Letter from Apple Regarding iPhone 4 [Apple's fix for the 'faulty' antenna]

Apple ^ | 2 July 2010 | Apple Press Release

[Yo-Yo]

July 2, 2010 Letter from Apple Regarding iPhone 4 Dear iPhone 4 Users,

The iPhone 4 has been the most successful product launch in Apple’s history. It has been judged by reviewers around the world to be the best smartphone ever, and users have told us that they love it. So we were surprised when we read reports of reception problems, and we immediately began investigating them. Here is what we have learned.

To start with, gripping almost any mobile phone in certain ways will reduce its reception by 1 or more bars. This is true of iPhone 4, iPhone 3GS, as well as many Droid, Nokia and RIM phones. But some users have reported that iPhone 4 can drop 4 or 5 bars when tightly held in a way which covers the black strip in the lower left corner of the metal band. This is a far bigger drop than normal, and as a result some have accused the iPhone 4 of having a faulty antenna design.

At the same time, we continue to read articles and receive hundreds of emails from users saying that iPhone 4 reception is better than the iPhone 3GS. They are delighted. This matches our own experience and testing. What can explain all of this?

We have discovered the cause of this dramatic drop in bars, and it is both simple and surprising.

Upon investigation, we were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong. Our formula, in many instances, mistakenly displays 2 more bars than it should for a given signal strength. For example, we sometimes display 4 bars when we should be displaying as few as 2 bars. Users observing a drop of several bars when they grip their iPhone in a certain way are most likely in an area with very weak signal strength, but they don’t know it because we are erroneously displaying 4 or 5 bars. Their big drop in bars is because their high bars were never real in the first place.

To fix this, we are adopting AT&T’s recently recommended formula for calculating how many bars to display for a given signal strength. The real signal strength remains the same, but the iPhone’s bars will report it far more accurately, providing users a much better indication of the reception they will get in a given area. We are also making bars 1, 2 and 3 a bit taller so they will be easier to see.

We will issue a free software update within a few weeks that incorporates the corrected formula. Since this mistake has been present since the original iPhone, this software update will also be available for the iPhone 3GS and iPhone 3G.

We have gone back to our labs and retested everything, and the results are the same— the iPhone 4’s wireless performance is the best we have ever shipped. For the vast majority of users who have not been troubled by this issue, this software update will only make your bars more accurate. For those who have had concerns, we apologize for any anxiety we may have caused.

As a reminder, if you are not fully satisfied, you can return your undamaged iPhone to any Apple Retail Store or the online Apple Store within 30 days of purchase for a full refund.

We hope you love the iPhone 4 as much as we do.

Thank you for your patience and support.

Apple

[LeGrande]

Look back in the thread, you’ll see I asked for measurements. But your dishonesty will prevent you from admitting to that.

Well I have looked back and you did ask for measurements. Now will you apologize for calling me dishonest?

You’re right it doesn’t have anything to do with apple. They are just another company. It has to do with the dishonest and hateful attacks by the macbots who feel their religion is threatened.

I told you, I don't own an IPhone, or even a cell phone. Are you going to apologize to me or are you worse than what you accuse the MacBots to be? I have simply wanted to see the evidence. Is that so bad?

[LeGrande]

LeGrande, this is the attitude I've been putting up with from driftdiver. He will dance and weave, obfuscate, and insult you.

Yes that is precisely what I have seen.

Obviously he has some kind of mental disorder. One can only hope that he gets the proper medical attention and care that he needs.

[driftdiver]

“Now will you apologize for calling me dishonest? “

So in one post you admit you were wrong and ask for an apology and then the next you throw more insults.

[LeGrande]

So in one post you admit you were wrong and ask for an apology and then the next you throw more insults.

Ahh, so this is just about slinging insults. I can do that too.

You sir, are an insufferable reprobate, whose mental inadequacy is only exceeded by your genitals.

To help you out, now it is your turn to one up me with an insult and we escalate until you call me a Nazi at which point you lose.

[driftdiver]

“Ahh, so this is just about slinging insults. I can do that too. “

Yes you can, similiar to what you were shouting in the last election. See I didn’t return the insults, I just pointed out your insults.

