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Rain Drops Signal Cell Phones

Posted by Zonk on Sat May 06, 2006 04:35 AM
from the re-using-technology dept.
Wireless Networking Communications Hardware Science
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.'"
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  • what was that? (Score:5, Funny)

    by celardore (844933) <celardore@gmail.com> on Saturday May 06 2006, @04:38AM (#15276072) Homepage
    Sorry what was that? The signals patchy, with some sunny spells towards the afternoon...
      • 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

  • Headline? (Score:5, Insightful)

    by Anonymous Coward on Saturday May 06 2006, @04:44AM (#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.
    • They either meant "Rain Drops Cell Phone Signals", "Rain Drops Signal of Cell Phones" or "Measuring Rainfall With Cell Phone Signals"

      • Re:Headline? (Score:5, Funny)

        by $RANDOMLUSER (804576) on Saturday May 06 2006, @05:30AM (#15276167)
        Actually, they meant "Fireplace Ladder Telephone Sandwich Tree".
      • It's easy to figure out if you just try some word substitution:

        "Gum Drops Signal Cell Phones"

        "Eye Drops Signal Cell Phones"

        "Cough Drops Signal Cell Phones"

        Er, wait . . .
      • These weird headlines remind me of this article [slashdot.org]. Instead of writing to report a story accurately, people only care about getting the right keywords in there so that their page can get indexed. It's like the headline is just a bunch of keywords put together so that if someone searches for rain drops, this will appear. We should be writing to report, not writing to enhance page rank. The headline is just saying, "the rain drops are signaling the cell phones". As time goes on, we will have more and more terrib

    • Re:Headline? (Score:5, Funny)

      by Elemenope (905108) on Saturday May 06 2006, @05:25AM (#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.

  • The weatherman? (Score:5, Funny)

    by RealGrouchy (943109) on Saturday May 06 2006, @04:53AM (#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>
    • 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, @04:55AM (#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.

  • Spans the globe? (Score:4, Insightful)

    by Wild Wizard (309461) on Saturday May 06 2006, @05:01AM (#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.
    • 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.
  • Turns out the Verizon's "Can you hear me now" guy is a meteorologist after all.

  • 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

  • Feature Creep. (Score:5, Funny)

    by RoffleTheWaffle (916980) on Saturday May 06 2006, @05:39AM (#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?

      Ooops.

      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, @06:31AM (#15276269) Journal
    that the cellular coverage rate in Israel is bigger than 100% because many people own more than one cellular?

  • Details of TFA--it uses the backhaul link (Score:5, Informative)

    by dtmos (447842) on Saturday May 06 2006, @06:47AM (#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 [etsi.org]).

    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 [telesat.ca] 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.

      Geez.
    • 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.

  • How did they substantiate the claim (Score:3, Interesting)

    by mapkinase (958129) on Saturday May 06 2006, @07:00AM (#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 [sciencemag.org] 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.

  • Weird title. (Score:4, Funny)

    by Vo0k (760020) on Saturday May 06 2006, @07:27AM (#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.

  • Not new, not even old, it's ANCIENT NEWS (Score:4, Informative)

    by Ancient_Hacker (751168) on Saturday May 06 2006, @07:56AM (#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

  • The shape of raindrops (Score:2, Informative)

    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:// [suite101.com]

    • Re:turbo button for cell phone reception (Score:5, Informative)

      by Gordonjcp (186804) on Saturday May 06 2006, @05:24AM (#15276148) Homepage
      Well, there's an upper legal limit on effective transmitted power, but often a sector is run at lower power to reduce interference with neighbouring sectors.

      If you find you're getting a drop in signal due to rain fade, you can bump it up a bit. Most stuff uses ATPC (automatic transmit power control) so does it by itself, but you can get graphs off it with SNMP.

    • i did not know they coudl boost the signal any more then what it was at.... i kinda figured they would already have it as high as they could. i mean why woudl they not jsut keep the signal "boosted" all the times soem places still have dead zones so that coudl help some??

      Probably to avoid interference with other nearby phone cells using the same frequency.

      This is pure guesswork on my behalf, but here goes:

      I would imagine that the cell network is laid out so nearby cells use different frequencies with

      • Correct. The size of the cells used by telephones varies enormously, and hence the power to cover the cell properly also varies. In crowded areas with heavy cellphone use, such as city financial centres, the cells may be only 100 yards across. The power is turned doen so as to avoid invading nearby cells. On the other hand, in isolated regions, they want to make a few masts cover as much area as possible, so they turn up the power so the cells may be tens of miles across. But whatever power you are using, y
    • On the actual handset, it will only use as much power as it needs to get a signal. If you're in a zone with really crap reception, your handset will ramp up its signal power to try maintain contact. Conversely, if you're only a few hundred metres from a cell tower, it uses hardly any.

      I can only guess that for towers the power alters based on an average of the signal strength to all its handsets, so it is also possibly to save power on the handsets. As for interference, there's no point keeping each tower up
    • A post this badly written doesn't really deserve a response, but here goes:

      • CDMA (I don't know about GSM) has dynamic power control built in, so that transmission power is kept at the bare minimum required -- why use more power if it isn't really required?
      • Extra power drains batteries faster.
      • May interfere with neighboring cells.
      • In a spread spectrum system (both 3G standards use spread spectrum, so this will apply to most networks in the near future), every transmission occurs on the same frequency band, so someone raising their power level is seen as noise on the other communications, which in turn requires everyone to raise their power level.

      Oh, and the turbo button actually slowed down the processor down to the speed of a 4.7 MHz 8086. When in turbo mode the computer would run at nominal speed.

    • Re:Detect rain... and anything else that blocks si (Score:4, Interesting)

      by RubberDogBone (851604) * on Saturday May 06 2006, @09:48AM (#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

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