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Your Computer and Cell Phone Are Lying To You
Ant writes with a story from Dan's Data, which says that the battery meter and connection-strength displays in your portable electronics are lying to you, "and not just when they whisper to you in the night." Quoting: "Mobile phones, and most modern laptops, have signal strength and battery life displays. One or both of these displays has probably been the focus of all of your attention at one time or another. Neither display is actually telling you what you think it's telling you. The signal strength bars on a mobile phone or laptop do, at least, say something about how strong the local signal is. But they don't tell you the ratio between that signal and the inevitable, and often very considerable, noise that accompanies it ..."
And I bet you're going to tell us next that DRM isn't for our own good and is just a way for conglomerates to steal more of our money with little effort done on their part. Hah!
The article was indeed interesting, and believable. But it has a bad case of [Citation-Needed].
Belief? Hope? Preference?The Existential Vortex
Who cares? When it's full, my laptop or cellphone works great. When it's empty, the thing stops working. When there's only a few bars left, I either plug it in / move to a different location. IMO, it perfectly performs its intended duty. Anything beyond that is geek pedantry and nitpicking.
An old-timer with old-timey ideas.
Are we giving sentience to our cell phones and laptops now? They are not just "misprogrammed" or "wrong"...they are actively lying to us now? Are you implying that they all got together at the factory during the worker's break period and conspired to give false information to their human overlords?
TDz.
And I even have a little meter for it mixed in with my signal strength.
I find it pretty useful.. I'm pretty sure everyone's wireless chipset can tell them how much noise or at least how many mangled packets arrive. It's just the little dummy strength meter doesn't convey any of that. I liken most of those sorts of things to the CEL light in cars anyway. Good to know when something's not *perfect* but not so good for understanding why (nor whether it's just a gas tank cap seal broken, or a head gasket blown.)
Exsqueeze me?
I've written a wifi signal strength meter for an embedded product. During my research, I found it was pretty much standard to base the bumber of bars on the signal to noise ratio, not the raw signal strength.
This article gives me a hunch why my no-name laptop battery dies so quickly even when Ubuntu still thinks it has 10% charge and several minutes left. Didn't happen with the manufacturer's battery...
Ubuntu usually does an excellent job analysing how good your battery really is (not sure if it's the kernel ACPI or HAL or GNOME that's actually doing it). But when the battery lies so blatantly, it seems even Ubuntu can't keep my laptop from sudden death without a proper warning or shutdown.
muuhahah
Both my Blackberry and my Sony Ericsson sometimes decide not to connect a call when I have close to full signal. Judging from TFA this could then be because of high noise ratio.
At the same time, I have always wondered why my phones do not give me any indication why the calls were not connected at the time. They both just return to the main screen after a long period of connection attempts.
If I'm being lied to, will my tinfoil hat help in this case?
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
of those, how do they call it, oh yes, proofs. Like, a disassembled and commented piece of firmware that does what an article claims it does. Not that I don't believe it, but I want to be absolutely positively convinced. Just because.
The engineers dilemma, at least for battery levels:
- how the real value taking into account all variances including current usage and thus constantly move up and down the value
- average out the results to something close, but not exact, since this is what satisfies most people
Jumpstart the tartan drive.
Is it just my luck or are all cars like that? You go 200km on the first 25% of the gauge, but can barely get to 550km before it's empty?
Every phone I've had (although I expect this is universal) has had a really unhelpful battery meter, that would remain displaying full battery (4 bars) for the majority of the batteries life, then the last 3 bars after that would slip away in less than a day.
This might be an accurate measure of remaining battery power, but it's annoying when trying to plan battery usage, as 4 bars could mean I have anything between 5 and 1 day of juice left.
Would it be that much to ask for it to just decrease at a constant rate?
Dan doesn't seem to know much about batteries. Check out batter power discharge curves and such...
http://www.mpoweruk.com/performance.htm Remaining power is estimated based on the charge of the battery. If you notice on those graphs, when you get out to the end of the stored charge, it drops off very quickly, which is why the gauge goes from half to empty quickly.
It's just like the fuel tank in my gas-hungry 300M... I can go 300km before I hit the half empty mark, but only 125km before it's empty.
On another (more geeky) note, it's also like the progress bar of any install program. It take 2 minutes to get to 98% done, and another 5 minutes before the install is actually completed.
Progress bars, meters and measurement instruments are there only to give you an approximate indication of where you are compared to where you were. Some are more precise (ruler, multimeter) than others (battery life, signal strenght).
Why would this be modded flamebait? I totally agree here...My devices are as accurate as they need to be...beyond that who cares?
In a world of acronyms, the words are the real victims.
It really does not matter what these meters say as long as they are consistent. From long experience, my grey-ware then interprets the bars to give me a realistic expectation of battery life or signal strength. Move along now please. Nothing of interest here.
That's funny, because when I have no bars, I can't call out, and when I have all the bars, my calls are great. Likewise, when the battery indicator is full, i can talk for a long time, but when it says it's low, it usually dies soon after that. That's all I need them to tell me. I could care less if it's counting signal strength or magic pixie dust, as long as less pixie dust means the phone is going to die that's fine with me.
stuff |
Are you trying to tell me that the constantly changing field of electro-magnetic radiation pouring through my laptop does not always match up precisely to the five bars in the display? Frankly, I find that hard to believe.
