Join CrazyEngineers to reply, ask questions, and participate in conversations.
CrazyEngineers powered by Jatra Community Platform
@jeffrey-xA7lUP • Mar 28, 2013
To a small distance I think through a coax cable we can transmitproffyhi friends, I got confused reading one article on LANs.
Can anyone tell me if we can transmit digital signals(not digital data) via any physical media such as wired cable/coaxial cable, or a wireless media without any modifications to it.
thanks
@anand-tamariya-DnfjEX • Mar 28, 2013
@yepsailon-z333Lk • Apr 15, 2013
@anand-tamariya-DnfjEX • Apr 15, 2013
Signal degradation in this case is not because of noise, but simple resistance in the conducting wires.YepSailOnActually, digital signals have better noise immunity compared to analog ones because you only have to worry about two levels. So, they can be transmitted farther before signal degradation reaches unacceptable levels.
@jeffrey-xA7lUP • Apr 15, 2013
Modulation in LAN cables are not necessary as the net distance to transfer the data is very less and can provide lesser resistive pathYepSailOnActually, digital signals have better noise immunity compared to analog ones because you only have to worry about two levels. So, they can be transmitted farther before signal degradation reaches unacceptable levels.
I'm not certain if modulation is used in case of physical media like lan cables, afaik it isn't. Modulation is used with telephone cables though (ppoE) but in case of wireless technologies, modulation is obviously necessary. Also, digital signals aren't always 5/0 Volts
@yepsailon-z333Lk • Apr 16, 2013
In any communication system, noise is what determines how far you can transmit something. Any signal be it continuous or discrete will degrade, the amount of noise in the channel (the wire in this case) determines the level beyond which the signal can be accurately received.Anand TamariyaSignal degradation in this case is not because of noise, but simple resistance in the conducting wires.
@yepsailon-z333Lk • Apr 16, 2013
That's what I was wondering too, who said digital transmission is noiseless? 😛 What I said specifically was that compared to a continuous signal, the digital one has better noise immunity because we are only concerned with two levels. A logic 0 or a logic 1.ConquerorModulation in LAN cables are not necessary as the net distance to transfer the data is very less and can provide lesser resistive path
But in the case of telephone cables or those that are to be transmitted through longer distance then the need of modulation is a must as the signal noises become really a matter of concern
And Who said Digital transmission is Noiseless analyse the fourier spectrum of the signal in digital form along with white noise the noise component is significant But it is limited due to Noise figure of the system
@anand-tamariya-DnfjEX • Apr 16, 2013
An ounce of practice is better than a pound of theory. Why don't you test out your hypotheses and let me know your results about how far can you transfer digital signal?YepSailOnIn any communication system, noise is what determines how far you can transmit something. Any signal be it continuous or discrete will degrade, the amount of noise in the channel (the wire in this case) determines the level beyond which the signal can be accurately received.
Noise is always present and as you've said the wire impedance would cause it to degrade over distance. At some point in the cable, the noise level would exceed the signal and it would therefore be incomprehensible.
@jeffrey-xA7lUP • Apr 16, 2013
I think it is going to be a long explanation But you should now that when a Digital transmitted wave is received the noise is only present in the transition points from 0 to 1 and from 1 to 0YepSailOnAlso, could you explain further what you were saying with respect to the Fourier analyses? From what I know, the Fourier spectra of a digital signal has several components, ie there are several frequencies for a given digital wave, but how does that relate to noise?
.
@yepsailon-z333Lk • Apr 17, 2013
I thought it over again. My understanding of digital signals was that they were any signal with two discrete levels, +5/-5 or a signal with two discrete frequencies (FSK) but I think that's considered to be modulation too, so you're right, purely digital signal wouldn't travel too far.Anand TamariyaAn ounce of practice is better than a pound of theory. Why don't you test out your hypotheses and let me know your results about how far can you transfer digital signal?
@yepsailon-z333Lk • Apr 17, 2013
Just tell me what you understand of it. From what I remember, the Fourier transform of a square wave would have infinite frequency components. Were you talking about these components?ConquerorI think it is going to be a long explanation But you should now that when a Digital transmitted wave is received the noise is only present in the transition points from 0 to 1 and from 1 to 0
This can be effectively studied using the frequency spectra than in time frame That is wat i meant need clarifications go through Allan V Oppenheim's Signals and system
@jeffrey-xA7lUP • Apr 20, 2013
Not really In digital transmission there is a accumulation of errors only in the transition point due to serial filters that attenuates the errors in other constant part of the signal.YepSailOnAs for the noise, did you mean that every transition point of any pure digital signal would CAUSE noise rather?
