CIS 505 Week 8 Discussions STR

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CIS 505 Week 8 Discussions STR

CIS 505 Week 8 Discussion 1

The three mentioned satellites are used for communications, whether marketable or in customary native groundwork is inaccessible or capricious, circle in the earth in three orbits. Satellites are used as a way to communicate around the globe.  The broadcast industry as well as the telecommunication companies and weather satellites uses GEO to serve as its main access to communicate.

Geo configuration advantages are the stationary relative to the earth which leaves no issues for frequency changes due to the relative motion of the satellite and antennas on earth. Tracking is simplified by earths stations.  At 35,838 km above the earth, the satellite can communicate with roughly one-fourth of the earth; three satellites in geostationary orbit separated by 120x cover most of the inhabited portions of the entire earth, excluding only the areas near the north and south poles.

LEO or the original AT&T satellite proposal was for low earth orbititng satellites, but most of the early commercial satellites were geostationary. The idea of LEO sattelites is to use constellations of inexpensive.  A LEO satellite can be “seen” by a point on earth on the order of minutes before the satellite passes out of sight. If intermediate orbits are used—higher than the LEOS and lower than GEOS—a point on earth can see the satellite for periods on the order of hours. Such orbits are called medium-earth-orbiting satellites(MEOS). These orbits are on the order of 10,000 km above the earth, and require fewer handoffs. While propagation delay to earth from such satellites (and the power required) is greater than for LEOS, they are still substantially less than for GEOS. ICO Global Communications, established in January 1995, proposed a MEO system. Launches began in 2000; 12 satellites, including two spares, are planned in 10,400 km orbits. The satellites will be divided equally between two planes tilted 45x to equator. Proposed applications are digital voice, data, facsimile, high-penetration notification, and messaging services.

http://www.informit.com/articles/article.aspx?p=23761

http://www.harriscaprock.com/blog/high-throughput-satellite-communications-systems-meo-vs-leo-vs-geo/

“VSAT systems provide high speed, broadband satellite communications for Internet or private network communications.  VSAT is ideal for mining camps, vessels at sea, satellite news gathering, emergency responders, oil & gas camps or any application that requires a broadband Internet connection at a remote location. VSAT is an excellent way to connect your remote sites and workers with Internet communications for email, web access, video transmissions, Voice over IP telephone services, or other IP applications for your field operations. VSAT enables you to expedite your business processes by integrating field operations with your corporate wide area network.”

http://www.networkinv.com/technology/vsat/vsat-for-usa/

Coverage for the USA is on Galaxy 16, Galaxy 18 & AMC 9 satellites, provide options for connectivity across the USA. The coverage at sea is Maritime VSAT services.

The business applications currently being used to support VSAT is Television distribution, Long-distance telephone transmission, and Private business networks. Because of their broadcast nature, satellites are well suited to television distribution and are being used extensively for this purpose in the United States and throughout the world. In its traditional use, a network provides programming from a central location. Programs are transmitted to the satellite and then broadcast down to a number of stations, which then distribute the programs to individual viewers. A more recent application of satellite technology to television distribution is direct broadcast satellite (DBS), in which satellite video signals are transmitted directly to the home user.  GEOS (Geosynchronous Earth Orbit Satellites) are used mainly for communications and broadcasts. Business applications could be for satellite broadcasts, maritime phone calls, meteorological applications and cable and satellite tv as well.

LEOS (Low Earth Orbit Satellites) are also used in business for communications but on a more personal scale. LEOS are used for email and mobile phone networks, video conferencing, high bandwidth data connections and in government or business, can be used for spying and espionage operations.

MEOS (Middle Earth Orbit Satellites) are used in business for navigation. MEOS make up the backbone of the GPS enabled applications that are out there.

