Furuno FAR-2107 Series Service Manual page 46

Change to be made
1) Following FTC problems are eliminated: (a) FTC and GAIN filter out targets in long
distance together with rain clutter and (b) Targets in rain cannot be discriminated. With
new software, when Auto FTC function (AUTO RAIN 1 to 4) is applied, the strong targets
in long distance is AGC-controlled to prevent it from saturating in the IF amplifier.
To detect the target in rain, important is to adjust Gain, Auto RAIN, STC, Echo Average,
and Contrast properly.
IF input signal
Input signal to IF amplifier
Fig.1
2) Route problem is removed. When receiving the route (waypoints) from the GPS
receiver, the route is redrawn frequently; the key response is slow; and the system
freezes. These problems are eliminated. The new software handles only working route
(not complete route and all waypoints).
3) The heading data is always shown in three digits before the decimal point to meet
DNV requirement. For example, 10.5 degrees is indicated as 010.5 degrees.
4) Scanner unit number is shown in reversed video when it is not own scanner unit.
5) Echo trail appears in segments. This problem is improved. Note that the higher the
latitude, the more the distance between the segments.
6) Problem that local time is shown by *** is eliminated.
7) ARPA vector mode changes from TRUE to REL mode when HDG error occurs and
changes to TRUE mode when the HDG data is input again normally.
With V02.31 SPU, the mode does not change back to TRUE when HDG data is input
again.
Target echo?
Target echo
Rain/snow echo
Gain
Output signal from IF amplifier
Fig.2
IF output signal
V02.28
Target echo
IF output signal
V02.31
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