Abstract: A multi-frequency quadrature modulated signal is divided into a plurality of frequency bands. Each frequency band component is estimated as to variation in phase due to multi-path phasing, using its guard interval waveform so as to compensate the variation.

Abstract: There is disclosed a channel separating filter apparatus for separating a frequency-multiplexed signal comprised of channel signals into respective channel signals. A frequency-converting section frequency-converts the frequency-multiplexed signal into a plurality of channel signals, so that an average value of carrier wave frequencies of two channel signals which are located in the center of the frequency-multiplexed signal and are adjacent to each other becomes substantially zero, and then outputs the plurality of frequency-converted channel signals. Thereafter, a channel separating section separates the plurality of frequency-converted channel signals outputted from the frequency-converting section into respective channel signals each having only a frequency component of each channel signal, thereby separating the frequency-multiplexed signal into at least two channel signals.

Abstract: A space diversity reception system which minimizes the inband amplitude and/or phase dispersion by controlling the phase shifter is described. According to the present invention, the interference waves in the two antenna outputs are combined in anti-phase condition. The phase shifter control direction is decided by the sign of the two parameters. One of them is difference between two antenna levels at the center frequency of the pass-band, and the other is the difference of the combined signal levels at the extreme edges of the pass-band. The control means comprises four detectors for detecting said levels, two subtractors for providing said level differences between them, and the control circuit for deciding the phase shifter control direction.

Abstract: A space diversity reception system which minimizes the inband amplitude and/or phase dispersion by controlling the phase shifter is described. According to the present invention, the interference waves in the two antenna outputs are combined in anti-phase condition. The phase shifter control direction is decided by the sign of the two parameters. One of them is difference between two antenna levels at the center frequency of the pass-band, and the other is the difference of the combined signal levels at the extreme edges of the pass-band. The control means comprises four detectors for detecting said levels, two subtractors for providing said level difference between them, and the control circuit for deciding the phase shifter control direction.