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Communications Technology

Weather Monitoring Frequencies Subject to Pollution 139

Posted by michael from the rated-t-for-toto-we're-not-in-kansas-anymore dept.
jd writes "In a case of technology vs. technology, the ICU (the body governing the use of radio frequencies around the globe) has been asked to secure radio frequences used for weather monitoring. In-car radar, mobile phones and other commercial and military applications are now using these same frequencies. However, weather satellites can't simply be re-tuned. There is only one very narrow band that detects water vapor but not liquid water, for example. This frequency has been sold to developers of car radar systems. The more this happens, the less useful weather radar and weather satellites will be. The noise will simply swamp the data, making what is collected useless. The article doesn't give a 'doomsday' timeframe, when we'll have no better ability to forecast the weather than they did in the 1800s, but that is what they are talking about."
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Weather Monitoring Frequencies Subject to Pollution More

Weather Monitoring Frequencies Subject to Pollution

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  • Weather data weak (Score:5, Informative)

    by AlexTheBeast ( 809587 ) on Saturday December 18, 2004 @08:02AM (#11123906)
    Well, I am not sure how great we are at predicting the weather now.

    A kid at my son's school collected and analyzied common RSS weather feeds [tech-recipes.com] for a science project.

    He collected the data and used it to judge how accurate the weatherman's predictions were.

    Within 5 degrees and 25% chance of rain, he gave them credit. They got credit 50ish percent of the time.

    He then analyzied other ways of predicting the weather.

    By just saying that the weather today will be the same as the weather yesterday, he got credit 50ish percent of the time.

    I don't say this to belittle the weather people. I do this to say that the techniques we use now are not the greatest in the world. If we need those frequencies because they are the only ones that work, then maybe the gov't should buy them back. However, if those frequencies are used because that's the old school way of doing it, well, they aren't working at that great now.

    • Like my grandmother always used to say. "They're right 80% of the time. It's just that the 20% they're wrong is what's affecting you". I personally find it ironic that we can computer simulate the entire weather for a day using Chaos theory and powerful supercomputers about a WEEK after that day has happened.

      Don't ask me to cite where I got that from I remember watching it on Discovery once.
      • Isn't the point of Chaos theory that you can't simulate everything? That you're always missing something?
        • Uh, no.
          Chaos theory allows a scientist to identify which systems are chaotic, and which are not.

          Under certain conditions, it may be possible to coerce a system back into predictability. Obviously, the practical application of such coercion is limited when one is studying global weather systems. On the other hand, if a heart starts beating in a chaotic fashion, and if that heart is equipped with a pacemaker, the heartbeat can be corrected with a mild electric shock. The timing and voltage of that shock can

    • Re:Weather data weak (Score:3, Interesting)

      by izel ( 785077 )
      Well when I feel like cheating and not drawing up my own weather forecasts. I cheat by going and type "San Francisco Forecast Discussion" into Google or Alta Vista and read that. It is pretty accurate and they even translate the weather-ese for you. If the term appears in browser link colour just click on it and it will be translated in a nice little box for you. It isn't that hard to learn to do basic forecasting. I have managed to teach it to seventh to ninth graders, who are always cheered when they beat

    • Re:Weather data weak (Score:4, Funny)

      by Vellmont ( 569020 ) on Saturday December 18, 2004 @08:26AM (#11123947) Homepage
      The evidence you present for prediction innacuracy is "a kid at your son's school" and his "science project"? Have I fallen into the twilight zone where this is considered even remotely credible evidence?
      • Why is this modded flamebait? Seriously, on a tech & science - savvy site, you'd think people would know the difference between good evidence & an anecdote.

        And, no, I'm not new here, I'm just thick-headed.

      • Comment removed based on user account deletion
    • How good they are depends on how much it matters.

      The weather forecast in Melbourne Australia are very poor unless they are for a few hours away. The melb weather isn't going to kill you either unless its an exceptionally hot day. The cold days aren't below freezing and they seem to have no ability to forecast tornadoes which are very rare. Tropical storms void the area and there is geography that breaks up thunderstorms. 140 years ago some of the locals where reported not to own any clothes (which may

    • Re:Weather data weak (Score:2, Interesting)

      by mattj452 ( 838570 )
      I've seen somewhere that if you say "Tomorrow will have the same weather as today", you will have a probability of 73% to be correct. The meteorologists calculate the weather by creating a stochastic model, then simulate it maaany times in order and then get a kind of average weather from all the simulations. The probability of them being correct is about 78%...

