Android vs. iPhone 4 Signal Strength Bars Comparison 253
thisisauniqueid writes "In light of the clamor over the iPhone 4 Grip of Death, AnandTech recently reverse-engineered the phone's signal-strength-to-bars mapping. Because Android is open source, we can determine the corresponding mapping for Android in combination with the 3GPP spec referenced in the source, allowing the signal-strength-to-bars mapping for both Android and the iPhone 4 to be plotted on the same axes. This shows that the iPhone 4 consistently reports a higher percentage signal strength (as defined by the fraction of bars lit) than Android GSM devices at the same signal strength."
noise floor? (Score:5, Insightful)
These measures aren't very useful without considering the noise floor...
Re:noise floor? (Score:4, Informative)
The noise floor is around -174dBm/sqrt(Hz) depending on temperature.
This will be the same for all phones
Re:noise floor? (Score:5, Interesting)
You're sort of right.
-174dBm/sqrt(Hz) is the minimum that you can achieve at "noise room temperature" (290 Kelvin), because that is the spectral density of noise in the RF region that a black body will emit. But every component from the antenna, antenna switch, low noise amplifier, downconverters, filters, more amplifiers, and ADC's will add a certain amount of noise to degrade the signal further. This can be discussed as noise factor, noise figure, noise temperature, and so on, but those are all also equivalent to having an increased noise floor at the signal reaching the antenna, and by converting to input referred noise floor, the minimum detectable signal is often defined as the point where the signal power equals the input referred noise power.
This will definitely NOT be the same for all phones.
A very good cryogenic low noise amplifier like astronomers use for very sensitive radio telescopes might have a noise temperature of 5 Kelvin, corresponding to an addition of -191.5dBm/root(Hz) noise power at the input. However the low noise amplifier in a cell phone probably has a noise temperature around 75 Kelvin (1dB noise figure at room temp), adding -179.7dBm/root(Hz) noise power. The first amplifier would be able to detect a signal 15 times smaller because of its superior noise performance. In fairness though it probably costs about a thousand times more...
Re:noise floor? (Score:4, Funny)
Careful there: a whole bunch of fanboys will start keeping their phones in the fridge for a better facebook experience.
Re:noise floor? (Score:4, Insightful)
"the noise floor..." of the receiver.
I agree!
I think they should have looked at the signal levels that calls begin to drop or get garbled data. THAT would be more interesting. What if the iPhone4 is "over reporting" because it has a more sensitive radio? If I were apple, or any company, I would show signals bars based on the chance of dropping data, not the raw signal strength. With having half the range as 5 bars, seems like that's what they did.
*Disclaimer: I have a WinMo phone. I really don't give a damn about any of these platforms. None of them suite me.
Re:noise floor? (Score:4, Interesting)
I think part of the issue is dB ranges of 0-~100 = 4-5 bars. dB Ranges 100-113 = zero-3 bars. You don't enter the '3' bar range until you're already on a weak signal, and can 'death grip' your phone to death. The article reported a max of ~24 dB signal drop from poor holding. From the looks you don't have to hold it too improperly to suddenly go 3 bars->disconnect.
This becomes an issue since people check their reception.. okay, 2-3 bars, im good... Then go make a call, or hold their phone to their head, and boom, 15dB difference, bye call.
The idea of "showing more bars to make users more comfortable" (or 'showing more bars to make people who think bars are standardized across phones think ours are better)... backfires when your 'bar' range doesn't properly tell people how close to disconnect they are and is 'mysteriously' goes from 3 bars to 0 -- like some people report.
Re:noise floor? (Score:4, Insightful)
That would require they move away from their current setup that shifts away from 'inflating' your signal and 'inflating' apples awesomeness...
Ah, but from what I've heard the last few days (and this is also mentioned in TFA) it was AT&T who told Apple "This is how we want you to report signal strength on the iPhone 4/in iOS 4" and while Apple isn't without blame (they were after all the ones who implemented this) it could just as well be AT&T trying to hide flaws in their network that resulted in the iPhone 4 reporting signal strength in a strange way.
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Well duh ... (Score:5, Funny)
Re:Well duh ... (Score:4, Insightful)
What the difference between a Mac fanboy and a bicycle?
Slap a chain on a bicycle and it doesn't blog endlessly about how being chained up is an improvement.
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What the difference between a Mac fanboy and a bicycle?
Slap a chain on a bicycle and it doesn't blog endlessly about how being chained up is an improvement.
What's the difference between a Google fanboy and a bicycle?
Slap a chain on a bicycle and it doesn't blog endlessly about how iPhone users are chained up.
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What are you trying to say?
