TargetTalk

While experimenting, I noticed a few things of interest. My rifle has a 27" barrel and in the past I placed the barrel sensor almost directly under the front sight. Recently, I added an 8" tube/tuner setup and moved the sensor forward. First, I placed it again near the front sight and noticed an increase in trace length and POI changes. Then, I started placing the sensor back on the barrel and then closer and closer to the end of the stock. As I did so, the trace lengths started to decrease significantly. The L values varied from high 40's to mid 20's depending on location of sensor.

What have others found? Where do most of you using the SCATT locate the sensor? And what explanations do you have for my observations?

Dennis L

I've mounted it on several positions on the barrel but it don't find many differences in values. If I place the sensor to close/next to my tube the reflection of the aluminum seems to interfere the signal. This results in a malfunction, not other values. It just doesn't works and will after I moved the sensor closer to the stock.

Can't really remember having the issues you mention.

I always place the sensor as near as I can to the end of the barrel. Never noticed anything obvious but I wonder if your getting reflections pushing up the trace lengths ?

Rob.

If you think about it the further the sensor is from the axis around which the rifle is rotating, for the angular error at least, the "bigger" the movement the sensor will show. Move the sensor further back and things like trace length will shorten, although as some have said you may get interference from reflections from the metal of the barrel in certain locations that prevent the system from functioning at all.

Ideally I would think that the optimum position for the sensor to accurately gauge angular errors would be so that it is co-incident with the actual muzzle of the rifle. There is another consideration that you have to make, and that is if you are "shooting" at a closer distance to that you are simulating, what is the distinction between angular error and lateral error. Your angular error will change with distance, while the lateral error is constant at all distances.

Alan

Thanks for responses.

Alan - If the sensor is moved along the axis of the barrel and remains at the same distance from the barrel center, I do not see why there would be "angular error" introduced.

Dennis L

If you were to put a dial indicator on the barrel by the action and move it 2mm, the movement at the end of the barrel sticking out 27inches would move significantly more than the 2mm at the action. Just think about minutes of angles as it relates to sights or scopes and bullet impacts at different distances if you are familiar. The further out towards the end of the barrel it is mounted, the more movement there will be.

dlinden wrote:Thanks for responses.

Alan - If the sensor is moved along the axis of the barrel and remains at the same distance from the barrel center, I do not see why there would be "angular error" introduced.

Dennis L

I agree, angular error is identical no matter where the sensor is located. The whole point of the thing is that it tracks exactly where the sights are pointed. Plus a 10, 20 cm movement of the sensor could still not double the readings as it's a 1-2% change in overall distance from sensor to target (assuming shooting/training at 10M). Also if angular error were changing it would increase, not decrease as the sensor were moved backwards (along the axis of the barrel).

Same with most things scatt though, the best idea is to set it up identically each time and track changes, rather than absolute values. Also if using with an airgun, shoot it dry or live, don't try mixing it as you can really only compare like for like.

Rob.

The issue is that the sensor is not actually measuring the angular error of the movement of the barrel, only the lateral or vertical displacement. As I understand the SCATT system to operate it uses a single IR source at the target position and an IR camera in the gun mounted sensor that tracks the apparent movement of the IR source as the gun moves. A system of this type has no means of differentiating between a lateral/vertical displacement, which is constant for all sensor positions and target distances. Or an angular displacement of the gun the magnitude of which is dependant on both how far the sensor is from the fulcrum, as well as the distance to the target.

To determine both the lateral/vertical displacement as well as any angular displacement in two dimensions you would need a minimum of four IR sources at the target, one on each corner, although adding in four more, at the centers of the edges would increase accuracy. This would allow you to measure the change in angle of the sensor as the relative positions of the sources changes. Think of the way a building looks to be leaning backwards if you point a camera upwards at it to imagine the effect.

Although angular errors have a much greater effect the longer the distance you are shooting at, the angular errors involved are normally very small, even with pistol shooting, while the added complexity of measuring them is significant. For a cost effective training system such as the SCATT it is probably not worth the extra effort to incorporate angular measurement.

As Rob says when it comes to this sort of training it is better to keep your setup constant and base your analysis on relative performance over time rather than absolute numbers.

Alan