Apple's Signal Strength Display Changes in iOS 4.0.1 and 4.1 Detailed

Late last month, Anandtech detailed the signal strength drop-off experienced by iPhone 4 users when bridging the antenna gap at the lower left corner of the device, mapping how the "bars" of signal strength shown on the device correspond to actual signal levels and how holding the phone in various positions affected that signal under iOS 4.0.

160322 signal strength rescaling

Anandtech has now followed up with a test on Apple's iOS 4.1 beta released yesterday that includes changes to how the visual "bar" indicators correspond to actual signal strength. Anandtech has also confirmed that the changes in today's iOS 4.0.1 update have the same effect.

The results are conclusive - Apple has dramatically changed the signal strength to signal bar mapping in iOS 4.0.1 and the iOS 4.1 beta, making the dynamic range not only much broader, but the range values for each bar much wider. The range of signals that correspond to bars three and four are the same width, and bar two is only slightly less.

The cutoff value for two bars to one bar remains the same, but every other value has increased. The result is that the worst case drop of 24 dBm no longer makes all the signal bars disappear, but rather two.

Notably, Apple has adjusted the bar scale such that the lowest bar remains visible at a signal level down to -121 dBm, significantly lower than the -113 dBm limit in iOS 4.0. Anandtech's report claims that voice and data transmission on the iPhone 4 remained intact all the way down to -121 dBm, bolstering Apple's claims of increased overall sensitivity and reception with the iPhone 4's design.

The report claims that Apple's changes are doing away with a cover-up of AT&T's poor network coverage in many areas and will likely result in some confusion as customers see fewer number of bars than they are used to. The fact that Apple has also increased the heights of the lower bars alongside the change to the mapping of actual signal to bar display appears to be a ploy to somehow makes things appear better than they are, with the subtle, but baseless, suggestion that taller bars imply better signal.

The new signal strength visualization in iOS 4.0.1 is simply going to be more honest with iPhone users. Whether that's going to result in customers confused about why their phone performs "worse" after the update or simply get really mad at AT&T remains to be seen.

Regardless, many observers are expecting to hear more about Apple's response to the signal issue at the company's press conference scheduled for tomorrow. While the company's changes to the signal strength mapping and display may offer a more accurate representation of cellular coverage in a given location, it does not yet address the actual drop in signal seen with the iPhone 4's antenna design.

Related Forum: iPhone

Popular Stories

iPhone 17 Pro Blue Feature Tighter Crop

iPhone 17 Pro Launching in Three Months With These 12 New Features

Saturday June 21, 2025 2:45 pm PDT by
The iPhone 17 Pro and iPhone 17 Pro Max are around three months away, and there are plenty of rumors about the devices from credible sources. Below, we recap key changes rumored for the iPhone 17 Pro models as of June 2025:Aluminum frame: iPhone 17 Pro models are rumored to have an aluminum frame, whereas the iPhone 15 Pro and iPhone 16 Pro models have a titanium frame, and the iPhone X...
iPhone 16 Battery Life Feature

iOS 26's New Battery Life Mode Available Only on These iPhone Models

Saturday June 21, 2025 9:02 am PDT by
Last week, we reported that iOS 26 introduces an opt-in Adaptive Power Mode on the iPhone, alongside the existing Low Power Mode. Apple says that Adaptive Power Mode can make "small performance adjustments" when necessary to extend an iPhone's battery life, including slightly lowering the display brightness or allowing some activities to "take a little longer." The full description of...
All Screen iPhone 2027 Feature 1

iPhone Reportedly Moving to All-Screen Design in Two Stages

Sunday June 22, 2025 3:58 pm PDT by
Apple has long been working towards an iPhone with an all-screen design, and it might finally achieve the feat in a few more years from now. In his Power On newsletter today, Bloomberg's Mark Gurman said that Apple will shrink the size of the Dynamic Island on new iPhone models released next year. A year after that, he expects Apple to release a redesigned 20th-anniversary iPhone model....
iOS 26 Feature

Everything New in iOS 26 Beta 2

Monday June 23, 2025 2:57 pm PDT by
Apple provided developers with the second beta of iOS 26, introducing the first changes and refinements to the new operating system since it debuted after the WWDC keynote. Because we're early in the beta testing process, there are quite a few tweaks to iOS 26, which we've rounded up below. Control Center The background behind the Liquid Glass Control Center buttons has more blur, allowing...
ios 26 control center b2

iOS 26 Beta 2 Fixes Control Center Design

Monday June 23, 2025 10:58 am PDT by
With the second beta of iOS 26 that Apple provided to developers today, Apple addressed one of the major complaints that people have had with Liquid Glass. iOS 26 beta 1 on left, iOS 26 beta 2 on right The Control Center buttons are now slightly more opaque, making it easier to see the different control options even on a multicolored background. The new, more opaque look is apparent with the ...
iPhone 17 Pro Blue Feature Tighter Crop

iPhone 17 Pro's Alleged Vapor Chamber Cooling System Partly Revealed

Sunday June 22, 2025 6:37 am PDT by
Apple's upcoming iPhone 17 Pro and iPhone 17 Pro Max models are rumored to be equipped with a vapor chamber cooling system, and a leaker known as Majin Bu today shared a photo of an alleged copper thermal plate for the system. Many high-end Android smartphones like Samsung's Galaxy S25 Ultra are equipped with a vapor chamber cooling system, which can manage heat dissipation inside the...
Wi Fi WiFi General Feature

iOS 26 Adding Two New Wi-Fi Features, Allows AirDrop and AirPlay Alternatives

Saturday June 21, 2025 7:02 am PDT by
iOS 26 is gaining two new Wi-Fi features, including Captive Assist and Wi-Fi Aware. MacRumors contributor Aaron Perris discovered a reference to Captive Assist within the code for the first iOS 26 developer beta, but Apple has yet to enable the feature. It should be available by the time the software update is released later this year. In his Power On newsletter last month, Bloomberg's...
iOS 26 on Three iPhones

iOS 26 Includes These Five Smaller Features You Might Have Missed

Saturday June 21, 2025 11:18 am PDT by
While the dust is beginning to settle on the first iOS 26 beta, we continue to take a closer look at new features coming with the update. Below, we recap five smaller changes that you might have missed. Emoji Game Apple News+ subscribers in the U.S. and Canada can play a new Emoji Game, which tasks players with completing words and phrases with emoji. This is the fifth game that is...
airpods 4 blue

Apple Offering Free AirPods — Here's How to Get Them

Tuesday June 17, 2025 6:33 am PDT by
Apple is running a new promotion that offers free AirPods to qualifying customers. Now through September 30, college and university students in the U.S., Canada, Mexico, and Singapore can receive free AirPods 4 when they purchase an eligible new Mac or iPad from Apple. AirPods Pro 2 are also available at a discount. If you do not want AirPods, the promotion also offers various other...