Turbulent Turtle
F-TR competitor
The following is a write up of my experience with the Electronic Targets and a small synopsis on my understanding of how they work.
My first experience with the ETs was during the MR team match and it seemed that we were shooting in the dark or at a blank wall. The targets never moved and never had scoring or spotter disks on them. As wind coach with a spotting scope, I could not see where the other shooters were hitting or even who was active. So I put aside my spotting scope I did everything by flags. The mirage wasn’t even running because the wind was too strong and it was cold in Wisconsin and whatever mirage did show up was simply too fast to differentiate anything.
After the shooting was all over, I spent some time talking with the SMT guys and learned a few things which I will try to convey here.
The target line is composed of a series of posts placed between each target, about 4-6 feet in front of the target frame. Each post had two crossmembers about a foot long and placed parallel to the bullet trajectory. One is low, about 6 inches above the bottom of the target and the other one is high, about 6 inches below the target top. At each end the end of the crossmembers, there is a microphone. The setup is like a virtual box in front of the target. The bullet traverses the front and then the rear of the box on its way to the target.
The microphones only detect the supersonic signature of the bullet. This is important. The speed of sound (SOS) is the determining factor in this entire setup. As we all know, the only thing that materially affects the SOS in air is…? Yes, you in the back with the scruffy beard? Correct, the answer is of course, ambient temperature. Humidity is also a factor, but it is way too small to really matter for these purposes. So the temperature is recorded for each shot and used in calculating the location of the shot.
When the bullet arrives at the front side of the “box”, the microphones detect the crack, but a different times, because unless it’s a perfect X, one microphone will detect it earlier than the others. The first microphone to detect it will start the sequence and its time delay is 0. The next three microphones will signal their detection of the sonic crack and the system records the elapsed times for each.
Since the bullet is supersonic, the microphones will only detect the event horizon when the bullet is actually past the plane made by each array of 4 microphones. When the second array of microphones detects the sonic crack, they also signal that event and then the system knows where the meplat of the bullet crossed each side of the virtual box and how long it took to get from one side to the next. In other words, it knows the velocity of the bullet. The system plots where the bullet would hit the target 4 or 6 feet further down (I don't know the algorithm used for that,) adds the caliber size of the bullet to recreate the actual bullet hole and determines where on the target, the bullet hit and what the score is.
The diameter of the bullet is important to determine if the bullet would have touched a line, because if it did, the shooter gets the next higher value. The dimensions of the targets and the rings are recorded in files on the system, so this technology can be used with any size target and rings. It's pretty slick and it's immune to ambient conditions, including light and noise. I'm guessing the only thing that would confuse it is a whip.
Of course, the targets must be in exact register with the microphone arrays and when the target faces are redone, you must make sure the target is pasted correctly. The target system at Lodi is on two rails, so a pin was fashioned for each target to make sure that the target frame is in the same position after being brought down and back up again. The pin fit in a hole that was laser-drilled on the lifting mechanism.
Each bullet detected is recorded by the system, which stores the elapsed times from the microphones, the X,Y coordinates on the target, the temperature and the velocity, the score and the timestamp, etc, in files on a Linux box.
On the line, each position is provided with two tablets that are Wi-Fi connected to the network and running a web browser. When you get to your position, you login to the system with your competitor number. You then confirm the caliber of your bullet and you assign yourself as the shooter. The other tablet is used by your scorer. He or she also logs into the system and assigns themselves as the scorer. The scorer then sets up next to the shooter, in a chair or on a stool and then monitors the shooter’s activities.
The shooter places the tablet in a way that it is easily visible to the shooter and then the shooter starts to fire. The ETs at WGC were set so the score showed up right away and then 7 seconds later, the browser would display the impact on the target on the tablet. Remembering that it takes 1.5 seconds for the bullet to get to the target, you would have your score right away and the impact 7 seconds after that. The 7 second delay was used to mimic the effect of great pit service, but still prevented you from machine-gunning the bullets down the lane when there were exceptional conditions.
As each score is displayed on the tablets, the scorer records the score on the card and may or may not call it out to the shooter. The card is not really needed but it is used as a backup to the system and the scorer and shooter both sign it.
When there are unlimited sighters, the scorer presses the button “Go For Record” when the shooter confirms that he or she is now going for record. For the other matches with 2 sighters, the system keeps track of the shots and the scorer does not need to do anything once firing commences.
When the shooter fires the last round of the string, the tablets shows the total score and prompts for “scorecard ready,” on the scorer’s tablet. The scorer confirms the string is done by pressing that button, and the system then asks the shooter’s tablet to confirm the score. Once the shooter does that, the scorer’s tablet prompts the scorer to send the final results to the system. Once the scorer presses that button, the scores are recorded as final and the scorer and shooter log off on their respective tablets.
During the match, you can set up a view to show several targets on each side of yours but these were small and only showed the impact, not the score. That’s usually enough to get a trend of the conditions. During the LR team matches, I brought my Samsung Note Pro 12.2 tablet and it provided me with a much better view than the range-provided Lenovo tablets.
At the end of the day, they opened the local Wi-Fi network to everyone and you could then download your targets for the day and store them as PDFs or other on your device. Each shot had the value and the velocity recorded and it would give you the SD for the string.
