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Somebody please explain this line from the post: Radio waves travel at the speed of light 299 792 458 m/s.
Earlier quoted context omitted.
How did you access the data? Via a simple REST api?
> How did you access the data? We signed a contract, fulfulled our obligations, and paid them money > Via a simple REST api? I really don't remember. It might have been SOAP or something. It was an HTTP-based API, but I don't think it was REST specifically. There was also a 30s or so delay from request to when we'd get the location back.
If my phone is powered off can i be tracked? What if i remove the battery?
Questions like this one aren't very useful without a threat model. Who are you trying to prevent tracking you? If it's just your phone carrier then obviously turning off your phone and removing the battery will render it inoperable. But now you don't have a phone, and your location info wasn't very useful to begin with anyway unless you were involved in an operation where you need to conceal your location.
Somebody please explain this line from the post: Radio waves travel at the speed of light 299 792 458 m/s.
When you turn on a lightbulb, the light coming from the bulb travels at the speed of light, which is 299,792,458 meters per second. Radio waves also travel at this same speed, since it is also light.
An interesting question is whether radio waves, gamma radiation, and visible light all travel an identical speed through atmosphere.
The reason light slows down in atmosphere is because it hits atoms. It travels between each atom at the speed of light, but when it reaches an atom the radiation is absorbed and re-emitted, which introduces a delay. So the question that I'm wondering is: do different frequencies of radiation get absorbed and re-emitted at the same rate as every other frequency? That would give it identical speed. But if the absorption is different then presumably the speed would also be different.
If my phone is powered off can i be tracked? What if i remove the battery?
Yes, if you're in a city you're tracked constantly by dragnet surveillance. Questions like this one aren't very useful without a threat model. Who are you trying to prevent tracking you? If it's just your phone carrier then obviously turning off your phone and removing the battery will render it inoperable. But now you don't have a phone, and your location info wasn't very useful to begin with anyway unless you were…
A patron was telling me that the way the GPS is so accurate is because it uses the phones radio... Didnt know that either. (i mentioned to him that there is one spot in MA where our google directions are off by 1/2 mile.. Same place every trip.)
The phone companies already do this, more or less, as is shown in court cases where cell phone records are brought in as evidence A decade ago that data was a little more iffy (i.e. it was more a good estimate (typically within half a mile or less) than a true location), but with a combination of more towers (and therefore more data points), the ubiquity of smartphones (which check in more often, are doing geolocatio…
> The phone companies already do this, more or less, as is shown in court cases where cell phone records are brought in as evidence You can also arrange to buy this information. I worked for a place where you could request someone's location by phone number. There were a lot of contractual obligations around us having the phone owner "allow" us to do that, but no technical ones.
Note that a lot of the information from the BTS is already available to anyone who "asks nicely". The mechanism that provides roaming is based on trust, so anyone connected to the SS7 network can query the location of any phone in the world and even intercept its calls. Just say to the home carrier "hey this phone is roaming on my network, would you be able to send me all of its calls and texts?".
There was a talk/demo I saw a few years ago that went into great detail about how this works. I remember it was given by a German. Anyone know what I am talking about? Edit: It was a video.
The phone companies already do this, more or less, as is shown in court cases where cell phone records are brought in as evidence A decade ago that data was a little more iffy (i.e. it was more a good estimate (typically within half a mile or less) than a true location), but with a combination of more towers (and therefore more data points), the ubiquity of smartphones (which check in more often, are doing geolocatio…
> The phone companies already do this, more or less, as is shown in court cases where cell phone records are brought in as evidence You can also arrange to buy this information. I worked for a place where you could request someone's location by phone number. There were a lot of contractual obligations around us having the phone owner "allow" us to do that, but no technical ones.
> "We said that a tower covers a radius around it. In practice, this is sub optimal so that’s not how it’s done.
> Instead, a station is usually split in 3 independent beams of 120 degrees."
So it's not the intersection of two circles anymore, it's the intersection of two arcs, which will likely only have one intersection point, unlike circles.
Earlier quoted context omitted.
When you turn on a lightbulb, the light coming from the bulb travels at the speed of light, which is 299,792,458 meters per second. Radio waves also travel at this same speed, since it is also light.
It's worth mentioning that neither light nor radio waves travel at 299,792,458 m/s through atmosphere. That's the speed of light in a vacuum. An interesting question is whether radio waves, gamma radiation, and visible light all travel an identical speed through atmosphere. The reason light slows down in atmosphere is because it hits atoms. It travels between each atom at the speed of light, but when it reaches an at…
They don't. The index of refraction tells you about how the speed of light is changed by a medium, and the fact that it's different for different colors of visible light is why you get effects like rainbows.
This stack exchange question might interest you if you'd like to read more: https://physics.stackexchange.com/questions/196803/why-is-th... .