OzFclass

Rod,
If the WARA targets had big holes in the acoustic chamber then you will get missed registrations and inaccurate placement of shots. It comes back to the maintenance schedule that I mentioned earlier.

I believe that our frequency of target error is now lower than the frequency of manual marker error and I have been working in target galleries for a long time.

You may be onto something with your double rubber. We use a 4'X4' Kongsberg target at 300 metres (the only one in Australia) and that target survives for much longer than any other target without servicing even though the centre cops a real pasting. It has a double rubber system.

The only way to ensure that no shooter is disadvantaged by e-target error is to use a backing sheet for each shooter. That is, before each shooter starts, a sheet of paper is stuck on the back of the target and in the event of a dispute the actual fall of shot can be seen. Of course it requires a person to change the sheet between shooters in the gallery so it sort of negates many of the advantages of electronics.

Peter Hulett wrote:...The only way to ensure that no shooter is disadvantaged by e-target error is to use a backing sheet for each shooter. That is, before each shooter starts, a sheet of paper is stuck on the back of the target and in the event of a dispute the actual fall of shot can be seen. Of course it requires a person to change the sheet between shooters in the gallery so it sort of negates many of the advantages of electronics.

Peter,

For major events like the the CWG, this should be affordable. You would only need a small crew in the butts, backing sheets could be changed on request from the RO. A butts officer could look at any disputed target backing sheet, and discuss with the RO.

Alan

Peter Hulett wrote:The only way to ensure that no shooter is disadvantaged by e-target error is to use a backing sheet for each shooter. That is, before each shooter starts, a sheet of paper is stuck on the back of the target and in the event of a dispute the actual fall of shot can be seen. Of course it requires a person to change the sheet between shooters in the gallery so it sort of negates many of the advantages of electronics.

Ok, that might mean a combination of manual and E marking? Say one x pits person per 10 targets (or whatever) to put cheap and very easily replaced paper backing onto the target as the shooters come onto the mound or whatever. That really would solve the issue for the lost shots, and be a double check for the shooter and the RO.

I would propose even at this early stage of the idea, that the paper backing should only be used to "count holes", and not actually provide a score. This way, the RO can just provide a sighter or whatever as they see fit, or provided by any reviewed rules.

Backing sheets were used in Delhi at the insistence of the teams but no team member was allowed to see them. Apparently they were not even changed between shooters. All the safeguards in the world will not overcome sloppy management and downright pigheadedness. Also the use of backing sheets is dependent on the range having a safe area for markers such as a gallery. We at geelong don't have that and any range purpose built for electronics will not have a gallery either.

I return to my prior assessment. I believe that we have the level of errors on our electronic targets below the level of errors that occur with manual target marking. No system is perfect but we have improved accuracy of marking by using electronics. Unexplained missed shots were not uncommon when targets were manually marked and the reasons for that were many and varied. "Shot down the peg", "Hole is sitting on the line or in a crease in the target", "sloppy marking", etc.

Alan, the CWG may be the pinnacle of the sport but unfortunately the mechanics of the sport do not reflect that. The CWG in Bendigo were supposed to have been the best but believe me the targets there were a compromise as manually marked targets always are. You cannot produce 30 targets manually and have them all identical. At least with electronics you have a more level playing field to start with.

Peter Hulett wrote: I believe that we have the level of errors on our electronic targets below the level of errors that occur with manual target marking.

I have to disagree.

At our club PM, which is reasonably well attended considering where we are located, we had close to zero issues with manually marked targets. Almost all of the markers are kids (some mine), that have been trained very well, and know about shots down the peg and all that stuff. As far as I know, there were no missing shots, that could not be explained by the marker seeing a stray shot on the backstop, or a spare hole in the next target.

There were lost shots at 1000 yards, but who has been to any shoot and not seen a shot lost at that range?

There were quite a few shots just missing at the WARA Queens, with no explanation and no apologies. The shooter was wrong, the RO said tough luck and you lost the points. The same thing absolutely DID NOT happen at our PM.

I would like to add that the manual targets we use are very well managed, well maintained and we make sure the markers know what they are doing. Some are only 10 years old, which always gets funny looks from the shooters, as they were expecting much older humans pulling the targets based on the outcomes they were getting.

On the targets being exactly equal, this is removed due to the shooters moving target number for each detail or range, having then to shoot on a different target.

Rod,
We have had no problems with missing shots at any of our prize meetings on electronics either. So we are equal. You cannot compare badly maintained e-targets with well-maintained ones any more than you can compare well-trained markers with sloppy ones.

