Apple iPhone 4 Review - Part 2

Robot R1.0

Apple iPhone 4 Review - Part 2

A smartphone that promises it all
<div class="K2FeedFullText">In the first half of our iPhone 4 review, gave a brief historical overview of the iPhone platform since its introduction to the smartphone market in summer 2007, including its booming impact on the global smartphone market over the past three years. We discussed Apple’s design philosophy behind the physical dimensions and aesthetics of the iPhone 4, and we examined the truth behind the much hyped Retina Display.In this half of the review, we will take a look at the real story of the controversy behind the antenna design, internal hardware specifications and upgrades from the iPhone 3GS to the iPhone 4, the improved backside CMOS camera sensor with LED flash and new front-facing VGA camera, multitasking improvements in iOS 4 and overall market acceptance since launch day.

Antenna design and controversial reception issue

Unlike the previous three iPhone generations, the iPhone 4 sports a new antenna design that is meant to improve reception and overall call quality. The antenna is a split stainless steel band that runs around the edge of the phone. The shorter, left strip is used for WiFi, Bluetooth and GPS and the longer, right strip is used for UMTS/GSM cellular radio for voice and data. In perspective, it can be viewed as a return to some of the earliest phone designs from the 90s that featured external antenna poles and could be manually raised for improving reception. During Apple’s WWDC 2010 keynote, Steve Jobs exclusively noted that this was “some brilliant engineering – we use that stainless steel band as part of the antenna system,” and if the CEO of the company himself is telling his flock of prospective iPhone 4 consumers to “expect brilliance,” we hoped that his words would have resonated a positive marketing image for the new device when launch day came around. Unfortunately, numerous users have discovered that holding the phone in a certain way (noticeably when grasped in the left hand) appears to degrade signal, and ultimately drops calls and data throughput speeds.


Since the issue has become known, many iPhone 4 users have been carefully monitoring their AT&T 3G HSPA reception. In our personal tests with three different iPhone 4’s, we have found that covering the antenna gap on the lower-left of the device does not seem to affect call quality or cause any dropped calls on two of the phones. On the third phone, however, calls are typically dropped with a stronger than normal palm grip over the antenna gap, even in environments where all 5 bars are displayed.

AnandTech’s Brian Klug recently conducted a lengthy scientific analysis of the scenario, where he highlighted the potential for both unintended attenuation and detuning being much greater with an external antenna design than with a conventional internal design. Upon acquiring his iPhone 4, the first thing he attempted was to try and run the hidden Field Test application via the widely documented *3001#12345#* dialer code (it’s a nifty utility, give it a try). Unfortunately, Field Test is completely absent on the iPhone 4’s filesystem applications directory and only works on original iPhone, iPhone 3G and iPhone 3GS devices that have not been updated to run iOS 4 (or higher).

The Wall Street Journal recently ran a report to examine the math behind the number of signal bars displayed on cellphones. Author Carl Bialik explains that some handsets’ formulas can be approximated by using the field test mode, which allows users to see true signal strength numbers on some handsets. But when AnandTech and ran their tests they found that a relative narrow range of power corresponded to the range from one bar to four bars, thus wavering signal strength greatly without an accurate reporting based on environmental conditions.

Coming back to AnandTech, Brian Klug explains that iOS reports the quality metric of perceived iPhone signal bars with a compressed, optimistic dynamic range. In perspective, he notes that best reported signal possible for an AT&T UMTS 3G tower is -51dBm and nothing lower than that number. In Apple’s iOS 4, a signal with 4 bars begins at around -99 to -101dBm, a signal with 3 bars sits around -103dBm, a signal with 2 bars sits around -107dBm and a signal with 1 bar extends down to -113dBm. In other words, -113dBm is the worst possible signal possible before the phone is disconnected from the network entirely. Brian also explains that he happens to live directly across the street from an AT&T UMTS tower and has exceptionally strong signal throughout his house, in most cases around -51dBm and definitely about -65dBm in every room. However, when he squeezes the phone with his left hand and bridges the antenna gap, the result is a 24dB drop in signal degradation, but the iPhone 4 still managed to display the signal at 5 bars. In other words, there is an inherent flaw in the way iOS 4 is reporting signal strength and it is leaving many analysts and pundits in outcry to demand a recall.


