Correct me if i m wrong


#1

dsl feed is carried out in digital format. it means it will rather connect or will not. so on utmost bad cable it will be not connected to but if it get connected, its speed (feed) would be100% the same as fibre optic. the common belief that new cable results in better speed is a wrong notion.

m i right?


#2

[quote=", post:, topic:"]

dsl feed is carried out in digital format. it means it will rather connect or will not. so on utmost bad cable it will be not connected to but if it get connected, its speed (feed) would be100% the same as fibre optic. the common belief that new cable results in better speed is a wrong notion.

m i right?

[/quote]

it is a digital connection but when line conditions are bad packets tend to drop and those dropped packets need to be resent this resending is what slows ur connection down


#3

DSL transmission isn't digital. Its analog. Digital data is converted to analog signals and then sent. The reason this must be done is because sending analog signals does not require as much bandwidth as sending digital signals - why? Because digital signals compromise of lots of sine-waves which superimpose and produce your resultant digital signal. Read up on Fourier Transform.

The reason why there is a fluctuation in speed is mostly because of SNR i.e Signal to Noise ratio.


#4

[quote=", post:, topic:"]

DSL transmission isn’t digital. Its analog. Digital data is converted to analog signals and then sent. The reason this must be done is because sending analog signals does not require as much bandwidth as sending digital signals - why? Because digital signals compromise of lots of sine-waves which superimpose and produce your resultant digital signal. Read up on Fourier Transform.

The reason why there is a fluctuation in speed is mostly because of SNR i.e Signal to Noise ratio.

[/quote]

oh i guess i was wrong then

what abt wireless transmissions such as wimax are they digital or analog?


#5

Wireless transmissions are analog is well. Digital signals cannot ride airwaves. Modulation is required where the carrier signal is modulated with the payload signal for transmission. At the receiver end, the reverse process takes place to separate the payload signal from the carrier.

The keyword is "frequency". Whenever you come across this word, you can take it for granted that the transmission is analog. Digital signaling is measured by bandwidth/bit rate.

The only media capable of true digital transmission is optical as used in optical fibre.


#6

i have old line with one joint. what loss i should bear


#7

Anything that travels over wire, through air, via light is analog. Digital is simply 1's and 0's, the devices on either side of the "connection" convert analog (in its many forms) back into digital information.

To put it in perspective, even your Cat5 or network cable, is an analog medium where digital information is changed into signals are transferred to pairs of wires, and then back to digital by network cards or routers.

Hope this makes things clearer.


#8

[quote=", post:, topic:"]

Anything that travels over wire, through air, via light is analog. Digital is simply 1’s and 0’s, the devices on either side of the “connection” convert analog (in its many forms) back into digital information.

To put it in perspective, even your Cat5 or network cable, is an analog medium where digital information is changed into signals are transferred to pairs of wires, and then back to digital by network cards or routers.

Hope this makes things clearer.

[/quote]

No. A digital signal, technically speaking, is a composite of analog signals. To make a square wave, representing zeroes and ones, you will add sine-waves with different harmonics. A digital signal can also have multiple signal levels - agan, this is not zeroes and ones. A signal can go upto +5V, 0V and -5V (but these signals will ONLY represent 0s and 1s). Read up on different line-coding schemes and Fourier Transform.

In case anyone is interested in DSL, the technique used for the transmission is called 256-QAM (Quadrature Amplitude Modulation).

To the layman, there might not seem to be a difference. Afterall, adding oranges will just get you more oranges. But it is important and necessary to differentiate between digital signals and analog signals.

If we continue with your analogy, the data stored on a hard-drive is analog as well. But we know thats not the case; its not classified as analog, it is always treated as digital.

But without analog, digital cannot exist. As digital is just an approximation.

So to put it in perspective, lets say your DSL modem is connected to your computer through Ethernet. The data your PC sends to the modem is sent using a line-coding scheme. The modem understands this line-coding scheme because of the Ethernet standard. The modem then converts this received data into an analog signal, based on 256-QAM.

Like I mentioned before, we convert your digital data into an analog signal because of bandwidth constraints, your telephone line does not have the required bandwith.

I realize you might be thinking “but they are both electrical signals, so what does it matter?!”. The thing is, the electrical signal in Ethernet is discrete, it only represents 0s and 1s whereas the signal in your telephone represents a multitude of values.