Direction finding and interferometer analysis

Direction finding is a method to determine the direction of a transmitted signal by using two antennas and measuring the phase difference between the antennas (Figure 15.1). This process is called interferometry. In addition to using a static interferometer, further analysis needs to be done to calculate the direction when the interferometer baseline is dynamic; that is, the interferometer is moving and rotating in a three-dimensional plane. Thus, coordinate conversion processes need to be applied to the nonstabilized antenna baseline to provide accurate measurement of the direction in a three-dimensional plane.