NY Times blog Bits on PlanetIQ’s approach to forecasting the weather
"It uses signals from GPS satellites, but not for positioning. Instead, it measures distortion in these signals to learn about the atmosphere through which they passed."
"The company wants to put 12 tiny satellites into orbit that will do nothing except watch the GPS satellites rise and set on Earth’s horizon. The signals sent from these satellites are bent by the atmosphere at an angle that indicates the air’s temperature, pressure and water vapor content. PlanetIQ’s satellites can determine the angle because the way the signals are bent delays their arrival. The GPS signal already encodes the time at which it was sent; the time it should have arrived had there been no bend can be computed if one knows the distance the signal was supposed to have traveled."
"In PlanetIQ’s system, each satellite would take 1,000 readings a day from the GPS satellites, with each reading measuring the temperature and pressure of the slice of Earth’s atmosphere through which the signal traveled. The fleet would generate about 5.5 million readings a day, which would be integrated by a computer on the ground into a 3-D map of atmospheric data."
1 comment:
The idea of trying to derive information from the noise on the signal seem pretty obvious. There are all sorts of secondary uses for those RF signals bouncing around everywhere. And with GNSS, you have the advantage of knowing exactly what the undistorted signal should look like. What I don't get is why they need satellites to do it. It would seem ground based receivers could make the same calculations and it would be much simpler to populate a full network of sensors to get the required geometries.
Either way I don't see this going anywhere with the current atmosphere around government spending.
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