# When I'm in one place, why do the bars on my phone change? **URL:** \ **Category:** Factual Questions\ **Created:** [July 24, 2015, 5:15pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073 "2015-07-24T17:15:33Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [July 24, 2015, 5:15pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/1 "2015-07-24T17:15:33Z")
I have assumed that the cellular signal strength that’s available to me is mediated by the nearness of a relay tower and by any interfering structures between us. So why is it that I can sit in one place without moving and look at my cellular phone and watch as the bars go from, say, 2 to 3 and then back to 2? What else is the signal strength dependent upon? ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [July 24, 2015, 6:32pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/2 "2015-07-24T18:32:00Z")
They mean very little as there is no standard, even about what they actually measure. > [@](#): > > ~nobody really knows what the signal bars mean, as manufacturers are not working to a standard, a signal bar on a Nokia handset may suggest there is full signal available, where as a sony ericsson may suggest there is full signal available but only a portion of it is usable. > **[Mobile Phone Signal Bars - What Do They Really Mean?](https://www.streetdirectory.com/travel_guide/132102/cell_phones/mobile_phone_signal_bars___what_do_they_really_mean.html)** > > I have always being under the impression that the more bars you have, the more signal you have and the clearer the quality of your call ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 24, 2015, 6:52pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/3 "2015-07-24T18:52:24Z")
Often times, cell signals are reflected off of traffic. If there is an obstruction between you and the tower, the signal strength may be very dependent on the number of panel trucks passing in front of you… ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [July 24, 2015, 7:30pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/4 "2015-07-24T19:30:57Z")
I’ve suspected atmospheric changes. But it even happens in my home, for wifi. Sure, I know that if I’m on the edge, it could go either way (say, to one bar or two) and avoiding that would take unnecessary filtering to add hysteresis. But it can change by TWO bars, in my own home? The atmosphere isnt changing! 'Supwiddat? (Wild guess: interference from other wireless devices.) ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [July 24, 2015, 7:33pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/5 "2015-07-24T19:33:47Z")
It can be related to how busy your local cell tower is. Sometimes I get LTE on my phone but not always. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [July 24, 2015, 8:33pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/6 "2015-07-24T20:33:40Z")
> [@Learjeff](#): > > I’ve suspected atmospheric changes. But it even happens in my home, for wifi. Sure, I know that if I’m on the edge, it could go either way (say, to one bar or two) and avoiding that would take unnecessary filtering to add hysteresis. But it can change by TWO bars, in my own home? The atmosphere isnt changing! 'Supwiddat? (Wild guess: interference from other wireless devices.) If it’s caused by fluctuations in atmospheric conditions, then the conditions between the tower and your home would probably have an effect, not just the conditions within your home. ---
**Author:** ![TallTrees](https://avatars.discourse-cdn.com/v4/letter/t/8baadc/32.png) [@TallTrees](https://boards.straightdope.com/u/TallTrees)\ **Post date:** [July 24, 2015, 8:57pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/7 "2015-07-24T20:57:13Z")
I live in a hilly area with canyons and ridges. It’s not unusual for the bars to change when the phone isn’t moving. My take on this has always been that the phone was powering higher and lower to capture the signal when it’s in a weak reception area. Google maps will show which tower your phone is connected to (when the GPS function is off). We have friends whose house is slightly below a ridge that’s in-between them and the nearest tower for my Verizon service. When we’re there, the bars fluctuate between just one and two, and during a 4 hour visit, my phone can lose 50% or more of its charge even when unused during that period. I’ve tried to make calls from their house and it’s hit and miss. But that’s what I think accounts for the changing of the bars. One bar showing is marginal to too weak, the phone powers up periodically to get a better connection. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [July 24, 2015, 9:21pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/8 "2015-07-24T21:21:54Z")
> [@Bijou\_Drains](#): > > It can be related to how busy your local cell tower is. Sometimes I get LTE on my phone but not always. Yes the busier the tower the shorter the range and the less power it transmits. This would equate to a dropping of the signal strength, also why you can use the phone at some places only some of the time. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [July 24, 2015, 11:19pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/9 "2015-07-24T23:19:35Z")
I have a tuner with a loop antenna. There is one station that sometimes goes in and out of tune changing as I move around. But this doesn’t always happen and I assume that it depends on atmospheric conditions. I assume that the same thing can happen with cell phone signals. You must be just at the edge between 2 and 3 bars (whatever they mean–they must mean something, even if they are not standardized). ---
