A detector device , comprising: at least one receiver configured to receive radiation comprising a plurality of codes used for MIMO transmissions, each of the codes being associated with one of a plurality of transmissions, each of the codes being distinct from the other codes; and a processor that is configured to: obtain from a memory or determine a phase code spectrum for the codes; obtain information corresponding to the phase code spectrum for the codes; determine a demodulated signal spectrum of radiation received by the at least one receiver; determine at least one preselected characteristic of the determined demodulated signal spectrum , wherein the at least one preselected characteristic of the determined demodulated signal spectrum is determined by: determining a frequency value corresponding to a location of at least one peak in the determined demodulated signal spectrum of the received radiation; and determining a complex amplitude of the demodulated signal spectrum at the at least one peak ; adjust the phase code spectrum based on the determined characteristic to generate an adjusted phase code spectrum ; and refine the determined demodulated signal spectrum based on the adjusted phase code spectrum to generate a refined demodulated signal spectrum . at least one receiver configured to receive radiation comprising a plurality of codes used for MIMO transmissions, each of the codes being associated with one of a plurality of transmissions, each of the codes being distinct from the other codes; and a processor that is configured to: obtain from a memory or determine a phase code spectrum for the codes; obtain information corresponding to the phase code spectrum for the codes; determine a demodulated signal spectrum of radiation received by the at least one receiver; determine at least one preselected characteristic of the determined demodulated signal spectrum , wherein the at least one preselected characteristic of the determined demodulated signal spectrum is determined by: determining a frequency value corresponding to a location of at least one peak in the determined demodulated signal spectrum of the received radiation; and determining a complex amplitude of the demodulated signal spectrum at the at least one peak ; adjust the phase code spectrum based on the determined characteristic to generate an adjusted phase code spectrum ; and refine the determined demodulated signal spectrum based on the adjusted phase code spectrum to generate a refined demodulated signal spectrum . obtain from a memory or determine a phase code spectrum for the codes; obtain information corresponding to the phase code spectrum for the codes; determine a demodulated signal spectrum of radiation received by the at least one receiver; determine at least one preselected characteristic of the determined demodulated signal spectrum , wherein the at least one preselected characteristic of the determined demodulated signal spectrum is determined by: determining a frequency value corresponding to a location of at least one peak in the determined demodulated signal spectrum of the received radiation; and determining a complex amplitude of the demodulated signal spectrum at the at least one peak ; determining a frequency value corresponding to a location of at least one peak in the determined demodulated signal spectrum of the received radiation; and determining a complex amplitude of the demodulated signal spectrum at the at least one peak ; adjust the phase code spectrum based on the determined characteristic to generate an adjusted phase code spectrum ; and refine the determined demodulated signal spectrum based on the adjusted phase code spectrum to generate a refined demodulated signal spectrum . <EOS>