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In an urban environment, a multipath propagation is one of the basic phenomena affecting a quality of received signals. This causes dispersions in time and angular domains. Basic parameters describing these dispersions are the rms delay spread and rms angle spread, respectively. The delay spread is related to a frequency of the transmitted signal and the nature of the propagation environment. In this paper, we show a mutual relationship between the time and angular dispersions in the received signal. The obtained simulation results present a comparison of the described dispersions for two different frequencies. In this case, the multi-elliptical propagation model and standard model developed by 3GPP are the basis for the simulation analysis of new communication system solutions.

This paper presents using bit error rate (BER) measurements to evaluate operation correctness of traffic (inputoutput) interfaces in modem of very small aperture terminal (VSAT). Such functional tests are carried out, for example, when purchasing communication equipment for armed forces. Generally, available standards do not describe measurement procedures in this area. In this case, accredited laboratories should develop dedicated assessment methodologies. In this paper, we show the methodology for the VSAT modems, which is based on the BER measurements.

This article provides a detailed description of methods for automatic recognition of transmission protocols, used in radio channels, based on distinctive characteristics of the radio signal received as well as binary sequence existing at the demodulator output of the radio recognition receiver. Conclusions are presented as relates to the operational efficiency of the signal analysis methods described, followed by possibilities to use them in practice. A software application has been presented, making use of methods for automatic transmission protocols recognition which are described in this article.