    • Re:Weather data weak (Score:4, Insightful)

      by liangzai ( 837960 ) on Saturday December 18, 2004 @08:35AM (#11123967) Homepage
      Remember that a meteorologist is a TV starlet. He/she needs to show up, in addition to a pretty face/boobs/legs or for whatever reason them "huaping" now are hired, some spectacular results. Thus, they run several simulations on them Beowulf clusters and then pick something that may be presentable on the screen.

      Weather prediction relies heavily on Navier-Stokes' equations, which are more sensitive than my girl friend's pussy; change a parameter one percent and that smooth sailing wind may turn into a storm. Meteorologists don't understand how to deal with these equations, but they know that they are a tricky son of a bitch.

      Basically, the only way to make the predictions better is to further minimize the FEM elements used in the calculations, which means even bigger Beowulf clusters (or equivalent). It also means that we need to have the best and most accurate data available to these simulations. I can easily see the predictions go way down south if the water parameters are fucked up the slightest. So we need to reserve them frequencies, or come up with a technique to filter out disturbances (vertical/horizontal direction comes to mind when talking about satellites).

      Weather predictions are generally speaking utterly unimportant, but sometimes they help save lives by warning for tornado build ups and similar. It is merely a matter of weighing the costs against the gains, as always.
      • Most weather forecasters are just reading NOAA or NWS feeds anyway.

        And your girlfriend's pussy isn't all that sensitive. Her backdoor, OTOH...
      • more sensitive than my girl friend's pussy
        That may be, but how many Library of Congresses does it hold?
        • "Library of Congresses"

          Erm, if there are multiple libraries, shouldn't that be "Libraries of Congress?"

          I don't really know, but it sounds funny either way.

      • Re:Weather data weak (Score:2, Insightful)

        by Dorsai42 ( 738671 )
        Good point here. It's important to not confuse repoting with entertainment. REPORTING NO LONGER EXISTS. In our media, everything is viewed as entertainment and must therefore pay its own way through advertising.

        Expecting usable information from entertainment is denying the reality of our media.
      • Weather reports are incredibly important to farmers, knowing how much rain will fall this growing season, when there will be a hard frost, et cetera is priceless.

    • Re:Weather data weak (Score:2, Interesting)

      by tpgp ( 48001 )
      A kid at my son's school collected and analyzied common RSS weather feeds [tech-recipes.com] for a science project.

      He collected the data and used it to judge how accurate the weatherman's predictions were.

      Weather reports != Meteorologist predictions.

      You would be amazed at how often and by how far the reports differ from what the meteorologists have predicted.

      A bunch of random RSS feeds are going to tend to be inaccurate. Your kid confirmed that - kudos to him - sounds like a great project.

      But hardly w

    • Re:Weather data weak (Score:3, Interesting)

      by redcliffe ( 466773 )
      I do a lot of forecasting based on computer models. You current accurately predict specifics, but you can work out trends quite accurately. Like I can look at time 3 days out and see that there is potential for severe thunderstorms. That doesn't say that they'll happen, but there's a potential for them. It's never absolute, but you can get an idea. With a combination of computer models and local knowledge you can get pretty good, but don't expect to be able to say exactly what the temperature will be, or if
    • This certainly explains the strange "rain" on weather radar maps in and around cities, when there isn't a cloud in the sky.

    • No need to buy back, as they can't be sold (Score:1, Interesting)

      by Anonymous Coward
      legitimately in the first place.

      The spectrum is a natural resource which belongs to everyone equally. No one, and no government, has any right to "own," or sell what belongs to everyone. The only legitimate role of government in spectrum is to regulate it to maximize the public good. It is false to assume that "selling" spectrum provides any public benefit at all (although those who support that would argue that increasing government revenue is somehow "good.")
      • The spectrum is a natural resource which belongs to everyone equally. No one, and no government, has any right to "own," or sell what belongs to everyone. The only legitimate role of government in spectrum is to regulate it to maximize the public good.

