1. Running head: TELECOMMUNICATION TERMS COMPARED 1
Week 3_Antonio_Telecommunication Terms Compared
Robert Naanes
NTC/360
February 14. 2011
Antonio Tovar
2. TELECOMMUNICATION TERMS COMPARED 2
This section discusses the difference between an Asynchronous system and a
Synchronous system. In an Asynchronous system the transmitter and receiver do not
correspond with each other to set parameters; the transmitter simply sends a packet of
information and the receiver has to read the packet to determine the timing, length,
configuration, etc.
A disadvantage of this system is that both the transmitter and the receiver must
be using the same encoding and decoding method and both must be able to view the
signal in order to find the data needed. Even though this system is a faster means of
connecting it is less reliable. The Asynchronous system is more efficient when there is
less chance of error because it does not spend time negotiating terms before the signal
is transmitted. They serve well as connections to the computer mouse and keyboard,
and where electric wire, radio, or laser beam is not reliable.
A Synchronous system does what the name implies; the transmitter synchronizes
everything about the transmission, with the receiver, before the signal is transmitted.
Time is consumed while this negotiation is taking place; however, when it is over and
the signal is ready to be transmitted both ends know what to expect and how to handle
it. Visit the website at www.inetdaemon.com for further information.
This section discusses the difference between Analog and Digital systems. The
first basic difference is that Analog translates an audio or video signal into electronic
pulses while digital breaks the signal down into “1”s and “0”s.
The terms Digital and Analog can apply to one or several aspects, such as input,
data storage and transfer, the way a device works internally, or its display features.
Most generally there is a mix of Analog and Digital systems which poses a
danger; the Digital must be separated from the Analog because its high power usage
can fry an Analog device. A simple converter can handle this difference.
The signal in a Digital device is broken down into binary code by the transmitter
and the receiver must reassemble this code back into the original signal. The advantage
of this technology is that a lot of binary code can be compressed into the space required
by Analog transmission. The Digital system provides more clarity that an Analog
system.
An added benefit is that the signal is broken up into bursts of data; therefore it is
more secure. Analog technology works fine for telephones, fax machines, modems,
and for outlying areas where Digital technology is not available. Visit the website at
www/articlesbase/com for more information.
3. TELECOMMUNICATION TERMS COMPARED 3
This section discusses the difference between XON and XOF. The function of this
software is to control the data flow between computers and other devices. X stands for
transmitter/ transmission and the on and off are exactly what they imply. The receiving device
sends an OFF signal to the sender when it cannot process more data and the sender stops
transmitting; as soon as the receiver can process more data it sends an ON signal to the
transmitter which then starts sending more data.
The XON/XOFF protocol system is generally controlled by the person to whom the data
is being transferred. The recipient sends an XOFF character to the person sending in the
information if it is unable to process any more data.
The sender immediately suspends the data transfer. When the receiver is able to accept
data again it immediately sends the XON character to the sender, and the transfer of data is
resumed once again. Visit the website at www.blurtit.com for more information.
In most environments, XOFF is achieved by pressing CTRL+S; XON is achieved by
pressing CTRL Q. Some Sun computers and Linux/Unix computers actually have a "Stop" key on
the keyboard that can be used to stop and continue text on the screen. Visit
www.computerhope.com for more information.
This section discusses the difference between Duplex and Simplex. Simplex
communication is permanent unidirectional communication. Some of the very first serial
connections between computers were Simplex connections. For example, mainframes sent
data to a printer and never checked to see if the printer was available or if the document
printed properly since that was a human job. Simplex links are built so that the transmitter
sends a signal and it's up to the receiving device (the listener) to figure out what was sent and
to correctly do what it was told. No traffic is possible in the other direction across the same
connection.
Connectionless protocols must be used with Simplex circuits because no
acknowledgement or return traffic is possible over a Simplex circuit. Satellite communication is
also Simplex communication. A radio signal is transmitted and it is up to the receiver to correctly
determine what message has been sent and whether it arrived intact. Since televisions have no
need to talk back to the satellites (yet), Simplex communication works great in broadcast media
such as radio, television and public announcement systems.
A Half Duplex link can communicate in only one direction at a time. Two way
communications are possible, but not simultaneously. Half Duplex connections are more
common over electrical links. Since electricity will not flow unless you have a complete loop of
wire, you need two pieces of wire between the two systems to form the loop. The first wire is
used to transmit; the second wire is referred to as a common ground. Thus, the flow of electricity
can be reversed over the transmitting wire, thereby reversing the path of communication.
Electricity cannot flow in both directions simultaneously, so the link is Half Duplex. Visit the
website at www.inetdaemon.com for more information.
4. TELECOMMUNICATION TERMS COMPARED 4
Full Duplex communication is two-way communication achieved over a physical link
that has the ability to communicate in both directions simultaneously. With most electrical, fiber
optic, two-way radio and satellite links, this is usually achieved with more than one physical
connection. Your telephone line contains two wires, one for transmitting and the other for
receiving.
Half or Full Duplex technology is required for connection-oriented protocols such as
TCP. A Duplex circuit can be created by using two separate physical connections running in half
Duplex mode or Simplex mode. Two way satellite communications are achieved by using two
Simplex connections. Visit the website at www.inetdaemon.com for more information.
