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Science Technology

Replacement For Aging Doppler Radar Being Tested 105

longacre writes "Due to its limited range and slow scan times, the backbone of weather prediction in the US since the early 1990s, the NEXRAD radar system, is deeply flawed in the eyes of meteorologists. A new system being tested by researchers at the NOAA and four universities called the Collaborative Adaptive Sensing of the Atmosphere (CASA) network aims to fill the holes left by NEXRAD, using radar nodes piggybacked onto existing infrastructure, such as rooftops and cell towers. From the article: 'Based on faster and more comprehensive data collection, [Distributed Collaborative Adaptive Sensing] processing can refocus the CASA radars on a particularly interesting part of a storm (like an area that looks like it might develop a tornado) without losing track of an entire storm cell. "The system is continuously diagnosing the atmosphere and reallocating resources using wireless Internet as a backbone," says [the CASA team director].' Testing has begun in Oklahoma, Houston, and Puerto Rico, and initial installations could begin in 5 years."
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Replacement For Aging Doppler Radar Being Tested

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  • Stealth hunter? (Score:5, Informative)

    by AHuxley ( 892839 ) on Wednesday June 18, 2008 @05:24AM (#23836209) Journal
    In many parts of the world this would be cover for a new passive radar system :-) []
    • Re:Stealth hunter? (Score:5, Interesting)

      by Rich0 ( 548339 ) on Wednesday June 18, 2008 @09:56AM (#23838389) Homepage
      Such a system may not have much utility in a serious war. There are a few good reasons:

      1. At best they give you an idea of where a target is - they're not suitable for guiding missles towards a target and shotting it down. That requires continuous illumination, which is hard when the illuminator doesn't easily get any feedback as to whether it is on target or not, and a missile can't see the reflections reliably.

      2. It still depends on RF transmission to illuminate a target, but instead it uses "civilian" transmitters instead of military ones. I use the term civilian very loosly since if your cell phone network is used to illuminate military aircraft it is no longer a civilian technology. In a war with serious stakes an enemy would just fire anti-radiation missiles or artillery at anything that emits RF.

      3. Civilian transmitters don't tend to have much in the way of infrastructure redundancy like military ones do. Blow up all the local power stations and batteries should be dead within a day or two, and blow up the fuel depots and even diesel generators aren't going to be much help - cell towers don't typically have huge fuel reserves like a military base would.

      The main advantage of this sort of technology would be the ability to use super-cheap transmitters in combination with super-expensive receivers. Since the two are not in proximity it would be much easier to conceal the expensive detection equipment, and transmitters could be made more disposable.

      In a less serious war you could rely on the reluctance of an enemy to destroy infrastructure that is primarily civilian in nature. However, in a less-serious war the enemy will probably not be so dependant on defeating your radar system - the only reason wars aren't fought seriously is because the conclusion is evident from the start.
  • Outdated information (Score:5, Informative)

    by lpangelrob ( 714473 ) on Wednesday June 18, 2008 @05:30AM (#23836235)

    From the article...

    Under the current NEXRAD Doppler system, a warning could be statewide, leading to false alarms for most of its residents.

    No, not so much. The National Weather Service has started issuing storm-based (polygon-area based) warnings since August 2007. Prior to that, they were county-based warnings, which were a problem (Cook County, IL being about 50 miles tall by 40 miles wide, while average tornado widths are about 100 yards) but nowhere near the "statewide warning" the article claims.

    Awful FAQ here: []

  • by TapeCutter ( 624760 ) * on Wednesday June 18, 2008 @05:34AM (#23836257) Journal
    ...lives will be saved, OTOH it also increases the likelyhood of a traffic jam of storm chasers in the the exact spot "the finger of God" lands.
    • by Anonymous Coward on Wednesday June 18, 2008 @07:17AM (#23836711)
      luckily, the jam will resolve itself quickly through natural means
    • by Gilmoure ( 18428 )
      That would be soooo coooool! If there was an ice storm on the ground, would be even better. All these SUV's all screeching towards each other and then sliding around trying to avoid crashes and cows why some are being picked up and slammed around!

