In this paper, considering general model of radio channel, where receiving signal is submitted by accidental fluctuations of the amplitude and phase, well known as fading, the aspect of composite fading parameters impact on the probability of error for GMSK modulation format, has been discussed. Composite shadowed Nakagami-m fading channel model is used to describe the statistical properties of wireless channel since the signal propagation is affected by three statistically independent phenomena: deterministic path loss, slow lognormal shadowing and fast multipath fading. Different models used for estimation of path loss in wireless channel were treated. For resolving problems, we used the new analytically derived closed-form expressions for the amplitude distributions and probability density function in gamma shadowed and varying Nakagami-m fading channel, which considers alternative approximation based on gamma-contribution. While solving the problem mentioned above, the analytical solution based on relevant approximation has been used, having in mind that there isn't any exact analytical expression for the static error probability for noncoherent GMSK receiver

In this paper a novel explicit analytical expression for the probability density function of the composite envelope in the presence of simultaneous changeable fast and slow fading is given. We use the term "changeable fast fading" to denote the fact that fast Nakagami fading, characterized by a given parameter m/sub i/, appears with probability p/sub i/. Analytical results are presented graphically for some characteristical values of parameters of fast and slow fading in the channel of mobile communications. This is a basic result, which opens possibilities to do explicit analytical treatment and analysis of the transmission quality in this channel. It is essentially a new contribution and quality in comparison with the present situation, where similar problems are solved using exclusively numerical integration methods or time-consuming simulation methods.

The paper describes DC/DC converter, galvanically isolated, with two types of rectifier in output part. The first type of rectifier is the full wave rectifier with or without center-tapped transformer, and the second one is the current doubler. It was shown how the comparative advantages of each of these two circuits can be used to obtain a combined rectifier circuit with extended range of output power.