l*****y
发帖数: 871 | 1 是独立的GPS 芯片
还是A-GPS，靠基站定位的？ | m****s
发帖数: 10867 | | m****0
发帖数: 837 | 3 A-gps 就是shit。 hd7 就是a-gps，没有gps 芯片。 在手机信号不好的地方经常没有
gps 信号。 | c****d
发帖数: 681 | 4 应该是独立的吧。我的streak没插sim卡，也能收到GPS
【在 l*****y 的大作中提到】
: 是独立的GPS 芯片
: 还是A-GPS，靠基站定位的？
| h**2
发帖数: 2841 | 5 我理解的a-gps是独立GPS基础上增加cellular network辅助定位
http://en.wikipedia.org/wiki/Assisted_GPS
Assisted GPS, generally abbreviated as A-GPS or aGPS, is a system which 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 mandate making the location of a cell
phone available to emergency call dispatchers.[1]
[edit] Description
"Standalone" or "Autonomous" GPS operation uses radio signals from
satellites alone. A-GPS additionally uses network resources to locate and
utilize the satellites faster as well as better in poor signal conditions.
In very poor signal conditions, for example in a city, these signals may
suffer multipath propagation where signals bounce off buildings, or be
weakened by passing through atmospheric conditions, walls or tree cover.
When first turned on in these conditions, some standalone GPS navigation
devices may not be able to work out a position due to the fragmentary signal
, rendering them unable to function until a clear signal can be received
continuously for up to 12.5 minutes (the time needed to download the GPS
almanac and ephemeris).[2]
An Assisted GPS system can address these problems by using data available
from a network. For billing purposes, network providers often count this as
a data access, which can cost money depending on the plan.[3]
Assistance falls into two categories:
1.Information used to more quickly acquire satellites It can supply orbital
data or almanac for the GPS satellites to the GPS receiver, enabling the
GPS receiver to lock to the satellites more rapidly in some cases.
The network can provide precise time.
The device captures a snapshot of the GPS signal, with approximate time,
for the server to later process into a position.
Accurate, surveyed coordinates for the cell site towers allow better
knowledge of local ionospheric conditions and other conditions affecting the
GPS signal than the GPS receiver alone, enabling more precise calculation
of position. (See also Wide Area Augmentation System and CellHunter and
openBmap.)
2.Calculation of position by the server using information from the GPS
receiver The assistance server has a good satellite signal, and plentiful
computation power, so it can compare fragmentary signals relayed to it
As an additional benefit, in some A-GPS device implementations, known as "MS
-Assisted," the amount of CPU and programming required for a GPS receiver is
reduced by offloading most of the work onto the assistance server.
A typical A-GPS-enabled receiver will use a data connection (Internet or
other) to contact the assistance server for aGPS information. If it also has
functioning autonomous GPS, it may use standalone GPS, which is sometimes
slower on time to first fix, but does not depend on the network, and
therefore can work beyond network range, and without incurring data usage
fees.[3] Some aGPS devices do not have the option of falling back to
standalone or autonomous GPS.
Many mobile phones combine A-GPS and other location services including Wi-Fi
Positioning System and cell-site triangulation and sometimes a hybrid
positioning system.[4]
High Sensitivity GPS is an allied technology that addresses some of these
issues in a way that does not require additional infrastructure. However,
unlike some forms of A-GPS, high-sensitivity GPS cannot provide a fix
instantaneously when the GPS receiver has been off for some time
【在 m****0 的大作中提到】
: A-gps 就是shit。 hd7 就是a-gps，没有gps 芯片。 在手机信号不好的地方经常没有
: gps 信号。
| l*****y
发帖数: 871 | 6 你确定你没有连接wifi?
【在 c****d 的大作中提到】
: 应该是独立的吧。我的streak没插sim卡，也能收到GPS
| m****0
发帖数: 837 | 7 不是所有的a-gps包括stand alone 的gps.
我联系了htc， htc hd7就没有gps, 只有所谓的a-gps. | w******x
发帖数: 4396 | | l*****y
发帖数: 871 | 9 dell feature写： GPS with A-GPS，
不插sim,关wifi,我在户外试了一下，无法定位，google map打不开，应该是没有地图
数据的原因。
有什么软件可以直接测GPS不？ | l*****y
发帖数: 871 | 10 昨晚用 gps info查了一下，无sim，关wifi，可以搜到9颗星。确认是有stand alone
GPS chip~!
好，GPS可以卖了，哈哈 | G********g
发帖数: 745 | 11 无语了...
先搞清GPS/AGPS再说,wiki上有。
【在 m****0 的大作中提到】
: 不是所有的a-gps包括stand alone 的gps.
: 我联系了htc， htc hd7就没有gps, 只有所谓的a-gps.
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