Tech Mystery: Cell Phone Bars

Posted on Jul 27, 2012 in Computer Fun, News, Small Business

Tech Mystery: Cell Phone Bars

Today I was browsing my Twitter Feed and one of my favorite Twitterers?…Tweeters?…Tweetists?…one of my favorite blogs to follow posted a great trick for all of the iPhone users out there.  LifeHacker posted an article called “See the Actual Signal Strength on Your iPhone…”  It’s a great read and a really handy hack that doesn’t require you to do anything damaging or illegal to your phone.

This hack will let you see the actual signal strength in dBm of your signal instead of just seeing bars.  So now you can see the strength in a tangible, understandable, only slightly confusing number from about -65 to -105 instead of 0 to 5 bars.  This got me thinking;

What do the signal bars on a cell phone actually mean?

The answer is simple and sort of surprising for the cynically challenged; not much.  The signal bars on your cell phone (iPhone, Droid, 1999 Motorola Flip Phone) all fail to take into account a very important measurement called EC/I0 (eee-see-over-eye-naught).  EC/I0 represents the noise level that your cell phone is currently seeing and if fluctuates so wildly that not one cell phone maker includes a visual representation of it on their phones.  Instead they use the much more stable but much less usable dBm.  dBm is the actual signal power that your cell phone is seeing and even that is poorly represented on your device, because the dBm power could range from -65 (Super Strong) to -105 (Barely There) , but you’re only seeing 5 Bars.  The real problem is that each bar means something different for each cell phone provider.  AT&T may set their phones so that 5 Bars represents signal strength from -65 to -80 while Verizon may decide to set the threshold at -65 to -75.  So 3 bars on my phone are almost guaranteed to mean something completely different than 3 bars on your phone.

Cell Phone Bars

It’s not quite this simple any more is it?

But wait, let’s not forget that the dBm measurement isn’t really very usable even if you are able to see the numbers instead of a vague bar graph.  Since you have no idea what the EC/I0 Level is, you could find yourself with 5 Bars and still not be able to make a call or vice versa you could have 0 bars and hold a perfectly clear conversation.

All that being said, I still like to be able to see a number representing my signal strength instead of bars…it makes me feel like I’ve beaten the system somehow.

What Tech Mystery would you like an answer to?  Do you have any input on this topic?  Let me know in the comments section below.

Dennis Edmondson Jr
Computing Concepts LLC

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