Sattelite Communication

Lançado em maio último (CRAIDE, 2017a), o Satélite Geoestacionário de Defesa e Comunicações Estratégicas (SGDC) foi concebido pelo governo brasileiro para atender a demandas telecomunicacionais relativas a políticas públicas e necessidades estratégicas – na seara da Segurança Pública e, sobretudo, da Defesa Nacional –, bem como comerciais.

Error correcting codes are used for detection and correction of errors in digital communication system. Error correcting coding is based on appending of redundancy to the information message according to a prescribed algorithm. Reed Solomon codes are part of channel coding and withstand the effect of noise, interference and fading. Galois field arithmetic is used for encoding and decoding reed Solomon codes. Galois field multipliers and linear feedback shift registers are used for encoding the information data block. The design of Reed Solomon encoder is complex because of use of LFSR and Galois field arithmetic. The purpose of this paper is to design and implement Reed Solomon (255, 239) encoder with optimized and lesser number of Galois Field multipliers. Symmetric generator polynomial is used to reduce the number of GF multipliers. To increase the capability toward error correction, convolution interleaving will be used with RS encoder. The Design will be implemented on Xilinx FP...

Cyber attack is an action that aims to harm someone’s computer and system, or to steal valuable information. Despite the complexity of systems and the security measures organizations deploy, satellites systems are vulnerable to malicious exploitation. The paper explains satellite systems, briefly discusses some of cyber attacks on them, and suggests some solutions or methods of prevention from cyber attacks.

This paper elaborates a comprehensive overview of a photovoltaic (PV) system model, and compares the attributes of various conventional and improved incremental conductance algorithms, perturbation and observation techniques, and other maximum power point tracking (MPPT) algorithms in normal and partial shading conditions. Performance evaluation techniques are discussed on the basis of the dynamic parameters of the PV system. Following a discussion of the MPPT algorithms in each category, a table is drawn to summarize their key specifications. In the performance evaluation section, the appropriate PV module technologies, atmospheric effects on PV panels, design complexity, and number of sensors and internal parameters of the PV system are outlined. In the last phase, a comparative table presents performance-evaluating parameters of MPPT design criterion. This paper is organized in such a way that future researchers and engineers can select an appropriate MPPT scheme without complication.

On September 5th, 1982 the very first space bridge  between the US and the USSR took place. Since then many unthinkable events took place, among them the collapse of the USSR and the advent of globalization.  In the last 30 years the world has not only become flat, as described by Thomas Friedman, but also liquid, according to Russian opposition journalist Yulia Latinina. In the liquid world it is easy to own property abroad, cross borders in jambojets and trade shares of a foreign company on Ipad virtually and wirelessly from anywhere in the world sitting in a Starbucks.

این مقاله به موضوع سیاست‌گذاری چگونگی مواجهه با شبکه‌های تلویزیونی ماهواره‌ای در ایران می‌پردازد. در ابتدا، برخی سیاست‌های فعلی و بارز جمهوری اسلامی ایران در این مورد، از جمله ممنوعیت قانونی بکارگیری تجهیزات دریافت از ماهواره و ارسال پارازیت بر روی امواج شبکه‌های تلویزیونی ماهواره‌ای را مرور کرده و مشکلات هر کدام را از نظر گذرانده‌ایم. سپس، سیاست‌های دیگر از جمله بهره‌گیری از برنامه‌های مطلوب و منتخب شبکه‌های تلویزیونی ماهواره‌ای، ارتقاء کمی و کیفی برنامه‌های رادیو و تلویزیون ملی، آموزش و ارتقاء سواد رسانه‌ای آحاد جامعه و گسترش زمینه‌های تفریحی- فرهنگی را که می‌توانند آثار زیان بار ماهواره را کاهش دهند، مطرح کرده‌ایم. در نهایت، نتیجه گرفته‌ایم که ترکیبی از این سیاست‌ها با توجه به شرایط و نیازهای روز جامعه می‌تواند بیشترین اثربخشی را داشته باشد.

