Echo Stretch; Echo Averaging - Furuno FCR-2107 Series Operator's Manual

2. Radar Operation
2.17

Echo Stretch

The echo stretch feature enlarges targets in the
range and bearing directions to make them easier to
see, and it is available on any range. There are three
types of echo stretch, 1, 2 and 3, and the higher the
number the greater the amount of stretching.
The echo stretch magnifies not only small target
pips but also returns (clutter) from sea surface, rain
and radar interference. For this reason, make sure
these types of interference have been sufficiently
suppressed before activating the echo stretch.
1. Use the trackball to select the ES indication at
the left side of the screen.
2. Push the left button to select the echo stretch level desired. The indication changes in the sequence of OFF, 1, 2,
and 3.
2.18

Echo Averaging

The echo average feature effectively suppresses sea clutter. Echoes received from stable targets such as ships appear
on the screen at almost the same position every rotation of the antenna. On the other hand, unstable echoes such as
sea clutter appear at random positions.
To distinguish real target echoes from sea clutter, echoes are averaged over successive picture frames. If an echo is
solid and stable, it is presented in its normal intensity. Sea clutter is averaged over successive scans resulting in
reduced brilliance, making it easier to discriminate real targets from sea clutter.
Echo averaging uses scan-to-scan signal correlation technique based on the true motion over the ground of each
target. Thus, small stationary targets such as buoys will be shown while suppressing random echoes such as sea
clutter. True echo average is not however effective for picking up small targets running at high speeds over the
ground.
Note 1: With echo average active it is harder to detect high-speed targets than stationary ones.
Note 2: Do not use the echo averaging function under heavy pitching and rolling; loss of targets can result.
Note 3: Echo averaging can be used without a heading sensor. For further details, contact your dealer.
Note 4: Echo averaging requires heading, position and speed data.
Before using the echo averaging function, reduce sea clutter with the A/C SEA control. Leave a little sea clutter on
the screen so as not to erase weak targets. Then, do as follows:
Select EAV at the left side of the screen, then push the left button to choose setting.
OFF: Echo averaging OFF
1, 2: Detects targets hidden in sea clutter. "2" is more effective than "1" in detecting targets hidden in strong sea
clutter. However, "1" is more effective than "2" in displaying high speed targets. Select the setting best suited
to current conditions. For effective monitoring of high-speed craft, you should use "2" together with Wiper.
3: Stably displays unstable targets; distinguish high-speed craft from sea clutter.
Echo average
2-24
Echo stretch