It has been many times stated (Rawer 1949; Booker 1950; Booker and Gordon 1950; McNicol and Gipps 1951) that the frequency characteristics of the sporadic E region are rapidly varying functions of the overall sensitivity of the recording p'f equipment. A very simple test of this statement has been made; and it has been found to be incorrect at Brisbane.
An important step in preparing for a nationwide, switched, video telephone service is the formulation of a transmission plan for the video and audio portion of the network. The transmission plan described in this paper features digital transmission for the long‐haul portion of the network and analog transmission for the local portion, close to the customer. The performance of each of the components of the network, that is, station equipment, local loops, trunks and switches, is discussed for the network as it is expected to be configured initially and as it might evolve through the 1970s.
.As a supplement to work reported earlier (Thomas, Svenson, and Brown 1956), in which the receiver gain of a P'frecording equipment was systematically changed from record to record, a similar experiment has been devised in which the power radiated by the transmitting aerial is systematically changed, thus altering the" signal-to-noise " ratio at the receiver. This should and does give results differing from those formerly obtained.
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