        The same could be said about land, or water, or trees, or grain, or edible animals, or sexual partners, or the products of other people's labor, or any other desirable thing that is either consumed or busied out by use. (In fact, it often HAS been said.) A
        • Blockquoth the poster:

          Territorial organization promotes prosperity for the little guys, self-esteem, and behavioral diversity.

          Sure. Because it never happens that, as one accumulates "territory", one uses it to enforce dictates on those who don't have it, or have less. It never ever leads to a runaway concentration of power -- to higher prosperity for some combined with general misery for most.

          Except of course that's exactly what happens.

          Consensus decision making falls apart, true enough. It can lead

          • At the risk of falling into an "it's not REAL [x]" argument let me disagree with some of your posting.

            Sure. Because it never happens that, as one accumulates "territory", one uses it to enforce dictates on those who don't have it, or have less. It never ever leads to a runaway concentration of power -- to higher prosperity for some combined with general misery for most.

            Except of course that's exactly what happens.

            "Teritory" can be used to enforce an owner's will on those who try to use the owner's prop
    • People tend to view weather accuracy on a micro scale, but meteorologists can only work on a macro scale. If you look at satellite images [ec.gc.ca] from Canada's weather service [ec.gc.ca], you can see that the city you live in is less than 1/20th the size of a pin-prick relative to a weather system.

      When a weather report going out 24 hours into the future says it will rain, it WILL rain... just not perhaps overtop of your little pin-prick. Considering the complexity of weather, realistically how effective can we expect a 3
    • Well, I am not sure how great we are at predicting the weather now.

      As someone who's lived through a half-century of weather prediction technology, I can assure you that it's gotten a LOT better.

      There's good reason to believe that, absent some major theoretical breakthrough, there's a "chaos limit" beyond which it can't go - causing the predictions to become unreliable after a few days - the number depending on the stability of the situation. And the current tools are able to both approach the limit and
    • cant understand why no one realizes this... your local weather is heavily influenced on geographical factors, just an short example:

      clouds ->
      spot A - ^HILL^ - spot B

      so whats happening?
      - clouds move over spot A, perhaps a bit rain
      - clouds start "climbing" up the hill -> air cools down (Wet Adiabatic Lapse Rate, about -6 degrees/1000m) -> condensation -> rain!
      - clouds climb down the hill -> air gets warmer (Dry Adiabatic Lapse Rate, +10 degrees/1000m) -> we have much dr
    • You need to consider that there are three factors involved in successful weather forecasting: Observational data, numerical simulations, and the forecaster's experience and expertise. Of the three, the only one that is absolutely reliable is observational data - satellite imagery, satellite soundings, the-guy-on-the-ground-looking-up, weather radar, etc. They provide snapshots of actual conditions at specific times. Numerical modeling works better all the time, but much of its accuracy is based on the origi
    • I've got a friend who used to do weather pattern modelling at the Met office [met-office.gov.uk]. Apparently they've got statistical modelling predictions for at least 6 months. The problem is, after a week or so, the probabilities of getting a type of weather on a certain day drops too low to have any kind of certainty about it.

      Somehow, I can't see swamping their sensing wavelengths with noise is going to improve that.

      The most useful (?) piece of info he came out with is that there's one prediction that is consistently 75%
    • I don't understand how you can check whether a predicted probability of rain is "within 25%". It either rains or it doesn't.
    • The problem is that most forecasts cover a huge area, especially ones designed for broadcast radio and television. Some TV markets have both desert and sub-tropical parts. Some cover mountains and sea. If the weatherman says it's going to rain, it's probably going to rain in some part of that market area.

      Look at a market like Chicago. The forecasters are serving an audience from Michigan to Indiana to Wisconsin to Iowa in addition to their home audience of Illinois. If they say it's going to rain, it
    • I think the weather prediction is quite good over here. It probably helps that the satellite can see a whacking great band of cloud over the atlantic headed our way, and can work out when it will hit. The computers tend to be less good at guessing about freak storms coming from france though I would think.

