Javad JNSGyro-4T, Operator'S Manual

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www.javad.com JNSGyro-4T Operator’s Manual 3-3
S E T U P A N D M E A S U R I N G
How to Work with JNSGyro-4T
the new Nose axis by the angle
ϕ
. The rotation matrix from the local
horizon frame to the body frame is given by
Differential corrections
As stated above, the unit consists of four receiver boards. One of them is
named
Master . The other three boards are named S lave2, Slave3 , and
Slave4 .
The Master board sends differential corrections to the Slave receivers. The
Slave receivers send back the base line vectors. The Master receiver
communicates with the user through the port A.
The JNSGyro-4 (T) can also operate in the RTK or DGPS modes receiving
corrections from a remote base station to provide differentially corrected
position and velocity.
The radio modem can be connected to the port A of any Slave receiver.
Differential corrections received from the remote base can be formatted as
CMR or RTCM. To instruct
Master about the format, the following setting
is used:
set,att/remote/imode,<mode>,
where mode = [none|rtcm|cmr], with none being default value.
The value “none” means that differential corrections are not received.
Delay and extrapolation
The attitude system operates as follows:
Master sends data to the Slaves ; Slaves process data and send results back
to Master . It processes the results and calculates the attitude. In so doing,
there appear delays caused by the data exchanges and calculations. More
specifically, there s a latency between the time when the attitude results
appear and the GPS time tag the results are related to. To compensate this
latency, the extrapolation mode may be used. Thus, the system can operate
in two modes: delay and extrapolation.
To switch from the delay mode to the extrapolation mode, the following
setting is used: