3 ms·

Yes, but with caveats. Disclaimer: just a hobbyist, not my professional area, corrections appreciated - oldschool radio direction-finding with a couple of dire

Yes, but with caveats. Disclaimer: just a hobbyist, not my professional area, corrections appreciated - oldschool radio direction-finding with a couple of directional antennas that are manually positioned and rotated (i.e. based on signal attenuation) doesn't really work for point-in-time things like a single brief signal unless you have massive arrays of well-positioned receivers, which is fine if you're building an HFDF installation but not fine if you're a squad on the move - multilateration on the basis of signal attenuation, analogous to that sort of oldschool RDF, is possible but IME doesn't perform very well; same problem where you often need a lot of well-positioned points to shrink the possibility envelope down to something useful - multilateration on the basis of time of arrival, analogous to more modern pseudo-doppler / correlative interferometry RDF techniques, can perform a lot better but requires a very high quality shared time source - if the model is analyzing info from an array of observers, this can be a problem on typical battlefield network designs that prioritize availability over performance - but this approach also enables single site setups where a local time source and a handful of receivers can read a bearing without actually needing to network at all, though this involves a lot of math

wbl 4y ago
GPS solves the sync issue to the order of nanoseconds. You can also have local TOA determine angles that get passed up to triangulate. The US Army deployed some of these techniques in antisniper work in Iraq.
- livueta 4y ago
  That's a good point, and required time precision seems like it should be proportional to the velocity of the signal being investigated. I had some bad experiences trying to use gps time for RDF, but that might not apply here. From https://www.usenix.org/legacy/events/mobisys07/full_papers/p113.pdf https://www.usenix.org/legacy/events/mobisys07/full_papers/p... > Our time synchronization approach yields errors signif- icantly less than 100 microseconds. As the sound travels about 3 cm in that time, time synchronization errors have a negligible effect on the system. Sounds like it? The anti-sniper systems I knew about already (Boomerang) are that single-site setup where time sync isn't a problem. The "Individual Gunshot Detector" sounds more like what you're describing. > The Individual Gunshot Detector (IGD) by Qinetiq consists of a shoulder-mounted unit with four acoustic sensors and a chest display that attaches to body armor. Still looking for more detail, but that sounds like a local ToA > pass up angles for triangulation type deal.
galangalalgol 4y ago
I read an ieee journal article over a decade ago claiming success with helmet mounted sensors. The system used the time of the sonic crack and the muzzle report as observed from each helmet. Its like GPS, if you have 5 or more observers you can solve for the time reference as well. Actually, it might be less since they had multiple observations from each helmet. It supposedly could then highlight the location of the shot using AR. It then went on to say they could tell what the firearm was from the muzzle report. Can't find the article now. Doesn't seem that outlandish, but as you say, accuracy would be the real question. The speed of sound can vary so much based on weather.
- livueta 4y ago
  Maybe this? https://www.usenix.org/legacy/events/mobisys07/full_papers/p113.pdf https://www.usenix.org/legacy/events/mobisys07/full_papers/p... > It then went on to say they could tell what the firearm was from the muzzle report. > over 95% caliber estimation accuracy for all shots, and close to 100% weapon estimation accuracy for 4 out of 6 guns tested. That's pretty cool. Gotta read the whole thing now. e: kinda relevant to the other subthread about time sync: > Correlating ToA measurements requires a common time base and precise time synchronization in the sensor network. The Routing Integrated Time Synchronization (RITS) [15] protocol relies on very accurate MAC-layer time-stamping to embed the cumulative delay that a data message accrued since the time of the detection in the message itself. That is, at every node it measures the time the message spent there and adds this to the number in the time delay slot of the message, right before it leaves the current node. Every receiving node can subtract the delay from its current time to obtain the detection time in its local time reference. The service provides very accurate time conversion (few μs per hop error), which is more than adequate for this application. Note, that the motes also need to convert the sensorboard time stamps to mote time as it is described earlier.
  - galangalalgol 4y ago
    Yeah I'm pretty sure that was it. They were getting really good classification results with simple statistical methods. Today I suspect someone would have thrown a hybrid CNN-LSTM at it and gotten similar results but no explainability and 100x the processor requirements. "Try the simplest thing that might possibly work". A few μs for all that work seems high when gps could get you to ns, or adding extra observers could remove the need for prior synchronization. I guess it is a more robust answer at least, in case GPS isn't there and some of the observers got shot already.
jasonwatkinspdx 4y ago
So there are products on the market that TDoA/Interfereometric emitter localization via ad hoc soldier portable units. ELTA has one product like this for example. They typically sync a decent local oscillator to GPS/GLONASS, and send that data stream along with any sampled signal that the network is communicating to do the computation.

