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4.1. HOW TO CONFIGURE THE ASTERX-U FOR RTK
4.1.3 How to configure the AsteRx-U in RTK rover mode using TCP/IP in a closed network
Step 1: Configure the Base station receiver
Set the Base station position as static
Section 5.1 describes how to configure the AsteRx-U as an RTK base station.
Configure the Ethernet connection and diff corr output from the Base station receiver
In the Corrections Output window click on New RTCM3 output to start the sequence of steps to configure the RTK diff corr stream and Ethernet connection over which the diff corr will be sent. In the example shown in Figure 4-10, RTCMv3 correction data are sent out over port 28785. The RTCMv3 messages necessary for RTK positioning are selected by default.
Figure 4-10: Click on New RTCM3 output to configure RTK diff corr output over an Ethernet connection
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4.1. HOW TO CONFIGURE THE ASTERX-U FOR RTK
Step 2: Configure the Rover receiver
Enable RTK positioning mode on the rover receiver
Ensure that RTK is enabled as a positioning mode. This can be done in the GNSS Position tab by checking the ‘RTK’ box in the ‘Position Mode’ field as shown in Figure 4-11.
Figure 4-11: Ensure that RTK is enabled as a positioning mode
Configure the Ethernet connection of the rover receiver
On the IP Ports window of the rover receiver, click on New IP Receive Connection as shown in Figure 4-12 to start configuration sequence. The Port and TCPAddress should match the port and IP address of the Base station receiver.
Figure 4-12: In the IP Ports window, click on New IP Receive Connection to configure the connection with the base station
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4.1. HOW TO CONFIGURE THE ASTERX-U FOR RTK
Step 3: Verifying the configuration
If the Base station and rover receivers have been configured correctly then graphics in the
Communication Ethernet windows should appear similar to those shown in Figures 4-13 and 4-14.
Figure 4-13: Ethernet window of the Base station receiver showing the position as static and an active output of RTCMv3 diff corr on server port IPS1
Figure 4-14: Ethernet tab of the rover receiver showing a fixed RTK position and reception of RTCMv3 diff corr on receiver port IPR1
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4.2. USING L-BAND PPP CORRECTION DATA WITH THE ASTERX-U
4.2 Using L-band PPP correction data with the
AsteRx-U
PPP (Precise Point Positioning) is high-accuracy positioning without the need for a local base station. PPP uses precise satellite clock and orbit corrections computed by a global network of reference stations and broadcast in real time by geostationary satellites transmitting in the
L-band. To receive PPP correction data, your receiver will need to be connected to an L-Band capable antenna 1 . The AsteRx-U can use PPP correction data from TerraStar (onshore) or
VERIPOS (offshore) as described in the steps below.
Step 1: Check you have PPP permissions on your AsteRx-U
The use of PPP services is permission-file controlled on the AsteRx-U. You can make sure that you have PPP permissions enabled on the About page selected from the Admin menu. Click on Permitted Capabilities and scroll down the list of permissions: PPP and Augmented
Data Svc should appear as permitted as shown in Figure 4-15.
Figure 4-15: Check that PPP is enabled in the AsteRx-U permission file
If you don’t have PPP permissions on your AsteRx-U, you can purchase this option from the
Septentrio sales department: [email protected]
.
1 Please note that PPP correction data is also available over an Ethernet connection using NTRIP and for this, an L-Band antenna is not required
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4.2. USING L-BAND PPP CORRECTION DATA WITH THE ASTERX-U
Step 2: Activating a TerraStar or VERIPOS PPP service
TerraStar is a PPP service aimed at on-shore applications and VERIPOS for off-shore.
TerraStar activation
To be able to get PPP correction data from TerraStar, you will also have to have a TerraStar subscription which can be purchased from your AsteRx-U dealer or from Septentrio sales department: [email protected]
. To activate TerraStar you will need to provide the
Product Activation Code (PAC) of the receiver. The PAC can be found on the Admin, About window as shown highlighted in Figure 4-16.
Figure 4-16: The Product Activation Code (PAC) required for TerraStar activation
VERIPOS activation
You can find out more about VERIPOS services via the link: www.veripos.com/services.html
.
To activate the VERIPOS service, you will be asked to provide the Augmentation User ID of the AsteRx-U which can be found in the Admin, About window and is shown highlighted in
Figure 4-17.
Figure 4-17: Augmentation User ID required for VERIPOS service activation
Both TerraStar and VERIPOS services are activated over the air. The AsteRx-U will therefore have to be powered on with a clear sky view for up to about 1 hour in order to receive the activation signal.
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4.2. USING L-BAND PPP CORRECTION DATA WITH THE ASTERX-U
Step 3: Connect an L-Band antenna
Ensure that you have an L-band capable antenna connected to the main antenna rear-panel connector. The AsteRx-U MARINE variant offers an additional connector for a dedicated
L-band antenna as shown in Figure 4-18.
Figure 4-18: Rear panel antenna connectors
Step 4: Select PPP positioning
Ensure that PPP is selected as a positioning mode in the GNSS Position tab as shown in
Figure 4-19.
Figure 4-19: Enable PPP positioning mode
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4.2. USING L-BAND PPP CORRECTION DATA WITH THE ASTERX-U
Step 5: Beam Selection Mode and Service
For TerraStar configuration, select the tab named TERRASTAR on the web interface. For
VERIPOS, the L-Band configuration window is named VERIPOS as shown in Figure 4-20.
