Skipper GDS102 - Screen Select; Brightness (Backlight) Adjustment; Day;Night; Gain and TVG (Time Variable Gain)

Page 29 of 77
SKIPPER Electronics AS
Edition: 2017-06-12
GDS102 Operation and Installation Manual
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Chapter: 2 Operation
Screen select
The SCREEN button facilitates selection of one of the 12 screen and soft key layouts. The 3 primary
operation screens may be cycled by repeatedly pressing the SCREEN button. Access to the remaining
screens is through encoder operation. The screens are cycled in an endless, bi-directional loop, e.g.
turning the encoder counter-clockwise, will activate screen 12 after screen 1.
Brightness (backlight) adjustment
Backlight may be continuously controlled by using the BRIGHTNESS button and the encoder. Press the
button and rotate the encoder until a satisfactory setting is obtained, then release the button. The setting
is maintained in the non-volatile memory, and the last setting is restored on power-up.
Day/Night
Day/Night vision may be selected by pressing this button.
Gain and TVG (Time Variable Gain)
Gain and TVG settings allow to form the resultant gain curve, used by the receiver ampliers. Signal
attenuation in water is proportional to logarithm of distance traveled. The formula G + T × log (R) + a
is used for gain calculation for each moment of time, where G is a GAIN setting, T - TVG, R - distance
of sound travel and a is a constant, compensating for dierent attenuation of signals with dierent
frequencies. The gain, in principle, is an oset used to compensate for tolerances of the transducers
resultant sensitivity (transmitting and receiving sensitivity).
TVG setting can be used to provide dierent suppression of the echoes returned closer to the transducer.
This may be desirable in case of strong reections from the temperature layers, air bubbles and other
obstacles. Higher TVG settings will result in lower suppression. Both GAIN and TVG should be adjusted
individually for each channel to achieve a stable bottom detection at all depths in the operating range.
Digital indication
On the operation screens, two sizes of large digital depth indicators may be selected from screen 2. See
“Fig. 2.3. Screen 2. Display and print settings.” on page 15.
Frequency
The operating frequency of each channel must be selected by using the DIP switches on the transceiver
PCB, see “Frequency setup” on page 56, while indicated values should be adjusted accordingly on
screen 4, see “Fig. 2.5. Screen 4. Transducer details.” on page 17.
Output Power
Power may be adjusted from 1 to 100 %. Power reduction can be useful in case of dicult shallow
water conditions. Too high power in such cases will possibly saturate the receiver or cause detection of
unwanted secondary bottom or surface echoes.