      To show off late at night, the BBC shows weather forecasts for random other continents (especially if there are certain sports events there). Hmm, Riyadh - it's going to be hot and sunny tommorrow :-)

    • I've got some experience with forecasting. I feel the need to answer this.

      First of all, there's several computer models that play a key role in forecasting. Basically, with a set of observations (surface observations, soundings, etc.) the model builds an initialization - an image of the current weather. There's really not that many observations, and even less soundings. Lack of available data really is a limiting factor in predicting the weather. Most models are gridded. This means that there's a limited r

  • Oh well (Score:5, Funny)

    by t_allardyce ( 48447 ) on Saturday December 18, 2004 @08:03AM (#11123908) Journal
    Don't bother asking the FCC for help - they're too worried about someone saying fuck or showing their tits. Seriously tho, what sort of idiot would actually sell these frequencies if they knew what they were used for?

  • Ca Radar (Score:4, Insightful)

    by iamthemoog ( 410374 ) on Saturday December 18, 2004 @08:04AM (#11123909) Homepage
    Why would your car radar be useful if the signal it emits is attenuated by water vapour? Drive through some fog & you're in trouble.. ?

    • The obvious answer there is: you should not be driving fast in fog anyway so that 'malfunction' is a 'feature', assuming it really does work like that (which I doubt).

    • Re:Ca Radar (Score:2, Interesting)

      by mattj452 ( 838570 )
      I believe the reason is that you don't want to get reflections from objects far away. A good way of doing this is to use frequencies that dampens the signal alot.

    • Re:Ca Radar (Score:3, Informative)

      by advocate_one ( 662832 )
      fog is NOT water vapour... it is a fine suspension of water droplets...
      • right, and the humidity in a fog is what again?

        • Re:Ca Radar (Score:3, Informative)

          by advocate_one ( 662832 )
          the humidity in general when there is fog about is 100% anyway... the fog is just a manifestation of it where the temperature has dropped below the dew point. Even when there is no visible fog just where you are, the humidity is still 100%. The attenuation factor is negligible over the distances involved in the radar application. This radar is short range... ie less than 400 meters.

          In fact, I'd be more worried on a hot humid day, because there is far more water vapour per cubic meter in the air than there i

    • Car Radar (Score:3, Informative)

      by ad0gg ( 594412 )
      Car radar is used to for cruise control on Mercedes line of cars which is used to both adjust the throttle and even apply the brake when needed. They are the only ones I know that using radar based cruise control. Infiniti and Lexus both use laser based cruise control. If you have a radar detector you can actually detect people driving with their cruise control on.
      • Car radar is used to for cruise control on Mercedes line of cars which is used to both adjust the throttle and even apply the brake when needed.

        It seems to me that if the cruise control does too much, one might fall asleep and wake up in Cleveland or other scary places :-)
        • It seems to me that if the cruise control does too much, one might fall asleep and wake up in Cleveland or other scary places :-)

          Or an inch from a tree going 60 miles per hour.

  • Cool, so Ka has double meaning now? (Score:3, Funny)

    by Motherfucking Shit ( 636021 ) on Saturday December 18, 2004 @08:05AM (#11123913) Journal
    There is only one very narrow band that detects water vapor but not liquid water, for example. This frequency has been sold to developers of car radar systems
    So now a hit on the Ka band could mean "Cops" or "Killer Avalanche?" And people are complaining? Give me weather alerts on my radar detector any time!

  • How would they enforce this? (Score:4, Interesting)

    by Xolotl ( 675282 ) on Saturday December 18, 2004 @08:09AM (#11123921) Journal
    Question to those who might know this - assuming the ITU agrees to these restrictions, how would they enforce them? The radar frequency was presumably sold by a national agency (a la FCC) which is clearly making money off the sale and doesn't seem to care about the reasons. So how would the ITU go about forcing them to behave?

  • One thing is for sure (Score:5, Funny)

    by eclectro ( 227083 ) on Saturday December 18, 2004 @08:11AM (#11123923)

    Our cars are more important than anything else. Everyone should know that by now, including weathermen who can't predict the weather anyway.
  • Blockquoth the article,

    There is particular concern about protecting the 23.6-24 GHz band, which has the unique property of being sensitive to water vapour but not to liquid water.