Yet, Apple claims that the iPhone 4 reception problem doesn’t exist. The company insists that the “dramatic drop in [signal bars] is explained by an erroneous iOS 4 signal display,” where 2 bars is reported as 4 bars and 3 bars is reported as 5 bars. In other words, they claim that iOS 4 on the iPhone 4 is reporting 2 more bars than it should, and promise that a software update will fix the way the device displays signal bars. Unfortunately, they don’t claim that this proposed software patch will solve the signal attenuation problem that Brian and many other have demonstrated. Gizmodo has posted a nice thorough analysis of Apple’s position and its contradiction to a realistic fix for iPhone 4 users.

On the other hand, the wireless antenna experts at AntennaSys have written a lengthy blog after having been contacted by numerous news organizations for an adequate explanation of the issue. They claim that the iPhone 4, and other 2010 smartphones including the Google Nexus One, several Nokia models and the HTC Droid Incredible, may all suffer from this problem due to FCC restrictions on antenna design, which happen to force antenna placement in an area where people are likely to hold the device.

This explanation lines up almost perfectly with our theory that the FCC is holding back some information from the public eye regarding iPhone 4 internal hardware specifications. In the few months prior to the iPhone 4’s launch, the FCC had been privately testing the device in order to clear the market approval process. These tests typically include SAR (Specific Absorption Rate) plots on the device’s various antennas, internal photos, external photos, testing verification documents and manufacturer declarations.


For some unknown reason, Apple was able to ask the FCC for an indefinite confidentiality on some of the device’s details that contain information of top priority. In other words, these details will remain exclusively confidential between Apple and the FCC until 90 days have passed from the signing of the agreement on May 31, 2010.

In a blog post on Monday that has fired up another round of pundit attacks, ConsumerReports’ engineers have just completed testing of the iPhone 4 and have confirmed that there is a problem with its antenna reception. However, the bigger news is that the group does not want to recommend the device due to the significance of the signal degradation issue, despite placing it at the top of the latest ratings of smartphones that it just released.

“Our findings call into question the recent claim by Apple that the iPhone 4’s signal-strength issues were largely an optical illusion caused by faulty software that mistakenly displays 2 more bars than it should for a given signal strength. The tests also indicate that AT&T’s network might not be the primary suspect in the iPhone 4’s much-reported signal woes.”

The group also advises that it has found an affordable solution for suffering iPhone 4 users – “cover the antenna gap with a piece of duct tape or another thick, non-conductive material. It may not be pretty but it works. We also expect that using a case would remedy the problem.”


As iPhone 4 hits seem to keep piling up, however, Apple has now found a friend in an electromagnetic engineer who claimed that the recent Consumer Reports study has only replicated the same uncontrolled, unscientific experiments that many of the blogging sites have done.

“To even reasonably run a scientific test, the iPhone should have been sitting on a non-metallic pedestal inside an anechoic chamber,” said Bob Egan, Global Head of Research and Chief Analyst at TowerGroup. “The base station simulator should have been also sitting outside the chamber and had a calibrated antenna plumbed to it from the inside of the chamber.”


With a credible engineering background and adequate knowledge of RF electromagnetic properties, we are led to agree with Egan. After all, he is simply explaining that the ConsumerReports test is not the authoritative engineering masterpiece that it’s purported to be. He also notes that he’s not refuting the idea that Apple may have a hardware problem, but he cannot determine which part of this issue is Apple’s and which part is related to the AT&T network.

“We also don’t know if placing a finger on the antenna bridge is detuning the antenna or detuning the receiver itself,” he adds. “Mr Jobs, silence is not golden [right now]. I’m quite sure Apple has these answers by now..If not, send me a few more iPhones (I bought three) and I’ll find a chamber and get you some answers in a day.”

