4 ms·

A piece of advice because you're using a throwaway account: it will be easier for people to believe your claims if you give some kind of inside information abou

by daenz 4y ago

A piece of advice because you're using a throwaway account: it will be easier for people to believe your claims if you give some kind of inside information about why it doesn't work other than "it just doesn't work"

hnThrow280 4y ago
hi thanks everyone for the feedback. I really wanted to include references to the research I did, but I was laid off at short notice (ahem, fired) for unspecified reasons, but it might have had to do with not introducing myself with pronouns. Not that I'm against it, I just felt that my freedom included the freedom to not use them. I was let go on a dime and didn't get to collect my research before I left. But to briefly summarize how these systems specify their accuracy, it's usually with a range of angles. e.g. +/- 10 degrees horizontal, and +- 15 degrees vertical. I just did a quick google search to try to see if anyone has rolled up the various devices like I did, but nothing. However, here's one decent, non-paywalled paper that shows results under very ideal conditions: http://nms.lcs.mit.edu/papers/ipsn07-girod.pdf http://nms.lcs.mit.edu/papers/ipsn07-girod.pdf As far as my words: "no device on the market, nor algorithm could figure out that close of a pinpoint", not your words: "why it doesn't work," consider the accuracy in an empty field in the above paper, but then add in several factors, including: 1. reflections, particularly in a dense urban environment, can causing reverberation 2. humidity and temperature fluctuations, particularly as they vary vertically causing acoustic lensing effects. also temperature fluctuations affecting sensor differently from air. e.g. direct sun heating sensor. 3. extremely high dynamic range of the signal. 4. synchronization of detectors, 5. vandalism of detectors 6. accuracy of layout of detectors, 7. characterization of detector beam. 8. detector distance This is not to say most of these can't be mitigated and improved, but they cost more money and time to work on all of them at the same time. The highly idealized results (open blank field) of a single shot in the above paper gave results +/- 8m in one direction and +/- 5m in the other direction with an average sensor distance of ~60m. So you're seeing about ~15% error in one direction and 6% in the other under ideal conditions and within a very short range. As sound propagates, the PV field evolves exponentially and it blurs and gets quieter and background noises interfere more. Note that I mentioend the systems generally specify angles (polar coords), but i used rectilinear here bc I have a diff job and don't have the time to convert just for the sake of this convo, but that would be a step I wish I had time for. If you want even more inside information from that side of the family, I will let you know that parallel construction with pseudo-private information is very real. This member, again trying to relate to me, brags about using social media to figure out many cases, hinting at having advanced access to e.g. facebook. I would go so far as to say that if you want to get away with crime, police will likely defer their attention to the low-hanging fruit of what they can solve with social media. for those who asked for papers, here some that I vaguely recognize from my research. Most of these are paywalled, and I used my privileged access from a fancy school to get to them: https://ieeexplore.ieee.org/abstract/document/5680318 https://ieeexplore.ieee.org/abstract/document/5680318 https://tj.uettaxila.edu.pk/index.php/technical-journal/article/view/1579 https://tj.uettaxila.edu.pk/index.php/technical-journal/arti... https://ieeexplore.ieee.org/abstract/document/8635092 https://ieeexplore.ieee.org/abstract/document/8635092 https://www.spiedigitallibrary.org/conference-proceedings-of-spie/6201/62011R/Operational-outcomes-of-the-SECURES-urban-gunshot-detection-technology-for/10.1117/12.665025.short?SSO=1 https://www.spiedigitallibrary.org/conference-proceedings-of... https://link.springer.com/chapter/10.1007/978-81-322-1823-4_15 https://link.springer.com/chapter/10.1007/978-81-322-1823-4_... https://ieeexplore.ieee.org/abstract/document/6637700 https://ieeexplore.ieee.org/abstract/document/6637700 https://ieeexplore.ieee.org/abstract/document/7098998 https://ieeexplore.ieee.org/abstract/document/7098998 https://ieeexplore.ieee.org/document/8289452 https://ieeexplore.ieee.org/document/8289452
- bobkazamakis 4y ago
  - throwoutway 4y ago
    Don’t do this. It’s against the site’s guidelines > Be kind. Don't be snarky. Have curious conversation; don't cross-examine. Please don't fulminate. Please don't sneer, including at the rest of the community.