Tic-Tac-Toe, Global Thermonuclear War, and relationships all have the same winning move.
...the cake is a lie?
very discouraging
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...duh.
Comment removed based on user account deletion
Signal strength and battery time remaining can get pretty complicated, the more you look into it. There are a ton of different measurements, historical information, performance expectations, etc. that are constantly changing based on how the device is being used, who is using it, etc. At some point, you need to condense all of that information into some pretty little bars that a *normal* user (i.e. someone who has never heard of Slashdot) can comprehend. Is there going to be some precision lost? Of course. Is the graphical representation going to convey all the data gathered and interpreted by the device? Of course not. But the idea is to make it as useful as possible.
Just because I can hook a shark from a boat, I do no offer to wrestle it in the water.
Cingular loves to tout "More bars in more places".
"Higher signal-to-noise ratio across a broader range of the United States" just isn't quite as catchy a slogan.
...they always tell me size doesn't matter
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
I used to work for a certain large cell phone maker so this is straight from the horse's mouth.
Remember those retractable antennas? Well, extending the antenna had no effect on the phone's range whatsoever. In fact, the retractable part was not connected at all. The retractable nature of the antenna was probably functional a long time ago; however, during my tenure they were only retractable due to customer focus group feedback. It made customers feel better to be able to pull the antenna out even though it had no effect.
During this same time period when I was in the biz, the battery and signal strength were in fact functional. It could be they're not now on some phones, based on my antenna analogy.
#1, even with a voltmeter you can't reliably predict battery life. With an alkaline AA battery, you could watch the voltage drop from 1.5V down to 1.1 and know that it was now dead - but with newer rechargeable batteries, the voltage doesn't drop until it's completely dead, so you can't easily guess how long it will take. The only way to do it would be to have the device keep a history of how long it is able to work before the battery dies completely and statistically predict future performance. As if they are going to waste time doing that!
#2 Yes, noise should be considered, but an exact signal to noise ratio isn't going to predict bandwidth or call quality, either. I'm pretty sure that the "signal" they measure is actually signal-to-noise anyway. But even just signal strength is still useful, since you can assume that noise isn't changing that much.
Gas gauges? How many people see that their car stays "full" for a long time and then drops sharply? Or says that it is empty when there's still a few gallons left? Mine will tell me "0 miles to empty" and drive for another 50 miles without coming close to empty. Speedometers? They can be off by 5 or 10% right from the factory. Really every gauge is inaccurate by some amount.
My guess is that companies make the gauges vague on purpose, so that people DON'T try to get too much (false/misleading) information out of them. If your cell phone can make a phone call with "2 bars" of signal, that is all the information you should be taking away from that measure. And if your battery says full for 2 days and drops sharply on day 3, you know that when it starts to drop it's time to charge it. That's all the information you need. Does anybody really think that consumers will be happy with a voltage display? I don't even know what voltage my phone operates at, let alone what the low-end of operating voltage will be.
For most phones the signal bars are NOT how well you can receive the tower, but the tower sending back to the the phone the RSSI (received signal strength indication) value. This is the tower telling the phone how well it can "hear" it. For sure, your tiny little phone is going to receive a signal from that tower better than it will receive one from your little 600mw handheld phone. Want a better signal? Use a 3-watt car phone.
This is tied to the battery life. A hand held phone will only transmit at the power needed to be received from the tower, only using it's full 600mw when necessary. (using the RSSI from the tower as the guide ). If you are in a situation where you're wobbling between zero and one bars, the phone will crank up it's power and... suck the battery down faster. If you're in an urban area dense with towers, your battery will last longer. Out hiking in the sticks with one bar (or zero when held between your hand and your head) your battery will poop out much quicker.
Your Computer and Cell Phone Are Lying To You
Oh, thank God! I was worried I was the only one who could hear them!
Those who believe the Internet is private,
find their privates are on the Internet.
It seems to me the phone's not the one that's lying. It's the marketing and promotion (I'm looking at you, AT&T) that implies that more bars = stronger signal. As the Chief Engineer succinctly puts it, "A computer doesn't lie." If we had some actual truth in advertising it would clear up many misconceptions about technology and how it really works. (Wow, my sig is actually pseudo-relevant in this thread!)
It's not a lie. It's the truth with lossy compression.
My first computer told me, Windows 95 was stable and secure...
The MAFIAA is a bunch of mindless jerks who will be the first up against the wall when the revolution comes
There isn't standard regarding what reported dBm value should be associated with 1-5 bars. It is purely up to the discretion of the programmer. I have heard RSSI referred to as Relative Signal Strength Indication as well, because the value is at the mercy of internal A/D tolerances. I have seen several copies of the same radios in a lab, (Faraday Cage) report drastically different RSSI values (AKA Bars). Nearby RF sources can influence the signal levels as well.
So that part of the article is true. I dare say anyone who actually knows anything about RF won't claim, bars guarantee connectivity. To say that it is lying to you because you don't understand how it works, makes the submitter look silly. Definition of "Lie" from Wikipedia: "A lie (also called prevarication) is a type of deception in the form of an untruthful statement with the intention to deceive"
We aren't trying to deceive you, we give you the indication because it is better than nothing, and most of the time it is good enough.
Gives new meaning to AT&T's new slogan.
