Low cost angle of arrival measurement system

A system for determining direction of arrival of a received signal, said system comprising:

• a plurality of interferometer antenna elements spaced apart from each other a predetermined distance and receiving the signal, said plurality of interferometer antenna elements being more than two antenna elements arranged in a linear array;
• a first switching network coupled to the plurality of interferometer antenna elements;
• only two interferometer receivers coupled to the first switching network, said first switching network selectively directing the received signals from two selected interferometer antenna elements to the two interferometer receivers in a sequential manner so that several pairs of the interferometer antenna elements are separately directed to the two interferometer receivers, said interferometer receivers measuring a phase difference therebetween;
• four guard antenna elements oriented 90° apart and receiving the signal;
• a second switching network coupled to the four guard antenna elements;
• a single guard receiver, said second switching network selectively directing the received signal from selected guard antenna elements in a sequential and separate manner to the guard receiver;
• and
• a controller coupled to the interferometer receivers and the guard receiver, said controller determining a phase difference between the measured phase differences of the two selected interferometer elements and determining a power of the selected guard antenna element.

A method of determining the angle of arrival of a signal, said method comprising the steps of:

• selecting a first pair of interferometer antenna elements from a plurality of interferometer antenna elements;
• connecting the first selected pair of interferometer antenna elements to a pair of interferometer receivers;
• measuring the phase difference between signals received by the first selected interferometer elements;
• subtracting a predicted phase difference from the measured phase difference between the signals received by the first selected interferometer elements to generate a nominal phase difference;
• selecting a second pair of interferometer antenna elements from the plurality of interferometer antenna elements that is different than the first pair of interferometer antenna elements;
• connecting the second selected pair of interferometer antenna elements to the same pair of interferometer receivers;
• measuring the phase difference been signals received by the second selected interferometer elements;
• and
• determining the angle of arrival of the signal received by the interferometer antenna elements based on the measured phase differences, said step of determining the angle of arriving including subtracting a predicted phase difference from each measured phase difference to generate a nominal phase difference.

A method of determining the angle of arrival of a signal, said method comprising the steps of:

• providing at least two interferometer antenna elements;
• measuring the phase of the signal received by each of the interferometer antenna elements;
• determining the phase difference between the measured phases of the signals received by the interferometer elements;
• and
• performing a linear transform on the phase difference to rotate phase trajectories represented by the phase difference to be aligned with a coordinate axis.

A system for determining angle of arrival measurements of a signal, said system comprising:

• a plurality of interferometer antenna elements spaced apart from each other a predetermined distance and receiving the signal, said plurality of interferometer antenna elements being greater in number than two antenna elements;
• a first switching network coupled to the plurality of interferometer antenna elements;
• two interferometer receivers coupled to the first switching network, said first switching network selectively directing the received signal from two selected interferometer antenna elements to the two interferometer receivers in a sequential manner so that several pairs of the interferometer antenna elements are separately directed to the two interferometer receivers;
• a plurality of guard antenna elements;
• a second switching network coupled to the plurality of guard antenna elements;
• a single guard receiver coupled to the second switching network, said single guard receiver selectively directing the signal received by the guard antenna elements in a sequential and separate manner to the guard receiver;
• and
• a controller coupled to the interferometer receivers and the guard receiver, said controller determining a phase difference between measured phase differences of the two selected interferometer antenna elements.

A method of determining the angle of arrival of a signal, said method comprising the steps of:

• selecting a first pair of interferometer antenna elements from a plurality of interferometer antenna elements;
• connecting the first selected pair of interferometer antenna elements to a pair of interferometer receivers;
• measuring the phase difference between signals received by the first selected interferometer elements;
• selecting a second pair of interferometer antenna elements from the plurality of interferometer antenna elements that is different than the first pair of interferometer antenna elements;
• connecting the second selected pair of interferometer antenna elements to the same pair of interferometer receivers;
• measuring the phase difference between signals received by the second selected interferometer elements;
• selecting a guard antenna element from a plurality of guard antenna elements;
• connecting the selected guard antenna element to a single guard receiver;
• measuring the signal power received by the selected guard antenna element;
• sequentially repeating the steps of selecting a guard antenna element, connecting the guard antenna element to the guard receiver and measuring the signal power received by the selected guard antenna element sequentially for all of the plurality of guard antenna elements;
• and
• determining the angle of arrival of the signal received by the interferometer antenna elements based on the measured phase differences.