      My God, it will be beautiful!
    • by catmistake ( 814204 ) on Wednesday June 18, 2008 @01:30PM (#23841837) Journal
      Right now, NEXRAD affords a 15-20 minute heads up on tornados, and its not clear if that can be increased. Chaos Theory tells us that if we had a grid of sensors in the atmosphere 1 foot apart all around the globe and took a reading, the accuracy of predictions based on that reading would break down in about an hour. Certainly, tornado watches could be issued earlier, but tornado formation happens so quickly there is a limit to how early they could be predicted with any certainty, regardless of how accurate a radar reading.
  • Rednecks. (Score:4, Funny)

    by retech ( 1228598 ) on Wednesday June 18, 2008 @05:52AM (#23836343)
    I use a very tried and true method of weather prediction - Rednecks. If they are by water, there will be a flood. If they are in a trailer park, there will be a tornado. If they are on a hill - a mudslide. In the woods - forest fires.

    We could save millions just watching the rednecks and avoiding those areas.

    As a side note, I do enjoy the "seed-neck" on the news. You know the one, holding a beer with a stained tank top and in their boxers they always say stuff like: "We lost everythin' but we's gonna rebuild cuz this is our home." It's an aluminum can, how much needs to rebuilt?
    • Re:Rednecks. (Score:5, Insightful)

      by Anpheus ( 908711 ) on Wednesday June 18, 2008 @05:57AM (#23836379)
      It's still property, it's still their home.

      And they still lost it.
      • Re: (Score:3, Insightful)

        Very true. It's funny to make fun of rednecks, but when it comes to tragedy, they are still people. Unless they really make the disaster bigger, than it should be, due to their actions.
      • by kv9 ( 697238 )

        It's still property, it's still their home. And they still lost it.
        • Re: (Score:1, Funny)

          by Anonymous Coward
          That *whoosh* was the sound of decency passing unnoticed by you.
      • Yeah, I was appalled by the grandparent as well. It is always amazing to me how much bias is still tolerated, nay tacitly encouraged, here in the US. If the GP had used "nigger" or "faggot" instead of "redneck" - he'd have been modded 'flamebait' or 'troll' and his post soon forgotten down in the -5 basement.
        But use "redneck" instead - and it's funny.
    • Re: (Score:1, Offtopic)

      by hyades1 ( 1149581 )

      Your term "Seed-neck" threw me a curve. I thought you were going to say that when these folks were interviewed, they'd generally say, "When I seed the twister comin' across the field near to where Bart's trailer was set, I figured I could get on America's Funniest Home Videos if I showed how it made my can of beer pour sideways."

    • If they are on a hill - a mudslide. In the woods - forest fires.

      Sorry, bud, but it's the rich folks in the Hollywood hills and the suburbs surrounding LA and San Diego that get hit most from those events. I realize that doesn't fit with your obnoxiously elitist premise, but there you go.

  • by Anonymous Coward on Wednesday June 18, 2008 @06:17AM (#23836457)
    The flying cows.
  • by Anonymous Coward
    "The system is continuously diagnosing the atmosphere and reallocating resources using wireless Internet as a backbone,"
    And by "wireless Internet" does he mean using people's unsecured wireless routers?
  • Slow (Score:5, Insightful)

    by Wowsers ( 1151731 ) on Wednesday June 18, 2008 @06:32AM (#23836511) Journal
    Suppose that doppler radar is slow, and that it takes 5 seconds for it to do a 360 degree sweep. Is a faster system going to improve the generally rubbish weather forecasts of "it might rain today"?
    • Re: (Score:3, Informative)

      Suppose that doppler radar is slow, and that it takes 5 seconds for it to do a 360 degree sweep. Is a faster system going to improve the generally rubbish weather forecasts of "it might rain today"?

      If anything the slow rotation rate radar might be better for this application. Radars with short rotation periods are used in military applications where you need to see what is happening from second to second, and are increasingly being used in ATC applications.

      But those radars need special software and hardware to deal with the fact that the returning signal is going to be coming from a significantly different azimuth (relative to the radar head) from where it was transmitted.

      It is a lot of needless

      • Re: (Score:3, Informative)

        by hcdejong ( 561314 )
        When TFA says "slow", it's talking about 5 minutes, not 5 seconds. IDK why the update time is this slow, since 5 seconds is feasible even for a long-range radar (ie. 400 km).
        • Re:Slow (Score:5, Informative)

          by DarthBart ( 640519 ) on Wednesday June 18, 2008 @08:52AM (#23837393)
          The radars take several scans of the sky per "update".