The default L-band beam selection mode is auto as shown in Figure 4-20. In this mode, the demodulator will try to lock on to a visible beam, preferring beams to which access has been granted.
In manual mode, the demodulator will attempt to lock on to the beam selected from the
‘Manual beam selection’ drop-down list ignoring all other beams. The beams in this list can be pre-set in the ‘Advanced Settings’ expandable field. A beam is characterized by a frequency and data rate.
Users of the VERIPOS corrections, will have purchased either ULTRA or APEX services which should be selected as the PPP correction type as shown.
Figure 4-20: Select L-Band beam and APEX/ULTRA correction type (only applicable for VERIPOS service)
Without a TerraStar or VERIPOS subscription, the AsteRx-U will still be able track visible
L-Band signals. Figure 4-21 shows the L-Band Tracker Status field when the AsteRx-U is locked onto signals from the AORE satellite which transmits at 1539.9825 Mz. After purchasing a subscription you will need to track one of the beams for activation over the air.
Figure 4-21: L-Band Tracker Status field when locked on to an L-Band signal
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4.2. USING L-BAND PPP CORRECTION DATA WITH THE ASTERX-U
Step 6: Verifying the configuration
With a valid TERRRASTAR or VERIPOS subscription, the AsteRx-U will be able to decode PPP correction data. The Access line in the L-band decoder Information field should show
Access Enabled as in Figure 4-22.
After a few moments, the AsteRx-U positioning mode should change to PPP as indicated by the highlighted icon in the upper status field.
Figure 4-22: L-Band decoder Information field showing that TerraStar decoding is enabled
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4.2. USING L-BAND PPP CORRECTION DATA WITH THE ASTERX-U
Step 6: Additional optional settings: RTK seeding
The AsteRx-U can use an RTK or DGPS position to reduce the PPP convergence time: a process known as seeding. The configuration fields for seeding can be found in the GNSS,
Position window as shown in Figure 4-23.
RTK positions are typically expressed in a regional datum which depends on the local
RTK provider whereas TerraStar and VERIPOS PPP positions relate to the global ITRF2008 reference frame. To avoid coordinate jumps each time the PVT engine switches between
RTK and PPP modes and to ensure accurate seeding of the PPP engine from RTK, the regional datum used by your RTK provider must be provided to the receiver. This can be done in the
Geodetic Datum field using the drop-down datum list. Alternatively, the datum shift can be removed in the PPP Datum Offset field. The dx, dy and dz values will be subtracted from all
PPP coordinates.
Figure 4-23: Configuration fields of RTK/DGPS seeding
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4.3. HOW TO CONFIGURE THE ASTERX-U FOR
ATTITUDE
4.3 How to configure the AsteRx-U for
Attitude
With two antennas connected to the AsteRx-U, the receiver can calculate Heading and either
Pitch or Roll. This section details how to configure the AsteRx-U in a two-antenna setup.
Step 1: Connect a second antenna
Connect a second antenna to the rear-panel connector labelled AUX ANT and indicated in
Figure 4-24.
Figure 4-24: Auxiliary antenna connector on rear panel
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4.3. HOW TO CONFIGURE THE ASTERX-U FOR
ATTITUDE
Step 2: Configure attitude settings
The attitude settings of the AsteRx-U can be configured in the GNSS, Attitude window as shown in Figure 4-25.
Figure 4-25: GNSS Attitude window when two antennas are connected
GNSS Attitude field
The recommended settings for a Heading setup are MultiAntenna mode with attitude calculated using Fixed ambiguities as shown. These setting are configured by default.
Antenna Location and Antenna Offset
The AsteRx-U assumes that the main and auxiliary antennas are placed along the longitudinal axis of the vehicle with the auxiliary in front of the main antenna. If the antennas cannot be placed in such a configuration, the reported heading and pitch may be biased. The default settings in the Antenna Offset and Antenna Location fields shown in Figures 4-25 can be altered to compensate for these biases.
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4.3. HOW TO CONFIGURE THE ASTERX-U FOR
ATTITUDE
Step 3: Attitude information in SBF and NMEA data
Details on how to output SBF and NMEA data can be found in Section 3.4.
SBF
Attitude information is contained in the SBF blocks AuxAntPositions , AttEuler , AttCovEuler and
EndOfAtt . These blocks are selected automatically when checking the ‘Attitude’ box when configuring SBF output via the NMEA/SBF Out window as Figure 4-26 shows.
Figure 4-26: SBF blocks containing attitude information
NMEA
You can output the attitude information from the AsteRx-U in NMEA format by selecting the standard NMEA HDT sentence or the Septentrio proprietary HRP sentence as shown in
Figure 4-27.
Figure 4-27: NMEA sentences containing attitude information
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4.4. HOW TO OUTPUT A PPS SIGNAL
4.4 How to output a PPS signal
The AsteRx-U can output a PPS (Pulse-per-Second) signal that can be used for example, to synchronise a secondary device to UTC time.
Step 1: Connect the PPS cable
Connect the PPS_OUT cable to the rear-panel connector labelled ‘PPS GPO’ and indicated in
Figure 4-28.
Figure 4-28: PPS connector on rear panel
Step 2: Configure the PPS settings
You can configure the PPS settings on the PPS/Timing window on the GNSS menu as shown in Figure 4-29.
Figure 4-29: The GNSS, PPS \ Timing window
The Interval is the time interval between successive timing pulses and is selectable between
10ms and 10s. The default Polarity of the PPS signal is a low-to-high transition which can be alternatively configured as high-to-low.
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