 VDB Generator
The VDB Generator application simulates a Ground Station by providing a versatile
source of VDB messages to exercise message decoding in the aircraft VDR or GNLU under
test. Depending on the test undertaken, the VDB Generator application provides the ability
to construct fully compliant DO-246 Type 1, 2 & 4 messages, or constructs data
sequences designed to test the upper or lower level decoding.
In addition to regular steady carrier, symbol rate and amplitude testing, the VDB
Generator permits additional special functionality to facilitate DO-253 MOPS testing. This
functionality includes the variation of time slot, frequency, transmit power and symbol
rate parameters as well corruption of CRC values.
VDB Analyser
The VDB Analyser is an essential tool for ensuring a GBAS (LAAS or GRAS) ground station
is operational. The VDB Analyser is designed to be used with the ADS Mini-VDR VDB Receiver
and utilise its RF analysis capabilities. The system operates independently to the
existing infrastructure, and provide a means of verifying both the RF parameters and data
content transmitted by the local GBAS ground station are in accordance with the relevant
specifications. The analyser can work as a monitor, but can also be set in alarm mode
which tests received messages against a series of user set parameters that makes the
operator aware when certain boundaries are not being met (Eg. Frequency Offset > 236 Hz
and time between successive Type 1 messages > 3 seconds).
The VDB Analyser has two display types; the Message Content Viewer and the RF Parameter
viewer. The Message content viewer provides information about message content in both raw
(hexadecimal) and fully decoded formats. A summary of parameters are also provided. The RF
parameter viewer provides a tabulated display of RF parameters for each VDB transmission,
and highlights parameters that are not within specification.
The combination of the Mini-VDR VDB Receiver and VDB Analyser provides an independent
solution that is ideally suited to operational monitoring and diagnosis of existing GBAS
stations to ensure transmitters are within RF mapping and message data specifications. The
system can be used during installation, maintenance, or fault finding of VDB facilities.
GBAS Analyser
The GBAS Analyser extends the features of the VDB Analyser by computing DGPS solutions
on a local GPS receiver using corrections received from the local GBAS station. The DGPS
computed solution is then used for analysis. The GBAS Analyser includes the functionality
of the VDB Analyser as well as providing the following additional displays:
- Plan View: A Real-Time scatter plot of the DGPS as well as the current
GPS solution parameters computed by a GPS receiver.
- FAS Waypoint View: Displays user navigation information such as
heading, distance and delta height to various FAS waypoints such as point on approaches
(LTP / FTP, FPAP, etc).
The linking of the Mini-VDR VDB Receiver and GBAS Analyser provides a complete and
independent solution that is ideally suited to short term functional testing of new and
developing products, or long term monitoring of existing GBAS or GVS infrastructure. The
system could be used during installation, maintenance, or fault finding of GBAS ground
stations. The system could either be used within proximity to the ground station or used
within a car or aircraft for:
- Logging of signal strength vs locations around the airport
- Monitoring the variability in the DGPS position solution
- Validating FAS data blocks before any aircraft flies approaches
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