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Your Computer and Cell Phone Are Lying To You

Posted by timothy on from the they're-in-it-with-the-aliens dept.

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 ..."

18 of 479 comments (clear)

  1. Pshaw by MistaE · · Score: 5, Funny

    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!

    1. Re:Pshaw by cushdan · · 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"

    2. Re:Pshaw by Godji · · Score: 5, Funny

      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, 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. Hah!

    3. Re:Pshaw by GameboyRMH · · 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.

      --
      "When information is power, privacy is freedom" - Jah-Wren Ryel
    4. Re:Pshaw by element-o.p. · · Score: 5, Informative

      After living in Alaska for nearly 20 years, I have found that if the road surface is so slick that braking is essentially nil, I can almost always stop the car and avoid an accident by gently nudging the curb with my tires. Unless you've already screwed up so badly that you are spinning out of control, there is almost always enough traction to change your direction of travel by a few degrees, and by rubbing your front tires against the curb, you can get enough traction to stop just about every time. I've only had to do this a couple of times when road conditions at an intersection were much worse than the conditions on the rest of the road, but it has always worked.

      --
      MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?
  2. pedantry by caffeinemessiah · · Score: 5, Insightful

    Neither display is actually telling you what you think it's telling you.

    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.
    1. Re:pedantry by Anonymous Coward · · 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.

    2. Re:pedantry by travdaddy · · Score: 5, Funny

      Maybe he was dictating it.

      --
      Adidas To Bring Back Sneakernet
  3. Wifi meters by lisaparratt · · Score: 5, Interesting

    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.

    1. Re:Wifi meters by lisaparratt · · Score: 5, Funny

      Not only can I write software, but since I can multitask, I can do your mom at the same time.

    2. Re:Wifi meters by tlhIngan · · Score: 5, Interesting

      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.

      ... which 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.

      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).

    3. Re:Wifi meters by russotto · · Score: 5, Insightful

      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.

      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.

  4. Batteries by fitten · · 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 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.

  5. Grey-ware needs input. by Therefore+I+am · · Score: 5, Interesting

    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.

  6. Comment removed by account_deleted · · Score: 5, Funny

    Comment removed based on user account deletion

  7. Re:[Citation-Needed] by fabs64 · · Score: 5, Funny

    I know it's de rigeur, but that was quite a lot of writing for someone who didn't RTFA.

    Dan is claiming that (at least in cell phones) there is a deliberately misleading fudge factor.

  8. Re:Ummm, doesn't "lying" imply free will? by sm62704 · · Score: 5, Insightful

    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
  9. Re:[Citation-Needed] by amram9999 · · Score: 5, Informative

    I used to work for Motorola, and I can attest that the standard 3 bar battery gauge showed:

    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.