This work is a continuation of a design of a phase radio navigation system for aircraft blind landing in case of nonequipped runways proposed in [1], where, the proposed system is based on measuring the phase shifts of signals received from four ground transmitters (antennas), placed on corners of the runway strip, which provide distance measurements accuracy in millimeters. However, there are two important points that need serious consideration. First, the phase measurement is going to give the total phase () ϕ ρ−

0, while the actual phase shift of interest is ‘ϕ’, 0 ρ is the transmitter initial phase. The second problem is that, the measured phase angle () ϕ ρ− 0 between the transmitted and the received signal can only be measured in the interval from 0 to π 2 radians, this problem is called phase ambiguity. The answer of these problems lies in the use of more than one frequency (signal). Two sinusoidal signals with different frequencies (1f and 2f) but the same initial phase can be used. Taking the difference of the measured phases, the initial phase 0 ρ can vanish. To get around phase ambiguity would be to make sure that the actual phase difference 12 ϕ∆ does not exceed π 2, this technique called equivalent or synthetic wavelength.

A new radio navigation system for aircraft blind landing is proposed. This system is based on measuring the phase shifts of signals received from four ground transmitters (antennas), placed on corners of the runway strip. The received signals phase shifts provide distance measurements accuracy in millimetres. The reception of these signals is made on the onboard antenna located on the aircraft. Three ground antennas out of the four will be sufficient for determining the location of the aircraft. As a result of the analysis, the coordinates of the onboard antenna, the coordinates of the centre of mass of the aircraft, and axis coordinate of the aircraft determined with respect to the runway coordinate system.

This work describes the architecture and design of an onboard digital receiver of the phase radio-navigation system for aircraft blind landing proposed in [1]. The proposed onboard digital receiver is a special case of a multi-channel narrowband digital receiver concept. The purpose of this receiver is to receive eight different RF frequencies (in four pairs) range from 960 MHz to 963.003749941 MHz, carry on them the required analogue and digital signal processing techniques to evaluate their phase shifts and then the difference phase shifts between each pair of them. The phase measurements lead to determination of the location of the aircraft with respect to the touch point on the runway with accuracy in millimetres.