    Dr English said: "There is no other frequency where this occurs. But car 'radars' will now be allowed to broadcast in this frequency band."

    What are the car 'radars' that Dr. English speaks of? As far as I know, radar (and laser) detectors don't broadcast anything, they simply detect certain frequencies.

    The article is based in

    • Radar Detectors (Score:5, Informative)

      by Detritus ( 11846 ) on Saturday December 18, 2004 @08:37AM (#11123969) Homepage
      Radar detectors, and most radio receivers, do transmit low-powered signals on the same or similar frequencies to those that they receive. It's called local oscillator leakage/radiation. It's especially common in consumer grade electronics equipment. If you look at the block diagram of a superheterodyne receiver, you will find one or more local oscillators that are used to mix down the incoming signals to fixed intermediate frequencies for filtering, amplification and demodulation. These local oscillators are often a source of radiation due to poor design and shielding. Radar detector detectors and TV detector vans take advantage of this by listening for local oscillator radiation.

    • Re:In-car radar (Score:4, Informative)

      by rusty0101 ( 565565 ) on Saturday December 18, 2004 @09:25AM (#11124048) Homepage Journal
      The radar in question is for follow collision avoidance. You set cruise control, and this stuff makes sure that you are not cruise controlling yourself into the rear end of the car ahead of you.

      -Rusty
      • Under the Americans with Disability act, many State DMV offices have been court-ordered that they cannot discriminate against vision-imparied individuals getting a license.

        That's why cars need the RADAR systems. The car talks to the driver and describes obsticals.

    • What are the car 'radars' that Dr. English speaks of? As far as I know, radar (and laser) detectors don't broadcast anything, they simply detect certain frequencies.

      What you are talking about are speedgun detectors, I assume (not sure, because here in Europe they are not very popular)?. The radars in the article are probably collision avoidance radars. The real stuff, transmitting and receiving signals to detect cars in front (slowing down). For my master's thesis I made an antenna for such a system ope

  • in the 1880s (Score:5, Funny)

    by Anne Thwacks ( 531696 ) on Saturday December 18, 2004 @08:13AM (#11123926)
    Yeah, I remember the 1880's - we had remote sensing of the weather by floating light-bouys, and processed the data with a Cray super computer.

    Oh, wait, I think that was the 1980s. In the 1880s, we had that thing with a man with a brolly and a woman in a summer dress hanging from seaweed. You could tell the weather according to which one came out of the house. AFAICT, the reliability was much the same as today.

    My uncle Jack sticking a wet finger in the air and saying "Arrh, it looks like a [fine|rough] day tomorrow - I think I need a wee dram!" was more fun though!

    • Re:in the 1880s (Score:3, Insightful)

      by Zoop ( 59907 )
      Serious addendum to this--

      While forecasting microevents like whether you get rain or sun 7 days in advance has not improved so much, there's one HUGE advantage we have now that folks then didn't:

      Gigantic storms like hurricanes and large hurricane-like winter storms can now be spotted and residents warned with fair accuracy 24 hours in advance. That may not seem like much, but it literally is the difference between life and death for thousands of people.

      Let's not totally diss technology just because your
      • Gigantic storms like hurricanes and large hurricane-like winter storms can now be spotted and residents warned with fair accuracy 24 hours in advance.

        That is a great advance and it does save innumerable lives, but it's not really all that impressive, and it doesn't involve much in the way of prediction. We can just look down with a satellite and see where the storm is and in which direction it's heading...

