A synchronous detecting device for detecting phase shift keyed waves utilized in satellite communications and the like multiplies the PSK signals by 2 in a first plurality of multipliers and multiplies a plurality of reference carriers in a second plurality of multipliers. The multiplied signals are applied to a plurality of phase detectors. The PSK signals and the reference carriers are applied directly to another plurality of phase detectors. The phase detectors produce outputs proportional to the phase differences between the multiplied signals and the multiplied reference carriers whereby n phase detectors discriminate 2.sup.n phases.
An N-phase PSK demodulator is disclosed wherein all circuits therein operate in a frequency band equal to or below the carrier band. The locally reproduced carrier is generated by a phase locked loop in combination with a frequency converter means and a divide-by-two frequency divider. The frequency converter means consists of n identical frequency converter circuits connected in series, where 2.sup.n =N. For a 2-phase PSK demodulator where n=1, the 2-phase PSK modulated wave is applied as a first input and the reproduced carrier divided by two is applied as a second input to the frequency converter circuit. A mixer and filter provide as an output the difference frequency between the first and second inputs. The latter output is multiplied by two and applied as the input to the phase locked loop. Where n>1, the first input of each frequency converter circuit except the first is the output from the preceeding circuit, and the output from the last frequency converter circuit is the input to the phase locked loop.
A circuit for extracting a clock signal from a double-binary phase-shift keying system is disclosed. The carrier wave form is regenerated at the receiver from the phase-shift keyed (PSK) signal input. The regenerated carrier wave is frequency doubled and frequency mixed with the PSK input signal which has also been frequency doubled. A desired clock signal is thereafter extracted from the mixed signal by a band-pass filter. The system does not include a frequency divider which would result in a phase ambiguity.
A one-way and two-way multichannel radio frequency transmission system and method employing a sectorized broadcasting technique is described. The system and method reduces the effective bandwidth of the broadcast signal by multiplexing available channels of signals into a set of formatted independent digital bitstreams--where each of the bitstreams includes all or a portion of the available channels provided by the system program provider. The independent bitstreams are transmitted to transmitting towers using point-to-point transmission methods. The transmitting towers phase modulate and amplify the bitstreams to generate a set of independent modulated signals. Each transmitter tower includes an antenna for broadcasting the modulated signals to a sectorized service area each sector in the service area receiving a different one of the set of independent modulated signals. The antenna includes a set of individual antenna panels each panel for broadcasting one of the set of modulated signals. Each subscriber site demodulates, demultiplexes and selects one channel from the received modulated signal. Each transmitting tower broadcasts all of the independent modulated signals at one of a set of operating frequencies such that adjacent transmitting towers broadcast at different operating frequencies. In addition, adjacent antenna panels of a given antenna transmit at opposite transmission polarity.
