Furuno FV-110, Руководство оператора

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Calibration
5-11
5.2.4 Cable calibration
1. On the page SERVICE > Calibration click Start in the section Cable calibration .
Figure 5-9: Web interface: SERVICE, Calibration, cable attenuator margin
Wait typically for 2 minutes for the calibration to finish. A message is displayed when the
calibration has been completed successfully.This screen shows how much attenuation
margin is left for the antenna cable. This indicates whether the antenna cable and
connectors are in good condition and well crimped.
It is recommended to make a cable calibration when servicing the system to check if the
antenna cable is still in good order. If the attenuator margin changes by 2 dB or more after
a cable calibration, it is recommended to do a P1dB compression measurement to verify
that the VSAT modem configuration is correct.
The FV-110 is calibrated now. If the calibration failed there will be a message on the
calibration screen.
5.2.5 Operation in gyro-free mode
Heading input: none
If input from a gyro compass is not available, information from the GPS position is used
when searching for a satellite.
When the VSAT antenna does not have ship heading input from the vessel's gyro
compass, the azimuth direction of the satellite is not known. In this case the antenna will
start a 360 degrees sky scan and scan until it finds a satellite. The satellite search time to
find the satellite and start tracking is therefore raised considerably. If the ship is on a
steady course and sails at a speed over ground above 5 kn, the system can use an
estimated heading from the current GPS position. This will reduce the search time, but it
will still be a longer search time than with heading input.
This mode can be difficult for inclined orbit satellites and elevations <5 and >70 degrees,
see the following sections for details.
If a VSAT system loses the signal from the satellite, i.e. due to blockage, and the duration
of signal loss is longer than approximately 1 minute, a system without heading input must
do a new sky scan to find the satellite when the antenna is out of blockage.
Inclined orbit satellites
If the wanted satellite is an inclined orbit satellite, the VSAT system does not have any
information of the satellite latitude position but only information about inclination. This
means longer search times, depending on the maximum inclination. With the increased
search time for a system without heading input the search time can be so long that it will
be more or less useless in practice.
Important
For operation when input from the vessel’s gyro compass is not available:
Change the heading input setting from
Fixed to None at Heading – Input .
Fixed heading is not allowed for sailing vessels!