Furuno 1830 - Gain Control Adjustment

letting the Gain Control
The GAIN Control is used to adjust the sensitivity of the receiver, and thiis
the strength of echoes aa they appear on the screen. It is adjusted so that
a speckled noise background is just visible on the CRT.
To become acquainted vrith the way the GAIN control works, try rolating it
between its fully counterclockwise and clockwise position as you observe the
display. To properiy set the gain, one of the higher ranges (12nni or
24nm) should be used—the speckled noisB hflfikgmiinfi is more appai*ent on
these ranges. As you slowly turn the GAIN control clockwise you should be
able to see the speckled background appear when the position of the control
is between 2 and 3 o'clock. If you set up for too little gain, weak echoes
rnay be ndssed. If you xurn the GAIN control too far clockwise, yielding too
much speckled noise background. strong targets may be missed because of
the poor contrast between desired echoes and the background noise on the
display. Fig.24 illnstrntes examples of gain eettings whioh åre too high,
proper, and too low.
(A) too high (B) proper (C; too low
Fig.24 Setting the Gain Control
In certain circumstances it may be useful to slightly reduce the gain to
iraprove range resolution; clear up the picture; or reduce dutter caused by
rain or snow.
Range resolution is a measure of the capability of a radar to display as
separate pips the echoes received from two targets which are on the same
beanng, and are ciose together radially. With reduction in the gain setting,
the echoes may be made to appear as separate pips on the display screen.
When sailing or GTkiising in orowded regions a elight reduotion in gain often
helps to clear up the picture. This should be done carefully, otherwise
weak targets may be trassed.
Bchoes from ships inside a squaJl or storm may be obscured if the gain is at
its normal setting, since the dutter may have masked, but not completely,
echoes from the targets.
In ^ cases, the gain should be returned to its original position after any
teraporary reduction is no longer required.
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