Two GPS units and a baby... heading vs track

All,

Before I shell out my first born to Nathan (surely, if anyone, he deserves it), I wanted to run something past folk who know more than me.

I have a need to try and work out the heading (as opposed to the track) of a specific object, say an airplane for the sake of argument. I don’t want to know what direction it is moving in, I want to know where it is pointed, without relying on magnetic sensors.

A loony idea entered my head today, that being using two receivers, one at the rear of the mythical aircraft in the tail fiberglass tip, and the other as far up to the pointy end with the big fan as I can. In a perfect world I would like be able to use the position reported from both sensors to determine a rough heading (+/- a couple of degrees would be adequate). Of course, I would get 25m resolution or <5m with WAAS, but I am not interested in the real position for some instrument approach, rather the relative position of the two antennae to each other. This way, I could theoretically determine the direction my fake plane is pointing in when it is completely stationary.

My crude understanding of GPS errors include satellite clock issues, receiver clock issues and atmostpheric distortions, but a pair of receivers 15ft apart should share (1) and (3) for any given sample. (2) is anyone’s guess.

Anyone given this a go before? More to the point, can anyone confirm just how fruit-loopy the idea is or whether it is worth me grabbing a pair of the new PG31s and putting a smile on Nathan’s face (in that order)?

Thanks,

AP

Have you ever looked at some of th LINX sensors? They have a signal stength indicator that with a little work can be used to determine the direction. I don’t remember the specifics off the top of my head, but I know it can be done because I saw a project at our unversity senior design competition that utilized it.