You too can have More Bars in More Places! All it takes is a customized firmware load and unscrupulous marketing...
I could easily believe that the wireless strength meter is "lying" by not reporting S2N ration but the battery meter is a different kettle of fish.
I, too, have seen how mobile phone batteries are full according to the meter then drop rapidly but I have always assumed this is because of the chemistry used. It's been a while since I studied chemistry but IIRC the way the "fullness" of a battery is measured is by it's potential. One of the really great things about Li based batteriees is that they have almost constant voltage across their whole discharge cycle (there is a sudden voltage drop just before they go flat) which is in stark contrast to say NiCd or Lead Acid. The problem with this behaviour is that it can make it difficult to tell how much charge is remaining in a Li based battery. My guess would be that mobile phones don't have very accurate volt meters in them and they partially guess at the remaining charge based on useage.
I used to have a better sig but it broke.
The article was indeed interesting, and believable. But it has a bad case of [Citation-Needed].
Cites are not required for independently verifiable claims.
This is the difference between faith and science. If you give someone information that they can independently verify, and they base their belief on the results of their independent results, that's science (even if they are wrong, it's still application of the scientific method). If you ask someone to believe something based on the idea that a person who says it is trustworthy, that's faith (although not necessarily religious faith). Insistence on credible "cites" to bolster physically verifiable claims or observable reality is not functionally different from a belief in biblical inerrancy. Believing something "because [insert authority figure here] wrote it in a science book" is just swapping one shibboleth for another.
To take over the world by slowly driving all of us insane. They've insinuated themselves in to all of our daily lives by robo-fying our cell phones and laptops.
I write system software and drivers for PDAs. The author is guessing.
There are two reasons for this. They are both bad.
Reason one: A battery that stays (apparently) full for a long time makes a phone look good. Even if it doesn't actually deserve to.
Reason two: When your phone still (apparently) has lots of charge left, you're more likely to use it. People who think their phone's going flat will make fewer, and shorter, calls. And that makes phone companies sad.
That's right - this is yet another example of the Curse of the Marketing Department. Both phone makers and cellular service providers want you to think that your phone is still pretty much full of charge even if it's almost half empty. For this reason, many of them tweak the charge meters to overestimate the remaining charge
Simply put, this is a load of bollocks. The guy who wrote this is guessing. He doesn't have any experience writing systems software.
I wrote a battery driver a few months back. Here's what I did.
I started a thread which would output the actual battery voltage an store it in a file every minute or so. Then charged it up overnight and ran it until the thing died. At the end of the run I have a battery profile that shows the measured voltage versus time. Then I did this a dozen times with different batteries, and under a few different usage scenarios - and made a composite graph of voltage versus time. Then I took a third order polynomial and fit that to the data. I could have done something with more math in it, but the unit I was working on doesn't have a floating point processor. The driver returns the remaining time as a percentage from the third order poly.
Now the problems - there is a fairly significant delta in between battery runs. In other words all batteries are not constructed alike. The number is approximate.
If you have an unusual battery, the numbers will be slightly off. And if you have a bad battery, all bets are off.
But tweaking the numbers? Never even heard of that. The author has no clue what is going on in there. Unless he's the lead developer, or the product is open source what he's proposing is a guess.
Weaselmancer
rediculous.
Then, once you get to the half-full mark, the battery seems to go flat surprisingly quickly[/quote]
My phone actually spends almost no time at 'full' or 'almost full'. At least.. not compared to that single remaining battery bar.. I've guesstimated That my phone's battery bars exist between 50% and 100% charge. Where the last bar is 50% AND everything less than that. Because you know.. People who almost never use their phone, and pay for that 'just in case' air time is where the profit is.. not in the people that buy 5,000 minutes and use 4,900 minutes because their phone still says full power.
Defective Logic
And that is all I had to say about that.
Something bad is coming when people are suddenly anxious to tell the truth.
Machines, how could you betray my trust in technolust like this!?
It's downright shameful.
You can't trust much of what you read on the internet, especially when it says computers lie
Cingular loves to tout "More bars in more places".
Then why does Cing^W AT&T advertise to people under 21, who can't go into more bars in more places?
It doesn't go the crap, scam way most devices go, but more like a car fuel tank. My iPod (4th gen) keeps on playing for quite a bit after it says the battery is empty. Compare that to every digital camera I own, where when it get to the last 1/4 or so it goes red and soon shuts off.
People really do make use of those.
Well, actually it's a fancy way of saying that some humans decided to lie to you, because it was cheaper.
Suppose I were the great shaman Watta Sucka, and you came to me with a cold. You want it treated, and maybe some way to know how long it'll last. I have no clue how to tell you either. So I chant some incantations, smoke the holy hemp, and then tell you, "Oh, yes, the great spirits said that to be rid of your demons, you must journey on foot to the sacred lake behind the power company's dam, along the highway to the east, and wash yourself with the holy waters. And the closer to the lake you are, the better you will feel, as its great magic repels the demons of your illness. And for only $499 you can also buy the sacred ancestral GPS device, showing the progress of your illness in km to the lake. But, remember, you must travel on foot."
Basically I'd bet that a cold goes away in a week, walking to the lake takes about a week, and you'll probably start feeling better along the way. And even gave you a sort of a meter from sick to healthy, in the form of that GPS device.
