The paper focuses on the new trend of increasing the accuracy of low altitudes measurement by frequency-modulated continuous-wave (FMCW) radio altimeters. The method of increasing the altitude measurement accuracy has been realized in a form of a frequency deviation increase with the help of the carrier frequency increase. In this way, the height measurement precision has been established at the value of ±0.75 m. Modern digital processing of a differential frequency cannot increase the accuracy limitation considerably. It can be seen that further increase of the height measurement precision is possible through the method of innovatory processing of so-called height pulses. This paper thoroughly analyzes the laws of height pulse shaping from the differential frequency presented by the number that represents the information about the measured altitude for this purpose. This paper presents the results of the laboratory experimental altitude measurement with the use of a so-called double-channel method. The application of obtained results could contribute to the increase of air traffic safety, mainly in the phase of the aircraft approaching for landing and landing itself.

The Technical Note presents the possibility of applying the classical onboard aviation radar altimeter in the function of a simple anticollision system. Currently, classical radar altimeter offers two important pieces of information for pilots: actual flight altitude and aircraft descent at the level of decision making. The goal here is to draw attention to the innovative technique of using the radar altimeter to generate further crucial information for the pilot of a helicopter or small aircraft for predicting the threat of collision with the terrain. This new technique is based on the evaluation of the Doppler frequency in the differential signal of the radar altimeter. The theoretical assumptions have been verified by simulation and experiment.

Presented paper concentrates on accidentally identified, specific method of mechanical vibration demodulation, radiated high-frequency signal of aircraft communication antenna, located directly on the aircraft. It describes the structure and solution of the designed laboratory workplace at which it is possible to evoke mechanical vibration demodulation as a specific phenomenon. The aim is to analyze possible physical electric characteristics of antenna as a source of mechanical vibration on “Monopole“ type of antenna. Next, transfer amplitude frequency characteristics of the antenna, as a mechanical vibration demodulator, are analyzed. As this is a basic research of this accidentally identified phenomenon, an observation method of experiment results is used to find out the analogies by the form of their comparison with a classical amplitude demodulator. The results show that if the mechanic influence of artificial ground is suppressed, the transfer amplitude frequency characteristics of such demodulated signal has minimal distortion in frequency range 200Hz to 3.5kHz. The paper presents brief summary of measured basic values on the base of which obtained results are analyzed and brief conclusions of observed phenomenon are defined. They are the first outputs of the phenomenon observations on the base of which it can be concluded that it is reasonable to deal with this problem. At the same time this is not just the antenna characteristics analysis but also the analysis of mechanical oscillations of the antenna from the viewpoint of its more secure fixing at the aircraft fuselage. Because the concurrent influence of two kinds of vibrations, primary – as a result of aerodynamic circumfluence of antenna during the flight in collaboration with the secondary – as a result of its radiation, places higher requirements on its mechanical fixation. Presented facts mean the increase of air traffic operation.