As far as shooters moving targets is concerned it doesn't equal out at top level shoots as there are only one or two ranges each day. We were talking about CWG, not prize meetings.

Again, I have been butts officer at many ranges and have prepared targets and managed many marker squads up to and including CWG level and regardless of the age of the markers I believe that the error rate on OUR e-targets is lower than on manually marked targets.

Ever measured the difference in size of targets in the morning and in the afternoon when the sun gets on them?

I understand that there were considerable problems at the National Queens with markers missing shots when smaller calibres were used.

I love that expression, "unexplained shots".

At the recent NRAA nationals, the butts established a procedure to avoid that old issue that Bill wouldn't put one on the wrong plate/wouldn't go from a V to a miss/must have put one down the peg. A call that became very commonplace would come through, "The shot on target xyz is a miss & we know where it went".

Some shooters has a naive belief that just because a marker pulls a target, there will be a hole to value somewhere. No way. A marker will drop the target when the shot is obviously in his domain of interest, viz if he feels it through the target frame or anywhere that he sees a shot registers in the window of the backstop directly behind his target. He might pull it down for a shot obviously to one side, but only if there isn't an adjacent target that might have been shot at - in which case, he'll likely wait until one of the two targets is called down. Surely if you've pulled targets yourself you've heard the call, "Dear me (expletive deleted), that shot was low/high/a tad wide".

The situation that Etargets do cure is the unacknowledged or unaccepted crossfire. As a range officer, I sometimes wonder whether some less than scrupulous shooters are getting a second bite at the cherry due to lax scoring when second holes magically appear on targets without a corresponding Message 1 adjacent. On the other hand, I recently witnessed a crossfire onto the next target not being noticed at all because shooter 1 had just finished & was clearing out, the scorers were correctly comparing their values & shooter 2 was looking over his shoulder waiting for the call to shoot. As luck would have it, the BO recodnised the amnomoly of a small calibre hole interspersed with .30s & reported the same. FO shooters, beware that you have the opportunity to crossfire where ICFRA targets are used.

Peter Hulett wrote:Rod,

.....We were talking about CWG, not prize meetings.....

Exactly, which was my point. If we can get a pretty good outcome, in both examples, why the hell can't the CWG people do it?

I heard first hand from shooters returning from Delhi, and wondered if we had run the event at our local club, we would probably had done a vastly better job, so would yours and many others. I would personally love to mark targets in the CWG. Or, on the other hand, be involved in the maintenance of ET's.

I think either way, there is no getting away from the human input at the target end of the range.

The other issue of crossfire and the shooter not owning up to it, is 100% down to lazy scorers. The scorer is there to make sure that a lost shot from his/her shooter is scored as a miss if in fact it is. This happened a number of times in Brisbane while I was there.

The scorer needs to pay attention. In my own case, I will call the number of shots fired on the target number after the shooter fires, this indicates that a shot has left their barrel, and must be accounted for. I notice a fair few other people do this as well to limit the fact of missing a shot. There is little chance a shot can be fired and not be allocated to a score or a miss.

This is stuff that should bring a ban from the event, or at least a severe penalty for cheating from the RO/match committee, and even a reprimand for the scorer.

JohnK, about F Open shooters crossfiring when we use ICFRA targets, at 2 Queens shoots now, I have crossfired onto Fullbore targets when we were using F Open Targets I remember on one occaision, I got 3 sixes, all going well I thought until I saw the Target rifle shooter on the target next to me give me a thumbs up and mouthed a thank you. 3 shots on the wrong target.

On a more serious note I very nearly gave one of our good 223 shooters a miss at a club shoot, spent ages looking for his hit. His last few shots were Xs and it was only when I noticed the missing rubber ring around the peg that I noticed the bullet went "down the peg". A few days later the same happened to him at Queens shoot and he got a miss after a few Xs in light conditions.
At my last shoot I had to call Message 1, 6 times during one target at the end of the day, obviously the marker was getting tired and wasnt looking for hits from my small caliber. maybe the electronic targets will be better in shoots where the markers get fatigued after a week of scoring. Markers are only human and I know I get sloppy after marking for an hour.

Unfortunately small calibre holes seem to be prone to getting missed by markers. If you did statistics on mysterious misses, 223s would be significantly over-represented, and its obviously due mainly to down the peg shots being missed.

Small calibres have both advantages and disadvantages.

Alan

It has been interesting reading this thread on the subject of electronic targets and what seems to be a common problem with them generally in that they apparently miss some shots. Enough to be a problem.

Well, I have been doing a considerable amount of research into this with my own targets, as it was an issue that popped up some time ago. Presumably others also developing electronic targets here are thinking about the same issues.