Except it's bogus. It's a lie. I don't really know what's wrong with you and really how long it will take, and the GPS device doesn't either. Maybe it'll go away faster, maybe it's bird flu and you'll be dead by tomorrow, or maybe it's a pneumonia and you've earned yourself a lot of hurt and complications by trecking through the wilderness for a week instead of taking antibiotics and resting. But at any rate, it's a lie. The "meter" I gave you, doesn't measure what I claim. It measures distance, which may or may not correlate with how sick you still are, but it still just measures distance. It's a different variable.
One way to put it metaphorically is to say that that GPS device lies to you. But in practice, it was me, the great shaman Watta Sucka that really lied to you.
A lot of tech devices and meters and gizmos are really the same kind of lie, and whether its makers even realize it or not, they decided to lie to you. Really measuring X (whether that's battery life, or whatever) is often more complicated than they can bother to do, or costs more and thus would cut into their margins. So they decide to lie you instead, by putting a bogus meter there. It's the same kind of lie as my sacred GPS device.
A polar bear is a cartesian bear after a coordinate transform.
I always assumed that usage data played in, because not allowing my phone to completely discharge seems to "set" the battery so that it says 0 battery just before I plug it in. But when I let it discharge once in a while, the battery rapidly seems to extend it's own life. Gurus - is this the case or am I missing it entirely?
I want a GSM phone that tells me if I am using GSM 850/900 or a GSM 1800/1900 network. Same goes for 3G phones.
Why ?
Because when a GSM phone is on a GSM 850/900 network it uses max 2W of transmitting power, but only 1W at GSM 1800/1900. With that information I can tell if my phone is using more battery or less.
Think about your typical laptop or cellular phone user. Something tells me that, to them, SNR would be some random number that means absolutely nothing. You need to keep things SIMPLE, that's why Apple is so successful (okay, besides the ad campaigns). The point is, your typical Wi-Fi or mobile user won't really care how many decibels of signal over noise you have. Hell, I would bet most of them don't know what a decibel is, let alone what signal to noise power even means. You just give them the bar system, which simplifies everything down to a graphical interpretation.
The voltage drops off drastically at the end, sure. But for that very reason you'd have to be insane to make a battery monitor that didn't sense the current in use and integrate that over time for a very good estimate of the battery life you have remaining. The voltage curves give you additional information, but they're certainly not the only source. You can see this if you look at your ACPI info for your battery in, say, Linux. It tells you the last full charge capacity, your current discharge rate, and how much time that is likely to buy you.
You mean that something with as many variables as strength and quality of a wireless connection can't be reduced to a value of "bars" between one and five without loss of information? Say it isn't so.
Slow news day, apparently.
Sure, cheap-ass wifi drivers don't tell you the strength of the usable signal, they usually just give you unitless bars that are basically hand-waving (example: Linksys or Netgear, etc); better quality (read as: higher priced) hardware comes with drivers that give not only the S/N ratio but the total signal strength, and sometimes even the noise floor reading (example: the Orinoco PCMCIA wifi card I have). Similarly, battery "charge" indicators that just read terminal voltage are cheap and they suck, better (read as: actual) state-of-charge indicators are based on actual charge-counting through a current-sense resistor, and if they took the time to write the code well, then it even accounts for capacity lost over time.
http://yro.slashdot.org/article.pl?no_d2=1&sid=06/12/02/0415209
http://news.com.com/FBI%2Btaps%2Bcell%2Bphone%2Bmic%2Bas%2Beavesdropping%2Btool/2100-1029_3-6140191.html
dunno about lying, but they're sure SPYING.
some moderator need to get a sense of humor... that is darn funny. As is her response.
The more bars you have, the less power your phone consumes. IIRC, 5 bars means the Power Amplifier is consuming a smaller amount, such as 50mw. Farther away from a base station (fewer bars) the power amplifier consumes far more (e.g. 200mw).
The amplifier is, by far, the biggest single power sink in a cellphone, consuming 2-5x the power as the rest of the phone. The more bars you have, the less it consumes.
There could easily be a signal quality meter, but I happen to like the signal strength meter myself.
With the experience on my ThinkPad A22m (an ancient model), GNOME reads data from the HAL, which in turn reads it from ACPI.
Neither display is actually telling you what you think it's telling you.
orly?
The signal strength bars on a mobile phone or laptop do, at least, say something about how strong the local signal is. But they don't tell you the ratio between that signal and the inevitable, and often very considerable, noise that accompanies it ...
Um, yeah. Signal strength means signal strength, not signal-to-noise ratio. So what you're telling me is the signal strength bar tells me exactly what I thought it meant, my cell-phone is not lying to me, but if I was stupid enough to think signal strength means something other than signal strength, I might feel deceived later because I'm an idiot. Okie dokie.
"Convictions are more dangerous enemies of truth than lies."
Along with that they had a somewhat nice MPG readout that you could see fluctuate widely, if you punched it from a complete stop, it dropped to something dismal like 6-7 MPG, on the highway, flat, cruising just the double nickle and back off a little it would briefly hit 44 MPG, then settle down again to like around 28 or so IIRC, been a long time now.. At least that is what I remember of them, that particular one was en el dorado, used to work on this medium rich guy's small fleet of vehicles for him so I drove all of them on occasion.
