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1.
INTRODUCTION
The
Lowrance X-1SB is a
highly
sophisticated
recording depth
sounder. Thanks to a
micro-com-
puter,
the
X-l5Bcan
do more than
any
other sonar unit
in its
price
range
plus many
that
cost much
more.
Thanks to a
waterproof
key-
board,
full control of
the
system
is
at
your
fingertips
to meet the
changing
demands of
varying
bot-
tom
conditions,
water
depth,
and
boat
speed.
You can
select the
unit's
sensitivity,
suppression level,
upper
and
lower
depth
range, pa-
per
speed, GRAYLINE,
and
many
more features.
The
patented
Lowrance
variable
suppression
system
combined with
the new
Discrimination
feature
not
only
fil-
ters out false
signals
without dis-
torting
the real
ones,
but is
synchronized
with
the GRAYLINE
function to
provide
clear
signals
under all
conditions.
2.
HOW IT
WORKS
When the
Unit is turned
on,
an
electronically regulated
motor
drives
a
lightweight
belt
located at
the
right
edge
of the
recording pa-
per.
The
stylus
is
éttached to
this
belt:
When
the
stylus
is
at the
top
of the
paper
a small
mark is
made.
This is called
the zero
mark,
and
represents
the surface
of the
water. The
stylus
continues
to move
down the
edge
of
the
paper
while the sound
pulse
is
traveling
through
the
water,
and
when an echo is
detected,
the
sty-
lus
makes
another mark on the
paper.
The
depth
of the
object
which reflected the
echO can be
read in feet
by
comparing
its loca-
tion on the
paper
to the
depth
scale
printed
on the
paper.
The
paper speed
is controlled
by
a
variable
speed
motor.
During
one revolution of
the
stylus
belt,
a
very
narrow mark will
be made
by
the
flexible
stylus,
but the
paper
will move a small
amount before
the
next revolution.
Each mark will
blend into the
one before so that a
composite
"picture"
of the
target
will
be
made,
one
tiny
mark at
a
time.
Due to
the
many
features
that
this unit
has,
this manual
has the
operation
section
split
into
two
parts.
The first
section is entitled
"Basic
Operation"
and covers
everything
that is
absolutely
necessary
to use
the X-15B in a
wide
variety
of
situations. It will
tell
you
how to use
the basic controls
-
Sensitivity,
Suppression, Paper
Speed, GRAYLINE,
Range, plus
a
few
special
functions. This
section
will be
adequate
for
most situa-
tions.
However,
once
you
have
mastered
the basic
operation
of
the
X-15B,
you may
wish to
try
some of
the
features
described in
the
Suppressor
control turned
down to minimum
when
looking
for fish.
However,
it is
helpful sometimes
to
have
longer pulse
width when
resolution is not a
concern. When
using
a
sonar in
deeper water,
it is
easier for
the unit to
detect a
long-
er
pulse coming
back
from the
bottom or from
fish. This is called
"Probability
of Echo
Detection".
The
probability
of the unit
being
able to
detect an echo
returning
from
deep
water is diminished
be-
cause
the further the
sound
pulse
has to
travel,
the weaker it
be-
comes.
By
broadening
the
pulse
length,
in
essence,
a
larger signal
is
tranmitted and
it is easier for
the
repeiver to detect
it.
For this
reason,
the
micro-com-
puter
in the X-15B
automatically
increases the initial
pulse length
of
the unit
as
deeper
lower limits are
set
by
the
operator. (Note:
Initial
pulse
length
is the
pulse
length
of
the unit
when the
Suppressor
con-
trol is
turned to
minimum.)
INITIAL
TRANSMIT
PULSE
WIDTH
(micro-seconds)
110
20
•130
30
160.
40-200
200
From 210 feet to 600
feet,
the
initial
pulse length
increases at the
same rate as the
depth.
For ex-
ample,
with the
LOWER LIMIT set
to
260
feet,
the initial
transmit
pulse
length
ouId be
26Oxs.
If
the
LQWER LIMIT is
set to 390
feet,
the initial
transmit
pulse
would
be 390
Finally,
from
600 feet
and
below,
the initial
pulse
length
remains at 600
micro-seconds.
The
transmit
pulse
length
can
be increased
from the
initial
point
at
any
time
by
rotating
the
Sup-
pressor control
clockwise. The
maximum
amount of
pulse
length
added
to the
initial
transmitter
pulse
length
is
approximately
aoo
micro-seconds. In other
words,
if
the
LOWER
LIMIT is set to
420
feet, and the
Suppressor control is
rotated
to the
maximum
position,
the
transmitter
pulse
length
would
be
1220
micro-seconds.
(420
initial +
800
=
1220.)
Earlier,
we talked
about the rela-
tionship
between
pulse length
and
target separation.
As
pulse
length
increases,
target
separaflon
or
resolution is
degraded.
However,
if
the
pulse
width is
decreased,
res-
olution
becomes much
better.
The
X-159
allows
you
to
take
advantage
of this
fact
by
making
it
possible
to
override the initial
transmitter
pulse
length setting
from
what the
micro-computer
selects
according
to the Lower
Limit.
The
initial
transmitter
pulse
length
can be
set from
30
ts
to
2000
p.s by
entering
it on
the
key-
board.
By
setting
the
initial trans-
mitter
pulse
width to
100
p.5,
a
three inch
resolution is
obtained,
50
p.s
is
equivalent
to an inch
and
a
half,
and 30
p.s
initial
transmit
pulse
length
is
equal
to
one inch
resolution!
No other
graph
re-
corder in the
market
today
can
give you
this
feature.
After
setting
the
initia( transmitter
pulse
length,
the
suppressor
control can
still be
used
to cancel
out noise
by
in-
creasing
the
pulse length
or
the
Discrimination
function
described
below can be
used to
eliminate
noise
and still have
good
Figure
1
LOWER
LIMIT
(feet)
10
-
r—
.--•
_—
PULLEY
TI]
1 DRIVE
L:
+-1STYLUS
• i
DRIVE
BELT
STYLUS
GRAPH
PAPER
PAPER
TRAVEL
-4-—PuLLEV
2
19
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