Fishfinder Alarms; Frequency Tuning - Raymarine gS Series Installation And Operation Instructions Manual

17.15 Fishfinder alarms

The following Fishfinder alarms can be set when a depth data
source is available.
• Fish — alarm sounds when a target meets the specified
sensitivity level and, is within the depth limits (if enabled).
• Fishfinder Deep — alarm sounds when the detected depth
is greater than the deep limit.
• Fishfinder Shallow — alarm sounds when the detected depth
is less than the shallow limit.
Setting up fish alarms
From the Alarms menu homescreen > Set-up > Alarms:
1. Select Fish.
The Fish alarms menu is displayed.
2. Select Fish so that On is highlighted.
3. Select Fish Sensitivity.
The fish sensitivity numeric adjust control is displayed.
4. Adjust the fish sensitivity to the require value.
The greater the fish alarm sensitivity, the greater the number
of target image depths displayed.
5. Select Fish Depth Limits so that On is highlighted.
The shallow and deep fish limit settings will be activated in
the menu.
6. Select Shallow Fish Limit.
The shallow fish limit numeric adjust control is displayed.
7. Adjust the value to the require setting.
8. Select Ok to confirm the new value and close the numeric
adjust control.
9. Select Deep Fish Limit.
The deep fish limit numeric adjust control is displayed.
10. Adjust the value to the require setting.
11. Select Ok to confirm the new value and close the numeric
adjust control.
Setting up fishfinder deep alarm
From the Alarms menu homescreen > Set-up > Alarms:
1. Select Fishfinder Deep.
2. Select Deep so that On is highlighted.
Selecting Deep will switch between On and Off.
3. Select Deep Limit.
The deep limit numeric adjust control is displayed.
4. Adjust the setting to the required value.
5. Select Ok to confirm the new value and close the numeric
adjust control.
Note: The Deep Limit cannot be set to less than the Shallow
Limit.
Setting up fishfinder shallow alarm
From the Alarms menu homescreen > Set-up > Alarms:
1. Select Fishfinder Shallow.
2. Select Shallow so that On is highlighted.
Selecting Shallow will switch between On and Off.
3. Select Shallow Limit.
The shallow limit numeric adjust control is displayed.
4. Adjust the setting to the required value.
5. Select Ok to confirm the new value and close the numeric
adjust control.
Note: The Shallow Limit cannot be set to greater than the
Deep Limit.
Fishfinder application

17.16 Frequency tuning

The frequency is dependent on the sonar module and transducer
in use. When using a non-CHIRP sonar module or a CHIRP
sonar module that is operating in non-CHIRP mode then the
transducer's frequency can be manually fine-tuned.
The advantages of being able to tune the frequency include:
• Optimization for particular species of fish and water conditions.
• Avoiding interference from other sonar operating nearby (at
the same frequency).
• Use of wide or narrow beam on a particular transducer.
Traditional and Legacy frequency tuning
The following frequency types are available on Legacy and
Traditional sonar modules:
• Auto — When operating in automatic no fine-tuning is needed
as the system will set the frequency automatically to suit your
transducer's operating conditions.
• Lower frequencies — (e.g. 50 kHz) — Produces a wide
sonar beam and penetrate the water well. Lower frequencies
provide a lower resolution image that may not be as good at
detecting small fish. Use lower frequencies if you require a
large coverage beneath your vessel or if you are in deep water.
• Medium frequencies — (e.g. 90 kHz) — Produces good
detail at most depths, with moderately wide sonar beam.
• Higher frequencies — (e.g. 200 kHz) — Produces a narrow
beam and produce a high resolution image. They are most
useful in shallower water (up to 1000 ft) and at higher speeds.
The graph below depicts fine-tuning of a Traditional or Legacy
sonar frequency (from –50% to +50%).
1. Tuning range
2. Transducer characteristics
3. Operating frequency
CHIRP frequency tuning
The list below provides details of the frequency types available
when using a CHIRP sonar module.
• Auto — When operating in automatic no fine-tuning is needed
as the system will set the frequency automatically to suit your
transducer's operating conditions.
• Low frequency — non-CHIRP mode (e.g. 50 kHz) —
Produces a wide sonar beam and penetrate the water well.
Lower frequencies provide a lower resolution image that may
not be as good at detecting small fish. Use lower frequencies
if you require a large coverage beneath your vessel or if you
are in deep water.
• Medium frequency — non-CHIRP mode (e.g. 90 kHz) —
Produces good detail at most depths, with moderately wide
sonar beam.
• High frequency — non-CHIRP mode (e.g. 160 kHz) —
Produces a narrow beam and produce a high resolution
image. They are most useful in shallower water (up to 1000 ft)
and at higher speeds.
• Low Chirp — CHIRP mode (e.g. 42 to 65 kHz) — No
fine-tuning is not needed as the CHIRP sonar module will
sweep the transducer's available frequency range in each
ping.
• Med Chirp — CHIRP mode (e.g. 85 to 135 kHz) — No
fine-tuning is not needed as the CHIRP sonar module will
-50% +50%
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