Echosounder Operation - Simrad CE33 ChartSounder Manual

CE33 Echosounder operation

7. Echosounder operation

The echosounder function of the CE33 determines the distance
between its transducer and underwater objects such as fish, lake
bottom or sea bed. It does this by utilizing the fact that an ultrasonic
wave transmitted through water travels at a nearly constant speed
of 4800 feet (1500 meters) per second. When a sound wave strikes
an underwater object such as fish or sea bottom, part of the sound
wave is reflected back toward the source. Thus by calculating the
time difference between the transmission of a sound wave and the
reception of the reflected sound wave, the depth to the object can be
determined.
The entire process begins in the display unit. Transmitter power is
sent to the transducer as a short pulse of electrical energy. The elec-
trical signal produced by the transmitter is converted into an ultra-
sonic signal by the transducer and transmitted into the water. Any
reflected signals from intervening objects (such as a fish school)
are received by the transducer and converted back into an electri-
cal signal. It is then amplified in the amplifier section, and finally,
displayed on the screen.
The picture displayed is made up of a series of vertical scan lines
(pings), one for each transmission. Each line represents a 'snapshot'
of what has occurred beneath the boat. The series of snapshots are
accumulated side by side across the screen, and the resulting con-
tours of the bottom and fish between the bottom and surface are
displayed.
Selecting echosounder displays
The CE33 provides various types of echosounder displays: standard
echogram, A-scope, bottom expansion (zoom) and VRM expan-
sion. Each display has its special advantages. Select the appropriate
setup for the echosounder display in the presentation "Setup" and
"Echosounder setup" displays, considering current sea area and
target fish.
Chapter 7-1