Assessments - 3, GPA: 2.7
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Facilidade de uso
ZOOM RANGE: Select the range to zoom in the marker and bottom zoom modes. You may select a range between 7 and 2500 feet. Default setting is 30 feet. B/L RANGE: The expansion width for the bottom-lock display can be selected to 10 feet or 20 feet. Default setting is 20 feet. 2.3 Demonstration Display The demonstration display lets you get acquainted with the features of the FCV-582L without connecting the transducer. You can activate it as follows: 1. Turn on the power while pressing any key. 2. Press the [] key. The following display appears: 2.4 Bottom Level If the depth indication is unstable in automatic operation or the bottom echo cannot be displayed in reddish-brown by adjusting the gain controls in manual operation, you may adjust the bottom echo level detection circuit, for both 50 kHz and 200 kHz, to stabilize the indication. Note that if the level is set too low weak echoes may be missed and if set too high the depth indication will not be displayed. 1. Turn on the power while pressing any key. 2. Press the ALARM key three times. The start-up screen appears and shortly thereafter the BOTTOM LEVEL display appears. BOTTOM LEVEL 50kHz= 80(20 200) 200kHz= 80(20 200) : 50kHz- + : 200kHz Figure 2-4 Bottom level display 3. Operate appropriate key among [], [], [+] or [–] to set level. 4. Press the POWER key to escape. DEMO MODE OFF ON - +: To set condition : OPTIONAL MODE Figure 2-3 Demo mode display 3. Press the [+] key to select ON. 4. Reset the power. “DEMO” appears above the depth indication on the video sounder displays and at the top right-hand corner on the data and graphic displays. To return to normal operation, turn off the demonstration display at step 3 in the above procedure. 2.5 TVG Level TVG (Time Varied Gain) compensates for propagation attenuation of the ultrasonic waves. It does this by equalizing echo presentation so that fish schools of the same size appear in the same density in both shallow and deep waters. In addition, it reduces surface noise. Note that if the TVG level is set too high short range echoes may not be displayed. 1. Turn on the power while pressing any key. 2. Press the ZOOM key three times. The start-up screen appears and shortly thereafter the TVG SELECT display appears. TVG SELECT 50kHz= 5(0 9) 200kHz= 5(0 9) : 50kHz- + : 200kHz Figure 2-5 TVG select display 3. Operate appropriate key among [], [], [+] or [–] to set level. 4. Press the POWER key to escape. 2.6 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, do the following to adjust echo level: 1. Turn on the power while pressing any key. 2. Press the SIG LEV key three times. The start-up screen appears and shortly thereafter the ECHO OFFSET display appears. ECHO OFFSET 50kHz= 0(-99 +99) 200kHz= 0(-99 +99) : 50kHz- + : 200kHz Figure 2-6 Echo offset display 3. Operate appropriate key among [], [], [+] or [–] to set level. 4. Press the POWER key to escape. Intensity difference in water depth echo Intensity difference in water depth echo INTERPRETING THE DISPLAY 3.1 Zero Line The zero line (sometimes referred to as the transmission line) represents the transducer’s position, and moves off the screen when a deep phased range is used. Zero line Shift Figure 3-1 Zero line 3.2 Fish School Echoes Fish school echoes will generally be plotted between the zero line and the bottom. Usually the fish school/fish echo is weaker than the bottom echo because its reflection property is much smaller compared to the bottom. The size of the fish school can be ascertained from the density of the display. Small school Large school Size of fish school Figure 3-2 Fish school echoes 3.3 Bottom Echo Echoes from the bottom are normally the strongest and are displayed in reddish-brown color (in default color arrangement) but the color and width will vary with bottom composition, water depth, frequency, sensitivity, etc. In a comparatively shallow depth, a high gain setting will cause a second or sometimes a third or a fourth echo to be displayed at the same interval between them below the first echo trace. This is because the echo travels between the bottom and the surface twice or more in shallow depths. The color of the bottom echo can be used to help determine the density of the bottom materials (soft or hard). The harder the bottom, the wider the trace. If the gain is set to show only a single bottom echo on mud, a rocky bottom will show a second or third bottom return. The range should be chosen so the first and second bottom echoes are displayed when bottom hardness is being determined. Second bottom Rock base Mud and sand Figure 3-3 Bottom echoes 3.4 Surface Noise/Aeration When the waters are rough or the boat passes over a wake, surface noise may appear near the zero line. As surface turbulence is acoustically equivalent to running into a brick wa...