Re:Well duh ... (Score:5, Insightful)
I am saying that I hear a LOT more from people saying what Apple fans would say than I am from the actual fans. Especially in threads that nothing to do with either.
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What's the difference between a Google Fanboi, Microsoft Fanboi, and Apple Fanboi?
Apple Fanbois sing once the chains are on.
Re:Well duh ... (Score:5, Insightful)
Why does a Mac critic have a problem with the chain on a bicycle?
It restricts what you can do with the bike.
Re:Well duh ... (Score:5, Insightful)
What the difference between a Mac fanboy and a bicycle?
Slap a chain on a bicycle and it doesn't blog endlessly about how being chained up is an improvement.
Then why is it always the Google fanboys who go on and on about the chains?
Re:Well duh ... (Score:5, Funny)
You can negotiate with a terrorist.
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I believe the correct engineering term for this reality distortion field is called the Bogon force field. The Bogon flux is measured by a Bogometer, in units of "bars." Apple has the most respected Bogonomists in the industry, but the Bogon is a strange quark that mysteriously vanishes when a detector is used.
dB attenuation? (Score:2, Insightful)
How about phones just print the dB signal loss and be done with it? A number should be far easier for someone to tell about signal strength than guessing by 0-5 bars.
Re:dB attenuation? (Score:5, Insightful)
Probably 99% of the population has no idea that -80 dB is extremely good and -100 dB is awful. Further, the curve is logarithmic, which makes things confusing because most people are only particularly familiar with linear.
Re:dB attenuation? (Score:4, Insightful)
They don't know that right now.
Switch every phone over to display dB directly and everyone in the world would understand it in 6 months, though some would bitch about it for years to come.
People don't need to know what the numbers MEAN, they need to know that at 100 it doesn't work, and at 96 just barely works, but 80 is golden, and they'll figure that out fairly quickly.
Of course in reality all people really want is the phone to give them a good reason why they lost their call, can't get calls or have shitty data rates, and that could more accurately be represented with a simple block of text when the users asks and a green or red light in place of the bars.
Re:dB attenuation? (Score:4, Insightful)
The whole point of a "signal strength" meter is so that one can determine when one is approaching a "no signal" zone and so that one can determine how well their phone will work at a given location without having to make a call. It is disappointing that traditional signal strength meters (with 3-6 "bars") fail to do this reliably.
You can tell if the phone will work or not should you try to make a call or transmit data by a simple on/off indicator like you said. If the meter just displayed the S/N ratio, it would be the equivalent of having a traditional meter with lots of bars. This would convey more information, probably take up less space on the display, and allow people to generate detailed enough data that they might be able to fix things in places where performance is bad.
The problem of large or mysterious numbers could be remedied by offsetting the value by some fixed amount so that "0" is where the S/N ratio is so bad that the phone can't do anything.
I'm all for it.
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Good point. Well I'm running iOS4 jailbroken, and SBSettings has a panel which allows you to change those settings.
Swipe your finger across the top of the screen.
Press more.
Press Extra's and Options.
Turn Numeric Wi-Fi and Numeric GSM on.
Now you've got it showing the dB in place of bars, and once Apple releases the update for iOS4 to make this measurement accurate, I'll have a better idea of signal strength.
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That just makes it a great marketing tool, as long as you talk about Android phones "having reception of NEGATIVE 80dB! And they can download porn! Think of the children!". Just saying, if I was paid by the lie (I am, but not for Apple) I would be all over it ;)
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Easy solution: tell people it's kinda like golf scores...the closer to 0 the better.
Comment removed (Score:5, Funny)
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Re:dB attenuation? (Score:5, Insightful)
Why not leave user interface design to people who know that there are a lot of colorblind people out there?
Re:dB attenuation? (Score:5, Funny)
Of course. Because the average phone user knows what a dB is and would much rather see it than a bar graph. My mother was just telling me the other day that she gets a -10dB attenuation in the kitchen compared to the lounge.
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How about phones just print the dB signal loss and be done with it? A number should be far easier for someone to tell about signal strength than guessing by 0-5 bars.
Yes, because "-70 dB" would be much clearer to your average cell phone user than "5 out of 5 bars"...
Keep in mind that many of those users also think it's a good idea to send text messages while driving. It would take a $10M advertising campaign just to convince those people that "-70" is better than "-100".
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So? change the comparison. 30dB is better than 0, non?
Whenever I see that on my wifi dealy, I always wonder, "70dB below what, exactly?" What are they comparing it to that is 10,000,000 times more powerful?
because most people don't understand decibels? (Score:3, Interesting)
How about phones just print the dB signal loss and be done with it? A number should be far easier for someone to tell about signal strength than guessing by 0-5 bars.
