Follow Slashdot stories on Twitter


Forgot your password?

Rain Drops Signal Cell Phones 86

An anonymous reader writes "Signals from mobile phone masts have been used to measure rainfall patterns in Israel, scientists report. From the BBC article: 'The University of Tel-Aviv analyzed information routinely collected by mobile networks and say their technique is more accurate than current methods used by meteorological services. The data is a by-product of mobile network operators' need to monitor signal strength. If bad weather causes a signal to drop, an automatic system analyzing the data boosts the signal to make sure that people can still use their mobile phones. The amount of reduction in signal strength gave the researchers an indication of how much rain had fallen.'"
This discussion has been archived. No new comments can be posted.

Rain Drops Signal Cell Phones

Comments Filter:
  • by celardore ( 844933 ) on Saturday May 06, 2006 @05:38AM (#15276072)
    Sorry what was that? The signals patchy, with some sunny spells towards the afternoon...
    • I thought low cloud cover actually increased signal strength...? The signals bounce back and forth from the earth to the clouds, instead of travelling up out of the atmosphere... like CB sidebanding (if I understand that correctly)

      I live in the shadow of a mountain, and all I know is that on sunny cloudless day, my cell reception sucks; I'd swear its better when it rains. When its dry but overcast I get the strongest signals.

      any /. physicists and cell pundits are welcome to explain... thanks

      • Cell phones operate at 900MHz and 1.8-1.9GHz, which do not skip off the ionosphere (as CB does at 29MHz). Skip is related more to radio frequency and the 11-year sunspot cycle than modulation (i.e., CB's AM vs. SSB [Single Side Band]). Additionally, water droplets tend to reduce signal strength, which is why satellite dish owners sometimes experience "rain fade".

        The only explanation that I can think of for increased signal strength would be the tower antenna's or radio's temperature due to a poor quality in
      • As IAAPACP(I Am A Physicist And Cell Pundit), scattering and lensing are most likely, I think.

        Visible light is not the only part of the EM spectrum that can be distorted by atmospheric conditions. Think mirage. Think radar. 1.8 GHz phones are definitely in the microwave class. Lensing with different layers of air with temperature and humidity variations might be your culprit. Think mirage where you are looking at the ground and see the sky or with your situation, your cellphone is "looking" over the mountai
  • Headline? (Score:5, Insightful)

    by Anonymous Coward on Saturday May 06, 2006 @05:44AM (#15276079)
    Is it just me, or are the headlines for some articles just downright incomprehensible?

    What does "Rain Drops Signal Cell Phones" actually mean? Are individual raindrops sending signals to cell phones? Did they actually mean that rain drops (degrades) cell phone signals? No, apparently they meant that cell phone signals can detect rain drops... and unless my ability to parse english is somewhat broken, the headline simply doesn't say that.

    I wouldn't mention this if it didn't happen at least once a week. I'm forced to spend a good ten seconds in a state of frustrated confusion as my brain struggles to comprehend absolute gibberish.
    • Re:Headline? (Score:3, Insightful)

      by Loconut1389 ( 455297 )
      They either meant "Rain Drops Cell Phone Signals", "Rain Drops Signal of Cell Phones" or "Measuring Rainfall With Cell Phone Signals"
    • by Elemenope ( 905108 ) on Saturday May 06, 2006 @06:25AM (#15276153)
      That's why I generally don't bother anymore. I just skip to the synopsis, which, while often containing lies, damned lies, distortions, exaggerations, editorial, and occasionally even statistics, is usually nevertheless not gibberish. Why spend ten seconds confused when you could be spending twenty seconds disgusted?
    • "Rain Drops Signal Cell Phones" really means:

      "I'm zonked, it's late, and I'm going to copy and paste
    • As I read the headline, there are three words that can be used as either verbs or nouns (rain, drops, signal. However, it appears that Zonk, in his infinite editorial wisdumb is using them all as nouns, which means there's no verb in there at all. Even if 'signal' is used as a verb, the headline still says the exact opposite of what the BBC article headline says, as someone else pointed out below. The quality on this site is appalling, yet it's still better than most tech sites out there. I find this very d
    • Slashdot also has "NASA Hacker Gary McKinnon Interviewed" in the Science section, about a person who never worked for NASA, and who is arguably not a hacker at all.
  • by RealGrouchy ( 943109 ) on Saturday May 06, 2006 @05:53AM (#15276095)
    I always knew not to trust the weatherman, but you're telling me to trust the cell phone people now? I don't think I can handle *that*.

