I read some books and discovered that digital communication is better than Analog because digital allows more channels than Analog so there is less interference between communications.

The same goes for Digital TV.

But what makes Digital Technology this unique and better than Analog??

does anyone know why this is so??

 

I disagree with the premise. Bandwidth is bandwidth , and an Ethernet channel takes 10 Mbits of bandwidth all day every day.

 

Digital television and radio require significantly greater bandwidth than the analog signals.

If you are interested in the subject, start off learning something about analog to digital conversion. That is the means by which analog signals get made into digital values.

 

The simple answer is:

Analog is real time. Digital is not.

This means that Digital is better because it can do everything analog can and then some. If you want to edit, encode, buffer and reproduce the output/input signals at the approximate same time of analog or at a later time, you can do so with digital.

The problem is that we live in an analog world. So most of the time we have to convert analog from digital and vice versa.

 

Digital television and radio require significantly greater bandwidth than the analog signals.

If you are interested in the subject, start off learning something about analog to digital conversion. That is the means by which analog signals get made into digital values.

okay, i will check that out.

 

Digital television and radio require significantly greater bandwidth than the analog signals.

Come again? Digital television uses less bandwidth than analog signals. This and the reason for content protection is why we are moving toward an all digital broadcast.
The FCC plans to auction off the excess bandwidth after the conversion.
You do not believe the government is doing us a favor only by 'giving us a better visual experience' with HDTV do you?

 

Nope, just selling off a public resource to the highest bidder (a pittance to government coffers, but big money to people buying it), and leaving people with old VCRs (especially) and TV's in the lurch. I'd like to see more articles on how it works though. The actual modulation and encoding schemes.

 

Come again? Digital television uses less bandwidth than analog signals.

This is not true. The analog channels were 6 MHz. wide, while the digital channels are 12 MHz. wide.

 

Nope, just selling off a public resource to the highest bidder (a pittance to government coffers, but big money to people buying it), and leaving people with old VCRs (especially) and TV's in the lurch. I'd like to see more articles on how it works though. The actual modulation and encoding schemes.

Can't comment about elsewhere in the world, but in the UK we use Quadrature Amplitude Modulation (a combination of 16QAM and 64QAM).

To the OP, for your original query into Digital Vs Analog for TV look into multiplexing.

Also, I'm still not totally sold on the whole HDTV thing (I accept the improved visual quality for HD-content), but having read some analysis in the latest IET magazine regarding HDTVs and SD-content its seems as though there are some conflicts of consumer-interest arising from the need to tailor SD-content for HD-technology.

Dave

 

http://www.dtv.gov/whatisdtv.html is the FCC website concerning the move to DTV.

Statistical Multiplexing will allow multiple programs on a single channel. This allows the broadcaster more opportunity for Pay per view as well as offering "free" TV.

The only way Digital has less bandwidth than analog is if you count the multitude of programs per MHz compared to the current system. Otherwise, it's like papabravo stated. The potential spectrum savings is there. Those channels (2-6 and 52-83) will become "excess" and recaptured and auctioned off as digital channels.

 

I read some books and discovered that digital communication is better than Analog because digital allows more channels than Analog so there is less interference between communications.

The same goes for Digital TV.

But what makes Digital Technology this unique and better than Analog??

does anyone know why this is so??

Digital is better because is less immune to noise than analogue. When you transmit a signal for a long distance you need to use subtransmitters to amplify it. By doing doing that you also amplify the noise introduced in the signal during its way, so you make it worse. However, when you transmit a digital signal, at the sub-transmitter you just detect its high and low values and reconstruct it to transmit it again. of course there could be errors (detect a high bit to be a low bit for example) but they occur less than an analogue signal. Also, with some methods of error correction you can detect these errors and correct them (if possible). The drawback of digital communications is that they require more bandwidth than analogue communications.

 

Of course as more compression is used you can expect the actual picture to suck rocks. On an analog signal when there is a weak signal or interference you get snow. On digital channels you get pixelation or worse yet a freeze frame until things improve. Definitely an unsettling experience.

 

They compress the digital signals to reduce their bandwidth.
They think that the average moron doesn't see the artifacts caused my the compression, and they hope he just doesn't know what causes the picture to breakup into big pixels when there is fine detail and motion together on the screen.

 

i don't get it!!! how can Analog have more Bandwidth than Digital yet Digital carries more channels???
can some one clarify on thos coz i am getting cofused!!!

 

The data in a digital signal can be compressed at the transmitter and uncompressed at the reciever. There is no free lunch so the picture quality must suffer.

In the early 1990's when digital TV was being contemplated the technology for putting an NTSC equivalent signal into a 6 MHz. analog channel was not available at reasonable cost. Each analog channel licensee was awarded an unused companion UHF channel that was also 6 MHz. wide. Using two 6 MHz. wide channels they could broadcast one uncompressed digital signal.

Fast forward to 2008 and DSP technology allows multiple digital channels to be compressed, tansmitted, received and reassembled in one old ordinary 6 MHz. wide analog channel.

Got it now?

 

Would you rather watch a sports game on tv or at the game itself? Would you rather go to a concert or listen to a cd? Analog is king because it is REAL. Digital can never be as good as analog in theory. The thing is, the human ear can't tell the difference between a 44kHz sampled signal and someone rocking ♪♫ right in front of them. So in reality digital is as good as analog, but i do not believe it can get better.

If we just talk about sending the signals over wires, then I agree that digital is better. It is just easier to send a high or low voltage instead of a varying voltage. The high or low can vary, but it will not matter for a digital signal. If an analog signal distorts then you will hear or see it immediately.

Sounds like i am disagreeing with myself... ah well

 

thanks guys. i now get it...

 

Perhaps someone should point out the difference between television screens and loudspeakers.

Loudspeakers are analogue. Some are better than others, but all produces a continuously varying output, continuous in time.

Colour Television screens are all digital. Any screen contians a finite number of points that can be activated. This is true for both older CRT types and modern TFT, Plasma and LCD types. Trinitron types have narrow bands not points.

So it makes sense to change to a system that addresses these points individually (digital), rather than using as system which produces redundant, smeary information between the points.

Yes your TV screen picture really is made of dots, like a newspaper picture.

 

The dots on the screen may be discrete, but the signal that illuminates them in an analog TV is continuously variable. It was not an inherently digital system.

 

I am aware how the old fashioned raster works. In fact I deliberately specified colour screens as older monochrome ones are indeed analogue output devices.

Nevertheless a system that produces output through a switch that addresses each individual dot separately is purely digital. This is the basis of the Texas Instruments DLP system. (Digital light processor).