Slow time frequency division multiplexing with binary phase shifters

A method of detecting at least one object, the method comprising:

• transmitting, from a first transmitter, a sequence of 2N first signal pulses within a period, each of the 2N first signal pulses having a first phase;
• and
• transmitting, from a second transmitter, a sequence of 2N second signal pulses within the period,
• wherein each of the 2N first signal pulses is simultaneous with one of the 2N second signal pulses, N second signal pulses have a phase shift of 180° relative to the first phase, others of the second signal pulses have the first phase, the N second signal pulses having the phase shift are immediately adjacent each other in the sequence, and N is an integer greater than 1.

A detector device, comprising:

• a plurality of transmitting means;
• and
• control means for controlling the transmitting means to transmit respective signals defined at least in part by a sequence of 2N pulses within a period,
• wherein:
• N is an integer greater than 1,
• a first one of the transmitting means transmits 2N first signal pulses within the period,
• each of the 2N first signal pulses have a first phase,
• a second one of the transmitting means transmits 2N second signal pulses within the period,
• each of the 2N first signal pulses is simultaneous with one of the 2N second signal pulses,
• N second signal pulses have a phase shift of 180° relative to the first phase,
• others of the second signal pulses have the first phase, and
• the N second signal pulses having the phase shift are immediately adjacent each other in the sequence.