583795
121
Zoom out
Zoom in
Previous page
1/134
Next page
111
Appendix I
Understanding Sonar
Understanding Sonar
If you are unfamiliar with basic sonar, or need help determining what is displayed on the graph,
this section may be for you. This section is intended to help the novice user gain some understand-
ing of how the GPSMAP 188/188C/238 Sounder operates and how it can help improve their fi shing
productivity.
To understand what the unit is displaying, it is important to have a general knowledge of how the
unit works and how it determines what to display. Briefl y described, the unit operates by transmit-
ting sound waves toward the bottom of a lake, stream or seabed in a cone shaped pattern. When a
transmitted soundwave strikes an underwater object such as the bottom, a piece of structure, or a fi sh,
sound is refl ected back to the transducer. The transducer collects the refl ected sound waves and sends
the data to the unit to be processed and displayed on the chart. The underwater data is displayed on
the chart in the order that it is returned: fi rst returned—fi rst on the chart. The diagram in the sidebar
demonstrates this showing an underwater scene as it would be displayed on the chart. Generally speak-
ing, if the only thing between the transducer and the bottom is water, the fi rst strong return will come
from the bottom directly below the transducer. The fi rst strong return sets the bottom level. Weaker
secondary returns provide the detailed data. Stronger returns displays in darker colors, black being
the strongest return. In Example 3 (page 113) you can see that the branches and the fi sh where the
strongest secondary returns are indicated in black on the display.
That is brief description of how your GPSMAP 188/188C/238 Sounder operates. Let’s take a look at
how this data can help you to improve your fi shing.
This fi sh is currently in a dead zone and is not detected by
the sonar. The fi sh is in the coverage area of the transducer,
but remember– the fi rst strong return sets the bottom level.
The fi sh will eventually be detected when the fi rst strong
return sets the bottom level below the fi sh.
188188C238 Manual Part 2.indd 111 6/30/2003, 3:32:51 PM
121


Need help? Post your question in this forum.

Forumrules


Report abuse

Libble takes abuse of its services very seriously. We're committed to dealing with such abuse according to the laws in your country of residence. When you submit a report, we'll investigate it and take the appropriate action. We'll get back to you only if we require additional details or have more information to share.

Product:

For example, Anti-Semitic content, racist content, or material that could result in a violent physical act.

For example, a credit card number, a personal identification number, or an unlisted home address. Note that email addresses and full names are not considered private information.

Forumrules

To achieve meaningful questions, we apply the following rules:

Register

Register getting emails for Garmin GPSMAP 188C at:


You will receive an email to register for one or both of the options.


Get your user manual by e-mail

Enter your email address to receive the manual of Garmin GPSMAP 188C in the language / languages: English as an attachment in your email.

The manual is 2,04 mb in size.

 

You will receive the manual in your email within minutes. If you have not received an email, then probably have entered the wrong email address or your mailbox is too full. In addition, it may be that your ISP may have a maximum size for emails to receive.

The manual is sent by email. Check your email

If you have not received an email with the manual within fifteen minutes, it may be that you have a entered a wrong email address or that your ISP has set a maximum size to receive email that is smaller than the size of the manual.

The email address you have provided is not correct.

Please check the email address and correct it.

Your question is posted on this page

Would you like to receive an email when new answers and questions are posted? Please enter your email address.



Info