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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.
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.
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.
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?
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).
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.
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I would have given you the answer, but I suppose you would rather that I speak axiomatic set theory or such.
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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.
#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.
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.
anthropomorphism is a common human tendency... get over it.
now if I can just get my laptop to stop humping my leg....
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
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.
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.
It's simply Anthropomorphism. I talk to my car when it runs bad. I don't expect it to hear me or comprehend, but I do anyway. I talk to the computer, too.
When I talk to machines, for some reason it's always cursing, as in "GOD DAMNED PIECE OF SHIT..."
mcgrew's razor: Never attribute to stupidity that which can be explained by greedy self-interest
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.
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.
It doesn't matter whether it was connected or not. It had an effect, thanks to the black magic which is RF. Moving pieces of metal (or even plastic, if they weren't metal) around in a cell phone can't help but have an effect. Granted, it may not have been the effect the users wanted, but it was an effect.
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.
In college, I had a 486/66 with "personality". I named her ("Talena" for you Gor fans out there), and talked with her. I got occasional strange looks, but nothing ever was harmed. She would periodically stop booting and I'd need to reseat all her cards and memory. You see, the dorm was a very dusty place and the temperatures were not that well regulated, and she was pretty cheaply made -- I couldn't afford much. I knew full well the physics of thermal cycles and the electrical properties that our dust had, but my math major roommate's eyes glossed over with that stuff until I said, "She's a girl, she needs me to pay attention to her once in a while". He understood my meaning, and appreciated the distilling of "the truth" into "easy to understand". She had a few other quirks that were related to the fact that no two components came from the same vendor, and that all were found in the back of my 15 pound Computer Shopper, and those piled up into choosing her name.
Anthropomorphism isn't about thinking things are really like people, it's about approximating real truths into things that allow our social brains to remember and interact with.
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.
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
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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.
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.
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.
By contrast, one of work's Vauxhalls (UK part of GM) that I was using said it had 13 miles of fuel left, and promptly spluttered to a halt when I started away from some traffic lights, and wouldn't restart until it was filled up.
Car analogies break down.
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.