Because 90% of the population has no fucking clue what decibels are? A logarithmic scale is a recipe for disaster in the consumer marketplace.
Actually, I think the unit in question is decibel milliwatts: http://en.wikipedia.org/wiki/DBm [wikipedia.org]
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Are you serious? Do they not teach the Dewey Decibel system in school anymore?
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You don't measure received signal strength in dB loss, unless you know exactly how much was transmitted for comparison. You measure it in terms of received power, usually in units of dBm. At the signal levels we're talking about here, you will see a range from -51 dBm all the way down to about -113 dBm. Good luck in getting anybody who's not RF tech-saavy to understand how a signal can have a negative level.
So, to make it simple on those who don't need to know (or really care about) the engineering behin
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How about phones just print the dB signal loss and be done with it? A number should be far easier for someone to tell about signal strength than guessing by 0-5 bars.
Brings to mind the early Ericsson phones which reported battery condition in volts.
Summarising... (Score:5, Insightful)
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All mobile phones have tradeoffs in antenna design in order to look pretty, because people don't like visible external aerials.
External antennas get bent or broken.
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"Apple buyers don't take any notice of negative publicity for Apple products."
Actually, some buyers do. Not the hardcore fanboy types, but my gf's parents saw a segment on the local news about the iphone 4 problems and have decided to look at Android phones rather than blindly upgrading their current iThings to the latest model. They may still get an Apple phone, but they would not have even considered alternatives if it weren't for the issues.
I was surprised that there was any general media coverage of t
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Note that the Nexus One suffers from the same problem with 3G reception if you grip the phone along the metal strip at the back.
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Hmmm, I'm guessing that's irrelevant, since it's probably just the same signal attenuation that's present on every cellphone.
The issue on the iPhone4 is the ability to detune the antennas just by touching both the GSM/3G antenna and the WiFi antenna at the same time with a sweaty finger - something that could have been so easily prevented with a dielectric coating. That's the reason people should be pissed, but a lot of people seem to be confused about what's really the problem.
Re:Summarising... (Score:4, Insightful)
It won't affect sales because in normal use, the iPhone 4 has better reception than previous iPhones. If there was a real problem, that would affect sales, but the average phone buyer doesn't read slashdot and gizmodo, and so doesn't get put off by this sort of hysteria.
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Me either. Which implies that when you hold the phone normally you get better reception with the iPhone 4 than with previous iPhones.
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And we know this because marketing experts have told us so.
I would trade a stubby little antenna for dropped calls any day. I really don't consider my phone a fashion accessory.
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It's not because it's visible. It's because bits that stick up tend to break. And the fractal-style antennas that are in modern phones have very similar performance to external aerials. Given the choice between the two, it's a no-brainer.
not a surprise (Score:5, Interesting)
my wife's iphone constantly reports 3-4 bars and 3g in places where my motorola milestone reports 1 or no signal. it's not until she goes to make a call that -- oops! no coverage.
dBm vs dB (Score:5, Informative)
In case you're wondering,the B is a Bel, which is a factor of 10. A dB is a deciBel, which is 1/10 of a Bel. dBm is decibels relative to a milliwatt of signal strength.
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That last point that you made for posterity is not correct, because the definition of dB relates to power ratios, and a 2:1 ratio of power is 3dB, whereas a 2:1 ratio of voltage results in a 4:1 ratio of power and 6dB of change.
So, a factor of 2 is only 3dB when measuring power, because for power dB is defined as: dB = 10 * log(P1/P0),
and 10 * log(2) = 3
But when measuring voltage, a factor of 2 is 6dB, because for voltage ratios, dB is defined a
So... (Score:5, Insightful)
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I am not sure which came first but it is good to hear a second opinion as I don't trust very much what Apple is saying these days.
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is anyone surprised? (Score:3, Interesting)
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heck, my understanding is that carriers can influence how many bars a phone will show via their base station config.
something about altering the minimum transmitted requirement for a call. As this requirement is then used as the zero point for the bar scale, one get multiple bars but so poor a signal thanks to the relative nature of the bars.
there is also the issue of channel saturation. full channels will not show up as zero signal on the bars, but you will still be unable to place calls or do anything els
Smelly code! (Score:4, Insightful)
Holy hell the code for the Android OS StatusBarPolicy in the StatusBarPolicy.java file is a stinking mess. So much for Google having the best programmers in the world. A single public method -- installIcons() at the class level, and a pile of private methods doing all sorts of things. Hundreds of lines of different private variables and worst of all the slew of private anonymous classes.
This sort of mess make single responsibility principle weep.
