Monopulse arbitrary phase detection and removal

A phase detector for detecting and removing an arbitrary phase difference between a sum channel signal and a difference channel signal in a monopulse tracking system, the detector comprising:

• a first input configured to receive a sum channel signal from a monopulse tracking system;
• a second input configured to receive a difference channel signal from the monopulse tracking system;
• and
• one or more sum/difference correlators, the one or more sum difference correlators each coupled to the first and second inputs, each sum/difference correlator comprising:
• a multiply block that receives the difference channel signal and one of a plurality of potential phase difference pairs φi and φi+π and shifts the difference signal channel according to the one of the plurality of potential arbitrary phase differences to thereby generate a phase shifted difference channel signal;
• an add block that combines the phase shifted difference channel signal with the sum channel signal to produce one of a sum+difference channel signal or one of a sum−difference channel signal;
• a magnitude estimator block that determines a magnitude of the sum+difference signal or the sum−difference signal;
• a selection block coupled to the one or more sum/difference correlators, the selection block configured to determine the magnitude of the sum+difference signal corresponding to a maximum in-phase correlation from the φi phase shift, and the magnitude of the sum−difference signal corresponding to a maximum out-of-phase correlation from the φi+π phase shift;
• and
• a processor block that uses the magnitude of the sum+difference signal corresponding to the maximum in-phase correlation and the magnitude of the sum−difference signal corresponding to the maximum out-of-phase correlation in an error estimate calculation.

A monopulse tracking system, the system comprising:

• A feed/combiner comprising two or more feed antennas and two or more combiners, wherein the two or more combiners are configured to combine signals received from the two or more feed antennas to generate a sum channel signal and at least one difference channel signal;
• a Radio Frequency (RF) detector assembly that is coupled to the feed/combiner and that receives the sum channel signal and at the least one difference channel signal, the RF detector assembly configured to perform down conversion on the sum channel signal and at the least one difference channel signal and to convert the signals into digital signals;
• and
• a digital arbitrary phase detector that is coupled to the RF detector assembly, the digital arbitrary phase detector configured to:
• receive the digital sum channel signal from the RF detector assembly;
• receive the digital at least one difference channel signal from the RF detector assembly;
• shift the at least one difference channel signal according to a plurality of potential arbitrary phase difference pairs φi and φi+π between the sum and difference channel signals to thereby generate a plurality of difference channel signals each having a different phase;
• combine the plurality of difference channel signals each having a different phase with the sum channel signal to generate a plurality of sum+difference signals and sum−difference signals;
• determine, based on the plurality of sum+difference signals and sum−difference signals, a maximum correlation magnitude difference between the φi and φi+π pairs;
• and
• use the maximum correlation magnitude difference from the φi phase-shift and the φi+π phase-shift in an error estimate calculation.