To alleviate iPhone 4 antenna problems, Apple will give free bumper cases to everyone who bought or will buy the phone through September 30. For people who already bought a bumper case, Apple will refund the cost. Users who are still unsatisfied can return the phone, with or without a case, for a full refund within 30 days. Apple CEO Steve Jobs made the announcement at a hasily-called press conference this morning.
An online application will go live on Apple’s website next week, where iPhone 4 owners will be able to choose a free bumper case from a variety of vendors.
Jobs stressed that the iPhone 4 reception issues are common among smartphones. On the iPhone 4, occur when the phone is held over its lower left-hand corner, blocking the external antenna. Nonetheless, Jobs said, he wants to keep customers happy, hence the free cases and full refund.
If you listened to the press conference, it sounded like “take the case and quit bothering me”. If it were me, I would get a full refund, then wait till they have a fix, then buy an Android. For now you can view the news conference here.
Just noting a couple subtle points not made clear in all the media coverage (both mainstream and technical). Attenuation occurs when holding every smart phone because the hand (part of the body) blocks some of the signal from being received and transmitted. The effect unique to iPhone 4 is not just this component of attenuation, but the added effect of making conductive contact with the metal antenna. This action detunes the antenna directly, causing further loss than just the body blocking component, an effect caused by touching the gap in the lower left corner that bridges two segments meant to be electrically isolated. The hand acts like a dielectric, much like in a capacitor.
Both effects should be separately quantified. In normal mobile network design, body loss of 6-10dB is factored into the design to account for these losses from holding the phone. The losses reported in various lab experiments, including Anandtech and Consumer Reports, indicate the “grip” on iPhone 4 has up to a 20dB effect, based on knowledge of the former bar graph vs dBm scaling used on iPhones. It seems that touching the iPhone 4 antenna has an additional X dB loss added to basic body loss. This is borne out by results comparing iPhone 4 with iPhone 3GS in Anandtech’s results.
Apple has not revealed the new formula used in iOS 4.0.1, but it is still logarithmic, and the dBm range allocation per bar is not equally weighted. This is done for a good reason. The signal strength a phone can process to make/receive a call varies from about -60 dBm down to about -110 dBm, about a 50 dB spread. Once the signal is say 10 dB or less above threshold (i.e. the minimum level the phone can receive), and assuming a good C/I (carrier to interference ratio) or S/N (signal to noise ratio), there is no significant difference in call quality, or in data throughput rate, other key test conditions remaining the same.
It is more important to know signal differences near the lowest than near the highest signal levels. That’s the reason the old formula unequally allocated 30dB to Bar 1, 10 dB to Bar 2, and 3-6 dB to Bars 3 to 5. So, if you are in a low signal area, holding any phone in a way that adversely affects its antenna has a more noticeable effect. Bars 1-4 may be only 20-25 dB apart, while Bar 5 is 30 dB in range alone. Adding to the confusion is the fact that bars are not updated instantaneously. Measurements are averaged over time and reported in time intervals. You may wait several seconds to see the bars change.
Hopefully, what comes out of this saga is more transparency from all operators in disclosing their “bar formulas”, locations and shapes of antennas in their phones, bar update periodicity, and separation of the effects of basic body attenuation (most common), and detuning from physical antenna contact (currently almost unique to iPhone 4).
It will now become standard to compare phone antenna performance like Apple tried to do today. Until all manufacturers calibrate equally, these comparisons have to be viewed with some caution. This is an opportunity for the FCC to set some standards for all to follow, enabling fairer comparisons for user choices/decisions in the future.
As of today, zero cell phones will get away with signal loss due to handling techniques.
As of yesterday all fingers pointed AT Apple.
The world has moved on.
remember this iphone’s premiere ??? and how jobs couldnt get it to work right?? until everyone else turned off their transmitters?
hell they let everyone know from day one how id didnt really work. :))
Why did it take so long to notice the effects of embedded antennas in modern phones (smart of regular)? When antennas were telescopic or “stubbies”, they were actually more effective electrically. You had a very defined standard vertical dipole shape perhaps with 2-3 dBi gain. But, this was a moving part, liable to be bent or broken, and embedded designs are now standard for aesthetic reasons (form wins over function).
