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Feet,
Fathoms,
Meters
The X-1SA will
display
the
depth
in
feet, fathoms,
or meters. Al-
though
the unit will revert back to
the feet mode whenever
power
is
turned
off,
it is
simple
to
change
to
any
mode
you
wish
by pressing
the 2nd
key
and then 1 for
feet,
2nd
-
2 for
fathoms,
and 2nd
-
3 for meters.
When the unit is in the Feet
mode,
only
one U will be dis-
played.
In the Fathom
mode,
two
I.! U's
will be
displayed.
Three
I.!
I.! U
's will be
displayed
in the
meters mode.
Example: Display
Fathoms
Press: 2nd
-
2
Result:
o
-u
H
---—-—--
—-----
H
lb lb
20
I
--
20
Figure
38
By looking
at the number of
U's,
one can determine the
depth
display
mode that the unit is
in,
i.e., Feet-, Fathoms-,
Meters.
Transmit
Pulse
Width
The noise
suppression system
in the X-15A is a
patented pulse
length
discrimination
suppression
circuit,
and is the same as the one
used on all the Lowrance's vari-
able
suppression
flashers
and
graphs. Basically,
it works on the
principle
that most noise
pulses
are of
relatively
short duration.
If
the receiver circuit can
be ad-
justed
so
that it will
accept
only
long pulses,
then the short
pulses
will be
canelled
out,
and
only
the
desired information
(fish,
bottom,
structure, etc.)
will be
displayed.
Of
course,
the transmitter's
pulse
length
would have to be increased
at the same time so that the re-
turn echoes would be
accepted
by
the receiver.
This is
exactly
what the Low-
rance
suppression system
does.
The
transmitter's
pulse length
is
increased
by
the front
panel
sup-
pression control,
and
the receiver
"tracks" the amount of increased
pulse
length, cancelling
out
any
narrow noise
pulses,
and
display-
ing only
the return echoes from
fish or the
bottom,
etc.
(Note:
Re-
ceiver
sensitivity
is not diminished
at all
by
this
process.)
The
only disadvantage
to this
system
is
resolution,
or the
ability
to
separate targets,
is
diminished
when the
pulse length
is in-
creased.
A
200
s (micro-second)
transmitter
pulse length
used on
the X-15A when
power
is first
turned
on,
will allow the unit to
display
two fish or
targets
that are
only
6 inches
apart.
In other
words,
if two fish that are 6 inches
apart
are
displayed
on the
graph
paper, they
will show
up
as two
separate
arches when the trans-
mitter is
operating
with a 200
ps
pulse length.
Now,
if we increase
the transmitter's
pulse length
to
400
jis, (by rotating
the
Suppres-
sor control
clockwise)
those same
two fish arches will blend
together
and show
up
as one fish or
pos-
sibly
even a "blob" on the
paper.
With a 400
ps
transmit
pulse
width,
those same two fish will
have to be at least 12 inches
apart
before
they
will show
up
as
two
separate
arches on the
graph.
This is
why
it is
important
to leave
the section entitled "Advanced
Op-
eration". This
chapter
will describe
several other features that will en-
able the serious
operator
to
get
the maximum benefit from this
equipment.
We
urge you
to read this man-
ual
thoroughly
and familiarize
yourself
with the
controls.
Al-
though
this is a
very
advanced
unit,
it is
easy
to
use,
thanks to
the
power
of the
micro-computer
and the front
panel
controls.
Should
you require
extra
help,
or
just
have a
question, please
call
our Customer Service
Department
toll
free 1-800-331-3889.
(Okla-
homa residents call collect
-
1-918-437-6881.)
Or check the en-
closed list for a service center in
your
area.
A
representative
will be
happy
to
help
you.
II INSTALLATION
Mounting
—
The
depth
sounder
may
be in-
stalled in
any
convenient
area,
provided
the unit can
be tilted for
the best
viewing
angle.
Holes in
the bracket base allow
wood
screw or
bolt
mounting.
A wood
stiffener
may
be
required
on the
back of
thin
fiberglass panels
to
support
the unit.
If the desired
location is closer
than
18" to a
magnetic compass,
a trial run should
be made with
the
unit in
operation
to be sure
that the
compass readings
are
not affected.
Power Connections
—
Twelve volt DC
power
for the
depth
sounder should
be
supplied
by
the boat's 12 volt electrical
sys-
tem. The
power
cable
may
be at-
tached to an
accessory
or
power
buss,
but if
you
have
problems
with electrical
interference,
the
cable should be attached
directly
to the
battery.
If a
longer
cable is
required,
use
ordinary
#18
lamp
cord available
at
any
hardware or electrical
sup-
ply
store.
Splices
should be sol-
dered,
however,
if this isn't
done,
then use
crimp-type splices. Tape
all
splices
with electrical
tape.
An
in-line fuse holder with
fuse
is
supplied
with the X-15A. Be cer-
tain to install this as close to the
power
source
(such
as the boat
battery
or
power buss)
as
pos-
sible. This will
protect
both the
sonar unit and the
power
cable
in
the event a short occurs.
Crimp
connectors are
supplied
to attach
the fuse holder to the
power
cable. The red wire in the
power
cable is the
positive
conductor.
The black wire is the
ground
or
negative
conductor.
The
graph
is
protected
from
ac-
cidental
polarity
reversals and no
damage
will occur if the
wires are
reversed. The unit
will not
operate
until the
proper polarity
is
applied.
9
—-— --——--.--—-—
8
2
-
2
Figure
2
18
3
Ground
(Negative)
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