Novatel OM-20000077 Sbas Receiver, Sbas Messages, Chapter Positioning Modes of Operation

Chapter 6 Positioning Modes of Operation

maintained close to GPS time to provide a ranging capability.

Geostationary

Satellite (GEO)

L1 L1 & C-band

GPS User

Reference Station Reference Station

GPS Satellite

Constellation

L1 & L2

Integrity data, differential corrections, and ranging control

C-band

Reference Station

Master Station	Integrity data,
	differential corrections,
	time control, and status

Figure 7: The SBAS Concept

6.2.1SBAS Receiver

Ground Uplink

Station

NovAtel SUPERSTAR II-based receivers are equipped with an SBAS feature. The ability to simultaneously track two SBAS satellites, and incorporate the SBAS corrections into the position, is available in these models.

These models can output the SBAS data in log format (refer to Message ID# 67, WAAS Data in the L1 GPS Firmware Reference Manual), and can incorporate these corrections to generate differential-quality position solutions. Standard SBAS data messages are analyzed based on RTCA standard DO-229B Change 1 Minimum Operational Performance Standards for GPS/WAAS airborne equipment.

A SBAS-capable receiver will permit anyone within the area of coverage to take advantage of its benefits.

6.2.2SBAS Messages

The command Message ID# 95, Track SV, enables the use of particular SBAS corrections in the position filter. Two SBAS-specific messages:

Message ID# 67, SBAS Data

Message ID# 68, SBAS Status

are also available. In order to use these messages, first ensure that your receiver is capable of receiving SBAS corrections.

StarView allows you to deselect GPS and SBAS system satellites. Select Tool Settings Deselect SVs from the main menu. To track one SBAS satellite in particular, do the following:

1.Select SBAS SVs

2.Select the SBAS satellite that you wish to track by deselecting all the others. This ensures that the receiver will search for a satellites that is known to be operating and thus a quick acquisition/re- acquisition of the active SBAS satellite.

3.By default, if you select SBAS SVs alone, the unit is only searching for satellite PRNs 120, 122 and

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