by: Gary Davis

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 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.

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.

By Gary Davis
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Webmasters: You may reprint this article in its entirety, providing you leave the Byline and About the Author sections intact, including the links to Dish Network Satellite TV.

About The Author
Gary Davis is the owner of Dish Network Satellite TV, has several years experience in the Satellite TV Industry and has written numerous articles about satellite TV.

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Email: customerservice@dish-network-satellite-tv.ws

By Keith Longmire

Coming to a Television Near You From 2008

In the UK the great digital switchover starts in 2008 and is due to finish in 2012. The analogue TV signal will be switched off leaving millions of televisions, video players and equipment obsolete.

Tessa Jowell, the Minister for Culture and Sport, announced the Great Digital Switchover on 15 September 2005 in a speech to the Royal Television Society in Cambridge. “Digital TV is no longer a probability, it is a certainty. And I believe it can leave us with a legacy of more choice for more people than anywhere else in the World” she said.

The Start of a New, Digital Revolution

Digital television is little short of the start of a digital revolution in our use of television in the home.

It heralds the convergence of two of the greatest technologies of our age – television and computers. In the future it is going to become ever more difficult, and the distinction more meaningless, to separate the functions of the two.

As exciting as the prospect of the digital revolution undoubtedly is, we must not loose sight of the fact that as far reaching as the implications of this change are in our use of TV, its implementation is a logistical exercise of immeasurable proportions.

Digital UK to Coordinate the Digital Switchover

The digital switchover will be coordinated by Digital UK – an independent, not for profit company set up by the broadcasters, commercial multiplex operators and their suppliers. Digital UK – formerly known as Switchco – will ensure that the public have timely and accurate information about switchover, including knowing when their transmitter is going digital and what they have to do to receive the signal.

Digital Receivers for Every TV and Video Recorder

Every TV set and video recorder in the UK will need to be connected to a digital receiver to work. In many parts of the UK existing TV aerials cannot receive the terrestrial digital signals and will need to be replaced The current generation of portable TVs many never be adapted to the digital revolution.

Small wonder then that TV manufacturers, engineers and media companies are rubbing their hands with glee. It wasn’t too hard a decision for the Government either. Digital signals are far less greedy in their use of available bandwidth. There seems little doubt that the Government has its eye on the handsome profit from the sale of the airwaves once the digital switchover is complete.

Who Pays?

No surprises here, you pay. The Government has announced a package of measures to convert one television for the old and needy. Everyone else pays for themselves. And the bill could be substantial.

Government statistics estimate that the average household in the UK has 4 televisions. Everyone must be connected to a digital receiver somehow. With freeview boxes currently costing around £40 and up and many home needing new aerials to receive terrestrial digital signals, estimates are that each household will need to spend between £400 and £2000.

Make sure you are prepared. Know when the digital switchover will take place in your region. Budget to convert or replace your existing televisions over a period of time.

And most importantly, don’t rush into anything. Digital technology is changing rapidly. Prices are high. New technologies are sure to emerge.

By Douglas Hanna

The hottest new thing in sound is called HD Radio technology. And what it does for radio is the same thing that HDTV does for TV – it makes it light years better! In fact, when you listen to HD AM radio, you’ll think you’re listening to FM. And when you listen to FM, you’ll think you’re listening to a CD.

What makes this possible?

HD Radio technology works much like traditional analog transmissions (AM and FM are both analog signals).

The difference is that the station broadcasting HD Radio technology transmits an extra digital radio signal, along with its normal analog signal. It can also broadcast a third signal for text data.

Your radio receiver receives the signal – just as it does an AM or FM signal. If you have a HD Radio receiver, it will decompress and translate the signal and viola! You get bright, clean, near-CD quality sound.

What happens if you don’t have an HD Radio technology receiver? It’s simple. You hear your normal analog radio– AM or FM.

AM radio has smaller sections of bandwidth than FM radio. This means there is not enough “space” to give AM stations the same near-CD quality as FM stations. But there is enough bandwidth that AM stations will be able to broadcast with the same clarity of signal as one of today’s analog FM stations. This performance boost is expected to make AM radio a better alternative to FM than it has been – to give you more listening choices.

Less vunerable

Digital FM radio is less vulnerable to reception problems. Your HD Radio tuner’s digital processors will eliminate all those annoying pops, hisses, fades and static caused by interference.

What happens if you lose the digital signal for some reason? Really nothing. HD Radio technology defaults back to analog mode in much the same way as conventional radios switch from stereo to mono mode when the signal is weak. Then, when the digital signal again becomes available, your HD Radio automatically switches back. What could be simpler?