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  1. Thread Author  Thread Author    #1  

    Default S-GPS vs AGPS

    I noticed the "feature" on the Bionic says S-GPS while the HTC and LG say AGPS (uses the phone network, right) . Whats the diff?
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    The difference between them is just simply GPS uses satellites only to get your location, while AGPS (Assisted GPS) uses your carriers network (towers) to assist in finding your location. AGPS is faster and more accurate, but they both do the same thing.
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    So does the "A" mean the GPS won't work out of network coverage? Is the "S" any better out of network?
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    Quote Originally Posted by jazaddict View Post
    So does the "A" mean the GPS won't work out of network coverage? Is the "S" any better out of network?
    AGPS is "Assisted GPS" and like Icon said, it uses your data network to assist in locating your position. AGPS is usually used in conjunction with regular GPS, for example when you open maps, APGS gets your general location first before the regular GPS locks onto your position.

    SGPS will work without network coverage, AGPS will not.

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    I have been out of all cell coverage and used maps to get a gps fix on my evo. Couldn't download the map but knew my position lol.

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    Proper A-GPS, as was already stated, is always used in conjunction with a full GPS chip. Early days of cell phones had a bastardized implementation where there was no real GPS chip and you would only get approximate locations. This isn't technically A-GPS but that term was used for it.

    Now a days A-GPS properly refers to a GPS chip that is assisted by the much higher power (compared to GPS signal) terrestrial cell network. Its sole purpose is to use the terrestrial network to help you get a GPS lock faster than you would otherwise.

    S-GPS is relatively newer in phones and stands for Simultaneous GPS. In the traditional implementation the GPS receiver shares a single RF Front End with the cellular network receiver. They each take turns using the shared components. In S-GPS There are two RF front ends so both GPS and the cell network can be receiving 100% of the time. The benefit for GPS is that its more accurate since its getting more data. Depending on the implementation you could also get the Benefits of A-GPS within S-GPS.

    So neither A-GPS nor S-GPS need network coverage to work, but it does help improve the speed of your GPS lock.
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    Default Re: S-GPS vs AGPS

    Quote Originally Posted by Icon View Post
    The difference between them is just simply GPS uses satellites only to get your location, while AGPS (Assisted GPS) uses your carriers network (towers) to assist in finding your location. AGPS is faster and more accurate, but they both do the same thing.
    thats not what he wants to know, im wondering the same thing. so far what ive found out is that the sGPS is kind of like the russians "GloNASS" which basically uses real satellite *sGPS=Satellite GPS* signal seperate from the phones network, you you can now talk on the phone & use the GPS at the same time, thats just one of the advantages. but theres something more, i think you dont need data from your network. thats all i know, something about the network not being needed to be used as aGPS & GPS for mobile phones do. i guess its like a separate GPS reciever all together?
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    Default Re: S-GPS vs AGPS

    Auzo actually has this right. aGPS (assisted GPS) is merely any system that uses the GPS signal in addition to some other data to help it get a fix faster and a more precise location. All GPS systems work by basically "zeroing" in on your location. aGPS as implemented in phones gets a fix faster because the data network can provide a rough guess of your location based on what towers you're associated. The trick here is that you're getting it via your phones data connection from your provider. You can still use the GPS without data coverage, but it will take longer to get a fix since the GPS chip isn't getting the assist from the data network.

    S-GPS is technically a type of assisted GPS but doesn't need a data connection. As Auzo pointed it out it can simultaneously use both GPS and network, so it's theoretically faster than traditional aGPS above. The distinction is that it directly looks at signal strength to cell towers versus the provider sending it via the data network. So even without a data connection, you'll still get a faster fix. If you have no signal at all, the GPS will still work from satellites, but will take longer to get a fix.

    There's a lot of variables involved, so one technology doesn't necessarily work better than the other in all cases. S-GPS is just a *newer* technology. It's particularly useful for E911 services. And uh....jayq, *ALL* GPS systems use satellites. If they didn't, it wouldn't be a GPS. GPS is by definition operated by satellites (currently 32 worldwide).
  9. #9  

    Default Re: S-GPS vs AGPS

    Doesn't the a-GPS also download information about the GPS satellites themselves?
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    Default Re: S-GPS vs AGPS

    First of all, GPS is system used to detect postion created by US millitery (later on unlocked for civil use), it's not name of technology but system. There other postioning systems like russion Glonass or Europian Gallieo which is under development (which will be first independent postioning system that is not under control of single nation), but they are not GPS and in general should not be called that way, because GPS is seperate system by it own devlopered by US Militery.

    GPS got one flaw, without extra information, GPS have problem locking satellites postions and may take even minutes and you need to wait long time until it start to work, you can check by yourself if your phone got good GPS reciver that can work by it's own (Galaxy S2 for example got good GPS), when you disable location detection from other sources it will take few minutes until it detect your location if you didnt use if for longer time (it lose the lock). Thats why they develop AGPS (asisted GPS) which use cell tower infromation to speed up this process, some manufactures to make hardware cheaper develop weak GPS recivers that have no ability to lock GPS sattlites by themselfs and require AGPS to actully work.

    i never heard of SGPS and as i see it's "Simultaneous GPS" which allows to use voice and location (AGPS i guess) in same time.
  11. #11  

    Default Re: S-GPS vs AGPS

    do either of these work on your phone's navigation system if you go to Europe?
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    Default Re: S-GPS vs AGPS

    Quote Originally Posted by Icon View Post
    The difference between them is just simply GPS uses satellites only to get your location, while AGPS (Assisted GPS) uses your carriers network (towers) to assist in finding your location. AGPS is faster and more accurate, but they both do the same thing.
    The difference is not trivial. A lot of devices with AGPS do not have "real" GPS. My old tablet is like this. If you are not near any wifi networks you effectively have no GPS.

    On devices with real GPS, aGPS will augment it and get your location faster and more accurately. On devices without real GPS, you will have very limited functionality from aGPS, if it works at all. "Real" in this context means an actual satellite sensor. Not all aGPS devices have that.

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