A few weeks ago, I got done binge-watching every episode of NCIS, and am now up to Season 4 of Criminal Minds. Naturally, this induces a bit of what I'll call cinematic paranoia. In what seems to be a majority of episodes, a victim gets attacked, usually ends up dead, and the plucky investigators are stuck trying to figure out what happened. Naturally, they usually do, but only after about 45 minutes of high-tension showtime. It occurs to me that what people may need, for physical security, would be what might be called a "personal black box", analogous to an airplane flight recorder. Or, a civilian version of a cop's body-cam. Any modern smartphone would have the basics of such a device: A high-resolution camera, microphone, and a huge amount of storage. And a quick 911-call if necessary. The mere possession and use of such a device would probably deter the large majority of potential attackers. And even if it does not completely protect a given user, it would allow far more easy identification of the perpetrator. Parts of this, of course, are not a new idea. https://www.sparkfun.com/news/702 https://www.theglobeandmail.com/technology/gadgets-and-gear/gadgets/your-own... https://www.zdnet.com/article/fitbit-activity-data-as-evidence-in-court-wear... https://www.medgadget.com/2005/08/cpod_a_personal.html https://newatlas.com/australia-black-box-flight-recorder-soldiers/51267/ However, storage is not enough: In use, in some instances, an attacker would presumably be aware enough to take or break the device, so some sort of continuous or discontinuous upload of the data could be done, to be available no matter what else happens. Say, a frame per second when nothing seems to be happening, and a greater rate when triggered somehow. Could a heart-rate monitor be employed, sensed one axis of the phone's accelerometers? Or if the wearer falls down? Or if a sufficiently-loud noise is heard, etc. Or if a trigger-word is spoken a la Siri? Can the data transfer be made economical? Even an average of 1 megabit/second would be over one gigabyte during a 3 hour usage per day. That's substantially greater than most people currently use. One possibility is that the phone could upload the data to the cell phone company, where it could be "parked" for a few seconds or minutes. If nothing happens to the phone to cause a trigger (some sort of attack) the phone could instruct the cell phone company to abandon the data. Conversely, if a trigger occurs, the cell phone company would move 100% of the data to a backup system for later retrieval. Presumably, the cell phone company would offer discounted rates for such transfers, and only offer that service if the local service is sufficiently unloaded at that moment. Jim Bell