Thanks for the links. I don't think D1 is a variable, they describe D2 as the Aircraft-Satellite Doppler shift, and you need two objects to measure a shift.

As the southbound aircraft passed the equator (satellite) you would indeed expect the aircraft's radial velocity component to drop to a minimum (something the north path would not see I expect). At the edge of the satellite coverage the aircraft will be close to the edge of the planet as seen from the satellite, so much of its velocity would be in the plane tangential to the Earth passing through aircraft and satellite (though not, one would expect, directly toward the satellite). The satellite has time variable velocity components that may be as high as 100 knots rel. to ground that also come into play. Its a continuum in between and a very interesting geometrical puzzle. Certainly the aircraft airspeed limits and norms would put a maximum limit on the Doppler shift due to aircraft motion.

With current trends they will only ever lease the hardware to you at King Zuck's pleasure. It will be a criminal offence to use the device in connection with another service, disable or circumvent "effective technological measures" to prevent data collection (DMCA-style), or to post a negative review.

That, or Zuck mistook it for a Google Glass killer.

Ok, so more geosynchronous than geostationary. It moves over a range of 3.336 degrees (0.058 radians) from north to south in ~12 hours. At 42164 km from the centre of the Earth that is a distance of 2454 km in twelve hours: a crude average of 204 km/hour or 110 knots. A jet aircraft typically does 450knots, so that satellite movement is significant in comparison to the aircraft. There will also be a slight east-west motion, and rise/fall in altitude. Looking at the irregular shape of the combined motions ( see http://www.satellite-calculati... ) the combined aircraft-satellite motions at each handshake event could provide the north-south differentiation claimed. I learned something today.

This is one of those cases where the settlement shakedown, even with the threat of publicly exposing one's porn viewing habits, has failed. Some more here: https://www.eff.org/cases/mali.... Maybe they will eventually give up the cause but I expect the X-Art lawyers to keep going in every other district and jurisdiction while there is still a buck to be extracted.

Indeed. Pretty graphics only get you so far.

Next time look at what is hanging from the tool belt of nearly every woodworker on the site. They don't carry a hammer for decoration.

Good luck extracting a nail with your nail gun Mr. Professional.

You can tell this is the PR guy and not the tech guy. Firstly, "Effectually"?

Secondly. The Inmarsat-3 F1 satellite is geostationary, it moves little and slowly relative to the Earth's surface. There is effectively no doppler shift due to motion of the satellite relative to the Earth. The doppler shift here would be that of the aircraft relative to the Earth/satellite. The absence of doppler shifts is the reason that Copas-Sarsat geostationary satellites cannot determine surface position of a emergency locator transmitter unless the transmitter sends that information. For beacons that do not transmit location the low-Earth orbit Copas-Sarsat satellites, which have motion relative to the surface, are used to determine location by multiple doppler readings (but it takes up to 90 minutes vs. seconds).

Nobody is claiming they are, just that the participants intend to make a quick buck.

Or day traders, or high frequency traders...

Mmmm, chutney

The FDR and CVR beacons operate an acoustic signal at 37.5 KHz. This provides good directional accuracy for homing, sufficiently small size and power requirement, and unfortunately limited range. They have to operate at 14000 feet underwater and typical examples work at 20000 so the detectable range is at least that. I found references to a detectable range out to about 3000 metres (120000 feet) affected by ocean conditions (noise, thermal layering etc.) and depth.

The classic Mode C transponder simply blurts out the four octal digit code programmed by the flight crew (at ATC request usually) every time it is painted by a secondary radar (typically associated with a primary radar and usable over longer range that the primary). The code is associated by ATC with that flight in that control zone for that time only. A Mode S transponder carries a 24-bit globally unique ID that is registered to the particular airframe. This code is attached to the response any selective query for altitude, airspeed, heading, rates of change etc. Although it can be changed in the equipment (e.g. for maintenance reasons) this is not a normal function of flight operations. An ADS-B system actively broadcasts much of the same information as Mode S including an absolute position and the unique ID. Turning off these devices negates the presence of the unique id.