Among different solutions for mobile antenna systems, phased array antenna in general, cannot be considered as low cost especially in case if two-axis main beam scan is applied. Despite of this drawback regarding possible commercial application, this approach still remains attractive due to possibility to provide very low contour, high system agility, lower antenna aperture noise temperature and global coverage avoiding equator problem. This paper presents a flexible concept that among similar known solutions can be described as a cost effective. The antenna only receive terminal has been fully in house developed for trials on workbench platform that has to provide similar in flight motions for outdoor trials. The antenna terminal composed of 768 dual polarized elements operating in the range 10.95-12.75GHz is ready for an extensive anechoic chamber and field test campaign.

Pengertian Satelit GPS Satelit GPS atau satelit navigasi adalah satelit yang menggunakan sinyal radio yang disalurkan ke penerima di permukaan tanah untuk menentukan lokasi sebuah titik dipermukaan bumi. Salah satu satelit navigasi yang sangat populer adalah GPS milik Amerika Serikat selain itu ada juga Glonass milik Rusia. Bila pandangan antara satelit dan penerima di tanah tidak ada gangguan, maka dengan sebuah alat penerima sinyal satelit (penerima GPS), bisa diperoleh data posisi di suatu tempat dengan ketelitian beberapa meter dalam waktu nyata. Cara Kerja Satelit GPS Global Positioning System (GPS) sebetulnya adalah kumpulan dari 27 satelit yang terdiri dari 24 satelit aktif dan 3 satelit tambahan sebagai backup. Sistem ini pertama kali dibuat oleh militer Amerika Serikat yang ditujukan untuk kepentingan navigasi militer namun sekarang sudah dapat digunakan untuk umum. Sebuah GPS Receiver bekerja untuk menemukan 4 atau lebih dari satelit tersebut untuk kemudian memproses informasi yang didapat dari satelit-satelit tersebut untuk dapat menentukan lokasi dari receiver tersebut. Operasi ini menggunakan prinsip matematika yang disebut dengan trilateration. Penjelasan Triliteration Bayangkan saja misalnya anda sedang berada di suatu tempat di Depok dan sedang kebingungan mengenai lokasi saat ini. Lalu anda bertanya dengan teman anda yang berada di Kampus UI Depok (A pada gambar) dan memberikan informasi bahwa lokasi anda berada pada 7 km dari Kampus UI Depok.

Nowadays the Mass Medias are source of production, reproduction and distribution of knowledge and they have important role in the political, social and cultural change in the contemporary world. In this study we have tried to determine of the relationship between the use of satellite television and the intergenerational value convergence among youth and middle age people.
Method of the inquiry is Survey. Statistical population is consist of young and middle-aged people of Tehran. Sample population is consist of 767 person that determined by the multi-stage cluster sampling and it has selected by random. The data gathered through questionnaire.
The result shows the influence of satellite television is 71%. It is more effective for younger generation than middle-aged people. The finding shows increasing the use of satellites television, reduced the role of traditional values for mate selection factors, wearing kind, legality, religious, responsibility and nationalism. Therefore, although the use of satellite television is connected to the intergenerational values convergence, but is not positive convergence and it caused decreasing the tendency of different generations to traditional social values in society.
Keywords: Mass Media, Satellite Television, Social Values, Intergenerational Value Convergence.

در دنیای امروز رسانه های جمعی بویژه شبکه های تلویزیونی، به عنوان یکی از مهم ترین منابع تولید، بازتولید و توزیع معرفت، نقش عمده ای در تحولات سیاسی، اجتماعی و فرهنگی جوامع مختلف بر عهده دارند. در این پژوهش تلاش شده است تا رابطه بین بهره مندی از تلویزیون های ماهواره ای و همگرایی ارزشی بین نسلی در بین جوانان و میانسالان مورد بررسی قرار گیرد. روش انجام پژوهش، پیمایشی و جامعه آماری شامل دو نسل جوان و میانسال ساکن در شهر تهران بوده است. جمعیت نمونه، 767 نفر را در بر می گیرد. ابزار گردآوری داده ها نیز پرسشنامه محقق ساخته بوده است. نتایج به دست آمده نشان می دهد که ضریب نفوذ تلویزیون-های ماهواره ای در جامعه مورد مطالعه قابل ملاحظه است. بین بهره مندی از تلویزیون های ماهواره ای و میزان همگرایی ارزشی بین نسلی رابطه وجود دارد اما در بیشتر موارد، این همگرایی مثبت نیست و منجر به کاهش گرایش نسل های جوان و میانسال به ارزش های اجتماعی جامعه ایرانی شده است.
کلید واژه ها: رسانه های جمعی ارزش های اجتماعی تلویزیون های ماهواره ای همگرایی ارزشی بین نسلی

