Furuno FAR-2107 Series Service Manual page 444

- Narrow trail
When the setting of Narrow Trail is turned on, a trail width is presented in one dot.
The narrow trail can be used when selecting the long trial time. This feature is not
available on the IMO and A type radars. The narrow trail is processed for relatively
strong and large echoes, the level of which is 8 to 32 and the signal on screen is 6
dots in azimuth direction and 3 dots in rage direction.
The narrow trail processing can be used for a echo which is in level 8 or higher for
echo level divided into 32 and has a size of 6 dots in a row in the bearing direction
and 3 dots in a row in the distance direction on the screen coordinates. To be more
specific, the narrow trail processing is not done for smaller echoes
2. Wiper processing (WIPER)
The setting of the wiper processing is performed in OFF/1/2 of [Menu] -> 1 -> 6:
WIPER.
To facilitate echo observation, the wiper processing manipulates the echo levels of
noises and weaker echoes due to sea clutter, rain and snow step-by-step for each block
(memory area) and displays them on the screen. The display by this processing gives
pictures as if viewed on the PPI radar screen.
Time required for rewriting one block is about 300 msec. Consequently, the number of
"steps" for processing differs according to antenna revolving speed. For instance, in
case that the antenna revolving speed is 24 rpm, one screen is processed in about 8 steps.
In case of 42 rpm, the number of processing steps is decreased to about 5
Changes of pictures vary for each memory area, not for each specific bearing interval.
This is because the wiper processing is performed by subjecting the input signal (r-
according to the distance and bearing to X-Y conversion and then subjecting this to
wiper processing for each memory area. The wiper processing differs according to the
setting of EAV (Echo Average). See page.7-43 for the information on EAV.
Table 7.3.3 Relation between EAV setting and wiper processing
Wiper-OFF
Wiper-OFF
EAV-OFF
EAV-OFF
Performs
EAV-1 EAV-1
processing
Performs
EAV-2 EAV-2
processing
Performs
EAV-3 EAV-3
processing
Wiper-1
Performs EAV-OFF processing
and then Wiper-1 processing
Performs EAV-1 processing and
then Wiper-1 processing
Performs EAV-2 processing and
then Wiper-1 processing
Performs EAV-3 processing and
then Wiper-1 processing
7-39
7.3 Processor Unit (RPU-013)
Wiper-2
Performs EAV-OFF processing
and then Wiper-1 processing
Wiper-2 processing is performed
so that the final echo level
becomes EAV-1.
Wiper-2 processing is performed
so that the final echo level
becomes EAV-2.
Wiper-2 processing is performed
so that the final echo level
becomes EAV-3.
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