How Fast is 1.21 Gigawatts Anyway? (3/6/2007)

Okay, so that title is a bit misleading, but I thought it’d be interesting to write a little blog post delving into the differences between a megabit and a gigabyte and so on.  I might be wrong, but in my opinion one of the most technically confusing areas of consumer technology is trying to figure out how to buy a computer.  For example, I constantly get asked “how much memory should my computer have?” Now the “correct” answer right now is “about a gig, maybe more if you plan to do some gaming or video editing”  But what they are really asking is “how big a hard drive do I need?”

The next most confusing thing in personal tech, in my opinion, is helping make sense of the bits and bytes.  So I’ll start with a couple of simple definitions (and these might not be absolutely perfectly technically accurate to an engineer, but are pretty reasonable to the rest of us):

• A bit is effectively the smallest piece of information.  It represents either a “1” or a “0”, like a true (1) or a false (0).  On its own, a bit can only mean one of those two things.  But if you put two together, you actually have a total of 4 combinations of possibilities (0 and 0, 0 and 1, 1 and 0, 1 and 1 – which are represented as 00, 01, 10, or 11).  With every additional bit of information, you double the realm of possibilities.  Once you get to 8 bits, you have a combination of up to 256 possible numbers, which is also known as . . .
• A byte contains enough bits (8) to represent a single letter of the alphabet (or a “regular” number).  While bits are interesting to computers, bytes are a bit more interesting to people, as they represent “real” information.  For example, a thousand bytes is a thousand letters, and also called a kilobyte (and no, I will not be explaining how the decimal system works, sorry).  You can extrapolate from there I trust.

So now let’s talk about bits and bytes in terms of your network connection (I could also go into storage, but I figure someone from Seagate can handle that on my behalf).  I’ll start at the slowest possible end, and work my way up.

• DSL. Most residents of the US who have DSL have ADSL services, which typically offer a connection speed of 384Kbps through 1.5Mbps.  See the lower-case “b” in bps?  That means bit, which means our speeds translate to a range of 384 thousand bits per second up to 1.5 million bits per second.  That’s a whole lot of 1s and 0s, right?  Well, it’s okay, but as you’ll soon see, it isn’t that much.
• Cable Modems.  Again, domestic cable modem service packages tend to range from 384Kbps to 6Mbps.  So now we’re up to 6 million bits per second.  So let’s take this as our moment to make our first important translation, which is into bytes, since that’s what really matters to us as people anyway.  6Mbps = 750KBps (ah, upper case B, yes, it means Bytes).  As of this sentence, this document is 28.0KB, which means it should be downloadable in much much less than a second compared to the available network speeds.  But that’s because we’re just dealing with a text document, and not rich media like music, photos, or videos.  But we’ll save that topic for a bit.

When it comes to your home network, there are only really a few ways to get hooked up, and I’ll address the most common here.

• 802.11b. This is the one that got WiFi going.  The first generation of real consumer-grade wireless technology.  802.11b has a maximum transfer rate of 11Mbps.
• 802.11g. At the time of writing, this is the ‘standard’ for wireless networking, and peaks at 54Mbps data rate.  Remember, that’s “peaks”, which means there’s an average somewhere, and it’s well below 54Mbps!
• 802.11n.  This one’s coming soon to a theater near you, but if/when it becomes the standard, will allow wireless connections of up to 540Mbps.  Wow, that’s fast.
• Ethernet.  Most wired networks today use 100Mbps connections.  For those keeping track at home, that’s roughly double the max speed of 802.11g.
• Gigabit Ethernet.  In case you have lots and lots of data you need to transfer, and Ethernet doesn’t cut it, with gigabit networks you have 1Gbps, or 1000Mbps.  Again, faster than fast.

Now in most cases, faster really does equal better.  There’s a little snag in the whole 802.11n rollout, in that we’re way off schedule and all, but if you are in need of making a snap decision, just buy whatever’s fastest and yet still affordable.  But if you want to understand a bit more, here are some common relevant bitrates:

• This Word document (again, at the time of writing and just prior to this sentence) is up to 31.5KB.
• The default bitrate for an MP3 (or other digital audio format) file is 128Kbps, although if you want your music to sound at all good you should use no less than 192Kbps (that’s just another one of those freebies I like to throw around).
• A 7-megapixel camera at max resolution generates pictures which are roughly 2.5MB large.
• TV-quality video streams in Windows Media Video format average 1.5-2Mbps.
• HDTV video in MPEG-2 format streams at 19.2Mbps.

I’m not going to go do all that clever math for you, because what fun would that be?  Instead, I trust you can go out and fish all on your own with all of these data points.  My goal was to help explain some of the differences in the terminology.  That said, I’ll make a few final points clear . . .

• Even the slowest WiFi (you can check above if you tried skipping that part) is generally twice as fast as the fastest average Internet connection in the US.
• Faster home networks are important if you want to play video games, do a lot of file transfers (backups, editing, etc), or stream video.
• WiFi and HDTV streaming do not mix, yet.
• Giga is bigger/faster than Mega which is bigger/faster than Kilo which is bigger/faster than no prefix at all.  Nanos are very small, and Minis were discontinued back in 2005.

Oh, and 1.21 gigawatts is so inconceivable unless one is driving a De Lorean.  So for now, I’d recommend the extra few bucks on a 802.11g (or maybe n) router with built-in gigabit Ethernet.

Jeremy Toeman
Consumer Technology and New Media Expert