From my observations [on my target(s)] there are a number of reasons why no hit is apparent - to the shooter at least. One is the possibility of communications problems between the various systems. This is mainly an engineerng issue.

More likely it is due to what's happening in the target and this is what we found.

First of all, with a target that has microphones in each corner, there are 16 possible combinations of order of "firing" of mics. But only 8 of these are valid, and theoretically it should be impossible for the invalid 8 to occur. But they do, and for explainable reasons.

Speaking for my targets and no-one elses...

My three sons and I have been giving this a lot of thought. (All sons are electronics engineers and two also have physics/maths degrees). We found that the problem, when relying soley on using air as the sound transmission medium, that the problem occurs when the impact is at a position equi-distant between two microphones. This made sense. The question was why, when it is theoretically impossible? Well, we have a theory and it is to do with a combination of the frequency response of the microphones (40Khz +/- 150hz in my case which results in a 6.25 uSec quarter period - roughly 2mm error) and any variable latencies thought the amplifiers and timing/logic systems resulting from operational tolerances of components - especially the microphones themselves.

Higher frequency mics are available but at unacceptable cost (in my view). For anyone interested, the mics I use are industrial grade with appropriate specifications (both environmental and electrical) for the task. They are not cheap ones from the local Jaycar shop.

So what does one do when the system throws up out of order microphone data? Well, in my case I _do_ address it but how is something I'm not prepared to elaborate on.

We have not [yet] considered the possibility of relying on something else as the primary sound transmission medium - such as a sheet of rubber across the target face. Instinctively I am not keen on that but I don't discount it. Likewise I am not prepared to consider the use of metallic bars in the target in which the mics are embedded (although I understand what their principle of operation is).

We are still researching this by hooking up an expensive high speed (500K 14-bit samples/sec/channel) simultaneous sample and hold data acquisition system to various stages throughout the target electronics. This results in an extraordinary amount of data to be analysed and we have tools to do this. The results so far have been somewhat interesting.

The view we are taking with this is that it is not good enough to simply accept that one requires "clean" targets in order to function correctly. We need to understand why "dirty" targets cause the problems they do and find a solution to at least allievate the problem without compromising [too much] accuracy (a subject in its own right).

We are also taking the view that any solution we devlop will be based on solid engineering data rather than perception and guess work. That is not to say that a considerable amount of experimentation is not required. But rather we want to examine the causes of these problems - that I suspect all E tgt systems are suffering from - rather than simply knock up some solution that masks the underlying cause. This takes time.

In light of what has happened in India, I suspect that considerably more focus will be on both target reliability and accuracy of detected shots. To this end, I and my sons are putting in a lot of effort in my particular targets to find out what's going on in those relatively rare occurrences that seem to become less rare as the ranges get longer.

I am under considerable pressure to "get my target system out" under threat of "going elsewhere". I am reluctant to do so until I am satisfied that I fully understand the target issues and have an _engineered_ solution to them. The recent problems encountered in India - whatever they are/were - and this particular thread on the subject have solidified my attitude: they're not going out until I'm happy with them. Even under the threat of shooters deciding to purchase some other target - that may or may not suffer from the same issues being discussed here.

Finally, some may disagree with what I have written above. All I can say to that is that I have attempted to provide an insight to our research and to explain in simple terms what we have discovered, and the approach we (my sons and I) are taking to address them.

Geoff.

Geoff,

I was under the impression that there was built-in redundancy with the number of sensors? If this is still not enough, could it be a matter of simply increasing the number of sensors (at some cost admittedly), and configuring the associated software to ignore those sensors that give an inconsistent value?

Alan

AlanF wrote:Geoff,

I was under the impression that there was built-in redundancy with the number of sensors? If this is still not enough, could it be a matter of simply increasing the number of sensors (at some cost admittedly), and configuring the associated software to ignore those sensors that give an inconsistent value?

Alan

I think it would be generally accepted that more sensors = greater accuracy. Whether or not three is enough to work with is a matter that could result in some argument. I don't really want to get into that.

We haven't found a way to effectively triangulate on what three [only] working sensors can provide us - remember that the first we know of a projectile is when the closest sensor "fires". What happens if it happens in reality to be closest to a broken sensor? You then only know about it when the first working sensor/mic hears it. I don't personally believe that it is worth pursuing this scenario.

Furthermore, triangulation is not necessarily the only way to resolve the position. Remember that what you have is the difference in the Time of Arrival at the three sensors after the first one fires, letting you know that an impact event has occured. If triangulating, that time needs to be converted into distance and to do that you need to know the speed of sound _relative_ to the sensors. And that is a function of the speed of sound through your primary medium - in my case air. But it is also a function of the slope angle of the supersonic cone which is in turn a function of the projectile velocity (in terms of mach no).

