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Inmarsat data tracks the Rolls Royce engines. The data they have isn't position or direction, it is a set of metrics that report on engine performance and cond
by buro9 13y ago
Inmarsat data tracks the Rolls Royce engines.
The data they have isn't position or direction, it is a set of metrics that report on engine performance and conditions.
They never had positional information, except by virtue of the timing signals for those data points to their satellite. Which is how they originally determined the arc shaped corridor.
They must have been able to cross-reference this signal with another satellite (or source) to say with certainty that the plane went down the Southern corridor.
I would be surprised if this was cross-referenced with one of their own satellites given that they could have done that a week ago. I'd speculate that they were supplied with access to some other source that had received the signals, and were able to use that to triangulate the position.
- berkut 13y agoWrong - it tracks the plane's Satcom. The RR data can optionally be sent via ACARS, which was manually switched off. So no data from that.
- omegant 13y agoI wrote a blog post last week explaining how the approximate track and final zone could be calculated using the ping data (if more than one ping exists) and dead reckoning (heading and speed). Mind you that I don´t really know the information available to the investigators, but it´s what I would do with some pings available. http://delorbital.blogspot.com.es/2014/03/how-to-estimate-mh370-route-using.html http://delorbital.blogspot.com.es/2014/03/how-to-estimate-mh...
- nly 13y ago> They never had positional information, except by virtue of the timing signals for those data points to their satellite. Does anyone have any more insight in to this? Was the protocol a one-way ping, or a ping-pong exchange? Previous reports have inferred that the data from the hourly pings were incredibly basic. Obviously timing signal propagation is the basis for GPS, but is it normal or even feasible to collect millisecond or microsecond transmission timings for engineering data fed via satellites like the ones operated by Inmarsat? What other variables would have been used for ranging? 1 millisecond at the speed of light is close to 300km.
- foobarqux 13y agoI thought the distance measurement was derived from received signal strength. edit: Other's have said that they are using Doppler shift.
- sateesh 13y agoThis story from Telegraph is scanty in details. But it also mentions Doppler effect. http://www.telegraph.co.uk/technology/news/10719304/How-British-satellite-company-Inmarsat-tracked-down-MH370.html http://www.telegraph.co.uk/technology/news/10719304/How-Brit...
- nly 13y ago> These pings from the satellite – along with assumptions about the plane’s speed – helped Australia and the US National Transportation Safety Board to narrow down the search area to just 3 per cent of the southern corridor on 18 March So it looks like the announcement today is actually old news. In any case, it's not entirely clear to me how the Doppler effect would distinguish between northerly and southerly passage.
- DrJokepu 13y agoMaybe it could be used to establish whether the airplane is getting closer to or getting further away from a satellite? Maybe even the relative speed?
- berkut 13y agohttp://www.pprune.org/rumours-news/535538-malaysian-airlines-mh370-contact-lost-356.html#post8393194 http://www.pprune.org/rumours-news/535538-malaysian-airlines...
- LoganCale 13y ago> Inmarsat data tracks the Rolls Royce engines. This is not strictly correct. The pings that were being sent to the aircraft and which satellites received confirmations from were to the SATCOM system on board the plane. This is a multi-purpose communications channel. The ACARS is a maintenance reporting system which can send out various information about the aircraft at certain points, and which issued two reports about the Rolls Royce engines, but there were no further engine reports after the aircraft hit cruise altitude (it generally reports at takeoff, cruise, and landing).
- tarre 13y agoI think even one satellite is enough, if you have enough data points. You can tune the clocks based on the signals captured, when the location of the plane was known. After that each signal gives you a sphere, on which the plane is supposed to be. With reasonable assumptions about the altitude and speed of the plane, you should be able to locate the plane with enough accuracy to determine, if it was in the middle of an ocean or close to land.