          They take scans at .5 degrees of dish elevation, 1.45 degrees, 2.4 degrees and 3.35 degrees. Those scans dissect the storm and look for rotation and intensity in different parts of the storm.

            Then the radars take an "echo tops" scan where the dish moves up and down to its limits while scanning horizontal. That lets the radars detect the total height of a storm, which gives another estimate of its strength.

          So, its not just the dish spinning around in a single plane.
          • Interesting. Military radars usually do 3D scans by transmitting several beams at different elevations. Faster, but more expensive.
        • Re: (Score:2, Informative)

          by tuxicle ( 996538 )
          True, but only if you want to do target detection. If you want to make quantitative estimates about your target, you need to "dwell" longer, which pushes scan speeds up. Echoes from weather are generally weak, and weather radars need to estimate their properties. The slower you scan, the longer you dwell, and therefore, the estimates have lower variance. The trick is to get low variance as well as scan quickly.
      • Re:Slow (Score:4, Informative)

        by afidel ( 530433 ) on Wednesday June 18, 2008 @09:16AM (#23837731)
        If you don't know why weather radar needs to be faster then you have never been watching during an active thunderstorm. Sweep periods are quite slow in high resolution mode, they can speed things up but it costs significant resolution loss. What is needed is synthetic aperture radar where you can point a small array of antennas at the storm and get multiple different elevation readings simultaneously. We've had the technology for quite some time but it's just now coming down in price to where we can think of using it broadly for weather stations.
        • Re:Slow (Score:4, Informative)

          by tuxicle ( 996538 ) on Wednesday June 18, 2008 @11:08AM (#23839459)
          Surely you mean phased array radar, not synthetic aperture. The idea behind phased arrays is to improve overall volume scan times by allocating the limited energy budget of the radar as appropriate. Conventional radars, by design, will radiate an equal amount of energy over the entire scanned volume (over time). Phased arrays, given their ability to instantly (electronically) position the radar beam to any point in the sky, can allocate more energy to those areas that contain "interesting" targets (such as thunderstorms).

          The DCAS part of CASA attempts to do this using multiple radars instead. So instead of each radar doing complete volume scans, a centralized system figures out where the "interesting" regions are, and directs the radars to scan only those sectors. The eventual plan is to use phased arrays at each radar node for even higher update rates.
          • by afidel ( 530433 )
            You're correct, I was thinking about the improved imaging available to mobile applications through the use of phased array.

            Aperture synthesis by post-processing of motion data from a single moving source, on the other hand, is widely used in space and airborne radar systems.wikipedia

            The two concepts are related in that you use a phased array to implement synthetic aperture, but you would not typically use synthetic aperture for weather radar. I think it was the mention of multiple disparate antennas i
    • Is a faster system going to improve the generally rubbish weather forecasts of "it might rain today"?
      No, but someone is going to get a lot of grant money to implement it.
    • Re:Slow (Score:5, Informative)

      by oodaloop ( 1229816 ) on Wednesday June 18, 2008 @06:53AM (#23836591)
      I think we'll see what's going on now with more fidelity, but weather prediction is still limited by chaos. Weather is sensitive to initial starting conditions, so no matter how well we know those starting conditions (today's weather), we will not be able to predict future weather more than about 10 days out with any kind of fidelity. We've also noticed that some weather patterns are more chaotic than others. You may notice sometimes they say stuff like, "The hurricane will make landfall tomorrow morning at 2am here." And sometimes they say, "We really don't know what this storm is going to do. It could land tonight or blow north. We'll have to see." What they do is run several simulations using variables a few decimal places off. Sometimes they all do the same thing, sometimes they vary so much there's no way to know what's going to happen. Adding new radar will not change the fact that weather is inherently chaotic and unpredictable.
      • Re: (Score:3, Insightful)

        by giorgist ( 1208992 )
        At this point the best weather predictor is ...

