MajorBooBoo

You think the wife would mind? Its early here still. You are just going to stand by yourself and drink beer anyway. Dont get your hopes up too high. Thanks for all your great input again.

I really think that might be ONE solution. But for the sound to arrive at microphone B 1 second after microphone A, there are an infinate number of places for this to happen (well, until the gun is so far away it can't be heard). Any place where the gun is 340 meters further away from microphone B than A, there will be a one second delay between the microphones picking up the report. I admit I don't have to math to back it up, just my witts.</font>

????????????????? If the distance between the sensors is constant, then moving the noise source in any direction will change the time differential. Accept it or why not try to disprove it? You are just talking in circles. The only special cases (here we go again) are when the sensors are equidistant or the two sensors and the noise source are in a strait line. What is so hard about this? Did my calc work? anyone have anything to say besides unsupported gobblygoop? [ February 15, 2002, 10:38 PM: Message edited by: MajorBooBoo ]

Booboo to Nebelwerfer thread..Booboo to Nebelwerfer thread..come in nebelwerfer thread... Its two seconds karch, I had to change to two seconds? Do the numbers compute? Please check in teh equations The gun is constrained by the two radii, if you move to the left/right, the radii change and so would the two second time diff, same for other moves. Its constrained...

It took me twenty minutes and I am flying a plane. I had to mix some drinks too and theres Tom Collins all over the dash. Hope those guages are working..Anyone need ice? Theres some on the wings...

difficult conditions but heres answr slope from origin to gun is prox 2.4, time from gun to origin 1.42 sec, time to (1300,0) is 3.43 sec, gun near (192, 460). Can anyone confirm?

i guess. I am flying my plane right now but have on my calculator watch. the watch has trouble with 1 and 4 (they are on top of each other and give me entry errors ie hit 4 and you get a 14). can I get the 1400 changed to 1300 and 1 sec to two? i will use 650*2 for 1300, I have probs with 7 9sometimes) above the 4 and 1 also. 350 is great. is this Ok? how will you know I am correct. must fly..strait..

The concentric circles should be such that the center of the two circles have X as the center. One circle should have A on the outside of its circum and B should likewise be on the outer circle circum. Busy right now and hope to be home later tonight.

Thank you for the drawing. The case of the simultaneous sound arrival at two receptors has already been discussed. I did this in my Q&A if you go back some pages. It is a special case only. Theres also the case where the sound is not simultaneous but the source and the two receptors are all in a line. In either of these special cases, only direction can be found (ie the gun is somewhere along the line). You are on on a good track but time is running out. I will type up the answer and post it here today in an hour or two. Someone also said: You can not do it with 2 microphones. You would be able to get a possible line, but not a specific point. Think about this logically. You don't know how far away the gun was fired. If the time differential was 1 one second, that tells you that the distance of the firing gun is 1 second further away from the gun. The speed of sound at sea level is 1115.7 (1100 for math purposes) feet per second. If the gun was one foot away from microphone A and 1100 feet from microphone B you would get a 1 second delay. If the gun were 1100 feet from microphone A and 2200 feet from microphone B you would get a 1 second delay. If the gun were 11,000 feet from microphone A and 12100 from microphone B (a 1,100 ft difference) you would have exactly a 1 second delay/differential.. This person is throwing out the important piece of information about the seperation of the surveyed receptors. This constrainment is vital. Without using it you fall into teh pitfalls that others have been doing here. use this: If you have two mikes (x1,y1) and (x2,y2) and a time=distance difference dr12 then you have three equations r1^2 = (x-x1)^2 + (y-y1)^2 r2^2 = (x-x2)^2 + (y-y2)^2 r2 = r1 + dr12 Use this: The knowns are: Speed of Sound 1000 meters between recievers. 404.74 time lag from sound (dr2) R1=R2-404.74 (or however you make your R's) exact cartesian coords of recievers Request: If you could post a image of two concentric circles with points at the center of the two cicles, a point on both the drawn perimeters, I would be very grateful. Make the points all look like a right triangle for the sake of clarity. The real starting point is to make a correct diagram.

Why are circles emanating from the receptors? Is this an active sensing scheme you are proposing? Sorry but you are a pied piper and have led the flock astray (ummmmmm shheeeeeeeeep). Think of a dartboard (a snooker board?) and the noise at the bullseye. Drink alot of Pints. The mics are on the outer edges of the rings. Think alot.

Is that everyone? Good to see JonS committing his chips into the pot. I think that Thomm might be smart enough to actually come up with another way. He found the only technically correct solution that was demonstrated, but did not really provide an answer if he thought the math was doable. I wonder if he agrees with asok? can the math be done in a reasonable amount of time Thomm? What happened to Brian? Last I read, he was supplying wrong information regarding Nebelwerfers placement of the warhead or some such. Has he posted in the last 4 pages? I will post friday. I will give some clues now. Ask yourself: 1. what logical information could they start with? would they have a reasonable idea of where the enemy was? the range limitation of their own equipment? 2. having Thomm's equations what would you do? they are the right equations and he should be commended. but theres just one more step... 3. can asok possibly be right? does it CHECK? try checking it, if it doesnt check then he isnt right. Christ, start with a known triangle like a 3-4-5 and that might help you. make all the distances and times known. It could give you aa clue. I always believe that theres a silent majority of people 2-3 times the number of posters in the current thread that follow the thread. If they would, please speak up and vote one way or another. Throw out some ideas also if you like. I was kind of hoping Charles would throw his chips in too!!!!

