[someonebaggy]

Getting a GPS fix from the satellites alone with no internet connection or stored data takes a few hours, not seconds. First you have to listen to the very slow data channel that tells you where the satellites are that takes a few hours to transmit the complete set before repeating.

[peterus]

No it doesn't, the time to first fix from cold start of modern GNSS receivers is in seconds (24s on the NEO M9N). Assisted GNSS using data from the internet reduces that to under 2 seconds (see https://content.u-blox.com/sites/default/files/NEO-M9N-00B_D...). Of course this can change based on the GNSS environment.

Even in the worst case the almanac (the data that is streamed at 50 bits/second) repeats every 12.5 minutes not hours.

[throw0101a]

> Getting a GPS fix from the satellites alone with no internet connection or stored data takes a few hours, not seconds.

It takes less than 15 minutes (in the worst case):

> The receiver is missing or has inaccurate estimates of its position, velocity, the time, or the visibility of any of the GPS satellites. As such, the receiver must systematically search for all possible satellites. After acquiring a satellite signal, the receiver can begin to obtain approximate information on all the other satellites, called the almanac. This almanac is transmitted repeatedly over 12.5 minutes. Almanac data can be received from any of the GPS satellites and is considered valid for up to 180 days.

* https://en.wikipedia.org/wiki/Time_to_first_fix

[xocnad]

This does not jibe with my experience with my long-in-the-tooth Garmin when it cannot connect to my phone and has been recharged after a total power down. It can take minutes but not hours.

[ryukoposting]

That's just false. I wrote firmware for cheapo GPS modules that got a DGPS fix in seconds. And there are other tricks you can play to bring the latency down, knowing the use case.

[RobotToaster]

I'm no expert on GPS, but once you have the stored data it's good for several days isn't it? So after the first fix it shouldn't be too onerous.

[someonebaggy]

That works for phones (and you can download it from the internet if out of date). It doesn't work for cameras which are usually turned off until you want to take pictures.

[throw0101a]

> It doesn't work for cameras which are usually turned off until you want to take pictures.

The GPS almanac is valid for 180 days, so if you can save it (it's 15000 bits, ~1.8 kB), and keep time within ±20s and assuming a position of ±100km of your last fix, you can do a "warm" start with-in a minute:

* https://en.wikipedia.org/wiki/Time_to_first_fix

A completely cold start takes less than 15 minutes.

And yes, cameras are usually turned off, but they do still trickle some power to keep the on-board clock going: so as long as you use your camera once every six months, and in the same city, there's a good chance you'll get a quick fix.

[RobotToaster]

All I know is I've never seen the GPS module for my 10+ year old Pentax k30 take more than a few minutes to get a fix after months of having the battery completely removed, and it has no network connection.