Furuno CH-500, Руководство оператора

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2. HORIZONTAL MODE
2-10
2.9 How to Choose a Frequency (CH-600 only)
2.9.1 Choosing the frequency
You may choose low frequency or high frequency, with the LF/HF key. The display
shows HI or LO at the top of the screen depending on your selection. Use the table
below to determine which frequency to use.
The dual-frequency display is useful for comparing the picture from one frequency
against the other to overcome deficiencies in both. Use the single-frequency for ob-
jective-specific fishing.
Frequency selection and mode
Single-frequency display or combination display (other than vertical scan com-
bination)
: The LF/HF key chooses low frequency or high frequency alternately.
Dual-frequency display (mix mode OFF) : The LF/HF key switches the frequency of
the high-and low-frequency displays alternately.
Dual-frequency display (mix mode ON) : The LF/HF key changes the frequency of
the left-hand display* (top display in dual-frequency vertical scan display) from low to
high alternately.
* Dual-frequency horizontal display, Dual-frequency horizontal expansion display,
Dual-frequency echo sounder display.
Item Low frequency High frequency
Detection range Longer range comparing with the
high frequency. Attenuation loss
is small on low frequency. Shorter range comparing with the low
frequency. Attenuation loss is great
on high frequency.
Detection depth Deeper than the high frequency.
Bottom echo is prominent be-
cause of wide beam width so fish
echoes are hidden. Shallower than the low frequency.
Bottom echo is less prominent be-
cause of narrow beam width so fish
echoes are easy to find.
Detection range
(detection “leaks”) Detection area is wide (beam
width is wide). Detection area is narrow (beam width
is narrow).
Detection of bottom fish Fish echo and bottom echo over-
lap.
(Wide beam width) Fish echo and bottom echo are dis-
played separately.
(Narrow beam width)
Detection of bait fish Not suited for this purpose.
(Bait fish are not easily detected
with low frequency.) Well suited for this purpose.
(Bait fish are more easily detected
with high frequency.)
Affected by air bubbles
from other vessels Low frequency is easily interfered
by cavitation from other vessels. High frequency is not easily interfered
by cavitation from other vessels.
High frequency
Low frequency