  • Federal Regulatory Powers (Score:5, Informative)

    by Detritus ( 11846 ) on Saturday December 18, 2004 @08:23AM (#11123940) Homepage
    The FCC has the power to ban the sales and use of any device that would cause interference to these frequency bands. I've owned radio transceivers that were made obsolete and worthless by FCC decisions to reallocate spectrum to other uses. The FCC had no obligation to compensate me for the loss in value of the radio equipment or to offer me other spectrum to replace what was lost. If car radar units are a problem, the FCC can prohibit their sales and use.
  • Using the results of a period of observation, assign a classifying neural net to distinguish water vapor reflections from the morass of noise. With human training (specifically, teaching it to distinguish RF interference from water vapor) it would very well have a chance to produce a markedly more accurate picture.
    • Unfortunatelly, I don't think it's that easy. I think the best you can do is to create (encode) a pulse in such way that all other pulses would be considered pure noise. The real problem here is that there are requirements on how high the noise can be and still have a working radar... If you have too much noise, then it would drown the radar signal completely
    • For all you algorithm specialists/electrical engineers, radio frequency interference (RFI) detection and mitigation is a newly emerging field that is mostly in its infancy. Interference in the water vapor emission bands is really just one example of all the RFI work that needs to be done. I went to a conference on this very subject, and yes people applied neural nets to the problem with a whole host of other methods but in the end it all just didnt work that great. And there are not too many people worki
    • Nice idea, but you'll quickly find out that neural nets in radiative transfer are... well, to put it lightly... completely useless except for classification. So, yes, you may be able to tell what is water vapor and what isn't, but you won't be able to tell anything from a mass that has a little radio noise and some water vapor signal? What do you do then? Trust the measurement?

      Neural nets are nice tools, but are not the solution to a lot of problems in radiation. If you just seek to classify, that's do

  • Hoisted on our own petard... again... (Score:5, Insightful)

    by Genda ( 560240 ) <marietNO@SPAMgot.net> on Saturday December 18, 2004 @09:25AM (#11124050) Journal
    Ever been to LA...

    You can drive in any direction for between 5 and 20 hours depending on day and traffic conditions, and never leave the monotonous suburban landscape. It's the results of unplanned, unconsidered, growth. From space it looks like the great god of suburban blight dropped it "Splat" from high altitude like some surreal cow patty.

    What the hell (you might ask) has any of that got to do with this article. The answer is that the same kind of thinking (or kack there of), is behind the morass that is our use of the electromagnetic spectrum.

    Empire building, despotism, political back-biting, greed and intrigue, technology working around the ideocy that is our regulatory system, and nobody asking whether the left hand knows what the right hand is doing... A Chinese Fire Drill would look like close order drill compared the slow motion Loony Tune that passes for what we've got.

    Sanity might look like;
    1. Determine that spectrum which serves to valuable or significant a purpose to avoid protecting, and declare that sacrosanct. Being able to track water vapor by the way is one of those sacrosanct uses.

    2. Give up on that selling the spectrum for fun and profit idea... it was a bad joke then and it hasn't gotten better with time.

    3. Put the millitary on a sane leash (they really don't need 50% of the workable spectrum.)

    4. Promote the hell out of advanced mutispectrum technologies and count the money.

    We really need to get a few folks in the FCC who haven't technological myopia, and have the cojones to push through an agenda based on growing use, and growing technology.

    Genda Bendte
  • Which group is ICU? That org doesn't ring a bell. It only makes me think of hospitals...

  • ICU?? (Score:3, Informative)

    by bromoseltzer ( 23292 ) * on Saturday December 18, 2004 @09:54AM (#11124097) Homepage Journal
    You are talking about the ITU - International Telecommunications Union [itu.int] - aren't you?

    ICU's are found in hospitals.

  • Spectrum allocation compromises (Score:5, Interesting)

    by dtmos ( 447842 ) on Saturday December 18, 2004 @10:08AM (#11124132)

    Spectrum allocation is a large, time-varying, multivariable optimization problem. This document [doc.gov] is an outline of some of the service requests/requirements, and how they need to mesh with each other, present and future technology availability, and physical limitations (like attenuation due to water at 24 GHz). Note that this document is only U.S. interests; every other country has a similar list, and all have to be coordinated. It's like the guy who goes into a store with three lists: What he wants to buy, what he needs to buy, and what he can afford to buy. Compromise is the name of the game, and reasonable people will make reasonable tradeoffs differently.

