Components of Satellite Communications Use

Components of Satellite Communications

Use of Satellite Communications

Advantages of Satellite Communications

Disadvantages of Satellite Communications

How Satellites Work

Enhancing Satellite Communication

Satellite Communication:

Satellite communication can be described as the use of artificial satellites to offer communication connections in different points on Earth. This type of communication plays a crucial role in the telecommunications systems across the globe since there are nearly 2,000 artificial satellites around the world. These satellites orbit the Earth transmitting analog and digital signals that contain data, voice, and video from one or various locations globally. This type of communication is based on two main components i.e. The ground segment and the space segment. While the ground segment is made up of fixed or transportable transmission, reception, and additional equipments, the space segment is basically regarded as the satellite itself.

The first true satellite communication to be launched in the world was known as TelStar, which was introduced by at&T telecommunications firm in 1962. Since then, there have been several communication satellites that have been established in different places with the utilized technology continuing to evolve and increase in complexity.

Components of Satellite Communications:

As previously mentioned, satellite communication is made up of two main components or basic elements as described below:

The Space Segment/Satellite:

This element consists of three different units i.e. The fuel system, the satellite and telemetry controls, and the transponder. The basic role of the satellite or telemetry controls is to reflect electronic signals. The transponder consists of the receiving antenna to obtain signals from the ground segment, an input multiplexer, a broadband receiver, and a frequency converter for re-routing the received signals through high powered amplifiers. The satellite can be used for observation purposes when equipped with cameras or several sensors.

The Ground Station/Earth Segment:

This element of satellite communication has two major tasks depending on whether it's an uplink or downlink. In an uplink or transmitting station, the segment transmits terrestrial data in baseband signals form through a baseband processor, a high powered amplifier, an up converter, and a parabolic dish antenna. However, the element works in the reverse form as the uplink in a downlink and eventually converts the obtained signals through the parabolic antenna to baseband signals.

Uses of Satellite Communications:

Since their inception, satellite communications have been used in different settings and for various purposes including:

Traditional Telecommunications:

The discovery of long distance telephone network contributed to the need to link telecommunications networks from one location or country to another. These long-distance connections have been accomplished in various ways including through the use of submarine cables. Nonetheless, satellite links have been used in large long distance carrier to establish connections with transoceanic points, remote areas, and poor nations with minimal communications infrastructures. One of the leading telecommunications firms that have fulfilled this service effectively across the globe is Intelsat, an international satellite consortium.

Cellular:

The second major way in which satellite communications has been used is in cellular where several schemes have been developed to permit satellites to increase bandwidths that are available to cellular networks that are based on the ground. In a cellular network, each cell separates a fixed range of channels that consists of either frequencies or time slots. Consequently, there is a likelihood of overloading to occur since a specific cell can only function within the channels that are allocated to it. Through the use of satellite networks, additional satellite channels are provided on demand to an overloaded network cell because satellites function at frequencies that are outside those of the cell. Therefore, satellites that provide service for a network of cells enable its own bandwidth to be used by a cell that requires it without location restrictions and terrestrial bandwidths (Hart, p. 3).

Television Signals:

Since early 1960s, satellites have mainly been used to transmit broadcast television signals between the television companies' hubs and their network affiliates. In certain cases, the whole series of programming is transmitted and recorded at the network affiliate immediately, with the broadcast of every segment at suitable times to the local viewing population. A significant development in the use of satellites for television signals in 1970s as it became possible for private individuals to download similar signals that networks and cable firms were transmitting.

Marine Communications:

Satellite communication systems offer good communication connections to ships at sea in the maritime community. In most cases, the connections use a VSAT type device to link satellites that connect the ship to point of presence in the land to the telecommunications system in specific countries.

Spacebourne Land Mobile:

Similar to the techniques that are used in marine community and communications, there are special VSAT devices that can be used to develop communication links with the most remote regions across the globe. Through the use of satellites, these devices can either be hand-held devices or devices that are fit into a briefcase.

Commercial Jets:

The other main use of satellite communications is for satellite messaging for commercial jets, which is provided by geosyncronous satellites. These satellites enable passengers on an airbourne aircraft to link directly to a telecom network that is based on land.

Global Positioning Service:

The other use of satellite communications is in global positioning service through another VSAT oriented device. In this case, small equipment with the ability to determine navigational coordinates through calculations of triangulating signals from various geosynchronous satellites is used.

Advantages of Satellite Communications:

As compared to terrestrial communications, satellite communications has several advantages including

Huge Coverage Area:

One of the major advantages of satellite communications is that its coverage area is largely beyond that of a terrestrial system because of its ability to link even the remote parts across the globe. This capability basically emanates from the fact that satellite communications use several techniques and devices that range from hand-held apparatus to those that fit into a briefcase. The other reason for the huge coverage area of satellite communications is that higher bandwidths are largely available for these network systems.

