CSI Wireless Seres, Справочное руководство

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Seres Reference Manual
11
To enhance the information provided by SBAS, the Seres system
extrapolates the ionospheric information beyond the broadcast
information. This increases the usable geography for WAAS and is
discussed in Section 1.5.5. This feature helps to improve the usable
coverage area of a SBAS service.
1.5.2 Signal Information
A SBAS transmits correction data on the same frequency as GPS from a
geostationary satellite (the space segment), allowing the use of the same
receiver equipment used for GPS. Another advantage of having SBAS
transmit on the same frequency is that only one antenna is required.
1.5.3 Reception
Since SBAS broadcast in the L-band, the signal requires a line of sight in the
same manner as GPS to maintain signal acquisition.
Currently, two commercial marine communication satellites are
transmitting WAAS data for public use, and one each is located above both
the Pacific Ocean and Northern Brazil. Due to their location, these
satellites may appear lower on the horizon, depending on your geographic
position on land. In regions where the satellites appear lower on the
horizon, they may be more prone to being masked by terrain, foliage,
buildings or objects, resulting in signal loss. The further that you are away
from the equator and the satellite’s longitude will cause the satellite to
appear lower on the horizon. Fortunately, the CSI Wireless COAST
Technology helps alleviate this problem by maintaining system performance
when WAAS (SBAS) signal loss occurs for extended periods of time. More
information on COAST is provided in Section 1.7.
The EGNOS System Test Bed (ESTB), also referred to as EGNOS in this
document, uses two geostationary satellites (separate from WAAS),
however, in this case, they are located over the Atlantic and Indian Oceans.
Similar to WAAS, the satellites may appear lower on the horizon,
depending on your geographic position on land. The further that you are