Hows my timbre?

If there WERE an infinite number of solutions, wouldnt we need an infinite number of sensors? All kidding aside, you really are not correct. Anyone agree with him? The fact is, that for a sound wave to pass over two points in a X-Y plane, and there IS a time differential measured between the passing of the wave over those two points, THEN there are only two solutions IN THAT PLANE that can be resolved for that circumstance. If we extend to X-Y-Z volume space, then a circle of points perpendicular to the plane, that includes the two resolved previous points in the X-Y plane, are the solution. Thats it. Take the problem to any real math/physics teacher and he/she should tell you it is so (in a ideal geometric world). Are you a teacher Asok? I will give this another day or so. It is getting to page 9 and some people are intent on derailing it. It IS very interesting. The material discussed and the behaviour exhibited.

But only if you personally are directing the conversation in a sufficiently arcane topic of your choosing in which you can come off as the master to our pupils. </font>

What is needed to know about Sound that makes sound ranging and direction critical? Sound is a form of energy that travels through a medium. The medium is air in this case. Sound is made up of frequencys. frequencys travel through air and lose energy at different rates. The frequencys all can be said to travel at the same rate for our discussion. What "sounds" does a gun make when it goes off? The propellent detonating and the gun barrel ringing are the two major noise events. The propellent is easily understood as a quick burning explosive. The gun barrel is like a tuned bell that has been struck, the shell accelerating and twisting through it, will strike (ring) it out. The ringing can then be a signature event for that particular gun barrel diameter and length and muzzle break (if it has one). The explosion has a greater amplitude because it masks the instantaneous ringing. After the explosion, the ringing continues and can be discerned. Explain how the series of events between firing of the enemy weapon and initiating, perception, recording and computation and relaying of data occurs in overview form. The enemy weapon is fired at some unknown distance and direction from friendly lines. The firing event is from a flashless weapon in daytime and is also behind a small hill. It is not observed visually. The sound travels outward from the fired weapon like a constantly increasing half-sphere. If looking strait down from above, this would appear as a constantly increasing circle who's radius rate is the speed of sound. The sound arrives at a forward LP (listening post). A person there is situated close enough to the front lines and far enough in front of the recieving stations (mics) that he can percieve the sound arriving over his position, he then signals (radio or some other communications method) the CP (command post that can turn on all the MICs), so that the mics are "online" when the sound wave will start to come over them and the recorder(s) are also turned on. The MICs then are transducers that respond to sound energy and produce an electrical signal from it. This signal (it could be amplified/filtered at this stage) is sent down a wire to the CP which has data recorders. The data recorders respond to the signals and scribe a measure of the intensity of the signal and the time event at which it occurs on paper that is moving past the pen. Computation can be made from a comparison of when the events are recorded. The Goal is the enemy gun location within an acceptable radius of error. This information is then relayed to a firing battery so that it can take the enemy gun under fire with the intent of destroying/neutralizing or forcing him to move. Why not leave this system on all the time? The need for "early warning" comes from the fact that the recorders are probably based on a paper/ink/deflected pen type technology (maybe till 1944). The paper is on rolls that are accelerated to a high speed (since the time precision is critical) and these cant be left on all the time. The take up reel would just fill up too soon or some other intefering mechanical problem/formality would erupt. The ink in the pen would run out from drawing a strait line. The electronics of the day, tube based, were susceptible to burning out (like cheap light bulbs) and drifting from calibration. What problem could there be at the LP? The LP might be human based. If the LP has a battle raging in front of him and the distant battery is behind this battle, he would be inhibited in his ability to discern the guns firing behind this "wall of sound". Likewise, any noise to his sides or above, a friendly battery firing, a column of vehicles passing, flights of planes overhead, etc. would make his job harder. The LP then, has to be far enough back that these events are minimized. Likewise, this pushes the MIC line back. And in turn, this limits the range of the overall system. How could this have been solved/improved? The LP would need its own frequency sensitive alert system. A MIC at his post that could aid him in the presence of the higher frequency ringing that the guns give off (it could beep lets say in harmony). He could then "see" through the rumble of battle to know that there was some guns firing somewhere that fit the frequency of an enemy battery. What is the limitation of this? Explosions are actually lower frequency and low frequencys travel better than higher frequencys (ringing). They can be heard at longer ranges. They arent attenuated by ground effects as much. Higher frequencys would drop off quicker. The LP then would have to be closer to the front with this freq sensitive alert system. Is there a need to make all the MIC cables back to the CP equal length? The sound, once converted to an electrical signal, travels at 3/4 the speed of light or so and any error this introduces is negligible. What are the time lags between the enemy firing and the counter fire? The sound has to travel to the friendly mics which is range dependant. The recorders have to be stopped once there is enough data, the paper taken off and information read off the ink marks. The computations have to be made (this is still a topic of interesting discussion and wont be layed out here) and the information radio/communicated to a counter battery. It could vary greatly depending on the skills of the people involved. 15 minutes has been cited in the German case. Heres some more in depth information... http://www.sfu.ca/sonic-studio/handbook/Sound_Propagation.html [ February 15, 2002, 12:02 AM: Message edited by: MajorBooBoo ]

