Optimal GPS polling frequency for long battery life

[D.P.]

I've spent an hour using google to no avail but I was wondering if anyone knew of any data showing power usage for various smartphones using the GPS at various polling frequencies such as every 5 or 1 minutes.

It is well known that using GPS continuously kills the battery but how bad is every 5 minutes? Initially one would think this is much less but there is a large cost in switching on the GPS sensor and getting a lock, thus doing that every 30s or 1 minutes could be worse simply leaving the GPS on continuously.

Would switching the GPS on very 10 minutes create a significant drain?

 

[D.P.]

Why not just let the user set the polling frequency. There's never going to be a "right" answer for every device.

If a software develop spending and hour on Google can not find any relevant information how is the average user going to be able to make an informed decision?

Anyway, I don't think i really made myself clear in the OP so I will rephrase:

"What is the energy cost (in J/mAH/W) of switching on the GPS to get a single reading every 10 minutes , on an average smartphone". For bonus points you can provide the STD to cover different phones.


The users wont get a choice, I just want to know if it will be a significant impact. I am opposed to the idea but the Manager wants this functionality in place so I am looking for evidence indicating the energy costs. If it turns out this has unnoticeable energy costs then that is fine and it will just be built in.

 

[D.P.]

As peterwalkley says, let the user decide but set the default to a value that is optimum for what you perceive your average users needs will be.I haven't delved into android for a while now but I thought that the OS makes certain decisions about actions that cause the phone to "wake up". If you had multiple programs all using the GPS I thought it used to lump them all into a "best fit" time plan so as not to be polling all the time as each program requests the location. As I say though, this was a few years back.

Have a read up on androids power saving routines and how it handles multiple applications request for similar information.

If another App is using GPS then there really isn't an issue for us, we will just piggyback o the GPS info.

I've spent some time looking at Andorid documentation but it doesn't at all give any specifics or guidelines for things like sensor polling frequency. Just lots of hand-waving about more efficient approaches and avoiding GPS if not necessary etc.

None of that is helping me. What I really want to see if a graph or table of several phones with the GPS switched on and off every 1/5/10/60/Never minutes and see what the battery life is like. I don't have time to test this and hoped that the data would be out there somewhere since it must be a common question.

 

[D.P.]

Somewhat naive question.. can the devices themselves (and the OS) decide things like this? You simply poll the OS and the OS decides if it should poll GPS or just use cached result?

I don't really get what you are saying. We want a GPS point every 10 minutes, leaving the GPS continuously on will kill the battery, switching it on and off when required will save a lot of energy. But the questions is, what is the energy cost of taking a GPS reading every 10 minutes compared to never taking a GPS reading.

 

[D.P.]

And I apologies if I sound aggressive. I am very thankful for all replies!

The manager wants to change the spec of the app at the last minute into a power hungry piece of spyware that I am really not happy about so I want some hard evidence on power usage.

 

[D.P.]

What I mean is your typical smartphone (iPhone and Android phones) won't allow your software to directly talk to the GPS device. I believe you can only access the GPS via an "OS" call, which may not let you to poll as often as you want.. it may cache the data or whatever. This is what I was asking.

Yes, that is right, there is a large interface layer. There is a location service and you can specify an update frequency but that isn't what we intend to do because leaving the location services will maintain the GPS powered which we want to avoid. So we will be deactivating the location services once we have a GPS fix, have a background timer, and every 10 minutes or so create a new location services object and get a new fix.