Independence of Transmission Cost:

The most notable feature of global or terrestrial communication systems and networks is that transmission cost is usually dependent on the distance from the central point of the coverage area. However, satellite communication systems differ from these kinds of networks since their transmission costs are largely independent of the distance from the central point of the network's coverage area. As a result, satellite communications have an advantage of transmission costs over terrestrial systems.

Effectiveness:

Unlike terrestrial communication networks, satellite communications have the advantage of effectiveness are long as the various devices and systems that are requires for the networks are linked properly and efficiently. Actually, communication from one satellite network to another is normally very precise.

Disadvantages of Satellite Communications:

While satellite communications have numerous advantages, especially when they are compared to terrestrial communication networks; they also have some disadvantages including the following

Higher Costs of Launching Into Orbit:

For a satellite communication network to achieve its goals and promotes easier and faster communication links from one location to another, it should be launched into an orbit. This necessity results into one of the major disadvantages of these communication networks since its very costly to launch satellites into orbit.

Increased Use of Bandwidth:

Due to the effectiveness and huge coverage area of satellites, there are many telecommunications firms that have launched into these systems to enhance their communication services. Consequently, satellite bandwidth is increasingly becoming used up as more companies venture into development of these networks, which is a huge disadvantage.

Delays:

As more and more companies are developing satellite communication networks, there is an increased use of these systems in communications across the globe. This has in turn contributed to another disadvantage because there is a larger broadcasting delay in satellite communication unlike in terrestrial systems.

How Satellites Work:

The effective functioning of a satellite communication basically involves the use of an uplink and a downlink to connect two stations at different locations. The uplink is the Earth Station that sends a transmission to the satellite, which is converted by the satellite Transponder and sent down to the second Earth Station known as the downlink. Generally, the satellite receives the uplink frequency and the transponder within it does the function of processing. Once the processing function and the frequency down conversion are completed by the transponder, it transmits the downlink signal at different frequency.

After this process, the earth station then receives the signal emanating from the satellite through a parabolic dish antenna (Sengupta par, 4). The station then processes the received signal in order to receive the baseband signal, which is then transmitted to the specific user through dedicated links or additional terrestrial systems as illustrated in the picture below:

In previous satellite communication systems large sized parabolic antennas with diameters of approximately 30 meters were used due to the weak state and faint signals which were received. As today's satellites have become much stronger, superior, and more powerful, there has been an automatic decrease in the size of the antennas that are currently used. As compared to the previous years, the antennas in the earth stations are no longer large in size because of enhancements in satellites.

A satellite communication basically functions and works in millimeter and microwave wave frequency bands that are estimated to range from approximately 1 Ghz to 50 Ghz. While there are different frequency bands that are used by satellite communication systems, the most common are the uplink and downlink frequency bands of 6 Ghz and 4 Ghz respectively. In essence the uplink frequency band usually ranges from 5.725 to 7.075 Ghz whereas the actual downlink frequency band is estimated to be around 3.4 to 4.8 Ghz.

In most cases, satellites function in three different orbits i.e. The low Earth orbit, medium Earth orbit, and geostationary orbit, which is also known as the geosynchronous orbit. While the low Earth orbits are placed at an altitude of between 100 and 1000 miles, the medium Earth orbit satellites function from 6300 to approximately 12,500 miles. On the other hand, the geostationary orbits are placed at an altitude of more than 22,326 miles above Earth mainly because they cover one orbit in a day and remain fixed over a single spot.

Important Factors in Satellite Communications:

In order for a satellite communication system to function or operate effectively, there are various factors that must be critically considered such as

Elevation Angle:

This can be described as the angle of the horizontal of the earth surface to the central point of the transmission beam in the satellite. The elevation angle is an important factor because it determines the coverage area of the satellite system and the fact that there is a lower elevation angle of earth stations. In most cases, an ideal elevation angle is 0 degrees in order for the transmission beam to achieve a visible horizon to the satellite across each direction.

Coverage Angle:

This is the second most important factor in satellite communication and it's defined as the measure of the portion of the surface of the earth that is visible to a satellite with regards to the minimum elevation angle (Charles, p. 6).

Satellite Footprint:

This is regarded as a crucial factor because the strength of transmission of the satellite tends to be more powerful in the transmission center and decreases further from the center because of the increase in free space loss. The free space loss is defined as the distance between the earth station and a satellite.

