Outline Of The Sequence For Capturing The Satellite - Furuno Felcom 250 Service Manual

1. Outline of the Sequence for Capturing the Satellite

The numbers for each item listed below match with the numbers in the sequence
described in the previous page.
(1) Turn the power of the ADU (Antenna unit) on
ADU will be automatically set to SEEK_ELEVATION_ST. The system will use the
Channel and elevation angle for when it had been in tracking status the previous time.
These data are saved in the nonvolatile memory for the Antenna unit's ATB module.
When the signal cannot be detected by using the previous value;
The Channel will be changed.
Although the system has shifted to tracking status by using the previous value,
the detected signal was unwanted signal.
Send TU_SIGNAL_STAT=1, and return to SEEK2_ST
(SEEK_ELEVATION_ST).
(2) Channel changing process (Main - > Satellite search)
When the satellite setting is set to AUTO: The satellite will be automatically
selected and acquired.
When the satellite setting is set to MANUAL: The satellite to be acquired is
fixed by user setting.
(3) When the signal had not been able to be detected within the predefined time when
the status is set to SEEK_ELEVATION_ST, and the status does not shift to
SEEK2_ST, move onto the next process.
The Antenna unit automatically detects the signal; when the signal cannot be
detected, it repeats SEEK_ELEVATION_ST unless there is a command sent
from the Communication unit. Establish a setting for time out, and monitor the
STATUS of the Antenna unit from the Communication unit, and if the STATUS
does not change until the end of the predefined time, move onto the next
process.
(4) When the signal cannot be detected with all of the predefined elevation angles
when the status is set to SEEK1_ST, and the status does not shift to SEEK2_ST,
move onto the next process.
The Antenna unit automatically detects the signal; when the signal cannot be
detected, it repeats SEEK1_ST unless there is a command sent from the
Communication unit.
Monitor if searching had been executed at all of the predefined elevation angles
(15, 45, and 75 degrees), and if the STATUS remains the same even after having
executed searches for all elevation angels, move onto the next process.
(5) Avoid loop -1
Avoid loop between SEEK_ELEVATION_ST and SEEK2_ST and between
SEEK1_ST and SEEK2_ST.
(6) Avoid loop -2
Since loop can be generated between the tracking status and SEEK2_ST, that loop
shall be avoided.
11-21
11.2 Antenna Unit: FB-1500/1250