VSAT (Very Small Aperture Terminals) is being used to support businesses in a couple different ways. First, it allows for businesses in remote locations to have access to Internet resources. Laying cable is time consuming and very costly for rural areas. VSAT technology allows businesses to remain competitive no matter where they are. VSAT allow for a high QoS which allows them to be great partnered with VPN access for businesses. The QoS is also improved because most VSAT connections are only single hop resulting in less lag and loss.

References:

http://old.repertoiremag.com/Article.asp?Id=524

CIS 505 Week 8 Discussion 2

  • Compare the four items related to channel capacity: data rate, bandwidth, noise, and error rate. Determine the most important and justify its significance over the remaining items.
  • Describe real-world examples of attenuation and white noise. Examine the effect on the information-carrying capacity of the link and present a way to avoid these types of interruptions. Data Transmission is the process of sending digital or analog data over a communication medium to one or more computing, network, communication or electronic devices.  Data Rate is the term associated with the rate of data transferred between two or more computing and telecommunication devices or systems. Bandwidth is a wider term, which is basically associated with the computer networking and digital technologies and measures the bit rate of communication resources available or consumed. Noise is unwanted electrical or electromagnetic energy that degrades the quality of signals and data.  Error rate is the degree of errors encountered during data transmission over a communications or network connection.

Noise is the most important component in the channel capacity. Noise can disrupt the flow of information. There are so many different types of noise one could face in a business setting: Environmental, Physiological-Impairment, Semantic, Syntactical, Organizational, Cultural, and

Psychological. Issues in communications that derives from the above mentioned noises could affect the sender, the message itself, the channel it is being sent through, or the recipient of that message.

Attenuation is a loss of communication signal strength measured in decibals (dB). Amplification is used to surge signal potency. Range, Interference and Wire size are the reasons attenuation happens.  DSL uses attenuation. Typical values for line attenuation on a DSL connection are between 5dB and 50dB.

White noise is a type of noise that is produced by combining sounds of all different frequencies together.All the imaginable tones the human ear can hear and combine them all together would form white noise.White noise is random noise that has a flat spectral density.The audible frequency range 20-20000 hertz. An example of white noise is the sound of the ocean or the sound the train or subway makes as it moves across the tracks. Ambulances, Fire Trucks or Police vehicles all use white noise.The white noise is over heard through traffic and makes these emergency vehicles more noticeable. When looking at the four items I would say that error rate is the most important because it is great that you may get more stuff transferred faster with less time but if it has a lot of errors in the data then it is not as useful.

Techopedia explains Attenuation

Attenuation can relate to both hard-wired connections and to wireless transmissions.

There are many instances of attenuation in telecommunications and digital network circuitry.
Inherent attenuation can be caused by a number of signaling issues including:

  • Transmission medium – All electrical signals transmitted down electrical conductors cause an electromagnetic field around the transmission. This field causes energy loss down the cable and gets worse depending upon the frequency and length of the cable run. Losses due to
  • Crosstalk from adjacent cabling causes attenuation in copper or other conductive metal cabling.
  • Conductors and connectors – Attenuation can occur as a signal passes across different conductive mediums and mated connector surfaces.

Repeaters are used in attenuating circuits to boost the signal through amplification (the opposite of attenuation). When using copper conductors, the higher the frequency signal, the more attenuation is caused along a cable length. Modern communications use high frequencies so other mediums which have a flat attenuation across all frequencies, such as fiber optics are used instead of traditional copper circuits.

Different types of attenuation include:

  • Deliberate attenuation can occur for example where a volume control is used to lower the sound level on consumer electronics.
  • Automatic attenuation is a common feature of televisions and other audio equipment to prevent sound distortion by automatic level sensing that triggers attenuation circuits.
  • Environmental attenuation relates to signal power loss due to the transmission medium, whether that be wireless, copper wired or fiber optic connected.
  • References

http://compnetworking.about.com/od/networkdesign/g/what-is-attenuation.htm

http://www.livescience.com/38387-what-is-white-noise.html

 

 

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