Hexagon CPT7, Инструкция по установке и эксплуатации

Страница: 98 / 186

Chapter 4 SPAN Operation
CPT7 and CPT7700 Installation and Operation User Manual v9 98
4.7.2 Configuring the Software
Sensor objects are defined by using the SETUPSENSOR command. This command allows the Event_In and
Event_Out lines to be specified as well as some parameters for the outgoing and incoming signals.
After configuring a sensor using the SETUPSENSOR command, any other commands that affect the
selected event lines will disturb this functionality. For example, if MARK2 Out is selected for a sensor,
but later the
EVENTOUTCONTROL command is sent, the EVENTOUTCONTROL command will
reconfigure the properties of the MARK2 line.
4.7.3 Using Timed Event Pulses
When sensors have been connected and configured, use the TIMEDEVENTPULSE command to queue
events on the system. TIMEDEVENTPULSE specifies the sensors that are affected, the GPS time for the
desired event (in weeks and seconds), and an event ID. You can queue 10 unprocessed events at a time. Any
time input specified via this command must occur at least 1 second after the command is entered.
The timing accuracy of the TIMEDEVENTPULSE output is 2 milliseconds.
4.7.4 Recording Incoming Sensor Events
After a TIMEDEVENTPULSE is sent, the system can be configured to accept an incoming pulse from the
sensor in order to produce a time and ID tagged inertial solution associated to that event. This is optional and
useful if a sensor provides a measurement TOV pulse. The produced log is a TAGGEDxMARKPVA where the
'x' is the Event_In line associated with that sensor (via the
SETUPSENSOR command).
For example, if the SETUPSENSOR command specifies SENSOR1 to use MARK1 in as the input event then
a TAGGEDMARK1PVA log will be produced when any pulses on that line are observed. In this case the
TAGGEDMARK1PVA log should be requested ONNEW to capture the data.
4.8 Azimuth Sources on a SPAN System
The SPAN system use three different methods to calculate the azimuth.
l
Course Over Ground
l
Inertial Azimuth
l
ALIGN Azimuth
4.8.1 Course Over Ground
The course over ground azimuth is determined using the position delta between two position solutions
computed by the OEM7 receiver. This is the simplest way to compute an azimuth and is done using either the
GNSS solution or the INS solution. This method does not work when the vehicle is stationary as any position
difference is due to position error and the computed azimuth is meaningless.
Course over ground azimuth is of greatest advantage in aerial or marine environments where the actual
direction of travel may not match the forward axis of the aircraft/boat due to winds or currents. This effect is
known as the crab angle. Course over ground azimuth is a great way to compute the offset if another means of
computing the vehicle azimuth is available.
Course over ground azimuths are available in several different velocity logs. See Table 17: Logs with Azimuth
Data on the next page.