CSI Wireless GBX, Справочное руководство

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GBX Reference Manual
6
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A DGPS beacon will broadcast either Type 1 or Type 9 messages, both of
which contain similar information. These two messages contain
pseudorange corrections and range rate corrections to each GPS satellite.
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The Type 2 message contains delta differential corrections that are used
when the remote receiver is using a different satellite navigation message
than used by the base station.
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The Type 3 message contains the position of the beacon’s reference
station, often accurate to within centimeters with respect to the WGS-84
reference datum.
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The Type 5 message contains GPS constellation health information used
for improving tracking performance of a GPS receiver
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The Type 6 message contains null information, and is broadcast so that a
beacon receiver demodulating the data from the broadcast does not lose
lock when the beacon station has no new data to transmit.
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The Type 7 message contains the radiobeacon almanac information
composed of location, frequency, service range, and health information of
sister stations for the currently tuned beacon.
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The Type 16 message provides users with a 90 character text string that
may contain information regarding the status of the system, weather
warnings, etc.
Radiobeacon DGPS is often referred to as a local-area service, as the
data broadcast is appropriate for use within the coverage range of the
station, and is calculated by a single, local GPS reference station.
1.4.4 Radiobeacon Coverage
Figure 1-1 shows the approximate radiobeacon coverage throughout
the world. In this figure, light shaded regions note current coverage,
with beacon stations symbolized as white circles.
The world beacon networks continue to expand. For more current
coverage, consult the CSI Wireless Web site at
www.csi-wireless.com .