As the Wall Street Journal has recently noted, the damage done with this issue may fall on the iPhone’s image of precision-engineered excellence. “It’s negative for the brand,” said Andy Hargreaves, an analyst at Pacific Crest Securities. “But does it mean they’ll sell fewer iPhones? Probably not.”

CPU, RAM and SoC Design Changes

When most companies go through the enormous expense of designing a complex chip, they usually never hesitate to tell the entire industry about it, which in turn riles up prospective consumers through a proliferation of flattery over various social media networks. Whether that information is transmitted through a whitepaper, a keynote, a press release or bite-sized snippets revealed to a select chosen few, word of a new processor or SoC design coming to market almost always materializes before the product hits store shelves. Unfortunately, this has never been the case with Apple. At this point, the company has it pretty much baked into its corporate culture that its secretive product cycle philosophy is one of the best practices it has ever chosen to maintain. Nevertheless, most argue in support of the idea that Steve Jobs simply loves secrets, and that they give him an elevated foothold over an industry filled with assumptions and speculations.


Whatever its motives may be, Apple decided not to reveal the specifications of its A4 processor during the iPad’s announcement in January, and only revealed the name of the processor itself. Of course, little did the industry know that the company would implement the same processor in its fourth-generation smartphone. Now that the product has materialized and has sold over 1.7 million units within its first three days, we can confirm without question that the device sports the same ARM-based 45nm A4 1GHz chip used in the iPad. But rather than being clocked straight at 1GHz, the A4 processor in the iPhone 4 runs at a variable clockspeed, allowing it to vary in speed and adjust according to application demands. It features a maximum clock of 1GHz just like the iPad, but for most applications it will essentially mimic Intel’s SpeedStep platform by adjusting voltages and clock speeds according to the number of applications running to improve power consumption efficiency.

In retrospect, the iPhone 3GS featured a 65nm ARM Cortex A8 with a 600MHz clock speed and 256MB of breathing room. By contrast, the iPhone 4 has been upgraded to a variable clock speed Cortex A8-based SoC that possibly runs between 750MHz and 800MHz most of the time. AnandTech was curious about the exact performance improvements between the two latest iPhone generations and conducted a few SunSpider Javascript performance benchmarks between some of Apple’s top competing 2010 smartphones, including the iPhone 3GS and the iPad. The results show that the iPhone 4 processor manages an overall score that is 25 percent faster than the iPhone 3GS processor in all of its CPU-specific tests. Given Apple’s unwillingness to discuss the architecture of its new phone, AnandTech assumes a safe bet that the ARM Cortex A8-based A4 chip runs around 800MHz in the iPhone 4 and 1GHz in the iPad.


(Flagship smartphone hardware comparison -

Memory has also been an interesting topic of discussion in the iPhone 4, as many analysts are now finding that the new device sports 512MB of onboard RAM (503MB of which is available to the OS and applications) opposed to the iPad’s 256MB. This was confirmed by’s teardown of the device right around launch time. The site notes that the increase in RAM allows for a larger amount of cached data, resulting a smoother and faster user experience.


(iPhone 4 SoC -

Alongside the A4 processor is the same PowerVR SGX 535 graphics chip found in the iPhone 3GS. Anand Shimpi went into great detail last year about Imagination Technologies’ fifth generation PowerVR architecture, a tile-based renderer that divides the screen up into small blocks, or tiles, and renders each one independently. In his iPhone 3GS review, he noted that this approach to graphics rendering is particularly important in the mobile space because there simply isn’t enough available bandwidth, and the mere milliwatts of power that smartphone are intended to consumer isn’t enough to drive a full scale rendering architecture.


Imagination Technologies fifth-generation PowerVR SGX architecture diagram

From our experience over these past three weeks, the iPhone 4 definitely provides a snappier overall user experience than the iPhone 3GS, and we aren’t ones to complain about any aspects of the CPU/GPU/DRAM hardware combo that Apple decided to implement in this generation. Despite not having a 1GHz Qualcomm Snapdragon processor like the HTC Incredible and HTC EVO 4G, we’ve found that the iPhone 4 adequately meets our expectations and even rivals HTC's offerings in terms of hardware performance (although iPhone OS vs. Android software performance is an entirely different topic).

