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#260842 - 05/22/13 11:46 PM Re: Preparedness Apps for Smart Phones [Re: chaosmagnet]
ireckon Offline
Pooh-Bah

Registered: 04/01/10
Posts: 1629
Loc: Northern California
Originally Posted By: chaosmagnet
Originally Posted By: ireckon
It makes sense that GPS works without data capability. I guess my real question is, how does my carrier (Verizon) treat that data coming from the satellite?


It's a different signal and a different receiver. Receiving GPS signals has nothing to do with your carrier.


Are you saying there is no way possible for the carrier to disable the GPS chip if the entire plan is disconnected?

In other words, if I completely discontinue my services with my carrier, the GPS chip will continue to operate as usual without having to do any kind of workaround?
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#260843 - 05/22/13 11:46 PM Re: Preparedness Apps for Smart Phones [Re: chaosmagnet]
Russ Offline
Carpal Tunnel

Registered: 06/02/06
Posts: 4987
Loc: SOCAL
Just took a walk down to the local park and turned cellphone stuff off like was in the backcountry. One problem I have using maps on an iPhone is that while I can turn off cellular data, I can't turn off all cellular without using "airplane mode" which also turns off the GPS. I tried this in the park and had a good lock on my position turning individual things off until I turned Airplane mode on which kills the cellular signal and apparently the GPS too.

With all the mapping apps out there, you'd think Apple would realize that GPS can function while in Airplane mode because the cellphone doesn't need to transmit, only receive; just give the GPS receiver its own on/off button in the location settings menu. After turning everything off using airplane mode you can turn the GPS back on to get maps working without draining the battery looking for a cell signal. Does that make sense? This should be totally doable with software.

Then again I noticed on the iPhone 5 location is provided by: Assisted GPS and GLONASS.
Quote:
Assisted GPS, generally abbreviated as A-GPS or aGPS, is a system that can under certain conditions improve the startup performance, or time-to-first-fix (TTFF), of a GPS satellite-based positioning system. It is used extensively with GPS-capable cellular phones, as its development was accelerated by the U.S. FCC's 911 requirement to make the location of a cell phone available to emergency call dispatchers.[1]...
From that I take it that maybe FCC is requiring the GPS be assisted, so Apple only powers the GPS when cellular is also on. IMO that is short sighted.

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#260851 - 05/23/13 03:03 AM Re: Preparedness Apps for Smart Phones [Re: ireckon]
chaosmagnet Online   content
Sheriff
Carpal Tunnel

Registered: 12/03/09
Posts: 3010
Loc: USA
Originally Posted By: ireckon
Are you saying there is no way possible for the carrier to disable the GPS chip if the entire plan is disconnected?

In other words, if I completely discontinue my services with my carrier, the GPS chip will continue to operate as usual without having to do any kind of workaround?


On the iPhone and many other smartphones with separate GPS receivers and chips, that's precisely correct. You can cancel your service with the carrier and the GPS will still work just fine. If you already have map data downloaded, then you're good to go.

Some GPS apps won't work without data connections, as they rely upon the cloud service for route guidance.

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#260853 - 05/23/13 03:06 AM Re: Preparedness Apps for Smart Phones [Re: Russ]
chaosmagnet Online   content
Sheriff
Carpal Tunnel

Registered: 12/03/09
Posts: 3010
Loc: USA
Originally Posted By: Russ
From that I take it that maybe FCC is requiring the GPS be assisted, so Apple only powers the GPS when cellular is also on. IMO that is short sighted.


On the iPhone (and on most other smartphones I know about) that is not the case. GPS works alone. The A-GPS feature improves the speed of acquiring a fix where it is available.

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#260855 - 05/23/13 03:26 AM Re: Preparedness Apps for Smart Phones [Re: chaosmagnet]
Russ Offline
Carpal Tunnel

Registered: 06/02/06
Posts: 4987
Loc: SOCAL
Then why is it that the mapping apps lose location input when I turn on Airplane mode? The GPS is a separate receiver, but it seems to only function when the cellular transceiver is also on.

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#260881 - 05/23/13 09:38 PM Re: Preparedness Apps for Smart Phones [Re: Russ]
MostlyHarmless Offline
Old Hand

Registered: 06/03/09
Posts: 982
Loc: Norway
Originally Posted By: Russ
Then why is it that the mapping apps lose location input when I turn on Airplane mode? The GPS is a separate receiver, but it seems to only function when the cellular transceiver is also on.