While this happened, more networks were built with more cell sites from more competitors in more populated areas. You were on average nearer to a cell site than before for more of your usage time. You got a stronger signal to receive a call, and your phone did not have to transmit with as much power to reach the tower, and antenna gain to extend the signal range was therefore compensated by greater density of cell sites in most places.
Embedded antennas can have a gain which is essentially less than 0dB. All they are trying to achieve is a matched load into the antenna for maximum transfer of transmit and receive power. So, we got used to holding our nice Blackberries and Droids and EVOs in our hands in any position, and having no problems, as long as we were in strong signal areas, where body losses do not drop signals down to receiver minimum thresholds. Bars were all 5 tall more of the time, and we thought of them as another reliable gauge of signal quality.
Well today, once the media force field of exaggeration, misinformation, and drama has subsided, and the real facts become more widely known and understood, perhaps we’ll see less blame on Apple as scapegoat and more scrutiny of other players toys.
I have an iPhone 4. I am not returning it. I have a bumper. I see it like the insulation that should have been over the metal antenna in the final embedded design. It does the job. Any other case has as much plastic to separate the antenna from the outer body which tends to equalize if no normalize performance with most embedded phones
It is nicely engineered with hardened plastic around the perimeter and softened rubber on the grasping edges. Cases may detract from the beauty of the product, but it would be foolish not to use some sort of case, whether a bumper style or full back cover or totally encased. The glass will shatter on impact on the right hard surface and the side could be indented from a fall. More people got cases for iPhone 3G/GS than original iPhone which had a mostly robust metal back. The same goes for your Blackberry or Droid of EVO. Durability gave some way to functionality, style and design.
Once the real, believable, and scientifically sound engineering comparisons are made, between Apple models and others, we’ll get a developing picture in coming weeks/months. Those who trashed the iPhone should beware, we are doing to look thorough your phones just as throughly. The days of advertising more bogus bars in more places by showing dubious coverage maps with no dBm signal level key are over.
Correction to last para of #37 post (sorry for the long posts today)
Those who trashed the iPhone should beware, we are going to look through your phones just as thoroughly. The days of advertising more bogus bars in more places by showing dubious coverage maps with no dBm signal level key are over.
Epilogue:
– bumpers/cases should be provided for as long as this design is cold.
– this issue does not reach the level of a recall (pundits are way off base)
– future antennas will be shielded by insulation that is part of the case.
– the bar/dBm mapping formula must be disclosed and standardized
– body loss “holding” factors should have a reasonable target not > 10 dB
I don’t own an iPhone but I guess it’s at least nice that Apple did a public press event about this situation. I have owned Blackberry’s for years and those always had outages and other issues but I don’t recall RIM ever coming out with a public apology. Sure, some of the Apple conference was covered in B.S. but at least they are trying to remedy the problems.
Nevertheless, I won’t be buying an iPhone because I won’t support the labor practices that their factories support.
In essence, when cellphone manufacturers stopped making phones with the slide-out antennas or external bump antennas, performance went to pot. The difference in this case being the fact the iPhone4’s antenna is sort-of external, a part of the case, and the design allows the use to actually touch this external antenna, impeding its performance. And the problem goes away when you use a case, something 99.999% of iPhone users do anyway. Nothing to see here, as there have NOT been hordes of angry users storming Apple stores demanding refunds or replacements. Moving on.
Know what surprises me the most about all this kerfuffle and yak?
That Jobs (and others), completely fail to identify the stingy signal strength allocated by the ISPs. As soon as the get some bandwidth, they cram and cram and cram. Contention figures (always denied but evidence contradicts this)way above that which they should be. Appalling identification of line faults where copper is used. They test the line at one time, not the time when you have the problem, and pronounce it ‘sound’. NOtice also the marketing fiddles designed to mislead, such as the old ‘up to #### bps’ where, users are always charged as if the maximum is the case, not the minimum, which is pretty nearly always the case. ALL ISPs get away with murder in the misrepresentation business (just thought of another, BIG LETTER advertising of the cost, small letter advertising of the fact that this is for three months only – if that isn’t misrepresentation, I don’t know what is).
