CSI Wireless Seres, Справочное руководство

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Seres Reference Manual
37
3.3 e-Dif Operation
Operation of the Seres unit with the optional e-Dif application requires
manual sending of NMEA messages. These commands may be
automatically issued through customized software or a simple terminal
interface running on a PDA or data logger. Chapter 5 provides detailed
information on the commands supported by the e-Dif feature.
3.3.1 Start-up
When you turn the Seres on with the e-Dif application running, it will
require a minimum of a few minutes to gather enough satellite tracking
information to model the errors for the future (up to 10 minutes may be
required depending on your environment). You do not have to keep the
Seres stationary for this process, but you should ensure that the Seres
maintains acquisition on the satellites available. We refer to this process of
gathering information for the e-Dif application as calibration.
3.3.2 Calibration
Calibration is the process of zeroing the increasing errors in the e-Dif
modeling process. Calibration can be performed either in a relative or
absolute sense, depending on your positioning needs. Relative positioning
will provide positions that are accurate to one another, however, there
may be some offset compared to truth. Calibrating for relative positioning
is easier than for absolute since any arbitrary position can be used.
Calibrating for absolute positioning mode requires that you perform this
task with the antenna at a known reference location.
3.3.3 e-Dif Performance
The positioning performance of the Seres unit is dependant upon the rate
at which the environmental modeling of e-Dif and the environmental errors
diverge. The more that e-Dif is able to model the errors correctly, the
longer that e-Dif will provide reliable, accurate positioning. As there’s no
way in real-time to know the rate of divergence, a rule of thumb is to set