“You sir, are an insufferable reprobate, whose mental inadequacy is only exceeded by your genitals. “

I could say you wife didn’t complain but would rather not stoop to your level.

“To help you out, now it is your turn to one up me with an insult and we escalate until you call me a Nazi at which point you lose.”

Godwins law, you lose.

[LeGrande]

Yes you can, similiar to what you were shouting in the last election. See I didn’t return the insults, I just pointed out your insults.

I didn't insult you until after you had repeatedly insulted me. That makes you a reprobate.

I could say you wife didn’t complain but would rather not stoop to your level.

No you're just angry that your wife enjoyed the jack more than you did.

Godwins law, you lose.

No, it will be me invoking Godwins law not you. Unless you run away screaming in terror like a little girl, which I admit may be more likely.

[PugetSoundSoldier]

At 1900 MHz the FCC limits you to 1W maximum output; at 850 MHz it is 1.5W. Most cell phones will transmit up to that power level if required to maintain channel SNR (QOS measurements in-channel to determine required TX power levels or if another cell is better suited for use).

Now let's look at the receive signal attenuation again:

Theoretically, when held naturally, I could use 125mW output from the Nexus One and have the same total channel SNR (TX plus RX) as the iPhone 4 at 1W output, due to the attenuation of the iPhone 4's RX sensitivity. That is a not-inconsequential difference.

It's also interesting to note that the least sensitive phone has the antennas external; those with internal antennas have higher sensitivity. I wonder if this is because of the use of shielding against the front of the phone, creating a ground plane for enhanced directivity of the antennas?

I'd expect a 4-6 dB increase in RX sensitivity from a half-space measurement versus a full-space measurement, and that would be equivalent to an internal antenna with full ground plane behind versus an external antennas on edge without ground plane.

[driftdiver]

Please please don’t try to bring a rational voice to the discussion. I tried to ask a simple question and they went beserk.

[LeGrande]

What is your source? Did you just randomly pull quotes from a couple of sources without any attributions or did you do the testing?

[PugetSoundSoldier]

Source for what? The FCC limits? That would be the FCC. Or the graph above? I showed and linked it earlier in this thread, I assumed someone who read to the second display of the graph would have seen and read the first display.

I assume the rest of my post is redundant and not required for anyone with an EE background.

[LeGrande]

Ahh, I went back to your earlier post it seems that you have randomly just selected quotes. That is why I was confused.

At 1900 MHz the FCC limits you to 1W maximum output; at 850 MHz it is 1.5W. Most cell phones will transmit up to that power level if required to maintain channel SNR (QOS measurements in-channel to determine required TX power levels or if another cell is better suited for use).

This is off topic, unless you are alleging that the IPhone 4 isn't transmitting properly. Are you? Do you have any data?

Now let's look at the receive signal attenuation again:

Your signal attenuation data shows clearly that how you hold any cell phone affects the signal. This isn't new. Also from your same source. "From my day of testing, I've determined that the iPhone 4 performs much better than the 3GS in situations where signal is very low, at -113 dBm (1 bar)." and "so it's readily apparent that the new baseband hardware is much more sensitive compared to what was in the 3GS. The difference is that reception is massively better on the iPhone 4 in actual use." Obviously the person who produced the comparison thought that the IPhone 4 was better than the 3GS, after testing.

Theoretically, when held naturally, I could use 125mW output from the Nexus One and have the same total channel SNR (TX plus RX) as the iPhone 4 at 1W output, due to the attenuation of the iPhone 4's RX sensitivity. That is a not-inconsequential difference.

Now we seem to be back to output, and again I am confused as to the point.

It's also interesting to note that the least sensitive phone has the antennas external; those with internal antennas have higher sensitivity. I wonder if this is because of the use of shielding against the front of the phone, creating a ground plane for enhanced directivity of the antennas?

What is the context that this statement is referring to? Without proper context it is a meaningless paragraph.

I'd expect a 4-6 dB increase in RX sensitivity from a half-space measurement versus a full-space measurement, and that would be equivalent to an internal antenna with full ground plane behind versus an external antennas on edge without ground plane.