    - RG>
    • Re:The weatherman? (Score:3, Insightful)

      by joe 155 ( 937621 )
      it reminds me of a quote that I read the other day about the problem with weather forecasts: It is right far too often for us to ignore it, but wrong far too often for us to rely on it. And mobile phone... they cut off too much to even be used as a full time emergancy phone, maybe this is just a way of getting twice the problems. Also it would look like it was always raining over my mum's house, she seems incapable of getting or keeping a signal... so it won't be perfect
    • You don't need a cell phone to know which way the wind blows. ...please tell me someone gets that
  • Can't grok headline (Score:3, Interesting)

    by What'sInAName ( 115383 ) on Saturday May 06, 2006 @05:55AM (#15276098) Homepage Journal

    Maybe it's just me (I'm up at 5:30am to catch a flight) but I'm having trouble parsing the headline. Sounds like the rain is signaling cell phones.

    Kind of interesting, but (having not read TFA, mind you) I wonder how small amounts of rain affect the signal. One would thing the signal would only be affected by heavy rain, and so the resolution of the resulting data would suffer.
    • Yeah, I'm with you. I read it a couple times and it still doesnt make sense. :)
    • Maybe it's just me but I'm having trouble parsing the headline.

      No, it is not just you... I thought it was just me too, but that's because english isn't my first language. Actually, it's my third language. Almost fourth.
    • I think perhaps the problem here is arrangement. "Drops" is supposed to be the action. "Cell phones" needs to be singular and before "signal". It's telling you what kind of singal it is ("Rain drops signal" is a perfectly good sentance, but it doesn't give you enough info). As it stands now it seems like "Rain Drops" are "signal" -ing the "cell phones", instead of "Rain" "drop" -ping the "cell phone" "signal".

      Or perhaps "Rain Drops Cell Signal" would be better...
    • What happen ? Somebody set us up the bomb. Rain drops signal. What ! Cell phones turn on. It's you !! How are you gentlemen !! All your calls are belong to us. You are on the way to distortion. What you say !! You have no chance to survive make your call.
  • Spans the globe? (Score:4, Insightful)

    by Wild Wizard ( 309461 ) on Saturday May 06, 2006 @06:01AM (#15276111) Journal
    But the information necessary for this novel approach is effectively free, continuous and comes from a dense network of masts that already span almost the entire globe.

    Oh really, these people need to get a clue, down here in Australia the mobile networks cover absoultely crap all of the continent and my moneys on Africa, South America, Asia (The real asia which is freaking huge) and Sibera are pretty much in the same boat.

    And don't get me started on the 2/3rd of the planet is covered in water bit.
    • The parts of Australia that don't have cell ph. coverage, are either, desert, most of central australia, and therefore no rain. Or jungle, northern queensland, northern territories, which rain all the time! :)
    • I was very impressed in scandinavia that round the main shipping/ferry routes, every crappy little rock has a tower stuck on it so that you don't drop coverage when sailing between countries.
  • If bad weather causes a signal to drop, an automatic system analyzing the data boosts the signal to make sure that people can still use their mobile phones. The amount of reduction in signal strength gave the researchers an indication of how much rain had fallen.

    Okay, so the cell phone providors can boost their signal strength whenever they want? Then why don't they just do that all the bloody time? I'm sick and tired of my mobile Internet connection randomly disconn(S&*(*S&(DH*&(SD*HS&D*H

  • Turns out the Verizon's "Can you hear me now" guy is a meteorologist after all.
  • "The amount of reduction in signal strength gave the researchers an indication of how much rain had fallen."

    What about fog? What about different sized rain droplets and velocities and differing amounts of signal boost necessary for the same volume of water? Can the cell tower differentiate between signal loss due to rain as compared to objects near the phone, like a car body or metal object?
    • by RubberDogBone ( 851604 ) * on Saturday May 06, 2006 @10:48AM (#15276871)
      Would you like a prize? Have one. Indeed, cell signals have been used to track objects, like aircraft.

      In particular, a US F-117 Stealth fighter was shot down over Bosnia. The shooters could not track the plane on radar -because it's stealth, you know- so they looked instead at the changing signal patterns of the cell system as the plane flew over.

      They didn't look for the plane so much as the "signal hole" it made as it moved through the sky. They simply aimed some missles at the "hole" and scored a hit. It was the first F117 downed by enemy fire.

