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Hi all! First post Question about Navigator.


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  1. Payvay

    Payvay Member This Topic's Starter

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    Hello everyone!

    I've been lurking on this forum for some days now and I haven't seen an answer on a specific question: Can Google Navigator locks a position without the 3g or the wi-fi on a N1 let say?

    I'm asking this because my device is always scanning for satellites with no success when I'm not on 3G or Wi-Fi. And why would the phone needs these? I thought a GPS enabled phone would only need satellites??

    Thanks!!

    Payvay
     

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  2. OfTheDamned

    OfTheDamned The Friendly Undead VIP Member

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    Welcome to the forum Payvay, glad you decided to drop your lurker status.:D

    A stand alone GPS unit will lock onto your position only using the satellites and can show you your position easily because the maps are preloaded in the devices memory.

    With most cell phones and smartphones that contain GPS (can't speak for all), while they do contain a GPS receiver they typically also use aGPS (the a is for assisted) which partially uses the cell towers around you for triangulation. You will notice this when you first turn on the GPS and open maps by the giant blue circle around your location. Once the GPS is able to lock on the big blue circle will go away and you are left with much more accurate location information. Our phones also do not have maps preloaded so they require some form of data connection to actually obtain the maps to even show location information. Once the lock is made and the maps are downloaded though, you can run without 3G turned on and as long as you don't deviate from the course set you are fine.
     
  3. uzetaab

    uzetaab Well-Known Member

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    I must have a death wish for this, but I have to disagree a little with OTD.

    Technically, the phone doesn't need aGPS to get a fix, in fact, I just got a fix with wifi & GPS turned off. I wasn't using Maps though, I was using Speed View (a GPS speedometer for your car). So, it is possible to use the GPS without data, but it depends on what your using it for.

    The rest is essentially right though, the main advantage of aGPS is that you can get a fix almost instantly, but it's not an accurate fix. The advantage is that you can quickly get a rough location which is often all you need if your, for example, walking down a street in Paris & want to check that your still going the right way.

    However, for google maps in particular, you need data because the maps are not locally stored on the phone & it needs to get them from the internet. Once it has the map & you set the navigate mode, you can turn data off, just don't leave the planned route.

    Please don't bite me OTD. *Cowers in a corner*

    It's also worth noting that there is an app available that stores the maps on the phone, but I forget the name. Is it from Garmin? Anyway, it's kind of expensive too.
     
  4. takeshi

    takeshi Well-Known Member

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    Let's get this straightened again. aGPS is not cell tower triangulation. GPS, by definition, always uses the GPS satellites to determine your position. The difference between aGPS and standalone GPS is that aGPS contacts an assistance server to obtain a faster GPS fix. There's no cell tower triangulation involved.


    It should be able to. However, IIRC, the Droid, for example, needs the CDMA radio active for some reason to obtain a GPS fix even though the CDMA radio isn't used. I think they share an antenna or something. I have no idea if the N1 is the same or has a similar quirk. I doubt it as the N1 is manufactured by HTC while the Droid is a Motorola device.

    Download GPS Status to see what's going on. The Droid will periodically have problems obtaining a fix. I've reactivated to address this in the past but GPS Status now allows you to reset the GPS if it's having problems obtaining a fix. I haven't needed to use the feature yet but it may help.


    Let's also clarify this. Maps aren't a phone limitation. They're specifically a limitation of the particular GPS app you're talking about. There are GPS nav apps such as CoPilot Live that store maps locally.

    Many people don't seem to understand that the GPS receiver and the GPS app are two separate and distinct entities in the device. The GPS receiver provides location and that's it. Everything else (maps, POI's, tracking, etc) are provided by the app.
     
  5. OfTheDamned

    OfTheDamned The Friendly Undead VIP Member

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    LOL

    When I'm wrong, I'm wrong and I'm woman enough to admit when I'm wrong.

    My mistake. I guess I have read it as cell tower triangulation for so long that it is just stuck in my brain that way. After reading your post I do remember that is is simply network assistance to speed along the process of getting a location.

    I was referring to the stock navigation application, which is what most people would be talking about here.
     
  6. Payvay

    Payvay Member This Topic's Starter

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    Wow oh wow! I never thought this forum would be alive like that! Thanks a million for the quick answers!

    So if I understand, once Navigator has a fix on me and has drawn the route, I must remember it and turn off Navigator because, as I understood, as soon as I leave the house and get in the car, my phone will drop the wi-fi (of course) and rely on the 3G to get the map loaded.

    How much bandwidth could it take approx to get to a location 300km away from the starting point? I'm asking this because I only have 250megs per month.

    I've been looking for CoPilot. Interesting! Is it a good app?

    Thanks again folks, you guys (and gal) rock!!! ;)

    Payvay
     
  7. DenverRalphy

    DenverRalphy Well-Known Member

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    aGPS does use cell towers. That's the information the device sends to the assistance servers. The assistance servers then provide the gps specific satellites to communicate with, as it maintains orbital data, and knows which satellites the gps can lock with. It's faster because now the gps knows exactly which satellites to look for instead of just putting out a general signal waiting for any random satellites to pick it up. So yes, tower location is definately used.

    As well, aGPS is widely used on most smartphone devices because it dramatically reduces the amount of power the GPS utilizes.

    This is because the Assisted part of aGPS needs the the tower information to send to the assistance servers. Without a data connection, this information isn't available. Blackberry devices on VZW used to have this problem as well (with our without a data connection), until google finally fixed google maps for BB by allowing the app to use normal GPS instead of aGPS. (although I have no idea why it was an issue for BB's when VZW opened GPS for free instead of charging for it anymore... it may have something to do with the point that BB's all go through servers in Canada <shrug>)
     
  8. RawlingsSc

    RawlingsSc Well-Known Member Contributor

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    A slight clarification: The GPS receiver doesn't transmit anything to the satellites. It receives only. The reason aGPS is faster is because it knows about where the satellites should be so when it starts receiving data it can more quickly pinpoint the location. If it has no idea where the satellites should be, it has to do a ton more listening to the signals and calculations to get the fix.
     

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