Converter for Astra satellite signal reception - selects two local oscillator frequencies so that second or third order mixing products fall between channels

摘要

The converter has a polarisation filter (11) for separating horizontal and vertical polarised signals. After the filter is a mixing stage (15',15") in each following reception branch (13',13") with local oscillators (17',17") for each mixing stage for converting the reception signals into IF, pref. with a combination diplexer (21) for feeding a common output line (5). The frequencies of the two local oscillates are chosen so that second or third order mixing products of the local oscillation frequencies in the IF plane lie frequency-gap increased w.r.t. the other channel frequency intervals. The products have a min. spacing of 14.75 MHz to the adjacent channels between the 15th and 17th, or 16th and 18th channel. USE/ADVANTAGE - For reception of Astra 1C satellite, with reduced channel interference.