MEASUREMENTS OF DIRECTION-OF-ARRIVAL OF HF SKY WAVE SIGNALS BY MEANS OF A WIDE-APERTURE ANTENNA-ARRAY AND 2 SUPER RESOLUTION DIRECTION FINDING ALGORITHMS
Em. Warrington, MEASUREMENTS OF DIRECTION-OF-ARRIVAL OF HF SKY WAVE SIGNALS BY MEANS OF A WIDE-APERTURE ANTENNA-ARRAY AND 2 SUPER RESOLUTION DIRECTION FINDING ALGORITHMS, IEE proceedings. Microwaves, antennas and propagation, 142(2), 1995, pp. 136-144
From measurements of the amplitude and phase of ionospherically propag
ated HF radio signals received at several spaced antennas, the directi
on of arrival of the signals in both azimuth and elevation can be dete
rmined. A series of measurements has been undertaken using a wide aper
ture antenna array on signals received from several European broadcast
stations at distances of up to about 1400 km, and the directions of a
rrival estimated by means of two superresolution algorithms; MUSIC and
an iterative null steering method (an approximate maximum likelihood
estimator) based on the IMP and DOSE algorithms. A detailed comparison
of the performance of the two algorithms has been undertaken, and it
is concluded that the null steering algorithm is significantly better
than MUSIC at resolving the various propagation modes, particularly fo
r short signal analysis periods.