I tried googling it but I guess my google-fu is not that great. Im reading a paper on adaptive delta modulation, and I want to understand as much as possible. My first road block was this: "The quantization noise can be made arbitrarily small at the expense of CHANNEL BANDWIDTH. Obviously, the challenge to be taken here is the optimization of system performance; that is, the minimization of both quantization noise and CHANNEL BANDWIDTH."

This leads me to another question, why is it desirable to decrease channel bandwidth?

My uneducated guesses are, channel bandwidth is the range of passband frequencies for a certain "channel". You want a smaller passband to "free up" other frequency ranges for... more channels?

What determines what a channel is?

 

Could you provide a link to the paper?

 

http://archives.njit.edu/vol01/etd/1960s/1967/njit-etd1967-004/njit-etd1967-004.pdf
Its toward the bottom of page 24 of the pdf. It's just the introduction, so I've moved past it, but I would still like to know the answer if anybody knows.

 

A signal with a wide passband is more susceptible to noise. Using a filter to narrow the bandwidth reduces the effect of the noise. You can hear the dramatic difference in a receiver with adjustable filters.

 

It is desirable to decrease channel bandwidth so that more channels can be used in a given space. Or to put it another way: the available bandwidth can be more efficiently used. Bandwidth is usually limited and/or expensive.

I disagree with Papabravo. A wider bandwidth signal can have lower noise.

An example is digital audio: If you sample the signal at a higher rate and quantitize to a greater number of bits the signal can be reproduced more accurately. But this is at the expense of more data which requires more bandwidth to transmit.

 

wider bandwidth signals require wider badnwidth filters. wideband filters let in more noise, kind of like a bigger window. the proper filter is one that is matched to the width of the recieve signal.

 

....................A wider bandwidth signal can have lower noise.

An example is digital audio: .........................

That's also true for FM.
But for a channel that is susceptible to amplitude noise, noise generally increases with bandwidth.