In the case of signal strength the IEEE fellows decided not to standardize how different manufacturers calculate the RSSI (Received Signal strength) for the antenna. just that it be a ratio showing signal strength and left the implementation detials to the vendors. what this means is that a signal strenght of 70% from vendor A may be much stronger than a signal strength of 100% from vendor B. not to take a crap on the hardwork of the Engineers involved ... but this is probably the only part of the 802.11 network that a 'novice' user is interested in .. and at the bare minumum it should have been standardized.
It is quite common for laptop batteries to overestimate the remaining time, it even gets worse the older the batteries are: As they expose a sudden and sharp voltage drop at the lower end of their capacity, it really is hard to determine, how much time really is left.
So even though the manufacturers tend to program too optimistic parameters into the drivers, they are bound to be inaccurate as time is passing and the batteries get old.
You can use tools like IBAM from http://ibam.sourceforge.net/ to profile your batteries more accurately and gain more trustworthy readings for your time left running on batteries.
Except it's still a trait of the brain, and it's not even just a human trait.
E.g., your dog is treating you as a bigger and stronger dog, and essentially only follows you because you're the alpha dog. Males around the age of 2 even get ideas about challenging you for who's going to be alpha. And apparently don't bother wondering what _would_ they do if thee roles were really reversed, with you as the pet and him as the master (really, alpha.) But essentially he sees you as a dog, and expects that you'd follow the dog rules there.
E.g., your cat almost invariably just accepts you as the alpha cat of the colony, and unlike dogs it's even realistic enough to not challenge someone 10 times its weight to a fight for alpha status. Mind you, alpha status in a cat colony doesn't actually mean they have to follow or obey. It just gives you dibs on food and the right to bully your underlings a bit, but not too much. If it's an apartment cat, well, it's your food in the first place, so having dibs on it doesn't really do anything. But anyway, there are plenty of signs that you're largely simplified to a big cat in a lot of aspects.
I'd call it anthropomorphising, but that's actually the wrong word there, because of the "anthropos"="human" root. You're just mentally assimilated to one of their own.
Mind you, both seem to realize you're not 100% a dog or a cat, but then humans anthropomorphising animals doesn't go to 100% either.
Both cats and dogs seem to basically treat inanimate objects as, at the very least, living. You can see it in, say, dogs instinct to chase off cars, or occasionally doing stuff like barking menacingly at some object which hurt them in some way.
So basically you can get all snotty and derisive about it, or you could realize that (A) that's how we're wired, as mammals, and spend less time pretending you're something else than human, and (B) it doesn't matter anyway, since none of us are that stupid as to really believe the computer is human or even alive. We might cuss at it or use some fucked-up metaphor like "my computer hates me", but, here's the important part, none of us actually takes either literally. We don't expect the computer to react to that cussing, nor to have its crashes really influenced more by "hate" than by its drivers.
So it's no more retarded than any other metaphor. We also talk about stuff like:
- the crack of dawn (yes, we _know_ that nothing actually gets cracked there)
- taking the piss, getting pissed, or pissing against the wind (no actual urine is involved in either)
- jumping the shark (no actual fish involved)
- burning one's bridges (it doesn't literally involve a bridge and fire)
Etc, etc, etc.
So unless you're against any non-literal kind of speech as a whole, I fail to see while you'd single out anthropomorphism. Again, trust me, nobody takes it any more literally than they take the above expressions. So what is the problem, really?
A polar bear is a cartesian bear after a coordinate transform.
From the article: >Not to mention further problems, like fuel injectors clogged with crud from the bottom of the fuel tank So the fuel doesn't exit the fuel tank from the bottom if your tank is half-full?
Cites are not required for independently verifiable claims.
What on earth do you mean? Of course citations are needed. Without citation, claims are just that: claims, hearsay, anecdote. Its citation and accountability that makes claims usable as evidence.
Very well, then. "The hare, because he cheweth the cud, but divideth not the hoof; he is unclean unto you." (Leviticus 11:6). Prove me wrong without resort to independently verifiable physical reality. No human is a more reliable cite than God, so you lose the cite war before it begins.
[snip]
There's a reason peer-reviewed journals don't accept papers without citation.
Yes there is. I doubt we'd agree on what that reason is, though.
What is the part from:
"Cites are not required for - independently verifiable - claims."
you do not understood? You really not a scientist
Is too easy to create many "citations" and put then on article to say "Hey, this is true because have citations!", I can say "my citation is from is the holy bible!" :)
But, a thing you can explain to others "how to test yourselves and conclude this is true" is a different matter and do not need a [insert your favorite VIP here] to say "is true", you only need to test yourself
Religion: The greatest weapon of mass destruction of all time
I did not know you could measure SNR on a battery...or did I misunderstand?
"My immediate reaction is "WTF? What kind of moron doesn't make things 64-bit safe to begin with?" Linus
Comment removed based on user account deletion
Signal strength is next to useless except for showing you when you have none. I filed this patent while at Nokia, but doubt they'll ever use it since it is NIF (not invented in Finland):
http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=17&f=G&l=50&co1=AND&d=PG01&s1=Deeds.IN.&OS=IN/Deeds&RS=IN/Deeds
The Inventor
I have to laugh....