by daenz 4y ago

hnThrow280 4y ago

hi thanks everyone for the feedback. I really wanted to include references to the research I did, but I was laid off at short notice (ahem, fired) for unspecified reasons, but it might have had to do with not introducing myself with pronouns. Not that I'm against it, I just felt that my freedom included the freedom to not use them. I was let go on a dime and didn't get to collect my research before I left. But to briefly summarize how these systems specify their accuracy, it's usually with a range of angles. e.g. +/- 10 degrees horizontal, and +- 15 degrees vertical. I just did a quick google search to try to see if anyone has rolled up the various devices like I did, but nothing. However, here's one decent, non-paywalled paper that shows results under very ideal conditions: http://nms.lcs.mit.edu/papers/ipsn07-girod.pdf http://nms.lcs.mit.edu/papers/ipsn07-girod.pdf As far as my words: "no device on the market, nor algorithm could figure out that close of a pinpoint", not your words: "why it doesn't work," consider the accuracy in an empty field in the above paper, but then add in several factors, including: 1. reflections, particularly in a dense urban environment, can causing reverberation 2. humidity and temperature fluctuations, particularly as they vary vertically causing acoustic lensing effects. also temperature fluctuations affecting sensor differently from air. e.g. direct sun heating sensor. 3. extremely high dynamic range of the signal. 4. synchronization of detectors, 5. vandalism of detectors 6. accuracy of layout of detectors, 7. characterization of detector beam. 8. detector distance This is not to say most of these can't be mitigated and improved, but they cost more money and time to work on all of them at the same time. The highly idealized results (open blank field) of a single shot in the above paper gave results +/- 8m in one direction and +/- 5m in the other direction with an average sensor distance of ~60m. So you're seeing about ~15% error in one direction and 6% in the other under ideal conditions and within a very short range. As sound propagates, the PV field evolves exponentially and it blurs and gets quieter and background noises interfere more. Note that I mentioend the systems generally specify angles (polar coords), but i used rectilinear here bc I have a diff job and don't have the time to convert just for the sake of this convo, but that would be a step I wish I had time for. If you want even more inside information from that side of the family, I will let you know that parallel construction with pseudo-private information is very real. This member, again trying to relate to me, brags about using social media to figure out many cases, hinting at having advanced access to e.g. facebook. I would go so far as to say that if you want to get away with crime, police will likely defer their attention to the low-hanging fruit of what they can solve with social media. for those who asked for papers, here some that I vaguely recognize from my research. Most of these are paywalled, and I used my privileged access from a fancy school to get to them: https://ieeexplore.ieee.org/abstract/document/5680318 https://ieeexplore.ieee.org/abstract/document/5680318 https://tj.uettaxila.edu.pk/index.php/technical-journal/article/view/1579 https://tj.uettaxila.edu.pk/index.php/technical-journal/arti... https://ieeexplore.ieee.org/abstract/document/8635092 https://ieeexplore.ieee.org/abstract/document/8635092 https://www.spiedigitallibrary.org/conference-proceedings-of-spie/6201/62011R/Operational-outcomes-of-the-SECURES-urban-gunshot-detection-technology-for/10.1117/12.665025.short?SSO=1 https://www.spiedigitallibrary.org/conference-proceedings-of... https://link.springer.com/chapter/10.1007/978-81-322-1823-4_15 https://link.springer.com/chapter/10.1007/978-81-322-1823-4_... https://ieeexplore.ieee.org/abstract/document/6637700 https://ieeexplore.ieee.org/abstract/document/6637700 https://ieeexplore.ieee.org/abstract/document/7098998 https://ieeexplore.ieee.org/abstract/document/7098998 https://ieeexplore.ieee.org/document/8289452 https://ieeexplore.ieee.org/document/8289452

bobkazamakis 4y ago
- throwoutway 4y ago
  Don’t do this. It’s against the site’s guidelines > Be kind. Don't be snarky. Have curious conversation; don't cross-examine. Please don't fulminate. Please don't sneer, including at the rest of the community.