Politics around the world (and in the US) had a major impact on technological research and development in the 20th century. This impact actually accelerated a trend that started in the 18th century with weapons development and continued on into the industrial revolution in the 19th century. Space and the technical "race" to be first was driven by a sense of discovery and a thirst for scientific knowledge but also, and most importantly, by the politics of "claiming the high ground of space" and, of course, for national security.

سوال اصلی این نوشتار این است که آیا ماهواره نداشتن یا ماهواره ندیدن، ماررا از جهان بیرون و واقعیتها و حقایق جاری آن بی اطلاع و عقب نگه نمیدارد؟
پاسخ به این سوال منوط به بررسی ماهیت و معنای ماهوار ه و تاثیر آن بر میزان سواد رسانه ای و تغیرات نگرشی می باشد. استفاده از ایزار ماهواره همانند استفاده از کارد آشپزخانه  است که هم می تواند مخرب باشد و هم مفید. همه آنها منوط به سواد و فهم کاربر آن است. آموزش هاي رسانه اي و ارتقا سواد رسانه اي در لايه هاي متني جامعه يک نياز و ضرورت براي فرهنگ، سياست و امنيت ملي ماست. در نظام آموزش و پرورش، در رسانه ملي، در مطبوعات و از طريق نگارش کتاب هاي گوناگون بايد سواد رسانه اي توده ها و حتي نخبگان ما ارتقا يابد

Filter is one of the most essential components of any vehicle fuel system. The filtration of
debris and or contaminations such as: dirt from fuel, rust particle form tank, moisture etc. is
effectively  carried  out  by  the  filter  to  enable  vehicle  healthy  in  good  condition.  Filter
clogging is hazardous to vehicle life hence it leads to failure mode which causes reduction
in system performance and efficiency.  The test bed  module is used  to ach
clogging scenarios in the laboratory with respect to fuel system test rig and filter clogging
diagnostics. The diagnostics applications are focused on how to determine the health status
of component or subsystem and determine the faults sev
fuel  system  efficiency  or  total  breakdown.  The  clogged  filter  fault  scenarios  will  be
emulated on the test rig using the direct proportional valve (DPV). The percentage opening
of  the  DPV  is  carried  out  on  the  diagnostics  test  rig  to  determine  the  filter  healthy  and
faulty condition. The NI cDAQ  9172 which have the capability to acquire data from the
hardware component (DPV) is configured to control the subsystem. The data obtained from
the DPV, during the test period is represented on the graph to represent the filter healthy
and faulty condition. The healthy condition is determine by the percentage opening of the
(DPV)  from  100%,  80%,  60%,  40%,  and  20%,  while  the  clogged  filter  faulty  condition
scenarios  is  actualised by  injecting  fault  in  to  the  (DPV),  and  then  gradually  open  from
100%, 80%, 60%, 40%, and 20%. This paper presents a data collection method for clogged
filter  in  the  laboratory  on  the  fuel  system  test  rig. The  system  response  for  healthy  and
faulty condition test results was plotted and used to determine the filter faults severity. The
data driven method is used in this paper work.

Among different solutions for mobile antenna systems, phased array antenna in general, cannot be considered as low cost especially in case if two-axis main beam scan is applied. Despite of this drawback regarding possible commercial application, this approach still remains attractive due to possibility to provide very low contour, high system agility, lower antenna aperture noise temperature and global coverage avoiding equator problem. This paper presents a flexible concept that among similar known solutions can be described as a cost effective. The antenna only receive terminal has been fully in house developed for trials on workbench platform that has to provide similar in flight motions for outdoor trials. The antenna terminal composed of 768 dual polarized elements operating in the range 10.95-12.75GHz is ready for an extensive anechoic chamber and field test campaign.