Apparatus and method for electronic polarization correction

In a transceiver system including a receiving apparatus for receiving signals of a plurality of overlapping frequency channels, with generally half of said frequency channels being transmitted at a first polarization and the other half of said frequency channels being transmitted at a second, different polarization and with adjacent of said frequency channels being transmitted at different of said polarizations, a polarization correction system for providing output signals associated with particular ones of said frequency channels substantially devoid of signal energy associated with other ones of said frequency channels, comprising:

• at least one antenna for receiving said signals of said plurality of overlapping frequency channels, and for providing first and second antenna output signals containing received energy arriving at said at least one antenna at respective of said first and second polarizations;
• a splitter network for splitting said first and second antenna output signals into a plurality of signal pairs, with each signal pair comprising first and second receiver input signals indicative of said first and second antenna output signals, respectively;
• a plurality of receivers, each for receiving one of said plurality of signal pairs;
• each of said receivers including a combiner having first and second input ports and an output port;
• each of said receivers including a first circuit arrangement for converting associated first and second receiver input signals to first and second combiner input signals, respectively, at respective of said first and second combiner input ports, with a controlled relative amplitude and a controlled relative phase with respect to one another, wherein said combiner vectorially combines signal energies of said first and second combiner input signals to provide a combiner output signal at said output port;
• each of said receivers including a second circuit arrangement for detecting signal energy of said combiner output signal at a predetermined frequency associated with that receiver to provide a detected signal;
• wherein said first circuit arrangement of each receiver is responsive to said detected signal to optimize said controlled relative amplitude and relative phase by continuously varying the relative amplitude and relative phase to produce time varying changes in said detected signal, said first circuit arrangement including:
• pseudo-noise generation means for continuously producing pseudo-random changes in said relative amplitude and relative phase;
• and
• correlation means coupled to said pseudo-noise generation means for correlating said time-varying changes in said detected signal with said pseudo-random changes to continuously optimize said relative amplitude and phase, thereby continuously optimizing cross-polarization rejection;
• whereby said combiner output signal of each receiver contains signal energy associated substantially with at least one of said frequency channels transmitted at one of said first or second polarizations, and is substantially devoid of signal energy associated with said frequency channels transmitted with the other one of said first or second polarizations.

In a receiving system capable of receiving a first electromagnetic signal having frequencies within a given frequency channel and transmitted from an external source at a first polarization, said receiving system also receiving a second electromagnetic signal having frequencies within said given frequency channel and transmitted from an external source at a second, different polarization, a cross polarization cancellation apparatus for canceling received cross polarized energy of said second signal, comprising:

• at least one antenna for receiving said first and second signals and for providing a first antenna output signal containing received energy arriving at said antenna means at said first polarization and a second antenna output signal containing received energy arriving at said at least one antenna at said second polarization;
• a first circuit arrangement for converting said first and second antenna output signals to first and second combiner input signals, respectively, with a controlled relative amplitude and a controlled relative phase with respect to one another;
• a combiner for vectorially combining signal energies of said first and second combiner input signals to produce a combiner output signal;
• a second circuit arrangement for detecting signal energy of said combiner output signal at a predetermined frequency to provide a detected signal;
• said first circuit arrangement being responsive to said detected signal to optimize said controlled relative amplitude and relative phase to provide said combiner output signal with signal energy associated substantially with said first electromagnetic signal, and substantially devoid of signal energy associated with said second electromagnetic signal;
• wherein said first circuit arrangement is operable to continuously vary said relative amplitude and relative phase to produce time varying changes in said detected signal, and said first circuit arrangement includes:
• a dither generator for generating a sequence of voltage pulses;
• a switch coupled to said dither generator for periodically switching said sequence of voltage pulses between a first switch output port and a second switch output port;
• first and second correlators coupled to respective of said first and second switch output ports, for multiplying said detected signal by said sequence of voltage pulses switched thereto to provide first and second multiplied signals, respectively;
• first and second integrators for integrating over time said first and second multiplied signals, respectively, to provide respective first and second integrator outputs;
• a first summing circuit coupled to said first switch output port and to said first integrator for summing said first integrator output with said sequence of voltage pulses switched to said first switch output port to produce a first control signal, and a second summing circuit coupled to said second switch output port and to said second integrator, for summing said second integrator output with said sequence of voltage pulses switched to said second switch output port to produce a second control signal;
• and
• an attenuation and phase shifting apparatus coupled between said antenna output ports and said combiner, for providing said first and second combiner input signals at said controlled relative amplitude and said controlled relative phase responsive to said first and second control signals.