Rain Drops Signal Cell Phones 86
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.'"
Re:turbo button for cell phone reception (Score:5, Informative)
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.
Old Story -- Prior Art (Score:1, Informative)
Details of TFA--it uses the backhaul link (Score:5, Informative)
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.
Re:turbo button for cell phone reception (Score:3, Informative)
You can bet that when a phon is advertised as having "up to 240 minutes talk time", that means you get that talk time when standing very close to the mast and therefore using minimum power. In real use, you will be further away, need more power, and get less talk time
Not new, not even old, it's ANCIENT NEWS (Score:4, Informative)
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!
Re:turbo button for cell phone reception (Score:4, Informative)
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.
The shape of raindrops (Score:2, Informative)
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://www.suite101.com/article.cfm/science_sky/9
When these water drops are inside an electromagnetic field, electric currents are induced on its surface which attenuate the field. Due to the flat shape, it results that the horizontal component of the electric field is the one which gets attenuated most.
This means that in order to minimize attenuation in a radio link during rain, it is convenient to use "vertical polarization" (which means that the electric field vector at any point within the electromagnetic field is contained in the vertical axis only) which is the component of the electric field which is least attenuated by rain.
Re:doesn't poor weather increase signal strength? (Score:3, Informative)
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 installation. Hotter temps (as when the sun is shining on it) can reduce radio performance. I must admit that's a stretch, though.