      Very creative. Everydamnbody in the world who's likely to be F117 targets took lots and lots of notes.
      • In particular, a US F-117 Stealth fighter was shot down over Bosnia. The shooters could not track the plane on radar -because it's stealth, you know- so they looked instead at the changing signal patterns of the cell system as the plane flew over.

        Not entirely true. From Wikipedia:

        According to Wesley Clark and other NATO generals, Yugoslav air defences tracked F-117s with old Russian radars operating on long wavelengths. This, combined with the loss of stealth when the jets got wet or opened their bomb

  • From TFA: The scientists believe the technique can also measure snowfall, hail or fog [...] The data is a by-product of mobile network operators' need to monitor signal strength [...] If bad weather causes a signal to drop, an automatic system analysing the data boosts the signal to make sure that people can still use their mobile phones.

    I follow the logic- except for one catch: how can researchers tell if the signal strength is reduced by rain OR snow OR hail (etc)?

    In other words, bad weather = signa

  • More accurate? (Score:1, Interesting)

    by Anonymous Coward
    They say they are more accurate than the regular met services ... and they measured this how?

    A dense fog and a light rain have the same effect on signal strength. Maybe they don't get fog.

    I had the opportunity to visit the control center for one of the national cell phone providers. It was a large room with large screens covering one wall. Some of the screens were weather maps. They used the weather predict where there would be degredation in the service.
  • by RoffleTheWaffle ( 916980 ) on Saturday May 06, 2006 @06:39AM (#15276180) Journal
    First, cellular phones were just that - cellular phones.

    Then came the ringtones and other customization features, and those were fun to toy with.

    Then there was web-browsing, which was even cooler, and actually served to make the phone more useful.

    Then came the cameras for still-image and video capture - why for nobody knows, but people love it anyway.

    Given all of that neat stuff, and the increasingly computer-like nature of cellular phones, what's the next feature on the horizon, you ask?

    Portable weather stations. It just makes sense.
    • Bullets and a trigger. Please please please. It could solve so many problems. Divert to mailbox? This button?


      Only in America.
    • Well, if they could figure out how to stuff a tiny barometer in the next generation of phones, meterologists could have some fairly fine grained data to play with.

      I'm not sure how useful it'd be, but more data can't hurt.

      P.S. TFA isn't about cell phone handsets, it's about the cell towers & other bits of wireless infrastructure.
      • I know it's about the towers and such, I was just making a joke about seemingly useless features that've found their way into phones.

        If you think about it, though, it shouldn't be especially difficult to cram a tiny barometer, thermometer, and humidity gauge into a handset. Creating a dongle for a phone that has all that and more would be a similarly painless process, and it could allow meteorologists and plain ol' hobbyists alike to carry around a tiny weather station wherever they go. This would be really
  • The team's method exploits the fact that the strength of electromagnetic signals is weakened by certain types of weather and particularly rain.

    What do you mean? I'm typing this on my Nokia phone in the rain and it's doing fin#$@^%@#%#@@!#NO CARRIER

  • Only means how hopelessly horrible their dedicated weather sensing hardware is.
  • Did you know (Score:3, Interesting)

    by Hemi Rodner ( 570284 ) * on Saturday May 06, 2006 @07:31AM (#15276269) Journal
    that the cellular coverage rate in Israel is bigger than 100% because many people own more than one cellular?
  • by Anonymous Coward
    In the late 1930's Robert Watson Watt was investigating the interference of thunderstorms with radio signals in order to warn of approaching bad weather. As we all know, this led ultimately to the discovery of radar. This story is just a modification of that technique. 1. Duplicate Prior Art with slight modification in frequency 2.**** 3. Profit!
  • by dtmos ( 447842 ) on Saturday May 06, 2006 @07:47AM (#15276294)
    The key point not brought out in TFA is that the rainfall prediction scheme is not based on the link from the handset to the cell tower, but on the wireless backhaul links of the cellular system. The backhaul link is the link from the cell tower to the rest of the world (or at least the phone system of the rest of the world)--in many places in the world it is fiber or some other line, but increasingly often it, too, is wireless, using something called digital fixed radio systems (DFRS; check out standard EN 301 751 at ETSI []).