Something like supermarkets making price tickets as small as possible, knowing full well that 85% of the population has defective eyesight. Notice how your elected representatives jump to stop you being misleaded in this way.
ok – I have a question. Since we moved from analog phones to digital phones – what the heck do the bars mean anyhow. Isn’t it 1’s and 0’s? you either have enough signal to send and receive data (1) or you don’t (0) – even at 1 bar, you can still talk – and send and receive data…. its not like you hear static when your bars drop
can someone please splain to me what bars are for?
#43 Good question. I’ll try to be short and not too technical.
Analog and digital radio still have to obey the laws of physics for radio wave propagation. It is the modulation and demodulation methods that are different. Your AM/FM radio stations are examples of analog. You modulated the amplitude or frequency of the RF carrier (e.g. 740 kHz AM, 101.1 MHz FM) to “carry” the information. Demodulators reproduced the audio. In digital, voice is sampled, quantized and encoded into bits by PCM (pulse code modulation). The bits are used to alter the phase of the RF carrier to “carry” the information. Verizon and Sprint use CDMA (code division multiple access), a digital technology. CDMA uses digital codes to separate one call from the other. AMPS used frequency separation, like your AM/FM station. AT&T and T-Mobile use TDMA (time division multiple access), also a digital technology, which separate calls by time slot sampling. Never mind the details, as this is just a quick overview of analog vs digital for mobiles.
Bars are a simple graphical method to tell the user the average signal strength of the signal. It’s like the grading system in school where A may be 85-100, B is 70-85, C is 60 and 70, D is 50 to 60 and F is below 50. A to E now represent 0-100 in just 5 steps. Notice this is grading on a “curve”, where each grade is an uneven numerical range.
Think of ABCDE as bars 54321.
In reality, RF signal strength is a variable number measured logarithmically, because it spans too wide a range for linear counting. Let’s say you had a graph with the Y axis from 0-100 in steps of 10. Now if you wanted to count from 0-1,000,000 in steps of 10 you would run out of paper. Counting 0-1,000,000 in logs, you can have steps of 10 dB which are actually 10x in each step.
Now to the relevance to the five bars. Your typical phone can measure signals with a range from about -60 dBm to -110 dBm, a 50 dB range. The number -60 dBm means 1/1,000,000 of a milliwatt of RF power and -110 dBm is 100,000 times lower than that. See why it is easier to count in log units than in linear units?
Bar 5 is roughly -60 to -90 dBm
Bar 4 approx -100 to -90 dBm
Bar 3 approx -100 to -106 dBm
Bar 2 approx -106 to -110 dBm
Bar 1 approx less than -110 dBm
(Note: -60 is highest and -110 is lowest, and it is all negative because we are counting with reference to 1 milliwatt, and everything is lower)
Each manufacturer uses a different range or formula for their bars, basically a different grading curve, making it hard to do comparisons.
Obviously, counting in bars is easier than counting in dBm. But, each bar represents a range, not an absolute value. There is a display format called “field test mode” that most phones can access by dialing a special number, which changes the home screen to show engineering data, including the bar information in absolute dBm and the ID of the tower you are on, and others around you, and your frequency, etc. In this mode you can compare all phones more or less equally.
Comparing bars for different phones is like comparing the grading curves for several teachers, where some may have a more generous or tighter percentage mark to get an A-C. One teacher may insist an A is 90 and above, and another may allow 80 and above.
The general media does not understand these nuances, so we have all these outrageous headlines from usually respectable publications that completely distort and misrepresent the truth. The average user listens and reads this nonsense and is influenced to make unwise decisions.
Apple is right, all phones experience “body loss” from holding them in the hand. This number varies by design, but it is not zero. Apple made their antenna exposed to the hand grip, adding to this loss. Insulating with a case or bumper reduces this effect. A better future design would be to insulate the metal antenna periphery with a see though compound to preserve the elegant look. That’s the only shortcoming of the phone. An exposed antenna outside the case would perform better than an embedded one, as long as you don’t touch it conductively.
“I’ll try to be short and not too technical.”
Try harder.