Lowrance electronic X-15A a , If

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

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

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)

PDF compression, OCR, web-optimization with CVISION's PdfCompressor