**Author:** ![SeaDragonTattoo](https://avatars.discourse-cdn.com/v4/letter/s/df705f/32.png) [@SeaDragonTattoo](https://boards.straightdope.com/u/SeaDragonTattoo)\ **Post date:** [July 24, 2015, 11:25pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/10 "2015-07-24T23:25:44Z")
> [@kanicbird](#): > > Yes the busier the tower the shorter the range and the less power it transmits. This would equate to a dropping of the signal strength, also why you can use the phone at some places only some of the time. This was how it was explained to me once. Fewer bars - likely connected to a tower farther away, so low signal. Tower closer gets less busy and phone connects to that one, and a stronger signal with more bars. ---
**Author:** ![leftfield6](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leftfield6/32/18780_2.png) [@leftfield6](https://boards.straightdope.com/u/leftfield6)\ **Post date:** [July 24, 2015, 11:51pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/11 "2015-07-24T23:51:00Z")
The phenomenon described above (cell sites getting bigger and smaller depending upon user density/usage) used to be referred to as “breathing” and it was the bane of many network engineers. CDMA (used for example by Verizon) suffers from the breathing problem far more than TDMA or GSM technologies. ---
**Author:** ![guizot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guizot/32/3636_2.png) [@guizot](https://boards.straightdope.com/u/guizot)\ **Post date:** [July 24, 2015, 11:51pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/12 "2015-07-24T23:51:46Z")
> [@bob\_2](#): > > They mean very little as there is no standard, even about what they actually measure. I’ve always suspected that. BUT, with Android phones, you can look at signal strength in the phone settings, and it gives you a number. (It’s a negative number, as I recall – I can’t check mine at the moment, because I flashed a new ROM which has a bug with this function.) How do I read that number? ---
**Author:** ![JWT\_Kottekoe](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@JWT\_Kottekoe](https://boards.straightdope.com/u/JWT_Kottekoe)\ **Post date:** [July 25, 2015, 1:21am UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/13 "2015-07-25T01:21:41Z")
Part of the explanation is [“fading.”](https://en.wikipedia.org/wiki/Fading) In a complex environment, their are many things that can reflect, obscure, refract, or delay radio signals. The signal that reaches your phone’s receiver is typically the sum of a number of different signals that take separate paths. All these signals interfere with each other, sometimes in a way that is exquisitely sensitive to minor details, like trees blowing in the wind, airplanes flying overhead, etc. This leads to seemingly random fluctuations in the signal strength. This is especially pronounced if your receiver is in a “deep fade,” i.e. a spot where the signals almost completely cancel each other. In this case, if one signals gets larger or smaller, the combined signal can change drastically. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [July 25, 2015, 2:14am UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/14 "2015-07-25T02:14:44Z")
> [@Learjeff](#): > > I’ve suspected atmospheric changes. Not very likely. Most cellphone transmissions are just line of sight to the tower (which is why they are high up on a tower). Nothing bouncing off the atmosphere at all, unlike commercial AM radio. Possibly real heavy rain might cause interference, but nothing much else. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [July 25, 2015, 4:12am UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/15 "2015-07-25T04:12:04Z")
> [@Senegoid](#): > > If it’s caused by fluctuations in atmospheric conditions, then the conditions between the tower and your home would probably have an effect, not just the conditions within your home. Perhaps I wasn’t clear. The interior aspects were for 802.11. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [July 25, 2015, 4:21am UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/16 "2015-07-25T04:21:02Z")
> [@t-bonham@scc.net](#): > > Not very likely. > Most cellphone transmissions are just line of sight to the tower (which is why they are high up on a tower). Nothing bouncing off the atmosphere at all, unlike commercial AM radio. Possibly real heavy rain might cause interference, but nothing much else. Thanks! Makes sense. I actually meant “environment,” including moving objects. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [July 25, 2015, 4:22am UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/17 "2015-07-25T04:22:38Z")
> [@Hari\_Seldon](#): > > I have a tuner with a loop antenna. There is one station that sometimes goes in and out of tune changing as I move around. good point: people count too, especially the person holding the phone. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [July 25, 2015, 4:24am UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/18 "2015-07-25T04:24:04Z")
> [@leftfield6](#): > > CDMA (used for example by Verizon) suffers from the breathing problem far more than TDMA or GSM technologies. Is CDMA used for 3 & 4G? I thought it was just 2G. ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [July 25, 2015, 12:01pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/19 "2015-07-25T12:01:57Z")
> [@Learjeff](#): > > good point: people count too, especially the person holding the phone. Yeah, except my question is why do the bars change when I’m in one place. ---
**Author:** ![Turble](https://avatars.discourse-cdn.com/v4/letter/t/8dc957/32.png) [@Turble](https://boards.straightdope.com/u/Turble)\ **Post date:** [July 25, 2015, 2:53pm UTC](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073/20 "2015-07-25T14:53:48Z")
> [@Learjeff](#): > > Is CDMA used for 3 & 4G? I thought it was just 2G. Yes. My phone is CDMA. At home, in a little valley with only one tower available, it sometimes connects at 2G, sometimes 3G, and out and about it sometimes goes 4G LTE. [Next page](https://boards.straightdope.com/t/when-im-in-one-place-why-do-the-bars-on-my-phone-change/726073.md?page=2)