В.Т. Поляков

The variants of the experimental antenna for simulation of lightning discharges are considered. The Q-factor, efficiency and field strength are estimated.

The paper proposed a new broadcasting system in the LW, MW and SW bands, based not on the traditional amplitude modulation (AM), but on the quadrature modulation (QAM). It is shown that at the equal transmitted power the effi ciency of transmitters with QAM and their range increase by several times. The receivers are recommended to carry on the heterodyne scheme with phase-locked loop (PLL). They provide better selectivity, noise immunity and signal quality demodulation.

The article describes the use of a beats method for Doppler ionospheric investigation with remote SDR-receivers, having output to the Internet. The advantage of this approach is the ultimate low cost and ease of use, the ability to analyze the propagation on remote paths and estimation of the forecast.

The article shows that telecommunication superheterodyne receiver with multiple frequency conversion and several different oscillators are, in general, inferior frequency stability as compared with receivers having a common reference oscillator. The effect is especially noticeable in infradyne receivers, i.e. at intermediate frequencies lying above the signal frequency. The appropriateness of a reference oscillator is concluded.

We propose a method for extracting the beat frequency between adjacent carrier frequency broadcast stations already having high frequency stability and working at certain frequencies in accordance with the HF broadcasting grid 5 kHz. Method dramatically simplifi es and reduces the cost of receiving technique.