Abstract: Reliable transmission of signals in a multi-channel system is achieved by transferring signal inputs from a defectively operating or inoperative transmitter to another transmitter which continues to transmit other channels. At least two transmitters are operated normally, each transmitting its own block of channels. A sensor detects when the output of one transmitter is improper or non-existent, and causes a change-over switch to operate. Operation of the switch adds the block of channels which had come from the one transmitter to the other (or one or more) of the transmitters, so that the remaining transmitter or transmitters now provide all the channels.

Abstract: A combination of broadband program materials, such as TV, plus digital communications services of all types, are broadcast to a cell in the same frequency band, such as 27.5 to 28.5 GHz. The combination of all the transmitted channels have a combined bandwidth substantially exceeding the frequency band. At least some of the channels are transmitted with two diversity characteristics different from those of other channels. In one embodiment analog signals transmit the broadband services, preferably using wide deviation FM modulation, the FM channels filling the band. By choosing carrier frequencies selectively, between 5 and 9 T-1 digital channels can be broadcast in each FM channel when polarization is the same. Differing polarization of digital and FM signals in the same band can enable selection and detection of the desired one of a full spectrum of digital signals, or any one of the analog signals.

Abstract: A low power, multi-function cellular television system for transmitting signals at super high frequencies. Each cell transmitter radiates signals with one polarization over one sector, and signals with a different polarization over the balance of 360.degree.. Sectors of adjoining cells are aligned to minimize interference from the adjoining cell. Adjoining cells may transmit different pluralities of carrier frequencies which are interleaved to minimize interference further, with each cell having one set of transmitted frequencies radiated for both polarizations, occupying at least 90% of a band used in common for the system.