News
iOS 4.0.1 signal strength indicator changes explained
As those who have successfully upgraded their iPhone 3G, iPhone 3GS, or iPhone 4 units to iOS 4.0.1 may have noticed, Apple made a visual change to its signal strength indicator bars in its latest update, increasing the size of bars one, two, and three, while keeping the tallest two bars the same. A more dramatic change was made behind the scenes, however, as Apple changed its formula for signal strength to signal bar mapping resulting in what is hopefully a more accurate representation of the phone’s current connection. Anandtech reports that Apple made the dynamic range broader, while also adjusting the range values for each bar to make them wider. As a result, in some areas where signal strength would have been great enough for the iPhone to report five bars under iOS 4.0 and earlier, it may now show only three. As the report notes, this means that the worst case drop of 24 dBm — seen when applying the left-hand “death grip” on the iPhone 4 — longer makes all the signal bars disappear, but just two. The new formula is also used in the iOS 4.1 beta released earlier this week to paid iPhone developers; illustrations of the difference in bar to signal strength mapping are available below.


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1
The re-mapping of the number of “bars” to signal values is fine. But Apple should’ve kept the visual size of each “bar” the same as before. The new bar images are too similar in length; for example, a single “bar” of reception should be dramatically smaller on-screen than the rest.
Posted by Farnsworth on July 16, 2010 at 8:11 AM (PST)
2
Height of the bars is even more meaningless than the bars themselves. Remember the old-timey LED volume indicators on stereo equipment in the 80s? All the bars were the same height or width. Didn’t make it hard to understand at all. IOW, it’s the number of bars that matter, not the height. And since there’s no real “standard” for the number of bars as it relates to signal strength, as we’ve seen, they’re less useful than they could be. We consumers have allowed ourselves to be sucked in by that “More bars in more places” tagline.
Posted by Woody on July 16, 2010 at 8:24 AM (PST)
3
Case of moving the goalposts?...
Posted by Bob Levens in UK on July 17, 2010 at 6:11 AM (PST)
4
“AT&T, more bars in more places”
If not, we’ll just get the algorithm changed to still be able to make that claim.
Posted by Charles Farley on July 19, 2010 at 5:57 AM (PST)