SX BLUE GPS iSXblue II+ GNSSTM, Руководство пользователя

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SXblue Series User Manual 56
where the SXblue Platinum, L-band differential satellite receiver, demodulates the
data.
Atlas
®
signal content is not RTCM SC-104, but a proprietary wide-area signal that
is geographically independent. With this service, the positioning accuracy does not
degrade as a function of distance to a base station, as the data content is not
composed of a single base station’s information, but an entire network’s
information. When the SXblue Platinum L-Band receiver demodulates the
proprietary signal, it converts it into a local-area format for input to the internal GPS
receiver (standard RTCM SC-104).
The SXblue Platinum receiver interpolates corrections from the wide-area signal,
specific to the location using Virtual Base Station (VBS) processing algorithms.
The resulting RTCM corrections are those that would be calculated if a reference
station were set up at the present location. This type of solution ensures a
consistent level of accuracy across the entire coverage area.
2.5.2 Signal Reception
The Atlas
®
L-band signal is a line-of-sight signal that is similar to GPS. There must
be a line of sight between the SXblue antenna and the geostationary
communication satellite in order for the L-band differential receiver inside the
SXblue Platinum to acquire the signal.
Various L-band communications satellites are used for transmitting the correction
data to Atlas
®
users around the world. When the SXblue Platinum has acquired an
Atlas
®
signal, the elevation and azimuth are available in the menu system in order
to troubleshoot line of sight problems. Contact Atlas
®
for further information on this
service and actual worldwide signal broadcast coverage maps. Atlas
®
contact
information is provided in Appendix C of this manual.
The Atlas
®
service broadcasts at a similar frequency to GPS, and as a result, is a
line-of-sight system. There must be a line of sight between the antenna and the
Atlas
®
satellite for reception of the service.
The Atlas service uses geostationary satellites for communication. The elevation
angle to these satellites is dependent upon latitude. For latitudes higher than
approximately 55° north or south, the Atlas signal may be blocked more easily by
obstructions such as trees, buildings, terrain, or other objects. In this case, the
Coast technology described below might enhanced the field performance of the
SXblue Platinum when used with the sub-meter VBS service.