The national information network is being implemented with the aim of providing the services needed by the people through internal infrastructure and independent of international internet platforms. Considering the geographical diversity of the country and in order to increase the reliability coefficient and access penetration coefficient in the national information network and also due to the needs of future services, it is not possible to rely solely on fiber and the use of satellite communications will be unavoidable. At present, satellite communication has not reached a worthy position in the country's communication network and is limited to some applications such as banking, oil and gas etc. However, due to the development of broadband networks and the increasing need for high-speed data transmission and the increase in data volume, as well as creating social justice and increasing the speed of access, as well as the Internet penetration rate in the country in order to access various services, it is necessary to develop satellite communications to should be taken seriously. In this regard, an analysis of the market of several categories of services in Iran has been done so that the amount of gap in the amount of service provision and the amount of need to receive services can be seen.

What is done in this paper is simulation of telemetry and telecomm and communication between satellite and earth station as what exists in real earth station. Three software: Satellite predictive motion software, Monitoring and Control (M&C) software, processing Software are used in the simulation. Satellite predictive motion software uses orbital equation extracted from Two Line Elements (TLE) to generate tracking elevation and azimuth angles of satellite. These angles as textile are input of M & C software. The M & C software has four modes as simulation mode, online mode, test mode and emergency mode. In simulation mode Acquisition Of satellite (AOS), Loss Of Satellite (LOS) and Pass Time (PT) are seen. The angles are produced and transferred to antenna servo system for moving antenna to desirable direction. Time of simulation is controllable and received signal level is displayed simultaneously. In this mode when satellite is observable, the telecomm and can be send. In online mode all explained capabilities are valid except changing of time. In test mode antenna axis could move in desirable velocity and acceleration. In the other hand, when the satellite becomes lost, the system enters to emergency mode for searching of satellite. In the normal mode after receiving the telemetry data by M & C software this data as textile transferred to processing software. Processing software by protocol which accepted by satellite (HDLC based) recognizes the .first and the end of telemetry frame and then extracts and displays the parameters. The telemetry parameters include online and offline data.

The world is embroiled in a pandemic of a new coronavirus at the end of 2019 and early in 2020, with such a large scale that it has severely involved the political, economic, and social systems in most countries around the world. The scale of the crisis is so widespread that many experts believe that the post-corona world will be substantially different from the pre-corona world. In the face of this massive epidemic, how people perceive risk and how to risk is communicated, plays a central role in deciding and choosing people's behavior. Fighting with this emerging phenomenon requires mobilizing all the possibilities of society and helping all people in the field of empathy and altruism. In this article, we briefly review aspects of the important concept of risk perception and communication in this pervasive crisis.

Nowadays, with the advent of new satellite services, the need for resource management in the emerging fifth generation satellite systems (5G-satellite) is inevitable. Thus, to solve this problem, the Bandwidth Manager for resource reservation in satellite link is mandatory. On the other hand, due to limited resources, their resource management¬ is essential. In order to resource management in 5G-satellite systems, can be applied in one phase or many phases. In this paper, resource management for 5G-satellite services is evaluated. The proposed optimization problem is to maximize mean response time under the propagation delay constraints in satellite links. We solve the considered optimization problem via the single phase and two phase algorithms. Finally, through simulation, the proposed algorithms are investigated and confirmed. In our scenarios, satellite is a Central node in call flows and ground stations are End nodes in 5G-satellite based on Internet protocol. So we simulated all of scenarios in matlab software for this reason.

In this paper, a new method based on Pareto Simplex Search (PSS) has been employed to find the communications satellite optimal transfer trajectory from geosynchronous transfer orbit (GTO) to geosynchronous orbit (GEO) as the destination operational zone. We solve this problem through using a mathematically efficient algorithm and in all transferring phases, considering transfer orbits to intermediate orbits; it is supposed that the orbital maneuver control unit has continuous performance characteristics. The system governing equations representing the two body system of a spacecraft and primary gravitational source and thrust force applying to spacecraft, are defined in a nonlinear form. In this systematic approach we incorporate system dynamics as the problem constraints, and both minimum-time and fuel consumption using constant acceleration simultaneously as the problem strategy to find the optimal transfer trajectory between two orbits. Set of optimal trajectories are plotted in Pareto Front and transfer trajectory can be selected from these points.

The purpose of this paper is designing a communications system and the required protocols for store and forward (S&F) payload of a LEO satellite. Considering users' dispersion in diverse places, split channel reservation multiple access (SRMA) technique, is applied through users to access the uplink channel. Different modulation methods are analyzed and PSK modulation and non-coherent FSK modulation are suggested for payload downlink and uplink, respectively. An error detection technique based on Reed-Solomon (255, 233) is used in the payload to improve the link performance and SR-ARQ approach is selected which is more efficient than other ARQ techniques. Moreover, communication protocols of the users' network, file transmitting to the satellite and file receiving from that along with their implementation are explained in terms of software. Finally, an appropriate hardware is proposed for this subsystem. Comparison of our design and the design strategy suggested in [4] show that onboard hardware complexity of current paper is less than [4]. Furthermore, our coding, modulation and protocol and Doppler compensation scenario is more efficient than [4].

In this paper, design and simulation of a deployment and release mechanism of a communication satellite antenna are described. Because of the simplicity and reliability of the system, a torsion spring is used to excite the antenna. Dynamic simulation is performed by Adams Software and the appropriate spring and damper are selected for the mechanism. Also, a thermal cutter mechanism is used for the release mechanism of the antenna that shows a good performance in the tests. Also, a finite element analysis is performed to ensure the structural strength of the mechanism by Nastran-Patran Software. According to the results of the tests and simulations performed on the system, one can say that this mechanism is a simple, functional and reliable mechanism and can be done well the assigned duties in accordance with the requirements of the employer and the ECSS standard.

This paper describes the design of 6W C-band power amplifier based on the GaN-technology for use in TT&C-transmitters. Simple design, relatively high efficiency are the main features of this design. The operational frequency range spanned from 3. 4GHz to 4. 25GHz. It was decided to design the amplifier with the 6W CGH4006P transistor, from Cree. In the design procedure, source and load pull simulations were performed in order to retrieve the optimal impedances for the transistor and as a basis for the design of the matching networks. The amplifier design was done using a large signal model from Cree in Advanced Design System. The simulated results showed that the design were capable of delivering 6W output power throughout the frequency band. P1dB is 39dBm in EM simulation. For this Amplifier the transducer gain is 11-13dBm. The power amplifier obtained a simulated power added efficiency (PAE) 54-60% at 39dBm output power. PA obtained a small signal gain above 13dB.