Your Computer and Cell Phone Are Lying To You 479
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 ..."
Pshaw (Score:5, Funny)
Re:Pshaw (Score:5, Insightful)
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!
skillful integration of two /. themes
"I already knew that"
"DRM is bad"
Comment removed (Score:5, Funny)
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Re:Pshaw (Score:4, Funny)
Ohhh, we represent the lily pad guild, the lily pad guild, the lily pad guild...
Re:Pshaw (Score:5, Funny)
Re: (Score:3, Interesting)
just like car manufacturers are telling you that driving an SUV is good for your safety while they make them with cheap truck chassis that are less maneuverable and do not reduce the impact of a collision nearly as much as a car chassis.
Based on some of the replies in this thread, the manufacturers propaganda is working well. Suckers seem to be lining up to defend their death trap SUVs.
But your post has been modded funny, no doubt as an attempt by someone who has a bad case of buyers-remorse that they can't admit to, to attempt to undermine your insight by getting your post labelled funny.
I bet the crack-addled moderator likes the laughter track on "comedy" like Friends because it tells him when he should be laughing. So he projects this l
Re:Pshaw (Score:5, Insightful)
Or you could try to not get into an accident. The best way to do that is to drive a small, agile car and watch where you're going (I can tell you it really works wonders! Even just watching where you're going and minding the objects around you makes a huge difference!). But why go through all that trouble? It's better to get the biggest cudgel of a vehicle that's practical and let physics sort 'em out!*
*hint: your safety is not determined solely by the G-forces you experience in an accident.
Re:Pshaw (Score:5, Informative)
Hint: Rally is done in small, agile cars, not in SUV's
Re:Pshaw (Score:5, Insightful)
I live in the snowbelt.
I've seen a lot of 4-wheel drive SUVs/trucks in the ditches, because they displace overconfidence (like you just did). Meanwhile I've driven a midsize or compact car, and have never had an accident in the snow. The key? "Don't drive faster than 30 miles an hour ya dope!"*
As for F=ma, there's also "energy absorbing crush zones" to consider. A crash-friendly chassis is more important than F=ma. i.e. A 5000 pound SUV that remains solid like a brick (but turns its occupants into scrambled eggs) is a lot more dangerous than a 2000 pound civic that crumples like a wad of paper (but protects its passengers from damage). What matters is how well the vehicle ABSORBS the energy, not its weight. Also worthy of note: SUVs are more dangerous than cars. Why? SUVs rollover and smash the occupants.
* (By dope, I'm referring to those numerous persons I see driving 65 on the interstate during snowstorms... I always wonder how they think they're going to stop while driving on slush.)
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Dude, get a Subaru and some snow tires. They're the national car of the Republic of Vermont.
Re:Pshaw (Score:5, Informative)
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I take it you've never seen two cars sliding towards each other on glare ice with nothing the drivers can do about it.
No, but I DO think that there's something to do with how every winter I see ~10 SUVs in the ditch for every car, when the actual proportion is about 50-50. Hardly see any trucks in the ditch, but they aren't everywhere on the road either.
Hint: 4 wheel drive vehicles don't brake any better than a 2 wheel drive one. A front wheel drive car will stop just as quickly in limited traction condit
Re: (Score:3, Funny)
I'm pretty sure his point is that if he pretends to understand physics, we won't notice that he's just another redneck that thinks driving a big truck is cool
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Its true that, from the statistics, you are, per accident, less likely to be injured in an SUV. The social downside is that the person in the other car is more likely to be injured in accident if you're in an SUV, but that's their problem. The personal downside is that you'
Re:Pshaw (Score:4, Insightful)
Or that the panels for your Trailblazer are cheaper than for the Cavalier. Repair costs have as much to do with insurance costs as the likelihood of an accident.
Re:Pshaw (Score:4, Funny)
Yes, because unionised flora is the only way to ensure fairness for plants at the hands of the oppressive petit-fauna elite.
[Citation-Needed] (Score:5, Insightful)
Re:[Citation-Needed] (Score:4, Insightful)
There is no citation needed. I can personally attest to the fact that unless you pay tens of thousands for the equipment it's metering capabilities are ONLY an indicator, more or less like your gas gauge, and not some sensitive sensing system. period. ever.
Most of the work done on electronics in the world is done without exacting measuring equipment. Yes, there will be those that argue, but *MOST* work is done with less than optimal equipment. Think that mechanic working on your car is using micrometers to do everything, or $2500 torque wrenches? For most of the world, good enough is ... well, good enough. Battery monitoring systems can only count down from full charge based on use and time. At best it is a simple calculation that cannot do much to account for aging of the battery or temperature compensation.
