Direction finding techniques have classically been based on multiple antennas systems employing multiple receivers. Classic techniques such as MUSIC and ESPRIT use simultaneous phase information from each antenna to estimate the angle-of-arrival of the signal of interest. In many practical scenarios, however, multiple receivers are impractical. Thus single channel techniques are of interest, particularly in mobile scenarios. Although the amount of work is considerably less than multi-channel direction finding, single channel direction finding techniques have been investigated. Specifically, the Watson-Watt technique and the Pseudo-Doppler technique are among the most prominent. These techniques are essentially analog techniques and suffer from different limitations.

In this research we investigate a new single channel direction finding technique based on a vector of Phase-Locked Loops (PLLs) in combination with a circular array. Our method is similar to the Pseudo-Doppler method in that it samples antennas in a circular array. The sampled data is fed to a bank of PLLs which track the phase on each element. The PLL outputs are then fed to a signal processing block that estimates the angle of arrival.

References

J . Keaveny, N. Harter, S. Venkatesh, and R. M. Buehrer, "Analysis and Implementation of a Novel Single Channel Direction Finding Algorithm", Submitted to MILCOM 2004, Military Communications Conference, October 31-November 3, 2004