We also ran a quick series of SunSpider JavaScript benchmark tests in mobile Safari to more accurately quantify the performance differences between Apple's mobile devices in web browsing. It's important to note that SunSpider tests tend to substitute the "micro benchmarks" found in Google's V8 tests in favor of real-world operations similar to those that developers perform. According to the results, the iPhone 4 sits right in between the 3GS and the iPad.


The new iPhone 4 hardware also incorporates a new 3-axis gyroscope in addition to the accelerometer. The combination of these two sensors will ultimately provide 6-axis motion sensing (see: PlayStation 3 SIXAXIS Wireless Controller). Using the CoreMotion APIs, developers can make use of the gyroscope to roll, pitch and yaw. With six degrees of rotation in a compact physical space, Apple hopes that its developers will design even more immersive gaming experiences that enable gamers to have full control over their virtual environments.


(iPhone 4 gyro announcement during Apple's WWDC 2010 keynote)


Network Improvements and HSUPA Upgrade

In addition to the CPU and memory upgrade, the iPhone 4 benefits from improved network speeds in areas where AT&T has deployed 5.76Mbit/sec HSUPA (High-Speed Uplink Packet Access), a theoretically major improvement over current speeds seen on the iPhone 3G and iPhone 3GS. Over the past twelve months, we have literally ran over 1,200 mobile broadband speed tests all around the Los Angeles / Orange County region of Southern California using the FCC Mobile Broadband Test app and can undoubtedly confirm that the maximum 3G HSUPA speeds on the iPhone 3GS typically average 0.24Mbps and never exceed 0.27Mbps.

Over the past three weeks alone, we have already ran over 700 mobile broadband speed tests with the iPhone 4 and can confirm that our average upload speeds have jumped to 1.12Mbps and top out at 1.24Mbps. In one situation, we even stood 10 feet away from a fairly high-volume local AT&T UMTS tower at various points of the day and managed to find maximum throughput at 3.76Mbps down, 1.22Mbps up and 289ms latency to the nearest packet test server.


As a side note, we've also consumed over 2.7GB of cellular 3G HSPA data in the past three weeks alone. It looks like AT&T won't be able to take this enthusiast smartphone user off his unlimited data plan in the future without a good fight.



Battery Life

We could go into a much lengthier conversation about the SoC platform in the iPhone 4 and its general hardware performance compared to the previous few iPhone generations. But one of the bigger facets of hardware design that has always concerned the majority of iPhone consumers is battery life. Indeed, Apple's efforts before the iPhone 4 have been a pretty poor selling point in comparison to other smartphones that have made it big in the past 24 months. Nevertheless, the iPhone 4 features a gigantic 3.7V 1420mAh Lithium-Polymer battery, and Apple claims it can get up to 7 hours of talk time on 3G, up to 6 hours of Internet use on 3G (10 hours on WiFi), up to 10 hours of video, up to 40 hours of audio, and up to 300 hours of standby. In comparison, the iPhone 3GS has a capacity of 1219mAh and the iPhone 3G has a capacity of 1150mAh respectively.


(iPhone 4's new 3.7V 1420mAh Li-Polymer battery -

Based on the teardown images, the battery connector is different than the one in the 3G and 3GS. Fortunately, the battery is not soldered to the logic board and should allow battery replacement on the device to be fairly easy to accomplish.

