Ambiguity-Resistant Three- and Four-Channel Interferometers
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
Interferometers are useful for implementing real-time estimates of the angle-of-arrival of radio-frequency energy from distant emitters. Although accuracy and resolution of these arrays improves with increasing length, so does their tendency toward ambiguous estimates of the spatial angle. Tolerance to ambiguity caused by channel-pair phase errors for three-element arrays of a given length improves dramatically when another antenna-receiver channel is added to the array. Extensions to array ambiguity theory clarifies the principles of three-element arrays, and provides exact synthesis procedures for four-element arrays of any length. The extended theory shows that while a three- element array 23 half-wavelengths long subject to phase errors of 12 electrical degrees rms has a probability-of-ambiguity pa of 45, the corresponding optimum four-element array has a pa of only 0.075. Computer-aided syntheses define the optimum four-element arrays from 4 to 42 half-wavelengths, and provide the resultant pa for system design purposes for phase errors from 8 to 20 electrical degrees rms.
- Computer Programming and Software
- Computer Hardware
- Test Facilities, Equipment and Methods