wbl 4y ago

GPS solves the sync issue to the order of nanoseconds. You can also have local TOA determine angles that get passed up to triangulate. The US Army deployed some of these techniques in antisniper work in Iraq.

livueta 4y ago
That's a good point, and required time precision seems like it should be proportional to the velocity of the signal being investigated. I had some bad experiences trying to use gps time for RDF, but that might not apply here. From https://www.usenix.org/legacy/events/mobisys07/full_papers/p113.pdf https://www.usenix.org/legacy/events/mobisys07/full_papers/p... > Our time synchronization approach yields errors signif- icantly less than 100 microseconds. As the sound travels about 3 cm in that time, time synchronization errors have a negligible effect on the system. Sounds like it? The anti-sniper systems I knew about already (Boomerang) are that single-site setup where time sync isn't a problem. The "Individual Gunshot Detector" sounds more like what you're describing. > The Individual Gunshot Detector (IGD) by Qinetiq consists of a shoulder-mounted unit with four acoustic sensors and a chest display that attaches to body armor. Still looking for more detail, but that sounds like a local ToA > pass up angles for triangulation type deal.

galangalalgol 4y ago

I read an ieee journal article over a decade ago claiming success with helmet mounted sensors. The system used the time of the sonic crack and the muzzle report as observed from each helmet. Its like GPS, if you have 5 or more observers you can solve for the time reference as well. Actually, it might be less since they had multiple observations from each helmet. It supposedly could then highlight the location of the shot using AR. It then went on to say they could tell what the firearm was from the muzzle report. Can't find the article now. Doesn't seem that outlandish, but as you say, accuracy would be the real question. The speed of sound can vary so much based on weather.

livueta 4y ago
Maybe this? https://www.usenix.org/legacy/events/mobisys07/full_papers/p113.pdf https://www.usenix.org/legacy/events/mobisys07/full_papers/p... > It then went on to say they could tell what the firearm was from the muzzle report. > over 95% caliber estimation accuracy for all shots, and close to 100% weapon estimation accuracy for 4 out of 6 guns tested. That's pretty cool. Gotta read the whole thing now. e: kinda relevant to the other subthread about time sync: > Correlating ToA measurements requires a common time base and precise time synchronization in the sensor network. The Routing Integrated Time Synchronization (RITS) [15] protocol relies on very accurate MAC-layer time-stamping to embed the cumulative delay that a data message accrued since the time of the detection in the message itself. That is, at every node it measures the time the message spent there and adds this to the number in the time delay slot of the message, right before it leaves the current node. Every receiving node can subtract the delay from its current time to obtain the detection time in its local time reference. The service provides very accurate time conversion (few μs per hop error), which is more than adequate for this application. Note, that the motes also need to convert the sensorboard time stamps to mote time as it is described earlier.
- galangalalgol 4y ago
  Yeah I'm pretty sure that was it. They were getting really good classification results with simple statistical methods. Today I suspect someone would have thrown a hybrid CNN-LSTM at it and gotten similar results but no explainability and 100x the processor requirements. "Try the simplest thing that might possibly work". A few μs for all that work seems high when gps could get you to ns, or adding extra observers could remove the need for prior synchronization. I guess it is a more robust answer at least, in case GPS isn't there and some of the observers got shot already.

jasonwatkinspdx 4y ago

So there are products on the market that TDoA/Interfereometric emitter localization via ad hoc soldier portable units. ELTA has one product like this for example. They typically sync a decent local oscillator to GPS/GLONASS, and send that data stream along with any sampled signal that the network is communicating to do the computation.