I take that as a polite FY. Sorry.. I may or may not oblige.
E-Targets for F-Class
- Thread starter Down South
- Start date
Nor me. WGC has 32 firing points on the high power / long range field. Number boards have one or two digits; those above nine the left one is significantly smaller than its partner to the right. They alternate white/black field with numbers black/white. Boards are roughly one full target's height above targets themselves so you have to be careful with every shot.
I know I've fired my share of cross-fires there (and elsewhere
) in the 15 years I've been shooting, and I've yet to shoot much with a scope. With match sights I know how easy it can be if one's not paying attention, can only imagine what it's like looking through a 40+ power scope.It's not a "tired" argument. It is a valid argument. Why do you want to take it offline?
Last time the entire thread got removed. It is unclear to me why but that doesn't matter. That was 14 months ago.
Yeah. I know! But I want to get us to 30 pages. (Am I alone?)
Geoff, I have investigated your 4 sensor method, solved it, evaluated it for merit. A 4 sensor single plane open target would have many advantages. The sensors could be as small as the brackets and mount permanently on the target. I really tried to make it work, even if it wasn’t as accurate it would be a key step towards a $400 personal product.
Unfortunately it doesn’t work. There are symmetries involved that make it work everywhere except the center horizontal and vertical line on the target. Which is the place people aim at.
Unfortunately it doesn’t work. There are symmetries involved that make it work everywhere except the center horizontal and vertical line on the target. Which is the place people aim at.
Not correct. It most certainly does work. In fact it works best in the centre of the target where the part of the isochronic curve (hyperbolas) we want to look at are in fact straight lines or close to it.
Who said anything about symmetries? Symmetry of what? Are you assuming that the positioning of the sensors are necessarily such that they form a regular square or rectangle? If so, you are wrong there also. The sensors - however many there may be - can be anywhere. We just need to know where they are relative to each other, and a reference point. Symmetry doesn't come into it. Nor do angles. Actually, it can help to not place the sensors in regular positions (such as at the corners of a regular rectangle) so as to not have any symmetry without in any way affecting the integrity of the result (if you're worried about it)
Multilateration is the mathematical basis of GPS, some anti-submarine warfare systems, and various other navigation systems. It is three-dimensional (trilateration is the two-dimensional version of it and either would work in an ET). It is used also by every other ET manufacturer other than (it seems ShotMarker and SMT). I wonder why? Are you seriously suggesting that everyone is wrong? (and that only you are right???) Your assertion that it "doesn't work" blows me away! It also has me question your credibility I'm afraid. I am not inclined to carry on with this discussion as a result, as I find it difficult to argue against this sort of thing (BS basically). After this post I think I will have to withdraw (to the cheers I am sure of some people reading all this).
Smarter mathematical minds than yours or mine have established these mathematical and engineering principles and methods. Sir Issac Newton comes to mind - in fact he developed the very method that I use a few hundred years ago. These are not new concepts.
I think you are attempting to divert focus away from your non-isochronic method that is dependent (it seems) on a potentially erroneous input parameter and simply bringing up phurphies to discredit something it seems you really don't know too much about. You are also discounting the very desirable byproducts that that multilateration can provide.
I suspect you don't know how to do it. If you did you would - there is no extra cost involved. Having Vt is certainly a nice number to have but it should not be essential in the event that it just might be wrong! (without you knowing).
Requiring a precise input value such a measured terminal velocity in order to make your mathes work is an unnecessary risk to the integrity of he result - just in case the velocity measurement is wrong. How do you know it is right and thus provide confidence that your resulting impact point is correct? Another input that has to be measured and used is air temperature and both methods require it.
Since (from an engineering perspective) error always accumulate it makes sense to remove where possible any sources of error. Errors never detract from each other. Vt is an obviously source of error and is easily removed from the equation - if the right equation (or method) is used that doesn't require it in the first place. How do you know that your Vt value is correct? I know of at least one of your systems here in Australia that has reported a terminal velocity higher than the muzzle velocity (that was measured by both a labradar and chronograph) and in that instance your software didn't pick it up.
You will always have errors in any system. We strive to minimise them, or at least their sources. Again, why would you risk the integrity of your result by utilising a potential major source of error when you don't have to?
Is this the sort of vulnerability you want in a system that is being seriously considered for use with the settings of state or national records?
