4-2 Single and Dual frequency fishfinding
When to use 200 kHz
The 200 kHz frequency is especially suitable for use in shallow and medium depth water, typically less than 500 ft. (150 m) and while running at speed.
At 200 kHz, the narrow cone reduces any noise caused by air bubbles.
The 200 kHz frequency generates a higher definition pulse which produces little shadow and returns excellent detail over a small area of bottom. Therefore, it gives excellent bottom discrimination capability and is particularly good at showing indi- vidual fish, including bottom dwellers.
When to use 50 kHz
The 50 kHz frequency is particularly suitable for use in deep water, typically greater than 500 ft. (150 m).
When to use 50/200 kHz
Operating the FISH 4500/4600 at both 50 kHz and 200 kHz simultaneously on a split display can be very useful when operating in shallow to medium water, typically less than 500 ft. (150 m), because the 50 kHz section of the display shows the general area, while the 200 kHz section can be viewed simultaneously for a more detailed look at any interesting feature.
Mixed frequency
The Mixed frequency combines the 200 kHz and the 50 kHz echoes on one sonar display, filling in detailed echoes in the centre of the sonar cone.
Mixed frequency
At 50 kHz, the cone covers an area of water about four times wider than the 200 kHz cone and penetrates to a greater depth with minimal loss of the return signal.
However, it produces a lower definition display with more shadow compared to the 200 kHz frequency. This means that a group of small fish, for example, could be displayed as a single item, while any fish very close to the bottom may not be found at all.
This frequency is useful for getting a deep, wide overview of the area so that any areas of interest can be identified and then examined in detail with the 200 kHz frequency.
Wide angle, less detailed 50 kHz cone
Narrow angle, more detailed 200 kHz cone
FISH 4500/4600 Installation and Operation Manual | NAVMAN | 17 |
