Triangulation

OK, let's talk about triangulation. I'll tell you why in a minute. In case you are wondering, triangulation is a term sometimes used to describe a process by which the source of a radio signal can be pinpointed using directional antennas and receivers. I speak about this with some authority, having passed my radio amateur exams some time ago. Stay with me, it's not as tedious as it sounds.

This is how it's done:

You take a receiver and fit it with a directional antenna. Directional antennas can take many forms, the most common of which is the yagi array, often used for terrestrial tv reception. This type of aerial will receive an RF signal from one direction only. In other words, it has to be pointing at the source of the signal to receive it. There are some other antennas that will receive RF from two directions. An example of this would be what I know as an RF loop antenna, which is essentially a circle of copper on a stick like a lollipop. This type of antenna receives RF in one plane, or two directions. In other words, the signal could be coming from in front or behind, you don't know which, but you can draw a line, and the source will be on that line.

Whatever type of aerial you use, you can't pinpoint the position of an RF source, you can only workout a direction. To actually pinpoint a source, you need to work out the direction of the source from two different points, and draw a line from each point towards the source. Where the lines cross you will find the source of your transmission. To make this simple, lets assume we are on an island, and we need to find the source of an RF signal somewhere else on the island. We have a receiver, and it's fitted with a yagi type antenna.



As can be seen from the diagram above, we have to stand at point A, work out the direction of the source signal, then walk to point B and repeat the process. We can then draw a line from both point A and point B in the direction of the source. Where the two lines cross, we will find the source of our signal.

You will note that we only need to do all this from two points on our island, and it doesn't have to be at the same time. Thus, we only need one receiver and antenna. No extra equipment is required. We do not need a transmitter, aerial amplifiers, or pixie dust.

You will note also, and this is important, that since it is an island, you don't even need to go to this trouble. If you stand anywhere on the coast with your back to the water, you can be fairly confident that the source is somewhere in front of you. In which case, you really only need to work out which direction the signal is coming from, and then start walking in that direction. Eventually you will trip over the source of your signal.

OK, here's where you find out why I'm telling you this...

Lost, series 1, episode 7, Sayid is trying to pinpoint the source of a radio signal that he has discovered on the island. It's been playing in an endless loop for 16 years, and he wants to investigate. Hey, so would I. So why is he poncing round the island fixing antennas in trees in three separate locations and sending up fireworks, when he could have just walked the line as I explained above?

When you consider that the Lost pilot episodes are reported to be the most expensive ever made, I heard $14 million, and they even went to the trouble of scrapping a 747 Jumbo and spreading it in pieces over a Hawaiian beach, why didn't they spend an hour talking to someone who at least had some idea of what triangulation is? I mean seriously, I wouldn't have even charged them for telling them they were spouting bullshit. What a load of old crap. I was really getting into it, and now it's just a joke. Is it just me?