Re:Smelly code! (Score:4, Interesting)
Code says 'Copyright (C) 2008 The Android Open Source Project', complain to them. Or better yet, fix their code. Isn't that the point of open source?
Re: (Score:3, Insightful)
There's no reason you can't get the job done and do it well at the same time. I'd rather work on well-written code by a "clueless programmer" than a spaghetti mess written by a top notch guru, every time.
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Looks like java written by a c programmer... Which is not all that unexpected. Main problem with it is a severe lack of comments. First comment it then refactor so you might be able to deal with it longer term.
If the rest of android is anything like this then there's a lot of work to do for anyone trying to maintain it long term.
Good programmers have learned to write maintainable code... If they don't then they are not a guru, they are a hack.
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an if statement is a goto
Except that an if statement only goes to the line after the condition. A goto can go to anywhere. An if statement may be a particular case of a goto, but it is a very narrow one.
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No, an if statement is a goto to the line after the if statement's body. Just about any compiler will (barring more aggressive optimization) compile
if(cond) { ... code ... ... more code ...
}
To:
if(!cond) goto endif; ... code ... ... more code ...
endif:
yikes (Score:2)
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You're right about one thing: You've reminded once again that I made the right choice in quitting the industry after holding a variety of lucrative sysadmin, software development, IT, and technical lead positions from 1983 to 2009. Too many projects where getting it done mattered more than getting it right, ending up in the software equivalent of a Deepwater Horizon rig explosion. I'm so glad to be done with that.
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Because the best programmers in the world don't mean shit when the hardware fucking sucks and is overpriced.
Where are the posters from Friday... (Score:2, Insightful)
that commented on /. about how Apple was making false claims about the incorrect signal bars? Surely if the responders on Friday had the balls to stand on a pedestal and make grand claims based on no evidence, they can have the balls to come back and admit they were wrong.
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I guess posting on slashdot is like standing on a pedestal? :-p
Other than the analogy, I agree with you!
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No one was claiming that Apple's response was a lie, just that it was misleading. There is still a hardware problem that won't be fixed for the users who have these devices, unless they want to slap on a case.
so what if the calculation is wrong (Score:3, Insightful)
so what if the calculation is wrong or different between phones! It has nothing to do with the problem the iphone is having. If you normally have 4 bars with the wrong calculation, and you hold it and get no bars with the wrong calculation, then there is something wrong with the design of the phone, All apple is doing is trying to confuse the masses with technical facts hoping to confuse the issue and save money from all the lawsuits that are being filed.
Re:so what if the calculation is wrong (Score:4, Insightful)
Shame on Apple trying to confuse people with "technical facts".
They should of course accept that everyone is as ignorant as you about the fact that ALL mobile phones get signal attenuation when you hold your hand around the antenna.
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Actually most modern cellphones DO have the antenna in the bottom, where a hand will be around it. Because in that position it's further away from the brain.
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Two antennas! (Score:5, Informative)
The article is worth reading. Right on the first page it explains what is really going on with the "grip of death".
In other news reports I have seen about iPhone 4, it was explained that the iPhone 4 has a strip of metal wrapped around the body of the phone that serves as the antenna. Not so! There are two strips, of different lengths, serving as two antennas. One antenna is for WiFi and GPS, and the other antenna is for cell phone service. The "grip of death" happens when you make an electrical contact between the two antennas (on the lower-left corner of the phone).
According to the article, bridging the two antennas with your hand causes a drop in cell phone signal to noise ratio of about 24 dB. This can be enough to cause a dropped phone call, if you are already in an area with weak cell signal strength. If you are in an area with good cell strength, you won't drop the call and you might not even see the signal strength bars change.
And according to the article, as long as you don't bridge the two antennas, this phone really does do a better job of locking on to a weak cell phone signal.
So, if you have an iPhone 4, definitely invest in some sort of case that insulates the two antennas. And the article scolds Apple for not having put some sort of insulation over the antennas; presumably a future iPhone will do so.
Other pages of the article discuss other things. I did like the page where Anand explains why Apple's claims are valid that the screen is sharper than the human eye can resolve.
steveha
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That's been known for a while. The question is, why on Earth did they not test the phones properly? And by properly, I mean in real world circumstances.
They did have a long testing period, but apparently the only left-handed prototype tester lost his iPhone at a bar.
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That's been known for a while. The question is, why on Earth did they not test the phones properly? And by properly, I mean in real world circumstances. It's not real world to have it covered in a fake mock up of a previous iPhone.
Remember that whole Gizmodo thing? Apple knew that's what would happen.
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Hindsight is always 20/20.
