How Does VOIP Work? by toriola1

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									                                                  Presented by Daniel Toriola


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                                                   Analog vs Digital Transmission
                                                                  By Gary Davis



    Analog vs Digital Transmission                        by Gary Davis


Analog vs Digital Transmission



By Gary Davis


Dish-Network-Satellite-TV.ws




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providing you leave the Byline and About the Author sections
intact, including the links to Dish Network Satellite TV.




 Remember the old days of analog TV, radio, etc. Most of us do unless you’re really young. And
still today there are plenty of analog systems in use. Normal radio still uses analog transmission. But
the digital age has begun and more and more we will use digital systems rather than analog systems.


Digital transmission systems have many advantages over analog transmission systems, like higher
quality of audio and video. How come digital systems can transmit higher quality signals than analog

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How to improve your digital photos from average to professional standard even if you've never used a digital camera before.
                                                                                                                              Page 1
                                             Presented by Daniel Toriola


systems? The truth is that they don’t. They just use some tricks to eliminate noise.


Analog Transmission Systems


When something like video and audio, is recorded by an analog system, the recording has a certain
quality. This recording (when done professionally) has a very high quality. When the recording is
transmitted it is modulated directly to a carrier wave, which is then transmitted through the air, cable,
via satellite, etc. During this transmission, the carrier and the modulated signal will loose amplitude
(power) and due to interference noise is introduced to the carrier and its modulated signal. The result
will always be a received signal that has a lower quality than the transmitted signal. Hence, the
modulated signal, the recording, will also be of lower quality than the original.


Analog transmission systems are unable to maintain the quality the original has.



Digital Transmission Systems


In the digital world the recording can be transmitted to another place without loosing any quality. An
exact copy of the original recording is transmitted. So how come that digital transmission systems
don’t loose quality when transmitting a signal?


Well..... Actually they do lose quality just like the analog transmission system does.


Surprised? No Problem. Most people don’t know that digital signals still need to be transmitted
by analog transmission systems. The trick is that a digital system doesn’t record analog signals,
but encodes analog signals into bits (zeros and ones). A sample is taken many times per second and
the size of each sample is written down in bits. For instance a sample with the value of 9 would be
1001 and 11 would be 1011.


The digital transmission system needs to transmit those zeros and ones, and it does this by modulating
the carrier wave. Low power for a 0 and high power for a 1 (This is the most simple way of modulating.
There are much more sophisticated forms of modulation, but it would take a whole book to describe
them all.)



So on the receiving end, it doesn’t matter anymore what the quality of the signal is, as long as it
still is possible to identify the zeros and ones. Noise in the received signal is no problem. A
“1” with noise is still a “1” and a “0” with noise is still a
“0”. Of course the noise can not be too high, otherwise mistakes would be made and a
zero would be received as one or a one would be received as a zero.

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                                                                                                            Page 2
                                                Presented by Daniel Toriola




So Digital Transmission Systems are better because they eliminate the effect of noise completely. You
don’t look and listen to a received signal from an original recording, but you look and listen to a
reproduced signal of the recording. The reproduction comes from an exact copy of the original
recording.



The quality of what you see and hear now depends on your TV and Sound System. A high quality TV
and Sounds System will give you high quality Video and Audio. The negative effects of the (still analog)
transmission have been eliminated from the process.


Satellite TV makes use of Digital Transmission Systems. What you see at home will always be of
Digital no (much less) noise Quality.



 Gary Davis is owner of Dish Network Satellite TV, has several years experience in the Satellite TV
Industry and has written several articles on satellite TV.




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How you can sell your digital stock images online today.
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                                 Presented by Daniel Toriola


                                   How Does VoIP Service Work?
                                           By Simon Ahtung



 VoIP technology is a one way of sending a voice signal also known as an analog signal in a medium
which is digital, i.e, the internet. In practice, the process works like this when you have a standard
analog telephone attached to your high speed internet connection with VoIP service. There will be an
analog telephone adapter or ATA between the phone and the computer.

In order to place what would normally be a long distance call to a person who doesn't have VoIP
service you key in the number you want. The analog telephone adapter converts the touch tones into a
digital format. The digital phone number is sent by the analog telephone adapter to the VoIP routing
system at the service provider's location. The VoIP service provider is located on the internet as well.

The VoIP service provider's routing system identifies the recipient's location and sends the call to the
Public Switched Telephone Network (PTSN) at that location. The phone rings at the other end and the
conversation can begin. Each time you speak, the analog to digital converter in the analog telephone
adapter changes the voice tones into packets of digital information that can be transmitted across the
internet. When the VoIP service meshes with the Public Switched Telephone Network at the recipient's
end, the digital packets which are the voice tones from you get turned back into an analog signal so
that you recipient of your call can understand what you are saying.

The reverse process, i.e. the transmission of what the other person says to you is a mirror image of the
first process. Their voice is transformed from analog to digital when it gets to the PSTN/internet
connection. The digital packets are sent to the analog telephone adapter at your location where they
are converted back into an audible or analog signal to be able to perceive the voice as that of your
caller.

The technology to do the conversion from analog to digital and back again has been around as long as
digital electronics. For example, your PC sound card converts digital CD information to analog signal
needed by the speakers on your computer. The difficult part of the VoIP technology is the necessity to
smoothly transmit the digital data over the internet and reassemble it in a continuous stream. This is
know as the protocol.

When listening to voice transmission, there can be no gaps in the stream of digital packets or the
voices will not be understandable. This part of the technology has only recently been available, but is
actually equal or better in quality than you get with standard telephone networks.

The equipment available today that uses VoIP technology can be an analog telephone adapter for your
head set through the computer. There are a few VoIP phones that act like a regular analog telephone
but have the ATA incorporated into the phone. It's actually a small dedicated personal computer in your
telephone. These VoIP phones can be plugged into the computer with high speed internet connection
or into the router.

Bramatelecom (http://bramatelecom.com) - Canada's internet phone service provider (
http://bramatelecom.com/home.php) offers low long distance rates (http://bramatelecom.com/rates.php
)



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Software Solutions.
                                                                                                          Page 4
                                               Presented by Daniel Toriola




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