Circuits detect communications from multiple transmitting antennas to multiple receiving antennas. A respective first block for each non-initial transmitting antenna determines partial distances for pairings of a first candidate and a quadrature-phase amplitude. A respective second block for the initial transmitting antenna determines partial distances for combinations of phase amplitudes. A respective second block for each non-initial transmitting antenna determines partial distances for pairings of a second candidate and an in-phase amplitude. A respective first selector for each non-initial transmitting antenna selects the first candidates from the pairings for the respective second block having smaller partial distances. A respective second selector for each non-initial transmitting antenna selects the second candidates from the pairings for the respective first block having smaller partial distances. An identifier circuit selects a final candidate with a smaller partial distance from the pairings of the respective second block for the last transmitting antenna.