This section discusses the difference between Serial and Parallel transmission. Digital
data transmission can occur in two basic modes: Serial or Parallel. Data within a computer
system is transmitted via Parallel mode on buses with the width of the Parallel bus matched to
the word size of the computer system. Data between computer systems is usually transmitted in
bit serial mode. Consequently, it is necessary to make a parallel-to-serial conversion at a
computer interface when sending data from a computer system into a network and a serial-to-
parallel conversion at a computer interface when receiving information from a network. The type
of transmission mode used may also depend upon distance and required data rate.
Using Parallel transmission, multiple bits (usually 8 bits or a byte/character) are sent
simultaneously on different channels (wires, frequency channels) within the same cable, or radio
path, and synchronized to a clock. Parallel devices have a wider data bus than serial devices and
can therefore transfer data in words of one or more bytes at a time. As a result, there is a speedup
in Parallel transmission bit rate over Serial transmission bit rate. However, this speedup is a
tradeoff versus cost since multiple wires cost more than a single wire, and as a Parallel cable gets
longer, the synchronization timing between multiple channels becomes more sensitive to
distance. The timing for Parallel transmission is provided by a constant clocking signal sent over
a separate wire within the Parallel cable; thus Parallel transmission is considered Synchronous.
Using Serial transmission, bits are sent sequentially on the same channel (wire) which
reduces costs for wire but also slows the speed of transmission. Also, for Serial transmission,
some overhead time is needed since bits must be assembled and sent as a unit and then
disassembled at the receiver.
Serial transmission can be either Synchronous or Asynchronous. In Synchronous
transmission, groups of bits are combined into frames and frames are sent continuously with or
without data to be transmitted. In Asynchronous transmission, groups of bits are sent as
independent units with start/stop flags and no data link synchronization, to allow for arbitrary
size gaps between frames. However, start/stop bits maintain physical bit level synchronization
once detected. Visit the website at www.bookrags.com for more information.
The two ways to allocate the capacity of transmission media are with Baseband and
Broadband transmissions. Baseband devotes the entire capacity of the medium to one
communication channel. Broadband enables two or more communication channels to share the
bandwidth of the communication medium.
5. TELECOMMUNICATION TERMS COMPARED 5
Baseband is the most common mode of operation. Most LANs function in Baseband
mode. Baseband signaling can be accomplished with both Analog and Digital signals.
This technique of dividing bandwidth into frequency bands is called ‘Frequency-division
Multiplexing’ (FDM) and it works only with Analog signals. Another technique is called ‘Time-
division Multiplexing’ (TDM) and it supports Digital signals.
Multiplexing is a technique that enables Broadband media to support multiple data
channels. Multiplexing makes sense under a number of circumstances because media bandwidth
is costly. A high-speed leased line, such as a T1 or T3 cable is expensive to lease; if the line has
sufficient bandwidth, Multiplexing can enable the same line to carry mainframe, LAN, voice,
video conferencing, and various other data types. Visit the website at www.suite101.com for
more information.
This section discusses the difference between Serial Line Internet Protocol (SLIP) and
Point-to-Point Protocol (PPP).
SLIP is an older protocol used to handle TCP/IP traffic over a dial-up or other serial
connection. SLIP is a physical layer protocol that doesn't provide error checking. It only supports
the transmission of one protocol, TCP/IP.
PPP is much more robust than its earlier cousin. PPP provides a physical and data link
layer functionality that fixes many problems that existed with SLIP. At the data link layer, PPP
provides error checking to ensure the accurate delivery of the frames that it sends and receives.
PPP also keeps a logical link control communication between the two connect devices by using
the Link Control Protocol (LCP). PPP also supports the dynamic configuration of the dialed-in
computer. Visit the website at www.blurtit.com for more information.
This section discusses the difference between File Transfer Protocol (FTP) and Hyper
Text Transfer Protocol (HTTP).
FTP and HTTP are both used to access information over local and remote networks.
These are basically the two protocols that are used over the Internet; however instead of
having the same function they differ in several ways.
FTP uses two network connection; one for controlling the session and the other for
accessing the data. HTTP, on the other hand, uses one connection for both control and data
exchange operations.
FTP has no encryption technique so the data is not protected in the process of
transmission. In HTTP this aspect is given priority and it uses multiple encryption and data
protection techniques to secure the integrity of the transmission of data.
6. TELECOMMUNICATION TERMS COMPARED 6
HTTP includes header information along with the file; this information is called Metadata
and is used by search engines when compiling information. This function is not present with
FTP.
HTTP is the language used to create and publish a website because strict control is needed to
ensure the look and content. However, when the new site, records, and updates, etc. are sent to
the publisher it is not necessary to encrypt them because the final product is for public view
anyway. So FTP is the most efficient way to transfer files that have no need for encryption. Visit
the website at www.ehow.com for more information.
This section discusses the difference between Transport Control Protocol (TCP) and
Internet Protocol (IP). TCP/IP allows information to be forwarded to different networks locally
or globally. Without these protocols, the Internet would not work.
The Open Systems Interconnect (OSI) model is a standards operation model with seven
layers. Each layer is independent of the others. The top layer is the application, followed by
presentation, then session, transport, network, data-link, and the physical layer, or layer one at
the bottom.
TCP occurs at layer four of the OSI model. Among the management tasks it controls are
segment size, flow control, and data exchange rate. This is where the delivery of packets of
information from one location to another occurs.
The only function of the IP is to contain the addresses for the TCP transmission. Visit the
website at www.ehow.com for more information.
Websites:
www.articlesbase.com
www.blurtit.com
www.bookrags.com
www.computerhope.com
www.ehow.com
www.inetdaemon.com
www.suite101.com