No citation needed. That is simply how life is, and why this is a huge 'duh' article, even if joe bloggs doesn't realize it. It's the reason that your vehicle gauges are not calibrated. This applies to just about everything we use.
Re:[Citation-Needed] (Score:5, Funny)
Dan is claiming that (at least in cell phones) there is a deliberately misleading fudge factor.
Re:[Citation-Needed] (Score:4, Insightful)
Re:[Citation-Needed] (Score:5, Informative)
50% of the battery life at 3 bars
30% at 2 bars
15% at 1 bar
5% at 0 bars
And yes, this was customizable by the carrier to make it better or worse. Of course, this is hard to prove to the sceptics unless the software is open source.
There are numerous other technical reasons why the gauges might not be accurate, but this is a big factor.
Re:[Citation-Needed] (Score:5, Insightful)
Every car I've ever owned has worked the same way. The bar will remain on "F" until 60% is reached, and then it gradually starts dropping. When the gauge claims I have "1/4" I really only have 15% of my fuel tank left.
I've heard stories of car companies trying to make more accurate gauges, but the customers complained that the car was "half empty" after "only" 150 miles. They prefered the old gauges that still showed almost-full, even though those gauges were lying.
So I suspect the real conspiracy is just "the ignorance of the average citizen" that led to deceptive gasoline and battery meters.
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Re:[Citation-Needed] (Score:5, Interesting)
Car manufacturers so the same thing with the gas gauge. the top half is more than the bottom half. If the gauge on my car is sitting at half, I'm down to 24 Litres out of a 60 Litre tank. Also, there's a gallon or two left when the needle is at E.
Cadillac invented this in 1984 when they rolled out the electronic gauges which were linear. Customers complained about bad mileage despite the car being thriftier than it's predecessor. Some research showed that they were going by *how*often* they were filling up, not by *how*much*. So they made the gauge logarithmic and allowed another unaccounted for gallon at the end for safety.
Re:gauges (Score:5, Interesting)
They REALLY should bring that back, Hell, all manufacturers should put that kind of thing in their cars. I can't think of a better way to make going for high mileage widely "cool". Like trying for the high score on an arcade game.
"Hey, guess what? I got 48MPG on my way to work!"
"Oh yeah? Well I got 52MPG! Beat that!"
Just simply harnessing people's competitive drive (not to mention the desire to save money) could do more than all the hybrids in the world, though that would likely lead to people buying hybrids in a quest for ever higher mileage.
Re: (Score:3, Funny)
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.
Wikipedia disease (Score:2, Interesting)
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
pedantry (Score:5, Insightful)
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.
Re:pedantry (Score:4, Funny)
Re:pedantry (Score:5, Funny)
These types of posts are getting on my nerves.
If you battery went you would not of made the post at all...I'm not stupid.
Re:pedantry (Score:5, Funny)
Re:pedantry (Score:4, Funny)
Actually, (s)he could have made the post if their battery went half way through, and here's why. The char
Re: (Score:3, Funny)
These types of posts are getting on my nerves.
If you battery went you would not of made the post at all...I'm not stupid.
Candlejack does the same damn thing.
If he really had snatched away a poster, he would not have been able to hit Su
Re:pedantry (Score:5, Funny)
what's the English word for using a meme incorrectly?
/.
Re:pedantry (Score:4, Insightful)
Anything beyond that is geek pedantry and nitpicking.
That is Slashdot.
flamebait? (Score:2)
Why would this be modded flamebait? I totally agree here...My devices are as accurate as they need to be...beyond that who cares?
Re: (Score:3, Insightful)
I don't know what this "when there's only a few bars left" thing is that you speak of. But then my cell phone can show a full charge for up to 4 days and then be dead less than 4 hours later.
It'd be one thing if the battery use was constant so I'd know that I just need to charge it every 3 days or so... but as it can also randomly decide to discharge itself in well less than 24 hours...
Well, lets just say that I never rely on it when I travel.
My laptop tells me how much noise there is. (Score:5, Informative)
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.)
Comment removed (Score:5, Interesting)
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It does seem a little dishonest though, don't you think? In the past when I had five bars I thought that meant that I'd a decent margin of error between a conversation and *NO CARRIER*. It just sort of made sense.
Re:Wifi meters (Score:5, Insightful)
Not in the least because many common wifi chipsets don't make raw signal strength available to the rest of the system. Cellular modules do, but if you ask a phone maker how the number of bars corresponds to the error rate and signal strength, they won't tell you. Although a bit of experimentation reveals that as long as the error rate is low and the signal is above the noise floor, you get full bars. That's probably marketing.
