How will the Revolution sense the controller?

[Jabbah]

Smaller variations are obviously going to go undetected, at lest through straight measurement, 3x10^8 ms is...30 cm in 1 ns, right? Which would be the sensitivity at 1GHz if I'm figuring this right, that the difference in distance from Revmote to left sensor versus Revmote to right sensor would have to be to register a 1ns delay. I don't know if there's any clever techniques though. Invariable there's some fantastic trick to get things to happen!

The problem is when you are perpendicular to the sensor bar your differences in distance are now down to a few centimeters at most, so you need to be able to register less than 0.1ns delays for large movements. eg if you are 3m away from the sensor bar and you move the bar from left to right over about a meter the difference in distances is about 9cm, so your going to need very high frequencies to get any response at all and it wont be accurate and probably unenjoyable.

Even if there was a way to calculate the distance to each of the ends of the baton accurately you are still left with a situation where you have a large vertical circle of possible positions that the controller could be in, so no height information could be inferred.

If you really wanted to do this despite all the drawbacks, ie 2D positioning and poor accuracy then I think the only way to do it would be to use the phase shift of a signal transmitted from the revmote. Every so often (every 1M cylces say) a "NULL" symbol (ie nothing for a single cycle) would need to be transmitted to synchronise the receivers. I'm not sure how accurate this would be but I dont think positional accuray on a 2D plane parallel to the floor to within a few centimeters with a signal in the GHz range would be out of the question. I really do not think Nintendo would do this though as I think it would be prohibitvely expensive for such a feature.

 

[Squeak]

Um, no. Not by a long chalk. The reason the light from a torch or bouncing of a wall can be differentiated by me is an incredibly complex data comparator/processor. The actual photons, if of the same frequency, I can't differentiate between.

I'm not talking about the torch being pointed directly at the wall, just "stray" light.
I should just be a matter of saying "the light should at least have x brightness, and only cover x^2 pixels".

Imagine you are a body-less entity floating in a room where the only light is two diodes spaced a bit.
Only by looking at the diodes you'll be able to tell whether you are moving left, right up or down or moving towards or away from the lights.

I don't see why my suggestion is so hard accept as at least a possibility.
It's the one offering the most robust and simple solution to the problem.

 

[Shifty Geezer]

Imagine you are a body-less entity floating in a room where the only light is two diodes spaced a bit.
Only by looking at the diodes you'll be able to tell whether you are moving left, right up or down or moving towards or away from the lights.

That's an idea, but the light from the 2 diodes needs a spacial relation on the receiver end. If the Revmote is to detect the lights, it'd need something like a CCD. EyeToy is a better example of a detector suitable for that task. A single point detector that determines presence (and intensity) and not position couldn't be used this way. Unless, the transmission from the bar was in two cones, one from each end, both at a different frequency and with signal intensity dropping off from the centre point towards the edge of the cone. The Revmote could then detect strength of the signal. 100% A and say 50% B would place it opposite the Bar's left transmitter. A strength of 75% A and B would place it in the middle. Signal strengths of 25% and 50% would place the Revmote on the far side of the Bar's right transmitter. That should offer a simple and robust solution.

 

[Squeak]

That's an idea, but the light from the 2 diodes needs a spacial relation on the receiver end. If the Revmote is to detect the lights, it'd need something like a CCD.

Which is exactly what I suggested on the previous page. I can't imagine a IR CCD being very expensive, it wouldn't even have to be very high resolution, with more than one bit PP.

Unless, the transmission from the bar was in two cones, one from each end, both at a different frequency and with signal intensity dropping off from the centre point towards the edge of the cone. The Revmote could then detect strength of the signal. 100% A and say 50% B would place it opposite the Bar's left transmitter. A strength of 75% A and B would place it in the middle. Signal strengths of 25% and 50% would place the Revmote on the far side of the Bar's right transmitter. That should offer a simple and robust solution.

An even simpler "analog" solution would be to have four photodiodes arranged in a diamond shape with a semi-translucent disc in front, least translucent at the rim and most at the center.
In front of each diode a lens is placed.
For this method you would only need one IR diode.

When the controller is moved in x and y, the light dot will (in four iterations) travel across the semi-translucent disc, and turn the current up and down in the diodes behind it.
When the current is rising and falling proportionally in each diagonal diode pair, the controller is only moved in a 2d plane. If the current is rising or falling in both diodes at the same time, the controller is moving in z.

But that solution wouldn’t be as reliable and exact as a CCD with two IR diodes.

 

[OtakingGX]

Even if there was a way to calculate the distance to each of the ends of the baton accurately you are still left with a situation where you have a large vertical circle of possible positions that the controller could be in, so no height information could be inferred.

You would actually have a large slice of a cone that you would be on. Knowing the distance between the transmitters and the angle the angle that the controller is at pinpoints your location (down to two points at least).

 

[Urian]

Blutooth 2.0 + Trigonometrical coprocessor.

 

[Cobra101]

I wonder how the Wii works with a front projection TV?