This is a picture of the microphone array at Lodi.
My first experience with the ETs was during the MR team match and it seemed that we were shooting in the dark or at a blank wall. The targets never moved and never had scoring or spotter disks on them. As wind coach with a spotting scope, I could not see where the other shooters were hitting or even who was active. So I put aside my spotting scope I did everything by flags. The mirage wasn’t even running because the wind was too strong and it was cold in Wisconsin and whatever mirage did show up was simply too fast to differentiate anything.
After the shooting was all over, I spent some time talking with the SMT guys and learned a few things which I will try to convey here.
The target line is composed of a series of posts placed between each target, about 4-6 feet in front of the target frame. Each post had two crossmembers about a foot long and placed parallel to the bullet trajectory. One is low, about 6 inches above the bottom of the target and the other one is high, about 6 inches below the target top. At each end the end of the crossmembers, there is a microphone. The setup is like a virtual box in front of the target. The bullet traverses the front and then the rear of the box on its way to the target.
The microphones only detect the supersonic signature of the bullet. This is important. The speed of sound (SOS) is the determining factor in this entire setup. As we all know, the only thing that materially affects the SOS in air is…? Yes, you in the back with the scruffy beard? Correct, the answer is of course, ambient temperature. Humidity is also a factor, but it is way too small to really matter for these purposes. So the temperature is recorded for each shot and used in calculating the location of the shot.
When the bullet arrives at the front side of the “box”, the microphones detect the crack, but a different times, because unless it’s a perfect X, one microphone will detect it earlier than the others. The first microphone to detect it will start the sequence and its time delay is 0. The next three microphones will signal their detection of the sonic crack and the system records the elapsed times for each.
Since the bullet is supersonic, the microphones will only detect the event horizon when the bullet is actually past the plane made by each array of 4 microphones. When the second array of microphones detects the sonic crack, they also signal that event and then the system knows where the meplat of the bullet crossed each side of the virtual box and how long it took to get from one side to the next. In other words, it knows the velocity of the bullet. The system plots where the bullet would hit the target 4 or 6 feet further down (I don't know the algorithm used for that,) adds the caliber size of the bullet to recreate the actual bullet hole and determines where on the target, the bullet hit and what the score is.
The diameter of the bullet is important to determine if the bullet would have touched a line, because if it did, the shooter gets the next higher value. The dimensions of the targets and the rings are recorded in files on the system, so this technology can be used with any size target and rings. It's pretty slick and it's immune to ambient conditions, including light and noise. I'm guessing the only thing that would confuse it is a whip.
Of course, the targets must be in exact register with the microphone arrays and when the target faces are redone, you must make sure the target is pasted correctly. The target system at Lodi is on two rails, so a pin was fashioned for each target to make sure that the target frame is in the same position after being brought down and back up again. The pin fit in a hole that was laser-drilled on the lifting mechanism.
Each bullet detected is recorded by the system, which stores the elapsed times from the microphones, the X,Y coordinates on the target, the temperature and the velocity, the score and the timestamp, etc, in files on a Linux box.
On the line, each position is provided with two tablets that are Wi-Fi connected to the network and running a web browser. When you get to your position, you login to the system with your competitor number. You then confirm the caliber of your bullet and you assign yourself as the shooter. The other tablet is used by your scorer. He or she also logs into the system and assigns themselves as the scorer. The scorer then sets up next to the shooter, in a chair or on a stool and then monitors the shooter’s activities.
The shooter places the tablet in a way that it is easily visible to the shooter and then the shooter starts to fire. The ETs at WGC were set so the score showed up right away and then 7 seconds later, the browser would display the impact on the target on the tablet. Remembering that it takes 1.5 seconds for the bullet to get to the target, you would have your score right away and the impact 7 seconds after that. The 7 second delay was used to mimic the effect of great pit service, but still prevented you from machine-gunning the bullets down the lane when there were exceptional conditions.
As each score is displayed on the tablets, the scorer records the score on the card and may or may not call it out to the shooter. The card is not really needed but it is used as a backup to the system and the scorer and shooter both sign it.
When there are unlimited sighters, the scorer presses the button “Go For Record” when the shooter confirms that he or she is now going for record. For the other matches with 2 sighters, the system keeps track of the shots and the scorer does not need to do anything once firing commences.
When the shooter fires the last round of the string, the tablets shows the total score and prompts for “scorecard ready,” on the scorer’s tablet. The scorer confirms the string is done by pressing that button, and the system then asks the shooter’s tablet to confirm the score. Once the shooter does that, the scorer’s tablet prompts the scorer to send the final results to the system. Once the scorer presses that button, the scores are recorded as final and the scorer and shooter log off on their respective tablets.
During the match, you can set up a view to show several targets on each side of yours but these were small and only showed the impact, not the score. That’s usually enough to get a trend of the conditions. During the LR team matches, I brought my Samsung Note Pro 12.2 tablet and it provided me with a much better view than the range-provided Lenovo tablets.
At the end of the day, they opened the local Wi-Fi network to everyone and you could then download your targets for the day and store them as PDFs or other on your device. Each shot had the value and the velocity recorded and it would give you the SD for the string.
This is a picture of the microphone array at Lodi.
