Device positioning using acoustic and radio signals

A positioning device comprising:

• an acoustic receiver configured to receive a first ranging signal from a first transducer, the first ranging signal modulated using a first sequence, the acoustic receiver also configured to receive a second ranging signal from a second transducer, the second ranging signal modulated using a second sequence;
• a signal processor configured to use first and second sequence to calculate a phase difference between the first and second ranging signals, and to calculate a time of arrival of the first and second ranging signals;
• and
• an anti-aliasing module configured to calculate an angle between the positioning device and a first axis referenced to the first and second transducer using the phase difference and the time of arrival of the first and second ranging signals.

A system including a plurality of positioning nodes, each positioning node comprising:

• a first acoustic transducer configured to transmit a first acoustic ranging signal that is modulated using a first ranging sequence;
• a second acoustic transducer configured to transmit a second acoustic ranging signal that is modulated using a second ranging sequence;
• an acoustic receiver configured to detect a first and second ranging signals from another positioning node;
• a radio transceiver configured to send and receive radio signals for communication with the another positioning node;
• a signal processor configured to use the first and second acoustic ranging sequences to calculate a time of arrival of the detected first and second acoustic ranging signals and a phase difference between the first and second acoustic ranging signals, the signal processor further configured to calculate a plurality of aliased angles of arrival using the calculated phase difference;
• an anti-aliasing module configured to use a difference between the time of arrival of the first and second acoustic ranging signals to select an angle of arrival from the plurality of aliased angles of arrival;
• and
• a position processor configured to use a difference between a time of arrival of radio signals received from the another positioning node and the time of arrival of the first and second acoustic ranging signals to calculate a distance to the another positioning node, the position processor further configured to calculate a position of the positioning node relative the another positioning node using the calculated distance and angle of arrival.

A method for determining an angle between a positioning node and a secondary device, the method comprising:

• receiving at an acoustic receiver on the secondary device a first ranging signal from a first transducer disposed on the positioning node, the first ranging signal having a first acoustic sequence;
• receiving at the acoustic receiver a second ranging signal from a second transducer disposed on the positioning node using, the second ranging signal having a second acoustic sequence;
• calculating a phase difference between the first and second ranging signal based on the first and second acoustic sequence, the phase difference calculated using a signal processor;
• calculating a time of arrival of the first and second acoustic ranging signals using the signal processor;
• calculating a plurality of potential angles between the secondary device and a first axis of the positioning node, the plurality of potential angles based on the calculated phase difference;
• and
• selecting an angle from the plurality of potential angles using a difference between the calculated time of arrival of the first and second ranging signals.