I am sorry for those of you that don't want to hear any of this. But the fact is for this application multilateration is the best (or at least a better) engineering approach to the problem. Don't take just my word for it - perhaps ask any engineer or mathematician who knows what it is and how/where it can be applied.
I can't believe I have engaged in this argument - I have people advising me (in fact telling me) to stop it (and not because they are afraid of what I say and/or don't want to hear it). Yes it is a valid argument, but I think for me the bones of the horse have now been picked clean and we are not going to get to 30 pages. At least not on my account.
Wow, just Wow,,,,,
I didn't see the 1st thread that people said was deleted but I could see why a thread with out of hand posts should be deleted. 100% causes more harm than any sliver of good.
If I were AM I would not even respond to this.
(maybe privately but certainly not publicly and I would only talk over the phone with a person like this as emails would very likely be twisted and posted publicly)
His time would be better spent building and shipping a great product that is working very well for over 1000 customers doing all that we need it to do and more in the 1st year of sales. Same applies to the Silver Mountain product that is also selling very well.
Geoff's post reads 99% like a personal attack / vendetta to me than a person looking to professionally discuss debate the physics / science of E Target Technology. Maybe even some jealousy and sour grapes thrown in.
We have already discussed how most of us here perceive berating your competition as very poor business practice. That and pricing turned me off to the other high dollar offering in this market.
Reminds me of that "wrestling with a pig saying"...
But that's just me and how it read to me.
AM and others may see it differently.. I bet Rick will love it...
George
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Medic505
Gold $$ Contributor
You keep making this threat, yet you come back for more. You might as well face it, you're not going to get the last word.
Yes, if you have vision problems, or if the number boards are small, or if the number boards show only the second digit, or if you npa is not good, or if the number boards are in the shade, you see the same color number board as before and the same digit, or the number boards are low and covered in heavy mirage and the list goes on
WE at lodi have shot with a 7 sec delay since we held the first nationals on e targets and there were many records set at that match as I am a whitness to how many hours were spent filling out national records forms. We have used a 7 sec delay since we started using e targets.
My personal opionin is that a 7sec delay is about right also not showing the group would make it more like it used to be but it is not a major factor to me as I learned to keep a score book when I began shooting
Why does multilateration not require Vt. Does it use the speed of sound?
Adam,
i have used both enclosed targets and built my own open faced targets and closed faced target utilizing a 4 sensor single plane method. Utilizing Multilateration and i can tell you it does work even in the center of the target. Comparing both the image and measurements provided on the screen and measuring the actual shot location it is extremely accurate and very repeatable.
Mike
The short (and possibly glib) answer is because it doesn't [require Vt]. It is entirely time based - the times being the TDOA's (Time Differences of Arrival) from which we create isochronic curves (hyperbolas) and exploit their properties. A four sensor system produces twelve usable isochrones from which we derive four triangles (triplets), the apexes (intersections) of which should coincide (and generally do). The amplitude of the resulting shape (polygon) indicates the accumulated errors (and area of uncertainty). Ideally, all intersections should be at the same point (no amplitude meaning zero errors). There are always errors but this number provides us with a indication of the current quality of measurements by that particular target.
We require speed of sound in order to convert time to distance.
To determine the speed of sound we require a temperature input. Temperature is pretty easy to reliably determine and calibrate.
So that's all we need: four (or more) TDOA's (one per sensor, with at least one being 0 - zero) and a temperature.
We (my son and I) are thinking about posting something a bit more comprehensive if indications are that anyone is really interested.
600 x 600 mm square target, 20 deg C
A. Shot fired 50mm left, velocity 500 m/s, sensor timings 0, 0, 149, 149 us
B. Shot fired 100mm left, velocity 369.5 m/s, sensor timings 0, 0, 149, 149 us
Near the waterline, where the top and the bottom are mirrored, you have a 1D problem with only left and right sensors being useful. Changing the X position of the shot, the velocity, or the incoming yaw angle changes the timings in the same way, so you can't differentiate. Not enough information.
A. Shot fired 50mm left, velocity 500 m/s, sensor timings 0, 0, 149, 149 us
B. Shot fired 100mm left, velocity 369.5 m/s, sensor timings 0, 0, 149, 149 us
Near the waterline, where the top and the bottom are mirrored, you have a 1D problem with only left and right sensors being useful. Changing the X position of the shot, the velocity, or the incoming yaw angle changes the timings in the same way, so you can't differentiate. Not enough information.
Jdne5b
Gold $$ Contributor
Sounds like an invalid attachment type?
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