Changing The Frequency Of Echoes - NorthStar 972 Quickstart Manual And Reference Manual

Changing the frequency of echoes

Reference section 7 — Echo sounding
108

Changing the frequency of echoes

The sounder uses two transducer frequen-
cies: 50 kHz and 200 kHz. The advantages
and disadvantages of each frequency are
shown below.
Table 2: 50 kHz vs. 200 kHz
50 kHz
Longer wavelength goes Shorter wavelength
deeper, but with provides a sharper
somewhat lower picture, but can't go as
resolution. deep.
Less resolution is better Finer resolution is better
at finding big fish, but may at finding small fish
miss the bait fish. (baitfish) and subtle
bottom details.
Wider beam is good for Narrower beam is very
seeing fish not directly focused. Reduces the
beneath the boat. influence of a rough sea.
You can choose from four settings for the
transducer frequency:
50 kHz displayed on a full screen
•
200 kHz displayed on a full screen
•
50 kHz on the left half of the screen,
•
and 200 on the right
200 kHz on the left half of the screen,
•
and 50 on the right
200 kHz
There are two reasons why you might want
to operate with your preferred frequency
on the right side of the screen:
the zoom function magnifies the
•
frequency on the right side
when adjusting the picture, you can see
•
the effect of changes on the right side
To choose the transducer frequency, press
Frequency until the desired combination is
shown.
When you change the frequency, echoes
already on the screen don't change, they
just move off the screen as they are
replaced by echoes at the new frequency.
50 and 200kHz displayed
Northstar 972