In almost every car, Honda, GM, Ford, Chrysler, when the gas gauge goes on "reserve" (the light goes on), it lies to you on purpose. That is, it says you have 30 miles to go, and in fact, you probably have more like 60. That's to preserve people from their own stupidity.
By contrast, when my BMW says "reserve", 50 miles to go, you in fact have 50 miles to go. So as the computer says "0", the engine will sputter and die.
I'll bet more than a few poseurs have had to walk to the gas station because of this.
I had no idea... I'd never really seen one... I didn't know girls were so scary!
Truth.
My Moto KRZR however lies about battery all the time. It will be at 3/3 all week and then one day it slips to 1 or 0. Often it'll show 3/3 and then I plug it in to charge and it realizes it's really 1/3. ...though my Nokia 3220 had 6 or 7 segments and was always right on.
what a bunch of spam. next you'll tell me the hourglass in windows doesnt actually indicate work properly and the estimated time to copy isnt accurate either.
Good people go to bed earlier.
Speaking as someone who has worked for a couple of cell phone companies in the past, I can tell you that this is complete fantasy. The "signal strength" doesn't actually measure signal strength because it's almost meaningless if your signal isn't analog. It's actually a measure of good/bad packets received from the cell site averaged over a period of time. The idea that a cell phone manufacturer would tweak this for marketing purposes is a ridiculous conspiracy theory.
I wonder what Dan was smoking when he wrote this paranoid fantasy piece?
-- Ed Carp, N7EKG erc@pobox.com PGP KeyID: 0x0BD32C9B What I'm up to: http://intuitives.mine.nu
I honestly don't give a shit. Every time I have more than 0 bars I can call anyone and hear what they are saying to me. Background noise doesn't mean a thing if I can hear what the other person is saying and they can hear what I'm saying.
If creativity is the field, copyright is the fence.
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This article is exceeding my noise ratio allowence.
the only permanence in existence, is the impermanence of existence.
now my cell phone and laptop? Is there no truth left in this world!
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On a related note, I was working with RFID tags several years ago. We worked very hard to give the customer an accurate read on battery life. We had a "dot-on-the-map" application that located items and if the battery died... not only would the item not be located but you might not find it to swap the tag.
We ultimately went with a GREEN, YELLOW, RED scheme in which the customer knew that the GREEN state was longest, YELLOW was shorter and RED meant immanent loss of power within a day or 2. Total shelf life was about 4 years.
Look at the whole picture, not just the hole in the picture.
To this day, when I'm shopping for a new cell phone I always search for one with a retractable antenna - despite the problems it causes when I try to pull it from my pocket. Many don't come with antennas like this anymore but it does weigh on my decision. I've never had a phone w/o an antenna like this and I'm happy for my decision every time I'm somewhere that people are complaining that they can't make a call, yet I can place and receive calls and text messages with ease.
In my office, if I hold up my phone [MOT e815] steady in free space, I can see a change in the "bars" when I put the antenna up and down. I don't think my phone has a sensor to detect whether it is up or down so it can lie to me - it's not a wired connection to the radio in the handset but it is RF coupled.
By having an antenna that I can selectively retract or deploy, I can reduce the transmit power my phone requires to make contact with a tower when I put it up. If the antenna is up, my handheld needs to radiate less power (they scale transmit power up and down both at the handset and tower to save power and keep RF emissions to a minimum) and that means less RF energy going into my skull. My retractable antenna is safer and saves power. My battery will last longer than if I did not have one - all else being equal.
It's annoying to deal with sometimes but I can go longer without a charge and I'm less likely to be without coverage. Worth it for me. I can unscrew mine if it gets in the way and still make calls if I'm in a good area.
(An old Ham adage is "You can't work 'em if you can't hear them." This is speaking to the fact that, regardless of how much transmit power you have - you can't communicate with someone else if they don't break through your noise floor on the receive section. Cell towers command the power level of the handsets they are trying to communicate with and if they are not getting a good signal, they will instruct it to increase the power output so the party you are talking to can hear you. The inefficient and hidden antennas on many of the "antennaless" handsets will often be asked to pump out more power so the tower can hear you. This reduces your battery life AND floods you and everybody around you with higher and higher levels of RF - probably not good for your brain and eyeballs, all else being equal.)
If you are having trouble connecting with one of those "antennaless" handsets, try holding it vertically and rotating your body and the direction the back of the phone is "pointing" until things improve. Many of these antenna configurations are very directional by the time you consider that the patch antenna and the attenuation your body has on the signal in the direction of your head. If the cell site is in the direction of your left ear and you are speaking with it on your right, that RF must both be received and transmitted either through your head or must bounce off some nearby structure. Just turn around and you might be able to make the call or not be required to scream or talk very slowly just so that you can tell your honey you will be home soon for dinner.
If you want to "calibrate" your bars, see how your phone responds to making calls while moving it in and out of a semi-closed metal filing cabinet - a great RF shielded enclosure. Do the bars drop out all at once, or slowly as the drawer is closed? If your office or home is far away from a cell site, how open does the drawer need to be open before you can place a call to it? See how your bars respond to this semi-controlled signal level experiment.
If I turn my body in front of the window to which cell sites are available, I can get the signal bars to scale up and down by the amount I am shielding the phone from access to the tower.