        "Tomorrow will be the same as today"

        It beats the weather man by far and wide

        • Re:Slow (Score:4, Insightful)

          by CastrTroy ( 595695 ) on Wednesday June 18, 2008 @08:52AM (#23837381) Homepage
          The problem with weather forecasting is that they try to forecast way too far in advance. Checking out my local forecast [], I see that they have until tuesday on the forecast. An entire week is too long to predict for weather. But they go further. There's now the 14 day trend []. None of that is even worth looking at. I only trust the next day or two, and even that is a little fuzzy sometimes.
          • Re: (Score:3, Informative)

            by afidel ( 530433 )
            With the current density of information collecting stations anything past about 10 days is just an educated guess, seven day forecasts are pretty darn accurate (generally getting precipitation chance and high and low temperatures to within a percent or two) with an additional three days being fairly accurate.
          • by rubah ( 1197475 )

            That's because some people are interested in what will probably happen at that point. Weather patterns tend to repeat themselves year after year, so you can get a good average idea.

            For example, in my hometown on a certain week of February, it usually goes up to 70 degrees for a few days. Someone from out of town probably wouldn't think to pack shorts for Arkansas in february, but they might end up wanting them.

            Also, it has snowed on the same day in february almost every single year since 2002 (which wa

          • Unless you live in south texas... It will be hot, high around 98, low around 76, cloudy and humid in the morning, burning off in the afternoon... for the next 3 months. Holy crap, I'm a god to the meterologist.
            • I was going to post something similar. It's easy to get the forecast right in certain areas, where the weather is generally the same every day (either no rain, or rain almost every day). In a lot of places, it's a lot harder to pinpoint exactly what the weather will be like on any particular day. If you look at the 7 day forecast for my region, the weather for the 7th day will probably change 3-4 times in most cases before the day occurs.
        • not in chicago our weather always changes, plus we have Tom FREAKING Skilling! he could have you killed if he wanted to.
          • Here in Oklahoma we have Gary England. He actually had a cameo on Twister. One of the local radio stations has a tribute to him sung to the tune of the Hallelujah Chorus from Handel's Messiah. There's even a drinking game meant to go along with his live coverage during tornadoes.
        • by chaim79 ( 898507 )
          That really depends on the area, I have friends in areas where it's sunny 90% of the year with little variation in temps, for me, I'm in WI right next to the Mississippi, for us the weather changes every 6 hours or so.
    • Re: (Score:2, Informative)

      by TigerPlish ( 174064 )

      Is a faster system going to improve the generally rubbish weather forecasts of "it might rain today"

      No, nothing can help that. It's really tea-leaf reading.

      What a faster system with a finer resolution will do is help better tell if that big nasty storm moving into your part of town will be an F1, or an F5 Magic Eraser.

      It also will help stretch the warning leadtime. It's still not good enough.

      Nexrad took the warning from pretty much after-the-fact to about +15 minutes these days. Nexrad, compared to the old-school FPS-77 and the like, is pixie dust.

      The real clincher, not mentioned in TFA?

      They're workin

      • Re:Slow (Score:4, Informative)

        by DeadChobi ( 740395 ) <> on Wednesday June 18, 2008 @09:06AM (#23837609)
        Well, if you're an atmospheric scientist doing research into weather, a faster system gives you finer resolution for studying the kind of time-dependent systems that they're interested in. Don't assume that this system won't ever be used to collect scientific data to analyze. One of the advantages of a faster sampling rate is that you can make better predictions based on your data. Essentially, you have a better idea of where some deterministic system has been, and so if you have a pretty good idea of the principles under which it works you can then get a better idea of where it's going. Hell, even if we don't have a technique for making better extrapolations in the face of higher resolution data, someone somewhere will come up with a way.

        The other useful thing about this kind of data collection ability is that it can also be used to improve models, especially if it has a better resolution for storm cells than the current doppler system.
        • Re: (Score:2, Interesting)

          by tuxicle ( 996538 )
          Also, by spreading smaller radars around, you observe stuff closer to the ground. This is typically missed by bigger radars such as NEXRAD, since the beams overshoot low-level features as you go further out in range.
    • Re: (Score:3, Interesting)

      In financial forecasting systems, the critical element is variance reporting. 'How wrong was yesterday's prediction?' leads to a sense of 'How much faith can you put in today's prediction?' Why, pray tell, is it that we NEVER see variance reports on the weather report?
      • by afidel ( 530433 )
        The meteorologists DO use variance reports to tweak their computer models and to select which model is currently the most accurate, but I can't imagine there are too many people that want that raw data.
      • NEXRAD and CASA are not about long range predictions, and by long range I'm talking more than a few hours. These systems are designed to determine what is going on right now and what it means for nearby communities over the next short period of time.
    • Re:Slow (Score:5, Insightful)

      by Hatta ( 162192 ) on Wednesday June 18, 2008 @09:29AM (#23837949) Journal
      5 seconds? We had a tornado here in Omaha a couple weeks ago, and the sirens provided no warning because it hit during the 5 minute blind spot in the radar. On one pass it was a severe thunderstorm, on the next pass it was a tornado on the ground.