Its too late. He felt the need and pumped his load into the nebelwerfer thread. He did manage to temper his inane post there with a little *smooch* on the butt for BTS. Very clever little silly man this Chef is.

I agree with Thomm. Its also that an Engineer can tell how you how it might NOT work due to real life glitches/foibles/human errors/etc. A technician can also show you a sneaky trick he discovered because he doesnt want to crank numbers all day. This is how things work in the real world. We take for granted the technology that we have today. Digital electronics, memory and sensor technology make everything inexpensive and easy. Leaving stuff on all the time is no big deal cause it uses hardly any power and doesnt affect the performance of the technology. This wasnt the case for 1940s technology or especially WWI technology. Nowadays, error reduction can make people assume that the technology acts very close to the ideal physical principles. A simple example is the gyrostabilized gun technology. People read how it was supposed to work, keeping the gun level and on target, and start thinking/modeling it as such is easy. In reality, it would be very hard to pull this off and KEEP IT WORKING under real conditions. Nowadays, its almost trivial. So I think this thread is enlightening because it shows that there can be intelligent discussion here, people can learn and appreciate the mechanisms behind things, theres different levels to discussing things, and that Iron Chef is a piece of work. BTW. Asok. You never responded to my answer/questions regarding your diagram. Can you , perhaps, go back and think about some issues I brought up? [ February 14, 2002, 10:16 AM: Message edited by: MajorBooBoo ]

How about a Mini-Hellcat? Take a M5 Stuart Tank and make it just bulletproof. Install a open-top TD type turret with a 6 pounder ATG. It gets ALL APDS and full gyro. This baby could spin tracks and does 50 MPH.

I hate to say this but this guy actually cracks me up. In a 'Peng' sort of way. Hes just so over the top wacky. Thanks Chef. You made me laugh.

http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/6-121/APPB.PDF Print out and read this. Direction can be obtained from some shell strikes by the way.

This would be in the benefit of the firer woudln't it? I had previously said that battles became all or nothings and this is the reason. A better tactic would be to time the sound arrival so that IT arrives at the mic line confounding the CB guys. Ripple firing at sporadic mismatches floods the receptors. Rnge would play in though. The energy levels might be discernable and the CB guys could seperate out whos who. If a forward gun can time his firing such that ITS sound arrives at the same time as a rear battery (same calber) on the mics, then HE' is flooding the floor and confounding the CB. He has to haul ass though. Theres more to it than just sound. Frequency plays in big as do other sound engineering principles. Is it the BOOM of the guns discharging explosive or the ringing of the guns barrel thats important?

Is this correct? I am not saying it is or it isnt. Does it check? Could sound (just think of the circles emanating from the two seperate source points X1 and X2 in ASOk's diagram (thank you for the visual aid by the way) really have the same time differential? Does a further gun produce a shorter time differential or a greater one? does it depend on the layout? Is it possible the guns could be on some line of possible answers? A curve/spiral of possible answers? I hope to hear from some others also. This is very interesting. Previously I said that theres mirror answers. Can that be true or possibly a clue or just false? Noone should take any offense or get aggravated/irritated. I am demonstrating that maybe NOONE (me too) KNOWS everything about CB here. Even that may not be true. I am fascinated on how the technology of that day could do it and have my suspicions.

So most other Nebelwerfers evolved towards a forward mounted HE charge (conventional layout)? Is that correct? I believe these also had inferior accuracy but dont know if thats directly attibuted to mass placement or just the size of the things. The germans did go for more HE thats for sure. What about the russians? Did they develop super katyushas? The germans stuck with the spin stabilization also. Interesting.

Very good. You are sticking to your "guns". No pun intended (what field are you in? again, no pun intended, I am not going to CB your "field") lets say that is right (it is, technically right), how long would it take to solve that equation with 3 mikes? If you had help (no maple programs/calculators or that sort)? Would you go AWOL if you had to do it 8 hours a day?

Pardon. i meant dr2. So R2 can be replaced with R1 +404.74? The knowns are: Speed of Sound 1000 meters between recievers. 404.74 time lag from sound (dr2) R1=R2-404.74 (or however you make your R's) exact cartesian coords of recievers Anything else? [ February 13, 2002, 11:37 AM: Message edited by: MajorBooBoo ]