Getting my amateur ticket in high school has probably saved me many hours of frustration and prevented many missed contacts just through an awareness of RF, antenna patterns, etc. Get your ticket(amateur radio license) - no Morse code required.
Progress bars are notorious liars as well. The early versions of Internet Explorer had a file progress bar that roughly indicated incoming html data on page loads. These were the modem days, so it mattered. It often took a few seconds for the data to start, so you often sat staring at a non-moving status bar, wondering if the site was going to time out.
But then an upgrade "improved" the status bar by always showing "progress" even when no data was coming in. The site would still time out if it was down, but the whole time the status bar would be chugging away, falsely reassuring you that the data was flowing.
This piece assumes that a 5-bar display should accurately drop in 20% chunks. Why is this?
Only a geek would expect bars to mathematically co-relate with percentage charge, or signal. All other humans would expect something far more complicated.
Folks, this is a MAN-machine interface (Human-Computer interface for the tree-huggers amongst us). That means you have to consider HUMAN responses.
And human responses don't generally match precisely to 'amount used' for anything. The way they go is "there's enough...there's enough...there's enough...whoops, it's getting low - better cut back..."
Where the Whoops comes is variable, but so long as you've got 50% of anything left, you're usually OK. 25% left, you start worrying. 5% left, you look for a fill-up.
That's what the bar code tells us. Myself, I can't see that it's a problem. Except for geeks, but who ever considered them? Besides, they can look after themselves...
I have AT&T and I think they got more bars in more places by using this simple formula. I now NEED 3 bars to reliably make a call. I used to be able to have some hope at 1 or 2, but not in the last year or so. I realize the point of this article is that bars don't mean anything anyway, but I feel they have been adjusted a lot recently.
I get around 135 miles to a tank...
For the first 100 miles, the gauge shows four bars. for the next 20 miles it shows three bars and for the next 10 one bar. When it gets to no bars and the idiot light starts flashing, I know I've only got a few miles left.
It's ridiculously non-linear and a common complaint on the bike forum I frequent.
Interested in a Flash-based MAME front end? Visit mame.danzbb.com
That's only true of TDMA or FDMA networks. CDMA allows you to dynamically squeeze in more channels with corresponding decrease in SNR due to increasing mutual interference.
Interesting. I didn't know that. Of course, if the tower is out of channels in the landline trunks feeding it, it doesn't really matter how much radio bandwidth is available. Anyone know what the limiting factor usually is? Or does it vary?
dragonhawk@iname.microsoft.com
I do not like Microsoft. Remove them from my email address.
I've experienced that quite often in my small sports coupe, the only thing you can do is lean on the horn. I'd chalk it up to badly aimed mirrors (a horrible epidemic right up there with underinflated tires), but I now also have a small offroading 4x4 (it has a very small footprint but is close to the same height as an SUV) and while I've had less incidents of people trying to change lanes into me while driving it, overall it doesn't seem to be much more visible, so I think that while a low-to-the-ground car is somewhat less visible to others, accidents where people don't seem to see you are mostly due to people just not looking where they're going.
"When information is power, privacy is freedom" - Jah-Wren Ryel
Have you looked at the name of the site you're posting on?
No sig today...
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1) Cell phones.
Cell phones use a so called RSSI value for the number of the bars. RSSI is a Relative Signal Strength Indication, which is a best guess of the device how well the data transmission will go. Most use SNR directly, some use a product of signal strength and bit error rate (BER).
The reason why it doesn't always match reality is that it's really a best guess by the phone, and reality is much more complicated than just that.
2) Laptop batteries.
Laptop batteries are using charge counters. Those are resistors with very small resistance ( 0.1 Ohm) tied to a precise voltmeter in a controller chip. By integration the controller knows rather well how much charge (how many electrons) have passed through it. With Li-Ion and Li-Pol batteries in use today, however, the situation got harder because the voltage of the battery varies a lot during discharge. Nowadays, modern batteries count energy, that is the product of charge and voltage as it moves in an out, giving a very precise output of remaining energy.
The reason some batteries die very quickly once they stop showing full is because as Li-Ion batteries age, their internal resistance increases. More energy is lost within the battery during the discharge process and the amount of energy lost (and voltage decrease) is directly proportional to the current taken from the battery. At the same time, modern devices have switching regulators which take more current when voltage decreases to provide the same flow of energy to the device. Combined, this means that once the battery voltage of an aged battery starts dropping, it drops very fast.
For cell phones, this is even harder, since they don't have charge counters - the batteries have to be cheap. There the remaining energy is guessed purely based on voltage. And old Li-Ion batteries will have almost full voltage when under light load, and fail when the load is applied, causing a phone to switch off.
Glad to see Dan's data getting slashdotted. He's been so good for so long, but not many people know of him.
Hope he doesn't become too cool to continue to answering my questions, now that he's hit the bigtime.
BTW: way to go dan's servers, not eating yoruself.
-G
What do you use for this purpose? On which OSs does it work?
What I can't understand is why my cellphone's signal strength bars go up and down rapidly, even when the phone is sitting on a desk in a single location. In New York City, where there's lots of signal. But even in Brooklyn and Queens, where there's only 3-5 storey buildings, and not a lot of chance for multipath noise.
Some places are sometimes stable. But sometimes those same places will see my bars jumping from 0-100% and points between, cycling randomly across a few seconds. No rain, or even wind.
