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Weather Monitoring Frequencies Subject to Pollution
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."
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 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.
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.
Mea navis aericumbens anguillis abundat
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.
Mea navis aericumbens anguillis abundat
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
You never know...
Doh. I'm a tard. I meant 20.6 GHz, not 21.6 GHz. It's early, cut me some slack. :P