HF Noise Measurement in the Western Part of Romania

Despite the extraordinary development of mobile communications, HF radio links have several advantages that make them unique in some application areas. Knowledge of HF noise is critical for the setup of a point to point HF communication. The paper presents HF noise measurements performed using a broadband antenna and Software Defined Radio equipment for signal acquisition, followed by offline signal processing. The recording has been split into several sub-bands of small bandwidth and for each sub-band the mean power has been computed, to find the sub-band with the lowest power. It might be assumed that the frequency band having the lowest power contains only noise. An analysis of the influence of sub-band size on the noise level hasalso been made. Measurements cover a large part of HF band and a large time interval to observe the noise behaviour.The paper analyses the noise level over short and long time periods, and over a large frequency band, and reports also simultaneous noise measurements in two locations in the western part of Romania, a dense urban one and a small town one, to highlight the differences caused by man-made noise of industrial type.