5 ms·

I could enable GPS and leave the phone on without charging... for THREE WEEKS at a time.

nexuist 6y ago
GPS is a completely passive signal, so it's not really surprising that it lasts a long time. You can get similar battery life with IoT SoCs deployed on the field. The difference between then and now is that modern smartphones use sensor fusion, combining cellular, WiFi, and GPS signals to generate a location. The end result is more accurate output, at the expense of battery life.
- waste_monk 6y ago
  My understanding is that cheaper devices (at least historically) tended not to have a discrete chip for handling GPS, which could run extremely efficiently and at very low power, and instead were forced to use the CPU to do the work - contributing to the reputation of being slow and power inefficient. Modern devices do the sensor fusion on CPU but it's just polling the GPS chip for coordinates as required, which handles all the actual signals processing stuff.
- Mandatum 6y ago
  Are there any phones that allow you to customize this? I recall Android having a Developer Options setting for GPS + WiFi or just GPS for Location Accuracy. But IIRC, this didn't make a substantial impact to battery life. Maybe because I'm not a passive phone user.
- est31 6y ago
  > The end result is more accurate output, at the expense of battery life. Do you have sources? GPS is passive, yes, but the signal is very weak and several orders of magnitude below the noise threshold. Keeping receiver circuits enabled for a long time costs battery power as well. WiFi information can be obtained entirely passively as well, as AP's transmit their info regularly. I think the difference rather comes from lots of bloaty background services on Android.
nradov 6y ago
That device was not continuously receiving a GPS signal. It was relying on network location services, and maybe occasionally waking up the GPS receiver.

GPS is a completely passive signal, so it's not really surprising that it lasts a long time. You can get similar battery life with IoT SoCs deployed on the field. The difference between then and now is that modern smartphones use sensor fusion, combining cellular, WiFi, and GPS signals to generate a location. The end result is more accurate output, at the expense of battery life.

waste_monk 6y ago
My understanding is that cheaper devices (at least historically) tended not to have a discrete chip for handling GPS, which could run extremely efficiently and at very low power, and instead were forced to use the CPU to do the work - contributing to the reputation of being slow and power inefficient. Modern devices do the sensor fusion on CPU but it's just polling the GPS chip for coordinates as required, which handles all the actual signals processing stuff.
Mandatum 6y ago
Are there any phones that allow you to customize this? I recall Android having a Developer Options setting for GPS + WiFi or just GPS for Location Accuracy. But IIRC, this didn't make a substantial impact to battery life. Maybe because I'm not a passive phone user.
est31 6y ago
> The end result is more accurate output, at the expense of battery life. Do you have sources? GPS is passive, yes, but the signal is very weak and several orders of magnitude below the noise threshold. Keeping receiver circuits enabled for a long time costs battery power as well. WiFi information can be obtained entirely passively as well, as AP's transmit their info regularly. I think the difference rather comes from lots of bloaty background services on Android.

nradov 6y ago

That device was not continuously receiving a GPS signal. It was relying on network location services, and maybe occasionally waking up the GPS receiver.