    The radar this article is discussing is a proposed future use of 24 GHz for collision-avoidance radar in passenger cars. 24 GHz is a popular frequency choice for short-range applications like this specifically because of the atmospheric attenuation. Note that the attenuation at 24 GHz, while higher than at other nearby frequencies, is still relatively low [doc.gov], only a few tenths of a dB per kilometer (although much higher in rain). This makes 24 GHz a good compromise for short-range devices on the Earth's surface, especially low-powered devices with very directional antennas pointed horizontally, away from satellites. (A better choice from this standpoint would be the oxygen absorption band at 60 GHz, and there is indeed another radar band there.)

    Meterologists are merely expressing their concern over how their measurements will be corrupted if millions of car radars are in operation, and their cumulative power is enough to be detected by their sensors. My personal opinion, however, is that 24 GHz is too low of a frequency to make a market-successful car radar; the antennas are too big. I think 60 or 77 GHz is a better bet; if so, that would preserve 24 GHz for water vapor measurements.

    In general, though, the interests of meterologists and others performing microwave sensing of the earth should be considered in the frequency allocation process; the publicity due to this article is one way of accomplishing this.

  • The same story as BPL (Score:3, Insightful)

    by borjam ( 227564 ) on Saturday December 18, 2004 @10:18AM (#11124152)
    It's the same with BPL. Now it's more important to use the frequency spectrum for businesses, despite its critical importance for public services. We will see the consequences in some years; just wait for the coordination in case of a catastrophe failing due to HF pollution, or to miss the prediction of an important storm due to polluted data.

    It seems that nowadays there is a sort of inherent "right" to turn anything into business, completely ignoring the impact to the public.

  • Some specifics (Score:5, Insightful)

    by ApharmdB ( 572578 ) on Saturday December 18, 2004 @10:30AM (#11124178)
    Ok, water vapor sensing is exactly what I did for my master's thesis. I'm going to keep it brief though.

    Water vapor has an absorption line centered at 22.235 GHz while liquid water's absorption increases with frequency^1.95. Vapor sensing radiometers do not generally measure at 22.235 GHz because the peak of the absorption line curve is extremely sensitive to pressure. There are points to either side where the curve is insensitive to changes in pressure allowing measurement throughout the entire atmosphere without having to know the pressure profile. That is why the scientists in the article want to keep the 23.6 to 24.0 GHz band for their measurments.

    My radiometer measured the emission spectrum at 21.6, 22.235, and 31.6 GHz. 21.6 and 31.6 GHz were the measurements of vapor and liquid water, respectively. 31.6 GHz is a window between the 22.235 GHz vapor line and the group of oxygen lines around 60 GHz. This makes liquid the strongest contributor to the noise temperature at that frequency. The 22.235 GHz was to experiment with. By using 22.235 and 21.6 I tried to see if I could get reasonably similar results even though both frequencies were more sensitive to vapor than liquid. Two close frequencies are measureable using one antenna thereby making the radiometer less expensive and available for more widespread use. I showed that the measurement could be made, but a lot more data needed to be taken to refine the data processing. Enough information was there in the measurements, but there were factors I couldn't account for in the time I had. Hopefully in time, radiometers could become a much more common piece of weather sensing equipment. You can get a lot more data on vapor with a radiometer than you can with a weather balloon, but radiometers are currently expensive and therefore limited in usability. Water vapor is the single biggest driving factor in the weather, we NEED to be able to measure it. Cheaper radiometers would let us get more data and improve weather modeling.

    • Re:Some specifics (Score:4, Informative)

      by ApharmdB ( 572578 ) on Saturday December 18, 2004 @10:33AM (#11124191)
      Doh. I'm a tard. I meant 20.6 GHz, not 21.6 GHz. It's early, cut me some slack. :P

    • Re:Some specifics (Score:2, Interesting)

      by ElysianAudio ( 651965 )
      A few questions for you, ApharmdB. I'm just curious.

      Your radiometer was ground based correct? Were you looking directly at down-welling radiation where a drop in your signal output corresponded with an increase in water vapor density?

      In order to use one antenna, it sounds like you had two tuned RF Front ends, one for each frequency. Did you use a standard heterodyne receiver architecture? What was your base-band bandwidth prior to your power detector or did you digitize? Polarization?

