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发表于 2009-1-23 11:57
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关于GPS
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( {7 p# q4 k7 p1 B$ \Your Treo 800w smartphone supports both stand-alone GPS and Assisted GPS (A-GPS). 2 ]3 D; _, G! _7 m
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* _+ B9 v! y. L; K, ?What's the difference?' V" Y& b/ o0 L
GPS (non-assisted, or stand-alone) gets its location data from satellites orbiting above the earth. When you first turn on the GPS function, there will be a delay while the GPS device searches for satellites. The wait time is exacerbated by poor signal conditions, such as when you're surrounded by tall buildings, you're indoors, or you're under trees. In addition, when first turned on in these conditions, some non-assisted GPS units may not be able to download the almanac and ephemeris information from the GPS satellites, rendering them unable to function until a clear signal can be received continuously for up to one minute. ) H! h# O/ A/ y ^
2 g# k( b, k# J2 cA-GPS gets its location data from nearby cellular towers, who in turn get their data from a constant connection to GPS satellites. The towers keep track of satellites in range, so your phone can ping the tower and know which satellites to try to connect to, speeding up the process greatly. ( h, G' |6 |& N- _& B
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GPS vs. A-GPS on the Treo 800w+ N2 e* w9 J: t7 s& t
Treo 800w supports stand-alone GPS and A-GPS. Stand-alone GPS is used when the cellular radio is off or the device is not connected to the cellular network. . E- L# l: Y: U M+ ~
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A-GPS
, U6 l; S2 n/ }( H0 H8 V: EFor optimal performance, the use of A-GPS is recommended because it significantly reduces the time to get the location fix. This requires data connection to cellular network, so your smartphone must be on and connected, and you must be subscribed to a data plan from your mobile service provider.
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) v; s. O: d1 {! t: p2 u6 p5 ySprint note: While a "Sprint Navigation" subscription is included in most data plans from Sprint (including the "Simply Everything" plan), this subscription is not required to use the GPS search bar on the Today screen or the Maps application in the Programs folder (Start , then Programs). However, users must subscribe to and use Sprint Navigation for turn-by-turn directions and audible directions. To launch Sprint Navigation, select Drive to… in the Maps application, or select Sprint Navigation in the Programs folder (Start , then Programs).
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GPS (stand-alone)
/ C( j$ v; D" g+ q' p/ j; b0 Z+ V) ZYou can use stand-alone GPS in the following cases: 6 o H/ t2 X6 J! J# d- {; M
9 x7 D0 z4 X: g% ?1 j8 x9 M3 ZWhen the data network is not available or the cellular radio is powered off. 8 g: s: o, y, a- G5 X" u
When your Treo 800w does not have a voice and/or data plan from a mobile service provider. , X5 e: X+ V7 F; r; H
To use stand-alone GPS: 7 Z& y# m+ W- j- h
& S. m2 @+ w6 |) [4 h) [1 IMake sure your device is outside and in an area with sufficient open space.
# o! a2 k' A q e' y9 QTurn on the cellular radio (press and hold the red button) to acquire the system time from the network. This is necessary to acquire the first GPS location fix. You can do this even if you don't have a voice/data plan from a mobile service provider.
2 v. Y& ?- W5 M" G9 rOnce the system time is acquired, turn off the cellular radion (press and hold the red button); it is not needed to get GPS location fix.
; T7 B& B( @4 s" L7 F/ Y4 }+ ]The step to power on the radio to acquire system time is necessary whenever Treo 800w is reset.
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( h* E$ @* ~5 K" UIt may take as long as 8 to 10 minutes to get a fix on a satellite. Once the GPS fix is obtained, the location must be shown on a map. For this, there are two options: 3 h" K, b& g0 O3 A: g- J
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Real-time maps: The maps for your location are downloaded real-time to your smartphone. The GPS search bar on the Today screen, the Maps application in the Programs folder (Start , then Programs), and applications such as Live Search for Windows Mobile behave in this way. To download the maps in real time, a data connection is needed. Since the cellular radio is off, you can use Wi-Fi to download the maps; the exact compatibility and the speed of download will vary greatly in this case.
0 b: f+ X" W2 V" k5 { t0 r* }On-device maps: The alternative is to store the maps locally on your smartphone. You can do this by adding a third-party application such as Garmin to your device, and storing Garmin's maps on an expansion card. In this scenario, you can use stand-alone GPS to get the device location, and the third-party maps on your SD card to display your location on the screen. No data connection – Wi-Fi or cellular – is necessary. & @7 _: O1 T) P. k
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等待翻译
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[ 本帖最后由 CyberVsQ 于 2009-1-23 12:59 编辑 ] |
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