What is bandwidth?

Read the article that everyone's commenting on.
Subscribe to the RSS Feed for comments on this article.

When you said "oldest metaphor", I thought you were going to talk about a 747 full of magtapes. :-)

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I think the Bible's just a little older. Been using that for
decades. I wrote about it on my personal blog a while ago,
btw... http://leo.notenboom.org/2008/05/_new_unit_of_me.html

:-)

Leo

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (MingW32)

iD8DBQFITqmICMEe9B/8oqERAlVqAJwL+XKgHuJEJUMjoIN+/ln+jrhnnwCfSNju
K4XxMx/t6qQ5CffzTcXjk/A=
=9wBa
-----END PGP SIGNATURE-----

"Bandwidth" used to refer to radio and other eletromagnetic wave phenomena. An AM radio channel (remember AM radio? 550 kHz to 1650 kHz?)was about 10 Khz wide. An FM radio channel is, I believe, about 10 mHz wide - the FM band is 88.7 mHz to 108 mHz. The greater BANDWIDTH carried higher-fidelity sound (like we need high-fidelity for Rap music?). CW (continuous wave) transmission - remember Morse Code? - needed almost no bandwidth. Since digital information is, like Morse Code, simply "on" or "off", I'm guessing that "bandwidth" is not the correct description of what's required for faster data transmission. I'm certain an electrical engineer can explain what goes through the wires and optical cables, and what permits greater speed. - Thanks - Alan

Gotta go with Alan. While the current usage of bandwidth is to describe speed of transmission or capacity (i.e. "I'll get that done tomorrow, I don't have the spare bandwidth today"), it does date back to the width of a radio band and what it could carry.

I don't see anything wrong with it evolving, though, especially when we're moving back into radio transmission with WiFi and WiMax.

An FM station uses 10 or 20 KHz, which gives an audio range that's about as much as most people can hear.

To me, Analog vs Digital transmission is like using a real wood fire vs fake fireplace logs with gas. I get a warm glow from the familiar and I'll miss it, but the new way makes enormously more sense from an environmental and an economic sense. Sigh.

Two items come to mind

- First, speed tests are often poor examples of sustained download speeds. Comcast, for example, provides a much higher rate of throughput initially, then slows the download to the "rated" speed. This makes websites typically load quickly, but large files (like operating system patches) can take much longer. My cable modem is rated as 6 mbps, but will burst up to 18 mbps for typical speed tests. When I download large files, it slows back down to 6 mbps.

- Second, many websites throttle how much throughput can be sucked up by a single connection. So, even though you may have the capability to download oodles of content very quickly, the website may restrict how quickly they will send it to you.

Speed is nice, but sometimes not all it seems to be.

I'm sure you've told us before but here goes....
How do you find out your upload and download figures ?

Great articles and thank you.

Often the high "burst" readings are inaccuracies in the way the timing is measured, because it is an average it relies on the last, lets, say, 15 seconds of transmission to show your speed. If you have only been downloading for lets say, 5 seconds, a speed calculated on the last 15 seconds is going to be erroneous - and depending on the exact calculation it may come out too high or too low.

As to the bandwidth - its the number of communication channels available at any time. So a bandwidth of 10Mbps means that there is a "wide" enough pipe/cable to transmit signals that contain 10Mbits of data in a second.

Also different technologies work differently - and different technologies are available in different countries. Whilst those speeds are typical for connections in the USA, in the UK the standard DSL connection is now 8Mbps (recently upgraded from 2Mbps). Some providers are rolling out ADSL2+ here which offers upto 24Mbps, though I'm not sure anyone actually gets that.

Cable is available in the UK at speeds between 2Mbps and 10Mbps.

This is laughable. So many errors.
T1 is 1.5 Megabytes no megabits. It is writen with a capital M. T1 cost about $360 a month (Speakeasy). Basic DSL cost about $15 a month (ATT)and will bring a speed of 96KBps or 768 kbps.
You can get speed up to 6.mbps (6000kbps or 750KBps) for $35 a month.
T1 is about 15 times faster than basic DSL.
In order to getr speed of 17237 kbps one has to shell out a thousand dollars a month!!

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

T-1 is 1.5 megaBITS, not bytes. Cable users can easily get
bursts of 17,237 kbps without paying thousands. (FIOS users
can do even better.) Yes DSL can go as high as 6mbps, I
quoted basic DSL - the slowest - which is 768kbps.

All the costs depend on your ISP and location.

So, I'm still not sure what all the errors you refer to are.

Leo

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (MingW32)

iD8DBQFIUFgACMEe9B/8oqERAgzFAJ4nszDgXiIQkPTCb1jMTXQV8pBaVQCfZwcU
2ZwBp53OywEoYr7wEsQ6GX4=
=59VC
-----END PGP SIGNATURE-----

To post a comment on "What is bandwidth?", please return to that article's main page.