      If they can't make the radar rotate faster, they should add more dishes to the same radar so it's looking in 2 or 3 directions at once.
      • Re: (Score:2, Informative)

        by Kumba ( 84067 )

        5 seconds? We had a tornado here in Omaha a couple weeks ago, and the sirens provided no warning because it hit during the 5 minute blind spot in the radar. On one pass it was a severe thunderstorm, on the next pass it was a tornado on the ground.

        If they can't make the radar rotate faster, they should add more dishes to the same radar so it's looking in 2 or 3 directions at once.

        The Radar, even if it lacked the blind spot, can't determine if there's a tornado on the ground or not. It can only detect if there's a significant amount of rotation that makes conditions favourable for tornado formation, and then issue a TVS, or Tornado Vortex Signature. The forecaster reviewing the data has to then decide if the radar's predictions are worth issuing a warning. They have to consider data not only from the radar, but current weather conditions and perhaps from the most important source

    • by PMuse ( 320639 )

      Is a faster system going to improve the generally rubbish weather forecasts of "it might rain today"?

      IMHO it's not so rubbish any more. Consider what we have now that we didn't have two decades ago.

      1. Precipitation predictions now have an accuracy of about +-1 hour for every 6 or so hours looking forward. That is, predictions 6 hours out are +-1 hour, while predictions 3 days out are +-12 hours. At 10 days out you're at +- a day and a half, but two decades ago we had nothing, so that too is an improvement.
      2. Temperature predictions are accurate to +-1 hour for every 6 as well.
      3. Rather than one prediction fo
    • Suppose that doppler radar is slow, and that it takes 5 seconds for it to do a 360 degree sweep. Is a faster system going to improve the generally rubbish weather forecasts of "it might rain today"?
      Exactly how much faster would you expect a 25' dish to rotate?
  • Being an American in Australia, I was blown away to see that the highest resolution radar available for sydney is this: []

    At that resolution, the best way to see if you're going to get rain is pretty much to look out the window. A new radar tower is supposedly in the works, I hope they hurry up!
    • B At that resolution, the best way to see if you're going to get rain is pretty much to look out the window. A new radar tower is supposedly in the works, I hope they hurry up!

      I use the same information in Melbourne. I often check it before riding my bike home, but I don't see a benefit in better resolution. The few big storms we have really are big (not tornadoes) and you can't really expect to avoid them. Normally when it rains it just rains everywhere and again, the radar isn't going to help you much.

  • Title is misleading (Score:4, Informative)

    by hcdejong ( 561314 ) <hobbes&xmsnet,nl> on Wednesday June 18, 2008 @07:33AM (#23836803)
    because it suggests they'll use some new radar technology to replace doppler radar. In fact, they'll just install lots more radars (which can be cheap, short-range items) to improve coverage. According to the CASA site, they'll use modified marine navigation radars, ie the cheapest type of radar available, and these invariably are doppler radars.
  • You know, this might be wonderful and everything but I don't feel like I'm being technologically enlightened. They didn't explain how the new system actually works. Doppler pings the storm clouds and all that... this system doesn't? If it does then I can't see it being that much faster. And if you're looking at the wireless system to speed things up then you're crazy. The scanning has to get faster first unless you're going to stagger their scanning. And might I ask what happens when the tornado seaso
  • by Anonymous Coward

    Hey It's cloudy outside I cant see the sun , that stupid Doppler radar doesn't show the clouds say many people Maybe this data is wrong or old
    No it inst

      Doppler radar detects motion and in this case rain. The clouds simply have no falling rain in them.
    You'll be surprised how many people don't know that Doppler radar does Not show clouds , it shows falling Rain ,
    Maybe the weather service needs to educate he public better ?
    • by dunc78 ( 583090 )
      First: You can detect stationary objects with a Doppler radar, just look at the zero Doppler components. The point of a Doppler radar is that you can distinguish between moving and stationary objects.

