This paper presents a survey of the models and software applications used in telecommunication networks that can be used to carry out network planning and traffic engineering processes in deployable networks. Deployable networks are intended to provide communication services for organizations with responsibilities for emergency response or for government structures.
In this paper, the authors want to highlight aspects related to the development, testing and use of an innovative technological product of the electric generator type with magneto, adapted for the production of heat and electricity. Its organology is based on a metal chassis to which is attached the heat engine and the generator with tensioner. The transmission of the rotational movement from the engine to the generator is done with the help of a V-belt. From a constructive point of view, the innovative aspect of the prototype is the adaptation of a moped-type electricity source, called here magneto, on a mobile generator structure that facilitates its independent and separate operation from the motors on which they are assembled. The heat engine has an installation attached to the section to exhaust the fumes resulting from the combustion of fuel. It accumulates heat that it releases into the outside environment. The tensioner allows the connection between the motor and the generator to be broken, allowing the motor to operate separately without generating electricity. The prototype has several constructive and functional advantages, such as: low mass, simple structure, energy efficiency and low operating noise.
The radio spectrum is a limited national resource, essential for some governmental applications and increasingly important for a series of non-governmental applications. The allocation of radio resources is done in a centralized manner, designating frequency managers of the defense system structures as local administrators of the resources allotted to the supported echelon. They have a limited number of frequencies they can assign to the emission sources in their area of responsibility. The article addresses the issue of radio spectrum management in the frequency allocation plans when using a large number of emission and reception sources for means of communication and non-communication in a small area. Locating several emission sources in the same site leads to different types of disturbing signals: emissions outside the bandwidth, harmonics and intermodulation. The article categorizes and describes these sources, presents the results of measurements distinguishing them, as well as the results of implementing some protective measures. Finally, the authors suggest a software solution for the local distribution of frequency resources.
Accurate noise estimation in the HF band is a defining aspect in the evaluation of SNR for communication links. The reference document that specifies how different types of electromagnetic noise can be taken into account by radio communication system planners is the ITU-R Recommendation P.372.Meanwhile a series of studies have demonstrated that Gaussian noise in the HF band is not always valid because this band noise is strongly affected by atmospheric emission sources such as lightning impulse. This leads to the idea that a distribution suited to express the noise variance is the Bi-Kappa distribution. In addition, over the past decade, SDR devices and real-time spectrum analysers, which can be used to evaluate this noise, have registered explosive growth. This article indicates technical solutions and procedures used to estimate the noise level in the HF subband which can be used for Near Vertical Incidence Skywave (NVIS) communications and proposes a measurement system based on a SDR solution which meets these requirements.
We present a short analysis of the prediction quality offered by Radio Mobile application when used for frequency band of TETRA systems in Romania. The simulation results provided by Radio Mobile were compared against own measurements made in multiple locations in Sibiu city. The correlation coefficient between simulated and measured values of signal power was of 0.907 while the maximum variation between data in the strings was 9.6 dB and the average standard deviation was 4.4 dB. These results indicate that the radio propagation model ‘Two-ray Irregular Terrain Model Point to Point’ (ITM) provides a prediction capability that offers a reliable planning of the radio coverage of TETRA systems.
In this article we propose the use of the persistence spectrum to accurately assess the user’s exposure to electromagnetic field emitted by new generation of communication terminals. Persistent display view available within a Real Time Spectrum Analyzer (RTSA) enables a graphical observation of the main statistical parameters of a signal. A simple case study of exposure assessment was conducted by measuring the electric field strength in the close proximity of a mobile phone operated in a LTE-Advanced mobile communication network. The proposed measurement procedure is presented and then applied to a limited number of operating situations (VoIP, Video streaming, File upload, File download). We made use of the persistence spectrum capabilities to directly access the signal strength statistics in time. By this procedure we demonstrate a supplementary facility that enables direct visual tracing of exposure dynamics during real time usage of a specific mobile application.
The differentiated designing of lessons from the virtual environment can have beneficial effects on the student. In order to achieve the objectives proposed in the course, the content should not only meet the student’s expectations but must be designed adaptively according to the defining elements of each learner. Adaptability in content is an essential factor in maintaining motivation, involving the student, and engaging him/her in the study. The paper analyses approaches for the adaptive building of content by identifying the elements that can influence the achievement of the objectives - motivation, expectation, learner’s style, a priori knowledge