Math, Doppler And The Missing Jetliner

mh370-tracksI just finished reading some technical data from Inmarsat and Ministry of Transport Malaysia concerning the analysis of satellite data transmissions from MH370. It’s this data that’s shifted the searchers from MH370’s planned route to a tract in the Southern Indian Ocean well west of Australia–nearly the opposite direction expected!

It is a brilliantly concocted method to get usable information from what should have been meaningless housekeeping transmissions.

Radio signals travel at the speed of light. If we know how long those signals take to go satellite-to-plane (or vice versa) we can start doing calculations and find the distance between the two.

Inmarsat was then able to calculate the range of the aircraft from the satellite, and the time it took the signal to be sent and received, to generate two arcs of possible positions – a northern and a southern corridor.

mh370 doppler shiftAs you probably know the northern track was thrown out. But why? That’s where the plane should have been flying. It was the most logical direction.

Enter Doppler!

Because the satellite and plane were both moving, their radio waves were subject to Doppler shift. This is an expected part of satellite work and equipment to compensate for it is built into the system.

The Inmarsat technique analysed the difference between the frequency that the ground station expected to receive and the one actually measured, known as the Burst Frequency Offset.

mh370 data versus tracksBecause the satellite wasn’t at the midpoint of the two project tracks, the expected northbound offset or shift was different than the southbound shift. What was actually seen only matched the southern track.

Depending on the plane’s speed the same Doppler shift could indicate slightly different positions. Unfortunately, that’s an unknown. It’s a good guess to estimate 400-450 knots. That’s why the area now being searched isn’t a single point, but a larger area.

Obviously, the plane hasn’t been found, there’s still no real explanation for what went wrong. However, this clever use of math helps bring those looking one step closer.

I know this is somewhat complex. I’m not 100% sure my explanation will be clear to everyone. Questions are welcome.

While Geoff’s Away

I went to Hudson, NY this afternoon to see one of my oldest, best friends. I’ll write about that later. Before I left, I showed Helaine an area on Pokerstars where there are ‘free’ satellite tournaments.

OK – two terms to clarify.

When I say ‘free,’ I mean you use points to play. These points are accrued as you play real money games. Since we’ve never touched our points, there were thousands in our account.

Satellite means a tournament which has a seat in another tournament as the prize. The satellite I showed Helaine cost 500 points, had 27 players, and paid the winner (only one winner) a $200 + $15 seat in a Sunday tournament.

What makes Sunday’s tournament so interesting is the total payout is guaranteed at $250,000+. The first place winner will make at least $56,000.

As of this moment, Helaine says there’s too much pressure for her to play. I’m not sure I feel any different. The tournament starts tomorrow at 4:30 PM.

With over 1,000 players expected, more than likely we’ll get nothing. But, the big question is which one of us will play?