2. SYSTEM MENU
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2.2.2 TVG level
TVG (Time Varied Gain) compensates for propagation attenuation of the ultrasonic waves,
reducing surface noise to provide a smooth display. The TVG lowers receiver sensitivity at the
time of pulse emission and gradually increases it with time, thereby making objects of same
reflectivity at different depths appear at the same intensity or colours on the display.
The TVG working depth is down to approximately 150 m on the 200 kHz system and 350 m on
the 50 kHz system. Outside this range the echoes from the seabed and fish schools are received
in full level. There is no perceivable deterioration in performance.
To adjust the TVG level or the TVG distance, see section 2.2.
Note: Do not switch transducers (frequency) at the Junction Box when setting the TVG level. If it
is necessary to set TVG level for a different frequency, turn off the FE-800, switch
transducers at the Junction Box and then turn on the FE-800 again.
2.2.3 Echo offset
The echo offset feature functions to compensate for too weak or too strong echo level.
If the on-screen echo level appears to be too weak or too strong and the level cannot be adjusted
satisfactorily with the GAIN control, see section 2.2 to adjust the TVG level.
2.3 How to Set TX Rate
TX rate adjusts the rate at which the FE-800 transmits a signal. The TX rate can be adjusted to
compensate for noise created by other sounders.
1. Press the MENU/ESC key to open the Main menu.
2. Select [System] using or , then press the ENT key.
3. Select [Parameters] using or , then press the ENT key.
4. Select [TX Rate] using or , then press the ENT key. This will open a pop-up window.
5. Adjust the [TX Rate] using or , then press the ENT key to apply the settings and close
the pop-up window. The higher the setting, the higher the rate at which the FE-800 outputs a
signal. To keep the default setting (10), press or the MENU/ESC key.
6. Press the MENU/ESC key three times to close the menu.
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