      Second: Clouds are not stationary objects.

  • by E-Lad ( 1262 ) on Wednesday June 18, 2008 @08:43AM (#23837267)
    From the article:

    The information is wirelessly transmitted to a central location over a 2-megabit-per-second DS3 connection.
    Sign me up for those wireless 2Mbit/s T-3s.

  • by lakshmanok ( 1208090 ) on Wednesday June 18, 2008 @09:00AM (#23837527) Homepage
    The summary statement gets things wrong in pretty much every respect, so this is mainly for those folks who read the summary and assume it's a fair reflection of the story.

    (1) CASA is not designed to replace the existing NEXRAD network. It is designed to supplement it. NEXRADs are designed for long-range surveillance. CASA radars see "under" the NEXRAD umbrella, up to 3km in height. The article makes this clear.

    (2) NEXRAD scans are not slow. The fastest volume coverage patterns (VCPs) in NEXRAD, used in severe weather, scan the atmosphere every 4 minutes. The only thing faster is phased array radar and it is still experimental (See: []). CASA radars don't have volume scans, but their antennas are about the same speed as NEXRAD's.

    (3) NEXRAD is not limited in range. It goes up to 460 km. A CASA radar's range is only 30 km. If any one thinks that NEXRAD is "deeply flawed" due to its limited range, they need to take it up with the Flat Earth Society (the range limitation is mostly because of the earth's curvature).

    Please make sure you understand an article before sending it off to Slashdot!
    • PAR systems have a bonus that CASA does not have: Active target tracking and targeting. You see, the SPY-1D system that is set up at NSSL Norman was pulled off of one of the Aegis nuclear-powered cruisers. Several advantages include graceful degradation. If something breaks on the panel, the system can adjust automatically to compensate, preventing an outage from knocking the unit out in case of a Major Event. One part breaks on the 99D's, game over until a tech gets out there to fix it. Another is no or f
      • by tuxicle ( 996538 )
        Trouble with PARs is calibration. Military folks don't have to worry about that, but when one or more T/R elements fail on a PAR, how do you measure and compensate for that loss? With the SPY-1, it's relatively simple since it's a space-fed array, but for true active arrays, nobody's come up with a good solution to tackle the calibration issue. Worse, the sidelobe characteristics change when elements fail, and this would affect the antenna gain. How would you compensate for that?

        There are some who pooh-pooh
    • Re: (Score:3, Informative)

      by RudeDude ( 672 ) *
      Your comments are helpful, but still not 100% accurate.

      The rotation rate of the radar is faster and the volume updates are faster as well. CASA currently operates on a one minute "heartbeat" where many scans at different elevations are completed which cover a large portion of the total reachable volume.

      While CASA radar does not provide a traditional "full volume" scan this is by design. For the first time we are dealing with a weather sensor that reacts to the environment automatically adjusting it's
  • I remember about 15 years ago all the news stations in my area upgraded their radars and would go on like used car salesmen about them: "Our radar is so powerful we can tell you where it's raining down to the square inch!". "Our radar will destroy their radar" and the like. I look forward to a new round of Doppler max 4,000 + eXtreme range boost.
  • ...the Resolution Effect Array Longitudinal Radar.

    Also known as REALRAD.

  • This year, the NWS has started the installation of RPG Build 10. This, which also requires an upgrade of the network at the forecast office--will increase the resolution of the WSR-88Ds enough to essentially double the range.

    Upgrade status: NWS Level II Radar Recieve Status []

    03 - Build 10 installed & the network updated to provide the LDM veed.
    04 - Build 10 installed, but lacking the network upgrade. Data is derived to fit the legacy Level-II bandwidth.
    NULL - Still Build 9, and no status of the network
  • We finally got doppler radar here in the San Diego area a few years ago--the last place in the nation because the NWS (justifiably) feels there isn't enough severe weather here to warrant it--and now it's obsolete already.

    Damn, living in Paradise can be such a bummer sometimes...

"If it's not loud, it doesn't work!" -- Blank Reg, from "Max Headroom"