Because "airplane mode" turns off ALL radio communications, incoming and outgoing. In airplane mode it won't even listen to GPS signals.

Technically, there is no reason why you shouldn't be able to use your GPS while in airplane mode. But regulations state "ALL radio equipment". A GPS receives radio signals from GPS satelites, so formally it could be defined as "radio equipment".

Sometimes it is easier to just comply with the letter of the law than to follow a sensible interpretation of the intention behind the law.

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#260882 - 05/23/13 10:01 PM Re: Preparedness Apps for Smart Phones [Re: MostlyHarmless]
Russ Offline
Carpal Tunnel

Registered: 06/02/06
Posts: 4987
Loc: SOCAL
Exactly, however when I turn Airplane Mode ON which turns everything Off, I can then turn WiFi ON and turn Bluetooth ON and I'm still in Airplane Mode. I'm just saying that an iPhone's GPS transmits less than WiFi and Bluetooth so there should be a no issues with giving GPS its own button so it can be turned on separately also.

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#260889 - 05/24/13 01:56 AM Re: Preparedness Apps for Smart Phones [Re: Russ]
Eugene Offline
Carpal Tunnel

Registered: 12/26/02
Posts: 2823
Originally Posted By: Russ
I'm just saying that an iPhone's GPS transmits less than WiFi and Bluetooth


A GPS doesn't just transmit less, it doesn't transmit at all.

However the reason that you turn off receivers as well as transmitters is receivers down convert the signals they receive by mixing with another signal. So to create that other signal you need an oscillator and that can transmit a small signal. Put an AM radio next to your computer and listen to the interference for a simple example.

Just so you don't think I'm crazy (well I may still be but at least I'm technically correct here)

http://en.wikipedia.org/wiki/Intermediate_frequency

You mix your received frequency with your local to bring the received down to where you can process it. All oscillators transmit a small amount unintentionally.


Edited by Eugene (05/24/13 02:03 AM)

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#260897 - 05/24/13 12:44 PM Re: Preparedness Apps for Smart Phones [Re: Russ]
bws48 Offline
Old Hand

Registered: 08/18/07
Posts: 830
Loc: Anne Arundel County, Maryland
Originally Posted By: Russ
Then why is it that the mapping apps lose location input when I turn on Airplane mode? The GPS is a separate receiver, but it seems to only function when the cellular transceiver is also on.


I wonder if this is a design "feature" of that iphone model? When the engineers sit down and design the hardware and software, somewhere along the line a decision as to what gets shut down when airplane mode is implemented has to be made---and someone decided to shut down GPS also. GPS is a passive receiver: no RF emissions, so it does not need to be shut down to comply with airline regs. But someone might have decided to play it on the safe side.

My Samsung android does keep GPS operating in Airplane mode, but nothing says all phones have to implement Airplane mode in exactly the same way.
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#261301 - 06/13/13 04:08 PM Re: Preparedness Apps for Smart Phones [Re: Dagny]
Dagny Offline
Pooh-Bah

Registered: 11/25/08
Posts: 1916
Loc: Washington, DC

WEATHER APPS:

Stormy week here and I was unnerved the other night to not know of a tornado warning until noticing an alert crawl on the television. So I doubled-down on weather apps and am using them all (not that you need them all):


RadarScope -- Doppler Radar $9.99

http://www.basevelocity.com/RadarScope/index_ios.php


RadarCast Pro $1.99

http://www.technewsworld.com/story/Radar-Cast-Pro-Puts-a-Meteorologist-in-Your-Pocket-78223.html


iMap Weather Radio $9.99

http://www.wired.com/geekmom/2012/04/iphone-app-review-imap-weather-radio-stay-informed-stay-safe/

"While the name might suggest that itís a NOAA Weather Radio app, that isnít quite true. But itís the next best thing. iMap Weather Radio uses a smart deviceís geo-location technology to keep users informed of National Weather Service watches and warnings.

"If the app is left active (in other words, running in the background), when a notification is issued for your current location (or one of five other locations users can input), your phone will issue a distinctive alarm tone ó similar to that of a NOAA Weather Radio ó and will read the statement to yo
u."



Weather Alerts $3.99

http://weathersphere.com/products/weather-alerts

"Simple, no-nonsense app for quickly notifying you of severe weather alerts in a chosen radius from your current location, including Tornadoes, Hurricanes, Snow Storms, Frost Advisories, Flood/Fire Warnings and hundreds more. Alerts you with sound even when the phone is lying unused with screen off!"


.

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