Eagle ULTRANAVGPS Specifications download pdf (Page 46)

MOW

LORAN-C WORKS ROUTES

The Loran

system

consists of

three to five transmitter stations.

These

are

called a "chain." The letter "M"

designates

the master station

inside the chain. The other

stations in the chain are the secondaries.

Their names

are

W, X, Y,

and

Z, although

not all chains have four

secondary

stations. The

secondary

transmitters are

synchronized

with the

master which transmits at

precise

time intervals. This time

interval

is called the

Group Repetition

Interval or GRI. Each chain has

a

different GRI.

The

secondary

stations transmit at

precise

time

intervals after the

master station

transmits. Since these transmitters are

located hun-

dreds of miles

apart,

it takes a different time for

the

signals

from each

transmitter to reach

you.

The Loran

receiver measures this time

difference between

the master and two of the

secondaries. The

UltraNav

automatically

chooses the best

master-secondary pairs

for

your

location. The time

difference or

(TO)

is

measured in micro-

seconds.

Plotting

the TO on

a chart with Loran-C lines results

with

your

position

somewhere on

a line of

position (LOP).

A line of

posi-

tion

is an

imaginary

line on

which the time

delay

between the master

and one of the secondaries

is the same. In this

example

the

boat is

located somewhere on

the 14605.2 LOP.

The Loran receiver

then measures the

time difference between the

master

and another

secondary.

The

example

on the next

page

is

31882.8. If

you

plot

this LOP on

a

chart,

you'll

notice that it crosses

the first

line-of-position.

Your

position

is at the intersection of the two

lines.

The UltraNav

gives you

the

ability

to

go

to several

waypoints

in

a row.

This feature is called Routes. A

route consists Of two

or more

way-

points.

When

you

run a

route,

the UltraNav

givesyou

navigation

information

to the first

waypoint

in the route. As

you

reach the first

waypoint,

the arrival

alarm

sounds,

then the next

waypoint

is auto-

matically

selected

by

the unit.

Navigation

information is

displayed

for

this

waypoint

until the arrival alarm sounds and

the

process

repeats

for the next

waypoint.

This

happens

until

you've

travelled

to all the

waypoints

in

the route.

There are two

steps necessary

to create a route.

First,

you

must

select the route

number. Then

pick

the

aypoints

to use in

the route.

To follow a

route, you

simply

determine the

starting waypoint,

then

decide whether to follow the

route forward or backward. After these

steps

are

completed,

the UltraNav will start

navigating

on

the route.

Creating

a Route

To create a

route,

first

press

the MENU

key

while the

unit is in the

loran mode. The

menu on the left

appears.

Now

press

the

key adja-

cent to the ROUTES

label. The screen shown

below left

appears.

Next,

press

the

key adjacent

to the "CREATE ROUTE"

label. The

screen shown

below

right appears.

I am] j1i14 NI

athN!Th1 &I1

The

UltraNav has the

capability

to store

twenty

routes. Routes num-

ber one

through

five are

displayed

on

the screen. Press the

key

adjacent

to

the

up

or down label to move the

desired route number

into the

selection box at the

top

of the

screen.

A

ROUTE

1102

ROUTE

U03

ROUTE fl04

ROUTE 1105

—.

—

42

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