In our iPhone 3GS review last year, we noted that both the iPhone 3G and the iPhone 3GS supply the same amount of juice regardless of Apple's improvement claims at the time. The ARM Cortex A8 crunches through data in a way that, when used at full speed, makes the 3GS run out of battery faster than the 3G. Likewise, the same scenario can partly be said for the iPhone 4. Despite having a larger battery and faster processor clockspeed based on the same architecture, the 800MHz A4 will consume more power at full speed than its 600MHz predecessor, and will consequently cause the phone to run out of battery almost as fast as the iPhone 3GS. Of course, there's a remarkably easy solution to this, and it's built right into iOS 4 - simply close any unused background apps with the built-in task manager by double tapping the Home button and removing them from the selection list. We've noticed that many location-based apps, even when idling as background processes, will utilize the GPS radio and accelerometer for continuous tracking and can drain the battery very quickly. Thankfully, Google Maps doesn't exhibit this behavior, but popular third-party apps like MotionX GPS and Waze can pose a threat to battery life and will attempt to gulp the juice out of the iPhone 4 when unnoticed.

In contrast to the nature of battery consumption in Apple's rendition of multitasking, the iPhone 4 has a very impressive standby time under normal to light usage. We tested the phone overnight with an initial charge of 100 percent battery and checked up on it 14 hours later to find that it had only dropped to 98 percent. This behavior is similar to what the iPad exhibits when fully charged under normal to light usage. Overall, we're thankful that the new A4 architecture sips power under normal use conditions and can potentially spare us a few extra hours of standby time when the battery dips down to 6 percent and we're stuck in an emergency situation without a charger (hey, it happens to all of us).


Front and Back Cameras - New CMOS Sensors

Since the introduction of the original iPhone in summer 2007, the iPhone 4's camera system has been by far one of the more significant overhauls that the platform has experience and has been a notable topic of discussion since WWDC 2010. The original iPhone launched with a fixed-focus lens and a contemptible 2 megapixel CMOS sensor that lacked the capacity to produce any meaningful low-light, motion or close-up shots worth keeping. After twelve months came and went, the iPhone 3G appeared on the scene with the exact same sensor and produced almost identical shots with very subtle lighting improvements. Another twelve months went by, and the iPhone 3GS launched with a 3 megapixel sensor, autofocus, and a "tap-to-focus" system to link the focus control and autoexposure system to a specific point in the image. As many came to notice, it was also the first iPhone sensor capable of shooting VGA-quality video clips, however very limited in resolution. Despite the improvements over this 2-year product cycle, many critics remained unimpressed with these hardware changes and desired a product with focus more resemblant of a pocket sized point-and-shoot camera.


During his WWDC 2010 keynote, Steve Jobs said that getting great looking images wasn't just about increasing the camera's megapixels. It had more to do with grabbing more photons from the ambient environment. By increasing the photon count, more light gets let into the sensor, and images will look better. Let's take a look at the sensor differences between the iPhone 3GS and the iPhone 4.

The iPhone 3GS features a 3.1MP, 1/4" CMOS sensor from OmniVision. According to Apple, that sensor has 1.75µm pitch individual pixels. In contrast, the iPhone 4 features a 5MP, 1/3.2" backside illuminated CMOS sensor.. By increasing the size of the sensor itself, the size of the individual pixels remains the same at 1.75µm pitch, but the backlit sensor has circuitry on the back of the chip, keeping it out of the way of light and effectively allowing more light to reach individual photo diodes in each pixel location.

The weekend of iPhone 4 launch day, we attended a concert by one of our favorite bands in San Diego and attempted to capture our very first iPhone 4 snapshots using the new CMOS sensor in the iPhone 4. The results were quite impressive, the quick response time of the autofocus lens significantly enhances the value of capturing motion shots by improving shutter lag.


5 megapixel still shot (2592x1936) taken at Moonlight Beach in Encinitas, California. Full resolution here.


5 megapixel action shot with 5x Digital Zoom taken at Moonlight Beach in Encinitas, California. Full resolution here.


5 megapixel night shot taken in Cypress, California. Full resolution here.

The fact that Steve Jobs even mentioned the specifications of the new CMOS sensor during WWDC is a sign that Apple is taking the camera much more seriously with this generation. Based on the product brief published by OmniVision, "the OV5653 delivers the industry's best low-light sensitivity of >1300mV/(lux-sec) - a 40 percent improvement over previous FSI devices - and a 2x improvement in signal-to-noise ratio (