrier frequencies. The separation between the two pairs of carriers F 1 , F 2 and F 3 , F 4 may be about 20 mc/s. to avoid coupling between the transmitters and receivers at the same station.