    The wireless backhaul links are much better for the meterological application than the handset link, because:
    (a) It's a fixed link; since the cell towers don't move, like the handsets do, the location of the link, and therefore the rain, is known, and
    (b) It's at a much higher frequency. The DFRS links used in this paper are at 8-23 GHz, much higher than the 0.8-1.9 GHz (depending on your local regulatory environment) of the handset link. This is important because rain attenuation increases [] as the signal frequency increases; it would be quite difficult to reliably detect rain fades at the handset frequencies (although in a bad enough storm--a cyclone comes to mind--it's probably possible; TFA notes the anecdotal evidence of fading television signals in bad weather).

    I note in passing that the web-based supplimental material to the article references a US patent application, # 60/698,491.
    • Ah, that would be, "meteorological" and "supplemental."

      Sorry, rented fingers.

    • Yep, measuring handset attenuation would be pretty tricky. Since signals are weaker inside a building, which is where people often go when it rains, you'd expect to see a signal dropoff on rainy days. But it wouldn't necessarily be directly related to the rain intensity at that moment.
  • by mapkinase ( 958129 ) on Saturday May 06, 2006 @08:00AM (#15276318) Homepage Journal
    that this method is "more accurate" than gauging and especially radar? I did not find it in BBC article and I do not have access to full text in Science, but the abstract [] says:

    The global spread of wireless networks brings a great opportunity for their use in environmental studies. Weather, atmospheric conditions, and constituents cause propagation impairments on radio links. As such, while providing communication facilities, existing wireless communication systems can be used as a widely distributed, high-resolution atmospheric observation network, operating in real time with minimum supervision and without additional cost. Here we demonstrate how measurements of the received signal level, which are made in a cellular network, provide reliable measurements for surface rainfall. We compare the estimated rainfall intensity with radar and rain gauge measurements.

    No claims about accuracy as you see. Whoever have access to full text please provide some clue (by Monday when I will have the access, the topic will be gone, so please post now).
    • From the Science article:

      The skill of our method (correlation with rain gauges) is 0.86 for a 15-min-interval rain intensity and 0.9 for an hourly interval, versus 0.81 and 0.85, respectively, for radar, when evaluated from the maximal value over a 3 x 7 km2 area.

      • So, in other words, "cell" method beats radar in terms of accuracy in a rainfall estimate for a point area compared, of course, to gauge, which is in this case apparent standard and it beats gauge in coverage compared to the radar for obvious reasons. I guess the first one was non-trivial to guess.
  • by Vo0k ( 760020 ) on Saturday May 06, 2006 @08:27AM (#15276375) Journal
    There are so many ways to rearrange the words in the title to make sense of the article, and they have chosen one that is plain dumb. Cell phones don't get signalled by rain drops, nor rain makes you drop cell phone meant to signal.

    Rain drops drop cell phone signal.
    Rain drops cell phone signal.
    Rain signalled by cell phone signal drops.
    Cell phone signal drops signals rain.
    Cell phones signal rain drops.
    Drop in cell phone signal signals rain.

    and quite a few more.
  • by Ancient_Hacker ( 751168 ) on Saturday May 06, 2006 @08:56AM (#15276434)
    IIRC when Bell Labs was experimenting with microwaves, circa 1939, they noticed their signals were a LOT weaker when the weather was humid.

    So much so, that when they rolled out microwave telephone relay towers, circa 1950, they intentionally boosted the transmitted signal by some 20db (that's 100 times) more than necessary on a dry day, just to allow the signals to still get through during damp or fog or rain.

    So this isnt even old news, it's going on 68 years!

    • That rain affects radio signals is not news this has been known for a long time. That you can use this effect to quantify rainfall in a very localized way is. Now for those of you who have never been here Israel is a desert. (Some parts more than others) and there is normally no rain between April and September so when it does rain we want to make the best possible use out of it. If the country can get 5% more productive use out of each rain fall that will really help out a huge amount. Israel has invested
  • by Anonymous Coward
    Here goes a curious fact about the shape of raindrops and its effect on radio waves.

    Many people think that raindrops have the typical shape of a tear, others think by looking at the rain itself that the drops are vertical lines of water. The first impression comes from pictures and literature, the second is caused by the fact that the raindrops fall at high speed, thus appear vertically blurred.

    In fact, the tears start up being roughly spherical and end up becoming flat because of the air resistance.
    http:// []
  • How can they state that their measurements are more accurate than existing meterological infrastructure?

    I mean besides setting up their own measuring stations and... Oh never mind.

Information is the inverse of entropy.