R&D Report 1978-20 : Narrow-band f.m. system for television links: a feasibility study. R.Storey
The use of fm television links at uhf (Band-V) depends, at present, upon the availability of a number of adjacent 8 MHz broadcast television channels to accommodate the 16 MHz bandwidth occupied by the transmitted signal. Because of the expansion of the uhf transmitter network, fewer spare sets of contiguous channels are expected to be available. To overcome this difficulty, it was proposed that the fm signal could be modified to work within a bandwidth of only 8 MHz. To evaluate the proposal, an experimental narrow-bandwidth fm system was constructed. It was found that fm television signals could indeed be transmitted successfully in a nominal bandwidth of 8 MHz, instead of the nominal 16 MHz used at present. As a consequence of the bandwidth reduction, both linearity and signal-to-noise ratio were slightly impaired, nevertheless it is thought that a link of this kind should be advantageous under certain conditions.