Hello,
what physical properties of channel makes it to be called as time variant or invariant system?
why do they offer different delays to different frequencies of signal?
why do channels have non linear properties?
Thank you.

 

Can you be more precise about what exactly you mean by a channel? I don't want to assume one thing when you might mean something else entirely.

 

Sounds like Homework.

 

Can you be more precise about what exactly you mean by a channel? I don't want to assume one thing when you might mean something else entirely.

Channel can be coaxial cable or any other transmission medium related to communion systems

 

Hello,
what physical properties of channel makes it to be called as time variant or invariant system?
why do they offer different delays to different frequencies of signal?
why do channels have non linear properties?
Thank you.

Let us start with an article on what time invariant systems are:
http://en.wikipedia.org/wiki/Time-invariant_system

I'm not familiar with any transmission medium (aka channel) that is time variant, so any further discussion of physical properties that might affect that is premature.

Delay, or velocity of propagation, in a cable is a function of the arrangement of the conductors and the composition of the dielectric material between them. I know that the attenuation of a signal and its phase shift are functions of frequency. This is due to a cable looking like a distributed series inductance and distributed shunt capacitance. It is essentially a low pass filter.
http://en.wikipedia.org/wiki/Transmission_line

What non-linear properties are you talking about?

 

Hello,

A lot more information on transmission lines can be found in the links of this page of the EDUCYPEDIA:
http://educypedia.karadimov.info/electronics/transmissionlines.htm

Bertus

 

Let us start with an article on what time invariant systems are:
http://en.wikipedia.org/wiki/Time-invariant_system

I'm not familiar with any transmission medium (aka channel) that is time variant, so any further discussion of physical properties that might affect that is premature.

Delay, or velocity of propagation, in a cable is a function of the arrangement of the conductors and the composition of the dielectric material between them. I know that the attenuation of a signal and its phase shift are functions of frequency. This is due to a cable looking like a distributed series inductance and distributed shunt capacitance. It is essentially a low pass filter.
http://en.wikipedia.org/wiki/Transmission_line

What non-linear properties are you talking about?

non linear property is output collected is not proportional to transmitted signal levels

 

non linear property is output collected is not proportional to transmitted signal levels

Can you cite an example of where this might be the case?

 

Can you cite an example of where this might be the case?

when i was reading about wave guides in microwave communications i have noticed it.

 

Waveguides, is unfortunately one area where I have limited familiarity. My RF experience is confined to the area of the spectrum that microwave engineers refer to as "nervous DC".

The only insight I have is that solutions to the PDE for a particular waveguide have a great deal to do with the boundary conditions.