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The thing I never understood -- back in the days of pagers, a pager could last for a month or more on a AA battery. A pager has to be constantly listening for

by derekp7 12y ago

The thing I never understood -- back in the days of pagers, a pager could last for a month or more on a AA battery. A pager has to be constantly listening for a signal, then wake up and take action. So couldn't a phone be designed the same way? Have the main processor at idle, and offload event listening/processing to another low power processor chip. Then, wake up the main CPU when more advanced processing is required.

jobposter1234 12y ago
Umm... smart phones do this? It's a big reason phones can last so long with serious power requirements. A big reason for the phone/mobile specific chipsets was to enable these features.
- derekp7 12y ago
  But what I'm still confused on -- if a pager can sit an listen to a signal for 2 - 4 weeks on a AA battery, why can't a phone (smart or otherwise) do the same thing? Or in other words, what specifically is there about listening for a "You have an incoming call" radio signal, that causes more power drain than listening for a "You have a page with this message contents" signal? For simplicity sake, lets assume even a dumb phone, with no internet -- just calls -- they never did have a fraction of the standby time of a pager.
  - jobposter1234 12y ago
    Late to see this. But the answer to your question is because even though they are superficially accomplishing the same end result, they are not nearly doing the same thing. Your smartphone is running a full blown modern operating system, with all the processors and memory and store requirements. The pager is likely running a very lean embedded processor and doesn't have nearly the same energy requirements.
  - k-mcgrady 12y ago
    >> "if a pager can sit an listen to a signal for 2 - 4 weeks on a AA battery, why can't a phone (smart or otherwise) do the same thing?" They do. For example the iPhone 6 Plus lasts 16 days on standby. Remember they also have to listen for other messages (push notifications, local notifications, alarms, calendar events etc.). Regarding your dumb phone statement they had about the same standby time as the iPhone 6 Plus I mentioned but they had much smaller batteries and the battery technology (I guess) was much less developed. [1] https://www.apple.com/uk/iphone-6/specs/ https://www.apple.com/uk/iphone-6/specs/
ufmace 12y ago
I haven't followed much what's been happening in mobile CPUs lately, but I remember reading at least a couple of years ago that they were already making multi-core CPUs set up to run a single core at low-speed, sometimes a specifically-designed low-power core, for routine sync tasks, and only fire up more CPUs and up-clock the running ones when required. I'm sure they're either doing it already, or have stopped for good reason. Another thing that I believe Android has built into Lollipop is trying to coalesce app syncs - instead of letting each app sync whenever it feels like it, group them all together to run at once, so you only fire up the CPU and radios once. I also wonder now how those pagers worked. Seems kinda impractical to listen continuously at those power levels. I wonder if the device polled the tower periodically, or only listened at some interval?

by derekp7 12y ago

jobposter1234 12y ago

Umm... smart phones do this? It's a big reason phones can last so long with serious power requirements. A big reason for the phone/mobile specific chipsets was to enable these features.

derekp7 12y ago
But what I'm still confused on -- if a pager can sit an listen to a signal for 2 - 4 weeks on a AA battery, why can't a phone (smart or otherwise) do the same thing? Or in other words, what specifically is there about listening for a "You have an incoming call" radio signal, that causes more power drain than listening for a "You have a page with this message contents" signal? For simplicity sake, lets assume even a dumb phone, with no internet -- just calls -- they never did have a fraction of the standby time of a pager.
- jobposter1234 12y ago
  Late to see this. But the answer to your question is because even though they are superficially accomplishing the same end result, they are not nearly doing the same thing. Your smartphone is running a full blown modern operating system, with all the processors and memory and store requirements. The pager is likely running a very lean embedded processor and doesn't have nearly the same energy requirements.
- k-mcgrady 12y ago
  >> "if a pager can sit an listen to a signal for 2 - 4 weeks on a AA battery, why can't a phone (smart or otherwise) do the same thing?" They do. For example the iPhone 6 Plus lasts 16 days on standby. Remember they also have to listen for other messages (push notifications, local notifications, alarms, calendar events etc.). Regarding your dumb phone statement they had about the same standby time as the iPhone 6 Plus I mentioned but they had much smaller batteries and the battery technology (I guess) was much less developed. [1] https://www.apple.com/uk/iphone-6/specs/ https://www.apple.com/uk/iphone-6/specs/

ufmace 12y ago

I haven't followed much what's been happening in mobile CPUs lately, but I remember reading at least a couple of years ago that they were already making multi-core CPUs set up to run a single core at low-speed, sometimes a specifically-designed low-power core, for routine sync tasks, and only fire up more CPUs and up-clock the running ones when required. I'm sure they're either doing it already, or have stopped for good reason. Another thing that I believe Android has built into Lollipop is trying to coalesce app syncs - instead of letting each app sync whenever it feels like it, group them all together to run at once, so you only fire up the CPU and radios once. I also wonder now how those pagers worked. Seems kinda impractical to listen continuously at those power levels. I wonder if the device polled the tower periodically, or only listened at some interval?