Atmospheric Attenuation:

Since atmospheric reduction is normally caused by air and water, it's an important factor in satellite communication because it can weaken the transmission. During the development and establishment of satellite communication systems, this factor should be critically considered because of its impact on transmission and its severity during rain and fog.

Enhancing Satellite Communication:

The development of a healthy satellite industry and sector has been fueled by the recent advancements in satellite technology that has contributed to the provision of multiple services to Internet Service Providers (ISPs), broadcasters, governments, military departments and units, and other sectors. Satellite technology has mainly developed from experimental mechanisms to the complicated and more powerful mechanisms within a short period of time. Actually, future satellite communications will be enhanced or developed to include more onboard processing abilities, increased power, and larger-aperture antennas. The increased capabilities will increase the efficiency of satellite communications because they will enable the satellite systems to handle more bandwidth. The service life of satellites will also be increased from the current 10 -- 15 years to 20 -- 30 years with extra advancements in the propulsion and power systems of satellites.

The need to enhance the existing satellite communication systems is fueled by various important factors. These factors include the demand for more bandwidth and increased advancements of satellite technology. Such enhancements will result in the long-term viability of the commercial satellite industry in the next generation and century. However, satellite communication can be enhanced through various means including & #8230;

Partnerships to Increase Training Capabilities:

One of the major ways to enhance satellite communication is through partnerships and enhanced delivery of training that is geared towards improving the deployments of satellite communication. The increased standards of various operational effectiveness for governmental agencies is being encouraged through the provision of training that facilitates the deployments of satellite communication systems ("Partnerships to Improve," par, 1). The initiatives are taking place at a time when there is increased dependence upon VSAT-based solutions for most of the communications across the globe.

Increased delivery of trainings for technicians will significantly contribute to the enhancement of satellite communication systems. Currently, various companies have been involved in such partnerships to provide practical VSAT installation trainings for technicians in different agencies and departments that are involved in satellite communication systems. An example of such partnership is the one between by Light Professional it Services, the Global VSAT Forum, and SatProf. As a result of the partnership, SatProf has been able to provide an online curriculum development and course administration for satellite professionals and technicians. These companies have partnered to help in lessening the future satellite interference in commercial and government industries.

Enhanced Network Engineering and Design:

The other most suitable way of enhancing satellite communication systems is through making improvements on the existing network engineering and design mechanisms. This is mainly because improved network engineering and design can contribute to lower costs of bandwidth use, which is critical for the efficiency of satellite communication. In most cases, network systems engineers usually have access to numerous variables to optimize the satcom link such as terminal specifications, satellite parameters, and intonation and coding mechanisms. When these network engineers manage these parameters effectively, the suitable network engineering and design can result in lower costs of bandwidth usage while facilitating increased optimal usage as well as enabling users to do more with less (Hunsicker p, 3). The need to improve network engineering and design in order to enhance satellite communication is also based on the fact that most satellite networks normally use Internet Protocol (IP) as mechanisms for data transportation.

Use of TCP/IP Technology:

According to the findings of many satellite designers, Internet protocol is the future of enhanced satellite communications that range from Earth observation to several military applications. Similar to the manner with which Internet technology has transformed workplace communications, satellite designers argue that the technology will have similar impacts on satellite communications in both the commercial and military fields. Through the use of TCP/IP technology for these systems, satellite communications will facilitate the ability for people to have office-like connectivity even in the remote parts on the globe. TCP/IP basically refers to Transmission Control Protocol / Internet Protocol that focuses on the process of how the Internet formats and transmits data.

The Transmission Control Protocol Technology has the potential of revolutionizing satellite communications because it manages how data bytes are transmitted and ensure that there is delivery of correct information. On the other hand, the Internet Protocol acts as the electronic post office through ensuring that messages or information are delivered to the appropriate addresses. Some of the Internet protocols that are currently in use are the TCP/IP and the UDP/IP i.e. User Datagram Protocol/IP.

The need for the use of TCP/IP technology to enhance satellite communications is based on the inability of the existing satellite routing technology to meet the increasing demands by data users for more information on a daily basis. TCP/IP technology can be regarded as the most suitable mechanisms for enhancing communications via satellites because of their numerous benefits (McHale par, 5).

As compared to the UDP/IP that focuses more on speed than accuracy, the TCI/IP technology prioritizes accuracy over speed. Consequently, the technology normally requires the receiver to verify the receipt of data or information before the transmission or delivery of more information. In cases where there are transmission errors, the technology automatically delivers the appropriate data. This is unlike the UDP/IP technology where there is no feedback mechanism from the receiver to the source resulting in the transmission of data in error. Therefore, TCP/IP technology is a more reliable mechanism that the UDP/IP for enhancing satellite communications.