What is that? Is my phone lying about something? Is it some kind of cry for help?
--
make install -not war
There are actually standards for measuring receive strength. In the world of Amateur Radio, as well as commercial radio communications, we have something called the S-Unit. On some radios, these are displayed on an analog meter, and on some radios, they are displayed as "bars" on an LCD or with LEDs.
Basically, each division ("s unit") is ideally about 6dB different than the next, meaning a signal must double in strength twice to make a 1 s-unit difference. The top or near-top of the scale, called "S9" is typically calibrated at around 50 micro volts (at 50 ohms).
Wikipedia has more information:
http://en.wikipedia.org/wiki/S_meter
The point being, there is a standard for measuring signal with bars. Of course, manufactures don't always adhere to it. In the case of cell phones, who knows. But they probably could...
It seems that every corporation wants to make a product "seem" high quality and long lasting. But you also have to have more intelligent consumers as well. I have driven my car on the E for several days sometimes. Of course I live very close to work, but still, E should mean empty, not "hey your empty but not really". To combat the frustrated consumers when the companies actually correct these intentionally false readings, just give a almost empty warning. TahDah! Everything is good.
It should have been
Momentum Heavier car: 150000Ns -->
Momentum Lighter car: 60000Ns <--
Final momentum: 90000Ns --> Final velocity: 12.86m/s -->
Total impulse of driver of heavier car: |100kg*(30m/s-12.86m/s)|=1714Ns
Total impulse of driver of lighter car: |100kg*(-30m/s-12.86m/s)|=4285Ns
Your phone isn't telling you either the strength of your signal or the SNR.
It's telling you which level of transmit power it is using.
If your phone can show n bars, it has n+1 transmit power levels. Subtract the number of bars it shows from n+1 and you will know the integer value that is in its transmit-power variable. If you see 0 bars, your transmit power is cranked up to 4, for example.
Why does it vary the transmit power? Sometimes it's because the tower is measuring the power that it sees from your phone, and sends back an increase-power or decrease-power code in one of the messages they are exchanging. Your phone can't measure these things (waste of space and power). The tower doesn't want you blasting other phones off their links, either. If your phone can't see a signal it will simply go to full power and broadcasts connection requests (this is why your phone dies quickly when you go roaming).
If the tower can't see you any more, it just doesn't say anything. If you can't see the tower, you start transmitting at full power. "Can't see you" includes rejecting packets that are corrupted by noise. So if there is a enough noise to make the signal unrecoverable, regardless of the real signal strength, your phone will be trying to get through by going to full power.
The fact that some phones continue to send balky noises to your earpiece is a feature. It is giving you what it has rather than resetting the connection.
And the noise that causes those balky noises in your earpiece may not be radio noise in your area. They could be radio noise at the other end, or errors in any part of the transmission chain between your tower and the other end. There will never be a way to measure the end-to-end bit-error-rate in a cell phone. No point telling you in a number what you can already hear.
I have owned 3 different Motorola phones and all 3 have had problems where the battery meter never indicated the actual value of the battery.
I can't speak for linux or Windows, but Apple has had these issues covered for quite a while.
Wireless:
Apple updated their signal meter in Mac OS X Tiger (version 10.4 in 2005) to reflect just this - it previously indicated signal strength, but was updated to instead indicate throughput, since that's a "real" measure that user experience will actually match.
Battery:
Battery life (%) is indicative of how many milliamp hours remain as a ratio of current total battery capacity (again, in mAh). There's a cool utility, coconutBattery, that also lets you compare that to your battery's original capacity. Battery life (time) is the computer's best guess, based on current power usage patterns, at how long it can last, considering both the mAh and the burn rate.
TFA reads like the ravings of a conspiracy theorist. In at least some systems, there's hard logic behind these gauges and it really isn't a matter of tricking or marketing.
I just wish both my cell phone company and my city's transit would both learn to use freaking atomic time. Nothing like being dead-on one day (relative to one another), and 6 minutes late the next.
It's called a TIME SERVER, you bastards!
http://shirt.woot.com/friends.aspx?k=4113
Battery meters are VAGUE at the best of times.
Temperature, usage, vibration, etc.
So many factors that determine battery meters and
how they are displayed.
I don't remember anyone saying that the battery
meter is 99.99% accurate.
Maybe I'm wrong.
Please show me a 99.99% accurate battery meter
that doesn't cost three hundred dollars, that is
very small [ fits in an mini ipod ], and
compensates for battery degradation.
This is what consumers what : Simple.
FULL battery, half, and empty.
I don't know about the US (where odd phones like Motorola, etc are more common), but his certainly is not true for my SonyEricsson. The battery meter is quite reliable and drops kinda evenly, and I've had the phone work a whole day with some very short calls too, while on "no bars" battery. "Signal strength" is always a bit more random, though, but that too mostly indicated quite well if I can call or not... just updates a bit slowly. As I recall, my old Nokia was the same, though not quite as generous with battery time at "empty".
I've stopped treating battery indicators as linear displays some time ago, instead I read them as:
3 bars - Abundant;
2 bars - Sufficient;
1 bar - Low.
Perhaps the phone makers should ditch the bar symbols with fuzzier symbols.
Vs lbh pna ernq guvf, ybt bss abj. Tb bhgfvqr. Syl n xvgr.