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It does work very well. I have an iPhone 4 (got it on launch day) and I can replicate the "signal loss" by bridging those pieces of metal. I do lose bars (so my signal wasn't fantastic to begin with).
I've been watching this whole thing with interest. I've seen a ton of reports that the 4 is better at keeping calls when in a low signal area, at that seems to match my experience. It's a flaw, but really it's not that big. I've learned to keep my left hand (which I usually hold my phone with) about 1/2cm high
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Oh yeah I feel so bad for them. They only made one little mistake, and all that mistake does is catastrophically degrade signal levels unless the user holds the phone in a way that may be uncomfortable to many or even most users.
All they did was design a device where you have to fundamentally change your own personal habits to fit their phone, rather than spending ten minutes of QA to notice and designing the phone to fit the users instead.
I feel so bad that they're getting guff for this minor flaw, and so
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What does OSS have to do with it? (Score:4, Interesting)
Seriously?
You're comparing the iPhone using some physical technique to infer the signal level to bar mapping, taking into account all the variables of the phone hardware ...
And on Android you're just looking at the source ... not even the phone itself ...
And this is supposed to be some sort of comparison? Whats next? Submarine A goes 25 knots submerged, Space Shuttle X launches into space at 36k knots. Which one will get you to BurgerKing first?
When you compare things using completely unrelated ways of gathering your input data you find that your results are ALWAYS wrong, even if you can't see it or they agree/disagree with what you thought.
OS 2.1 (Score:5, Interesting)
After I got my iPhone 3G the very next software update included a change to the "bar algorithm" that was marketed as "improving user understanding of the signal meter" or somesuch. It was in response to user complaints of low signal strength, and somehow (miraculously) the reception improved... more bars.
So they're rolling back this change?
MJC
Can someone please get a RFEE to explain things? (Score:5, Insightful)
IANARFEE, but I am a EE who works with RF.
For all of the millions of dollars being lost on productivity aimlessly discussing 'bars'..
Can someone please dissect the antenna and then connect it to a calibrated spectrum analyser? This is so mindbogglingly trivial to do it is beginning to hurt my soul. I do similar exercises at work with new, untested antenna designs. I am sure I am not the only one.
For comparison, do the same to other phones and publish actual measurements of received signal drops and the effect from the disturbance caused from closing your hand around the antenna. This is similar to how touching an old rabbit-ears style antenna effects the picture on a analog TV broadcast, if the effect is as I suspect.
Voila! An actual, meaningful assessment of what the phone bars mean in real numbers from a calibrated instrument.
An uncalibrated receiver, such as the iphone, is not a proper tool to do this.
*grumble* *off my lawn* *grumble*
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Voila! An actual, meaningful assessment of what the phone bars mean in real numbers from a calibrated instrument.
But but.. what would /. be without mindless speculation? Take your schmience elsewhere!
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can't we standardise? (Score:2)
So... Why isn't the formula for calculating the bars standardised again?
Personally I'm wondering why part of it (on many phones) seems to involve dropping a couple of bars whenever I press the "call" button, without moving the phone. Presumably doing so invokes the "slightly less BS" mode. The other thing I'm wondering is why the more expensive the phone, the crappier the signal. I picked up a spare PAYG phone for about the same as what lunch cost me that day and it makes a very clear call everywhere. My ol
So apple was telling the truth? (Score:2)
Stick that in your hat, ya apple haters..
Still, how can a bug like that exist since day one and NO ONE noticed? Still smells like fish to me, and i like my iPhone.
Steve Jobs to Gray Powell (Score:5, Funny)
Why bars at all? (Score:4, Insightful)
Why do they use bars at all? Why don't they use numbers? I suspect it has something to do with early phones and a little dedicated LCD space of bars was cheaper than a full numerical display, but we're well beyond that now.
Jobs is channeling Nigel Tufnel (Score:3, Funny)
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Because it's not always receiving frames? Until you initiated a stream, there's no frames to check the error counts of.
Re:iPhone wins (Score:5, Funny)
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I usually lose track of bars after I goes to 6 or 7 of them.
Err no... (Score:3, Informative)
They compared the percentage, not the number of bars. From the article:
The iPhone 4 consistently displays a greater percentage signal strength than Android (as defined by the fraction of bars lit).
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I didn't think that sounded quite right, so I thought about it a bit. It turns out that your claim is partly true, iPhone OS will report a greater absolute number of "bars" about 1/2 the time, given a common baseline (both scales measure from the same zero, to the same peak "full" strength (which certainly isn't guaranteed).
Consider a scale from zero to twe
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Pfft. Even with Verizon you get zero bars in a dry county.