Radio system for two=way operation on two carrier frequencies - operates so that when station makes call, new channel is marked and all free stations are switched to it

摘要

The system comprises many mobile and fixed stations which can be connected with each other through a relay station with several switchable radio channels, and controlled by a central station. The central station monitors individual channels for their signal-to-noise ratio as the squelch criterion, and/or a certain continuous 1.f. tone is inserted into the 1.F. band proper as a sub-squelch criterion. A new free channel is marked by the central station at a first call of a subscriber station, and all not called stations are switched to the new channel, while calling and called stations remain on the originally marked channel.