Yes, and the point is?

PugetSoundSoldier, I am a little confused you have apparently taken 5 quotes out of context without sourcing them and apparently tried to say something.

What are you trying to show?

[PugetSoundSoldier]

This is off topic, unless you are alleging that the IPhone 4 isn't transmitting properly. Are you? Do you have any data?

No, and I did not allege that. Total channel performance of a duplex communications channel is a combination of the TX and RX; assuming TX is the same, then RX becomes the dominant factor for SNR. And if you have weak RX you can compensate by higher TX (since TX+RX is your total channel performance).

"so it's readily apparent that the new baseband hardware is much more sensitive compared to what was in the 3GS. The difference is that reception is massively better on the iPhone 4 in actual use.

This conclusion is not logical, by the article writer. Sensitivity is NOT concluded to be higher, only that total channel performance is higher, and that noise cancellation and audio signal processing allow for the iPhone 4 to produce higher quality audio with weaker signals. Improved sensitivity is not required to generate the data the author reports.

With typical cell phones, when the signal is below -100 dBm then the phone tries to switch to a new cell; it may be that the new iPhone does not, and maintains its connection because of other processing in the phone. That will reduce audio effects due to switching, but at the cost of higher noise in the channel (reduced SNR), which can be ameliorated with improved noise gating and dynamic bandwidth limitation (something I've used many times in phone conferencing systems).

Or, you can crank up your TX level to full strength (something that is rarely done) to compensate as well. This results in increased battery power consumption, which is also being reported in some iPhones.

Knowing how total channel performance is a combination of TX and RX, you can compensate for some loss in RX performance by increasing TX output. And that may be what is happening with the iPhone 4, and provides some improvement in total performance.

There is nothing taken out of context, and I thought for someone with some RF background and an EE degree this would be pretty obvious. The relation of these facts and surmising should be obvious for most EEs.

[LeGrande]

No, and I did not allege that. Total channel performance of a duplex communications channel is a combination of the TX and RX;

So then are you alleging total channel performance is impaired? Again what are your stats?

This conclusion is not logical, by the article writer. Sensitivity is NOT concluded to be higher, only that total channel performance is higher,

Ahh, so you agree that total channel performance is higher then? Those are your words aren't they?

Or, you can crank up your TX level to full strength (something that is rarely done) to compensate as well. This results in increased battery power consumption, which is also being reported in some iPhones.

Are you alleging that the IPhone has cranked up the TX? That is very easy to test. Do you have the data to back your claim?

Knowing how total channel performance is a combination of TX and RX, you can compensate for some loss in RX performance by increasing TX output. And that may be what is happening with the iPhone 4, and provides some improvement in total performance.

Again do you have any data to support that claim? Or are you being intentionally noncommittal? Words like 'may' are weasel words.

There is nothing taken out of context, and I thought for someone with some RF background and an EE degree this would be pretty obvious. The relation of these facts and surmising should be obvious for most EEs.

Nothing taken out of context? You haven't even clearly stated what you think is happening.

Please clearly state what you think is happening with evidence to back it up. I would really like to see APPLES to APPLES comparisons. Specifically on TX and RX values.

[PugetSoundSoldier]

So then are you alleging total channel performance is impaired? Again what are your stats?

Yes. Please see the aforementioned graph and the FCC limit on TX power. Put the two together. Then add in all the measurements and reports by users in the field where a held iPhone 4 either loses all connection or is much slower and weaker (in measured download rates) than iPhone 3GS models.

Ahh, so you agree that total channel performance is higher then? Those are your words aren't they?

If TX power is turned up to full, and the other phones leave it down, yes this is true. Like I stated originally, the Nexus One, when held, can have the same total channel performance with 125 mW as the iPhone 4 with 1W of TX power. If the Nexus One runs at 100 mW (and cell phones try to run as little as possible), then the iPhone 4 can have better total performance. At the cost of 10X the TX power, and subsequent issues with battery life.

Are you alleging that the IPhone has cranked up the TX? That is very easy to test. Do you have the data to back your claim?

It's an educated guess based upon a sum of the data points presented. Do you have data to the contrary?

