Inside Apple's changes to the iPhone's signal strength visual bars
With the release of iOS 4.0.1 on Thursday, Apple instated changes to the way its iPhone handsets visualize bars representing cellular signal strength, doing away with a previously optimistic approach that compressed the dynamic range of bars to make it appear that a user's reception was much stronger than it actually was.
In fact, AnandTech, which has been following the matter closely for weeks, discovered that Apple had compressed the dynamic range to such an extent that cradling the company's new iPhone 4 with the so-called "death grip" would make all of its bars disappear from just a 24 dB drop in signal.
Extensive testing of iOS 4.0.1 indicated a drastic change in the cutoffs for the 5 signal bar strength indicators. The pair that authored the report concluded that "Apple’s mappings have gone from having probably the most compressed dynamic range among handset vendors to less compressed than Android." iOS 4.0.1 also broadens the range for displaying a signal, with the lower limit shifting from -113 dBm to -121 dBm. Both testers were able to keep calls connected at the lower limit of -121 dBm when testing with an iPhone 4. They theorized that the increase in display range was to accommodate the iPhone 4's increased sensitivity.