      Sorry for all the
      • Not necessarily. There were a series of orbiting radiometers in the 70s on the Nibmus series sats. (I did my work with SCAMS - SCAnning Microwave Spectrometer on the Nimbus F sat and chewed through around 4000 7 track tapes of data from the NEMS - Nimbus E Mircrowave Spectrometer when I did my PhD on the topic at MIT) These later became the MSU units on the Tiros sats.

        The defense department has a number of sats up there in the DMSP program that use scanning microwave spectrometers. Sadly, you are lot likel

    • Re:Some specifics (Score:1, Redundant)

      by krray ( 605395 )
      It would be nice if we _could_ build radiometers cheaply. What could I imagine being utilized on every vehicle in the country? Data collecting GPS enabled radiometer that could easily tell the drive local temp/humidity (as they do now :) and "phone home" with the data.

      What could you do with data collected from even 1 in 20 vehicles in the country? I could also see where this type of device could be dual-utilized as a collision warning detection type system...

    • Re:Some specifics (Score:2, Informative)

      by BurntNickel ( 841511 )
      I thought I was the only person who had worked with measuring water vapor with microwave radiometry. The systems I worked with were all satellite based (~28, ~22 and ~37 GHz) and I have to imagine that radiating in these bands at the surface could easily overwhelm the thermal emissions from the surface and atmosphere. See the following for more info: http://topex-www.jpl.nasa.gov/technology/instrumen t.html [nasa.gov] and http://gfo.bmpcoe.org/Gfo/Mission/missiond.htm [bmpcoe.org]

  • SNAFU (Score:1, Redundant)

    by photon317 ( 208409 )

    Isn't the current weather prediction pretty much like the 1800's anyways? I get a better predictability just by watching the barometer on my patio that by looking at the official forecasts.
  • See how close those frequencies are on this chart: http://unihedron.com/projects/spectrum/ [unihedron.com]
  • How could the "I-C-U" not see this? How did the car radar bandwidth get sold from underneath them? If it wasn't legit, then I say the ICU start flooding the vapor/car bandwidth with higher-powered light of that color. We'll see who's got the upper hand, and who relocates to another frequency.
    • as far as it goes, 2.4 ghz wireless is on an "unlicensed" band as is the car radar probably. It's probably all under 100 mW, so it's not exactly high power. The 902-928 mhz range is used by a lot of people, it's "unlicensed" as well. Cordless phones, certain hospital equipment, garage door openers etc. etc. are used here. Amateur radio is a secondary user. From a legal standpoint, the weather people should have lobbied for exclusive use on this band if they needed it that damn badly. Then again,
      • Actually, the ICU should have omitted the narrow vapor resonance band from the "unlicensed" segment, as part of their stewardship of the spectrum. But I don't know if "unlicensed" is the actual status, as only the FCC (or foreign equivalent) even issues licenses, or requires their use. This whole boondoggle could be resolved by improving the technology, as the vapor band, as any other quantum phenomenon, must have a very narrow bandwidth, or set of fundamental frequencies with "shoulder" bandwidths around t
  • Perhaps if we pollute the air enough, the frequency of reflection will shift to an unused band. Who says nature is not accommodating?
  • Yeah, i'm going to have to go with a lot of the other posts on this one, weather prediction is really pretty useless. I live in the pacific northwest, our weather isn't just rain every day, our weather changes rapidly due mostly to ocean conditions. The weather predictions over here are just terrible, almost completely useless. The only thing all of this satellite weather data seems to be good for is making fancy graphics for the weather man to stand in front of and make his false predictions.

    Knowing wh
  • Let's see... does the FCC get more money from car manufacturers, or from the people that monitor the weather? I think that we have our answer.

    Everything's for sale. Duh.

    DT

  • The weathermen amy not be any better than 50% at predicting ordinary weather, but tornados, rain-caused floods, huricanes, monsoons, snow-storms, heat waves, high winds, droughts, etc. are predicted far better now than in the past.
    Would you like to be vacationing in Florida and get a huricane warning, or just get washed out to sea?
    Would you like to be in the tornado cellar in Kansas, or take a trip to LA via tornado?
    Get real.
    Modern weather prediction saves lives, money, property, insurance, boats, airplanes

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