Nothing taken out of context? You haven't even clearly stated what you think is happening.

On the contrary, I've been quite clear:

- iPhone 4 reception sensitivity is lower, as measured (see table above, and lots of other documented tests all over the Internet)
- some iPhone 4 owners have reported poor battery life, which would be consistent with the way cell-phones operate when having reception issues (TX power is turned up, and new cells are connected, both of which require more power)

Summation: the iPhone 4 may compensate for weak reception by increasing TX power and/or constantly seeking and connecting to slightly better cells. That would be a consistent, educated summation.

What is your position, and what is your documentation to substantiate it? Or is that only required of me?

[dennisw]

How soon before an enterprising individual comes out with a clamp on retractable whip antennae like my old transistor radio had. The music was so good back then that you didn’t care if it was AM and tinny sounding like the Rolling Stones playing “Satisfaction” on the beach on your lousy radio

Today the equipment is 1000x better and the (alleged) music 1000x worse

[LeGrande]

Yes. Please see the aforementioned graph and the FCC limit on TX power. Put the two together. Then add in all the measurements and reports by users in the field where a held iPhone 4 either loses all connection or is much slower and weaker (in measured download rates) than iPhone 3GS models.

You seem to be trying to contradict your own source. Again I quote, "It's amazing really to experience the difference in sensitivity the iPhone 4 brings compared to the 3GS, and issues from holding the phone aside, reception is absolutely definitely improved. I felt like I was going places no iPhone had ever gone before. There's no doubt in my mind this iPhone gets the best cellular reception yet," Here the author is talking about total channel performance.

If TX power is turned up to full, and the other phones leave it down, yes this is true.

Here you go again using weasel words like 'if', does Apple transmit at the FCC limit all the time? That is trivially easy to determine.

The acid test of course is the performance. And your own source said that the performance is great. Again what point are you trying to make?

It's an educated guess based upon a sum of the data points presented. Do you have data to the contrary?

An educated guess? By you? LOL Isn't that kind of like Military intelligence. I have no data at all. I don't even own a cell phone.

- iPhone 4 reception sensitivity is lower, as measured (see table above, and lots of other documented tests all over the Internet)

And yet you have clearly stated that it is the combination of TX and RX that is what is important and your own source claims that the IPhones performance with RX and TX is stellar. Do you see why I am confused?

some iPhone 4 owners have reported poor battery life, which would be consistent with the way cell-phones operate when having reception issues (TX power is turned up, and new cells are connected, both of which require more power)

Again you kind of make an allegation with a weasel word "some" surely that data is easy to come by. And wouldn't we both expect the cell phone to be transmitting at full power on the periphery of Cell tower range?

Summation: the iPhone 4 may compensate for weak reception by increasing TX power and/or constantly seeking and connecting to slightly better cells. That would be a consistent, educated summation.

Consistent, educated summation? First off transmission cannot compensate for weak reception. You are confusing total performance with a single aspect of the equation. And again you are using weasel words "may".

What is your position, and what is your documentation to substantiate it? Or is that only required of me?

I don't have a position, other than I am curious about how much attenuation is caused by proximity to the antenna and if it is excessive. About evidence, you are the one making the allegations, so yes documentation is only required from you.

I have designed several antenna's for airplanes and I am well aware that everything is a compromise. Your source who actually tested the unit indicated that the reception of the IPhone is fine "best cellular reception yet".

And yet you seem to be trying to disagree with your single source of actual data. Why is that?

[PugetSoundSoldier]

And so, we find out you don’t even have a cell phone, and have nothing to counter what I wrote or my estimates other than “nuh uh”.

Buh bye.

[LeGrande]

And so, we find out you don’t even have a cell phone, and have nothing to counter what I wrote or my estimates other than “nuh uh”.

Your estimates? You won't even make a clear claim. All you say is weasel words. Then to compound your ambiguity you don't even attempt to defend your obtuse guesses.

Buh bye.

At least you have the sense to run away and try to save what meager scraps of dignity you have left. Next time you try and post out of sheer ignorance, why don't you try and learn a little bit about the topic before you make an ass out of yourself.