The importance of high-precision determination of true azimuth
is emphasized by a number of practical applications in registration, navigation, targeting problem solving and object direction determination, high-precision orientation of communication systems, geodesy, and so on.
[[theta].sup.(true).sub.1] and [[phi].sup.(true).sub.1] denote the true azimuth
angle and the true elevation angle of the first incident signal, respectively.
Error (e) was defined as the difference between the true azimuth
([theta]), determined using a hand held GPS unit, and the estimated azimuth ([theta]) of the transmitter for each azimuth i and replicate j as:
As shown in Fig 1, the measured angle forms a right spherical triangle with the true azimuth
and the elevation.
Error arcs were derived by calculating the average deviation from the true azimuth
in field trials of personnel asked to locate transmitters placed at various positions in the habitat (Hurst, 1997).
In most systems, the processor also accepts information about the orientation of the baseline (relative to true north or true local horizontal) to determine the true azimuth
or elevation angle to the emitter.