The battery conspiracy thing is a bit silly. Rechargable battery chemistry follows an S-curve. There's a very short period at the beginning with the battery over the nominal voltage, a long and almost linear middle section, and a short period at the end where the voltage drops quickly. So a naive voltage measurement gives exactly as described in the article -- almost full most of the time with a quick drop at the end. A less naive measurement is very tricky because the voltage in the linear section depends not only on state of charge, but current draw, recent current draw, temperature, the age of the battery being used, etc. The best way to do it accurately is to track a particular battery through its charge cycle and monitor current in and current out. Smart batteries like those in laptops do. I don't think cell phone batteries are smart batteries.
Re:Wifi meters (Score:4, Interesting)
Comment removed (Score:5, Funny)
Re: (Score:2, Funny)
Are you my new daddy?
Re:Wifi meters (Score:4, Insightful)
[Showing signal to noise ratio] is then overruled by the marketing department because brand 'B' only uses the signal strength, so that makes your product look bad when compared side-by-side, since theirs has more signal bars.
Then show the signal in solid black bars and the noise in staticky bars. Suggest that the marketing department include something to this effect in the ad copy: "Sure you get a lot of bars, but are they good bars?"
Re: (Score:2, Redundant)
> that makes your product look bad when compared side-by-side, since theirs has more signal bars.
My phone has 11 bars.
Just saying...
Re:Wifi meters (Score:5, Interesting)
In the case of cellphones, it's the carrier that determines how the bars map to signal strength (or quality, if it's possible to estimate). Some carriers demand that you show 5 bars down to a really pathetic signal strength value (I've seen close to -100dbi - just as a quick comparison, most wifi chipsets lose all connectivity between -80 to -90dbi, and the best tend to disconnect around -96dbi). The headroom between that and when the baseband loses the signal completely isn't that much.
Which is why I laugh when I hear "More bars in more places". It's easy to get a "stronger" signal if you mandate that a phone must show more bars all the time.
Now, this was for a non-GSM phone, so it was mandatory to get carrier qualified. But GSM carriers are equally bad, except they don't have as much control since you can bring in any compatible phone onto the network. The only thing the carrier can claim is their phones get a "better" signal (see? more bars than your phone!).
I wonder if Apple had to jump through these hoops with the iPhone or just said to the carriers to screw it - they're designing the software their way and that includes battery and signal strength meters that make sense. Given what I see of cellphones, there's often a special baseband/firmware build for each carrier to cope with the differences... but the iPhone software seems to be either unified, or just a single build around the world. (Carriers oblige because the customers want the phone).
Laptop Battery Dying Too Soon (Score:5, Interesting)
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.
No connection on a full signal (Score:4, Interesting)
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.
Re:No connection on a full signal (Score:4, Informative)
Re: (Score:2)
This is also a plausible reason seeing that every radio base station can handle X number of connections simultaneously.
How do you know for sure that this is what is happening and that it is not the noise ratio that is too high?
A phone will not give you any indication as to what is going on behind the scenes.
Oh oh (Score:2)
The balance (Score:4, Insightful)
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
Fuel gauges also lie (Score:3, Insightful)
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The best part about my car is the huge dent in the bottom of the tank... previous owner had jacked up the car with the fuel tank.
Mine goes from 1/4 to empty REAL fast.
Re: (Score:3, Interesting)
There are a lot of factors involved that cause fuel tank gauges to not read linearly. For one, there is a "float" in the tank attached to a pivot arm that moves an arm across a rheostat to change resistance depending on tank level. Since the arm swings in an arc, the resistance change is not linear. Second, the tank is oddly shaped which throws off the reading. Third, there is usually a "reserve" capacity built in where the gauge may read empty, but there is still fuel in the tank below the level of the flo
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It's usually only fuel inside the float so that it sinks to the empty position. If you can find the hole you could easily fix it with a self tapping screw.
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There was a time, I believe, where the fuel gauge was connected to a float in the tank that would hit the top at around three quarters full and thus be pinned there, semi-submerged, from full to a little over half a tank. From half down it would be relatively accurate though. Perhaps this time hasn't quite ended?
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Batteries (Score:5, Interesting)
Dan doesn't seem to know much about batteries. Check out batter power discharge curves and such...
http://www.mpoweruk.com/performance.htm [mpoweruk.com] 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.
Re:Batteries (Score:4, Insightful)
You statement implies that you think it is more useful for the battery meter to display the charge level of the battery rather than the approximate amount of run time left.
For 99.99999999% of the people on Earth (that's everyone other than you), I'm pretty sure that a linear run time indicator is wildly more useful than an actual charge indicator.