So there are a number of variables to consider, and at least one guess, if you want to triangulate based on distances.

Also, to me it is not a matter of dealing with inconsistencies as such, but rather knowing what the tolerances are and dealing with them. There are no absolutes. If you are measuring temperature, to what accuracy? To determine the relative speed of sound, assuming you have a "good" temperature, how fast was the projectile going at the time of impact? Does this matter? It depends.

I think where we are now is at the crux of the matter in so far as electronic targets are concerned: reliability (or integrity), and verifiable accuracy and the limits of both that will be acceptable.

Obviously the easiest way - not necessarily the "best" way - to prove accuracy is to have something physical record the place of impact (like a backing paper) to compare with the electronic record. But how accurate is the Mk1 eyeball with a tear through a piece of paper? Can one really categorically state that they can measure the distance from the center of a jagged hole to another jagged hole to within say 1/2 a millimetre? Consistently? But I would accept a paper with holes in it as a good guide for sure as I consider it unrealistic to expect an electronic target to be any better. That's what I do when I am conducting accuracy measurements, I have to admit.

I think it is now time to consider dispensing with some myths and conjecture, in a technical sense, about electronic targets and their capabilities (or lack of) and perhaps put the desperation to obtain them to one side temporarily and consider instead the engineering challenges associated with long range projectile impact measurement. Because sales talk is cheap as are unsubstantiated claims of performance and accuracy. The damage that will result from such conjecture and assertions are unrealistic expectations of performance.

After 36 years fulltime dealing with electronics and associated technologies (including machine control software design), I personally do not believe that electronics is infallible. Equipment will fail at some stage for sure. But as designers of such equipment, for a particular market and operating in a particular environment (in our case potentially hostile), it is encumbent on people such as myself to produce something that not only works, but works consistently within definable parameters balanced against a realistic price tag. I don't criticise any electronic system that fails in 40 degree heat - electronics (semiconductors) hate heat and it's a tall order for even industrial grade components. When something fails - consistently - we need to understand what is causing these failures and design accordingly. Not simply assume something that sounds convenient. For that reason I will not contemplate my system employing consumer grade laptops as mound display units as they simply will not cut it when placed in the potentially hostile mound environment.

When it comes to the missing shot problem, I think Peter Hulett (earlier in this thread) is correct in his approach as a user: adopt a maintenance program that minimises the likelihood of the failures. But from my point of view it sure would be nice to know what causes the problem in the first place when the rubber in the centre is shot out leaving what I presume is a gaping hole in the center of the target. That might lighten up the maintence workload a bit and ultimately improve shooter satisfaction overall.

Geoff.

Geoff,

I will admit that my knowledge of the technology is very basic. However, regardless of how it might work, couldn't it be duplicated, or better, checked simultaneously with an alternative technology, so that if there is serious disagreement between the two results then the shooter is given another shot (immediately). I use my 2 chronographs in this way, set up in series. If they disagree outside certain limits, then I disregard both readings. There will of course be a cost penalty, but as the technology matures this should reduce. This might actually be a better approach than trying to make a single technology near perfect?

Alan

AlanF wrote:Geoff,

I will admit that my knowledge of the technology is very basic. However, regardless of how it might work, couldn't it be duplicated, or better, checked simultaneously with an alternative technology, so that if there is serious disagreement between the two results then the shooter is given another shot (immediately). I use my 2 chronographs in this way, set up in series. If they disagree outside certain limits, then I disregard both readings. There will of course be a cost penalty, but as the technology matures this should reduce. This might actually be a better approach than trying to make a single technology near perfect?

Alan

Yes. I see (especially for major events) now the prospect of a "backup" or secondary system being employed. The idea of using a paper backing has already been raised on this forum. But whether or not the vast majority of potential ET users want to employ such a system remains to be seen.

A duplication of the sensor system might also be viable but what would be the point when the issues of what is actually going on inside the target and the causes of problems are not fully understood in the first place? If they _were_ currently understood and/or addressed I'd argue that we would not be talking on this subject right now...

I guess the point I am making is that without the performance parameters being defined, and the performance of a particular system (even mine) being measured and released, on what basis would one make a decision at club or DA level as to whether or not this is required.

It could well be that known and defined inaccuracies are tolerable, when balanced against the cost of an alternative approach (such as you have raised). I am not aware of any benchmark applying to long range outdoor electronics targets.

Geoff.