[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Bandwidth (was QList Netiquette?)

From: Trisha Bethen <trishab@mv.mv.com>

>Hey, guys, what do you all mean by bandwidth?  <snip>

Hello Trisha,

Bandwidth is the range of frequencies used to transmit a signal.  In 
 radio terms, the bandwidth of an audio signal is from 3kHz (telephony) 
 to 20kHz or more (hifi or CD quality).  To broadcast a 15kHz bandwidth 
 audio signal might require 30kHz (AM) or 200kHz (FM).  Video signals 
 require a bandwidth of about 5 or 6 MHz.

The same term (bandwidth) is often used to describe the bits/second 
 required to transmit digital signals.  If you send a message of 200 
 words to me (200words is approximately = 1Kbyte = 8Kbits), and the 
 message takes 10seconds to transmit, then you are using 800bits/second 
 of bandwidth. 

Between your e-mail provider and mine there might only be a 64kbits/s 
 link.  If other people are downloading bitmaps using this link, then 
 they may well use almost all the available bandwidth which means your 
 message might only receive 100bits/s.  Now the message will take 
 80seconds to transmit (it still might not reach me for hours, but that 
 is because of the tortuous routes these messages take).

As more and more people join e-mail and the internet, less and less 
 bandwidth is available for each (unless governments install suitable 
 digital links).

Here endeth the lesson - sorry about the lengthy answer.