Rain Drops Signal Cell Phones

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.'"

Can't grok headline

[What'sInAName]

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.

Sounds good...but how?

[Zaphod2016]

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 = signal strength affected. Got it. But how do we go from that to distinguishing which form of bad weather caused the signal loss?

More accurate?

[Anonymous Coward]

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

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

I had the opportunity to visit the control center for one of the national cell phone providers. It was a large room with large screens covering one wall. Some of the screens were weather maps. They used the weather predict where there would be degredation in the service.

Did you know

[Hemi Rodner]

that the cellular coverage rate in Israel is bigger than 100% because many people own more than one cellular?

How did they substantiate the claim

[mapkinase]

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).

Re:Detect rain... and anything else that blocks si

[RubberDogBone]

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.

Re:Detect rain... and anything else that blocks si

[PeterBrett]

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 bays, made them highly visible on radar screens. The pilot survived and was later rescued by NATO forces.

The maths has also been done to show that you can use emissions from FM radio station transmitters and a pair of receivers (with a baseline of about a mile) to track F-117s easily (as long as you have enough computer power). This is one of the reasons that one of the first bombing targets in the Iraq war were civilian radio station transmitters.

The B2 doesn't suffer from this vulnerability -- it doesn't rely on geometry so much as materials that don't reflect radar radiation.