Re:Batteries (Score:5, Informative)
No, like the article, you dont get it:
They use this curves to make a voltage->charge conversion.
But take a look at them, and guess what will happen if there is only small calibration error/battery defect/heat influence, that shifts the voltage a few 10mV: Suddenly, you might already be on the curve sloping down while the device still thinks its in the middle of the platau.
Smart electronics try to learn from past discharge behaviours, but for many gadgets, its just not possible: The ipod you left in your car in the summer will behave diffrent for the next charging cycle than the one that was near freezing in the winter.
The cellphone that was just running for a week in standby will behave different after the next charge compared to the one that was drained dry in 3 hours by watching divx videos on it.
And dont even mention partial chargings, which add a hysteresis on top of this things.
Its a very difficult problem, and devices really try their best to solve it.
But there is a reason why the controller board of a bigger laptop battery (that has 1% accurate meassurements) is bigger than you whole cell phone...
Like my fuel tank (Score:2, Informative)
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, multi
Grey-ware needs input. (Score:5, Interesting)
yes, yes they do (Score:3, Insightful)
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.
Re: (Score:3, Insightful)
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 think the point is that it'd be nice if these things worked in a linear and predictable fashion.
Showing 'full' from 100% to 51% is neither linear nor predictable.
GASP (Score:5, Funny)
you can't trust anyone (Score:2)
At some point, you need to simplify for the users (Score:3, Insightful)
Easier for sales (Score:5, Funny)
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.
Re: (Score:3, Insightful)
Taking the article to heart, maybe the reason they have more bars in more places is because they start at 3 bars for no signal and go all the way up to 4 bars for full signal.
Re: (Score:3, Insightful)
Hey now - they said NOTHING about signal strength or SNR. Just "more bars". If (bars > 0) then bars++
I knew it... (Score:2)
Ugh (Score:5, Informative)
#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.
Re: (Score:3, Informative)
That's a guiding principal for conveying quantitative information. There's accuracy, and there's precision. The accuracy of a measurement tells you how correct the measurement is relative to the actual value you're trying to measure. The precision tells you how specific the measurement is, or to put it another way, now narrow the range of actual values the measurem
Re:Ugh (Score:4, Informative)
1) Li-Ion and Li-Po batteries have internal chips that can tell exactly how much charge is in a battery (you've never over-charged a Li-based battery). The curves are much more flat but under load it's not especially difficult to know the charge state quite accurately. Heck, IBM even will tell you the charge/discharge current to two decimal places with some of their utilities.
2) You're guessing. In addition, noise is often more dynamic than signal levels. SNR is a MUCH more accurate determination of quality of bandwidth.
Gas guages, yes they're inaccurate - likely because manufactureres assume people are stupid. I just watch the pump and see how much gas i put in, subtract from the full-tank size and it's not so hard to determine how accurate the guage is. Speedo's are allowed to be a certain % off of actual but you have to take into account that the diameter of the tires on a car change as they wear. So yes, consipracy theory this and that but a speedo is not going to be perfectly accurate by measuring the drive shaft rotation.
Did you even glance at TFA? You're simple repeating much of what was said. The rest - assuming people are incapable of reading a simple guage frightens me. I mean, if you have to coddle the general population because they're all THAT stupid we've got bigger issues than the last 3 minutes of talk time on your cell.
Oversimplified, not all right (Score:2)
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
Oh thank God! (Score:5, Funny)
Your Computer and Cell Phone Are Lying To You
Oh, thank God! I was worried I was the only one who could hear them!
The phone's not the one that's lying (Score:2)
My computer has always been lying to me... (Score:2)
As a developer (Score:4, Insightful)
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.
Battery Meter (Score:2)
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
What A Pointless Article (Score:4, Insightful)
Slow news day, apparently.
Reasons for inaccurate battery data (Score:3, Informative)
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.
new bars = old bars + 2 (Score:3, Interesting)
Bullshit (Score:4, Interesting)
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.
It doesn't matter. (Score:3, Insightful)
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.
Re: (Score:2)
Re:Ummm, doesn't "lying" imply free will? (Score:5, Funny)
I would have given you the answer, but I suppose you would rather that I speak axiomatic set theory or such.
Re:Ummm, doesn't "lying" imply free will? (Score:5, Funny)
now if I can just get my laptop to stop humping my leg....
Re:Ummm, doesn't "lying" imply free will? (Score:5, Insightful)
It's simply Anthropomorphism [wikipedia.org]. 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..."
Re: (Score:3, Insightful)
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 ve
Except it's built in (Score:3, Insightful)
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 foll
Actually, the humans lied to you (Score:3, Interesting)
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
Re: (Score:3, Informative)
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.