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MARNAV
C & E ASSOCIATES
119 PLACID DRIVE
FORT MYERS, FLA.
33919
MARNAV 1.0 DOCUMENTATION
SECTION I
INTRODUCTION
There is an increasing need for software which will convert
Latitude/Longitude data to LORAN-C delay coordinates and
vice-versa for the purpose of adding LORAN-C data to the many
charts and maps, both land and marine which are published with-
out this information. In addition to the LORAN-Geographic
conversion, MARNAV also provides a means of calculating all
delays for a given geographic location thus allowing a shift to
another slave in the event of technical difficulty or as a means
of double checking a position.
All LORAN-C Chains for which data is currently available
have been included in MARNAV. The chain data used is based on
information from the UNITED STATES COAST GUARD, Department of
Transportation as published in COMDTINST-M16562.3 (Old CG-462).
The following constants were used for all algorithms in the
MARNAV Program. Signal propagation velocity used is the velocity
of light in free space 299,792,458 meters/sec.., sea water con-
ductivity 5.0 mhos/meter, 0.01745329251993889 radians/degree.
All calculations and data in double precision. Calculations nec-
essarily assume an all water path.
In addition to LORAN-C Geographic conversions, MARNAV also
provides the ability to navigation from one pair of LORAN-C
delays to another pair within the same chain. In cruise
planning, waypoint data is generally listed during the planning
stage and since these data are already available it is conve-
nient to use them for calculating heading and distance
information. In addition it is also possible to calculate head-
ing and distance information from Latitude/Longitude data over a
rhumb line course. These programs do not parallel programs
available within typical LORAN-C units available today since
those computer navigation features calculate from measured
delays at present position.
Since the Navigation solutions are available it only seemed
logical to include a Time/Speed/Distance function. The simplest
data entry scheme appeared to be the query for each entry with a
calculated result for the one not entered.
MARNAV Documentation Page- 2
MARNAV has a data base of thirteen files, one for each of the
thirteen chains world wide. The Shareware version is distributed
with only one of these, the Great Lakes Chain (GRI 8970) which
will let you try all of the programs features. In addition to
these data files, one file is maintained to indicate the Active
Chain (The chain you are currently using). When you first bring
up MARNAV, it will read this active chain file and then the data
for the indicated chain. It is necessary that the program and
all of the data files be kept in the same directory since the
program looks for its data files in whatever directory you were
in when you first brought up the program!
The first screen gives the title and copyright data as well as a
message indicating what Active GRI data has been loaded. At the
bottom of the screen is the main menu. You will be able to
return to this menu from virtually anywhere in the program by
pressing the <HOME> key. In some cases you may also use the <M>
key as indicated on the screen at that time. Each of the menu
selections will be discussed below. Use the arrow keys to move
around the menu selections. When the blinking cursor is at the
end of any menu selection, the <RETURN> key will select that
menu choice.
Section II
LORAN >> LAT/LON-
As the menu suggests, when you make this choice, the program
will convert Loran delay data to Latitude/Longitude position.
You may enter delay data for any two secondaries. The program
will not only calculate and report your Latitude/Longitude posi-
tion but will also calculate the remaining secondary delays for
that position. This may at times be very useful since secondar-
ies do fail and it may be necessary to choose another.
A number of comments are in order at this point. Since Loran
positioning depends on the intersection of two Hyperbolic delay
lines, there are two valid intersections with the same delays.
These are usually far enough apart so they do not confuse the
user but the computer does not know which one you are interested
in and so may well calculate the other position. To avoid this,
it is necessary to provide the computer with an approximate
latitude and longitude position. Generally anything within a few
hundred miles is close enough. (2 to 3 degrees) Those are the
numbers appearing at the top right of this screen. They may be
changed by pressing <END> in the conversion routines or by using
the utilities and that will be discussed in a later section.
Notice that the Latitude/Longitude data is printed in three
formats: Degrees and decimal Degrees; Degrees, Minutes and deci-
mal Minutes; Degrees, Minutes, Seconds and decimal Seconds. This
is done since different charts and maps have grids given in any
one of these three formats depending on the scale.
MARNAV Documentation Page- 3
In normal geographic position data, West Longitude and South
Latitude are negative values. In order to avoid the inconve-
nience of worrying about the sign of these numbers, the quadrant
data near the top center of the screen defines the quadrants
which are defined with positive values. For example, the United
States is in the North latitude quadrant and the West Longitude
quadrant. Consequently, these Lat/Lon numbers are given as posi-
tive values. The quadrants selected may also be changed in the
same way as are the approximate latitude and longitude by press-
ing the <END> key in the conversion routines.
If the entered delays are unrealistically far from the Approxi-
mate Lat/Lon entries you will get a message:
NO USEFUL SOLUTION-CHECK INPUT DATA".
Press any key to
return to the Main Menu.
We will defer discussion of the "INCLUDED CORRECTION" column
until the Utilities are discussed in a later section.
Section III
LAT/LON >> LORAN
This menu choice lets you convert Lat/Lon data to Loran delays.
The Quadrant data and the Approximate Lat/Lon have already been
discussed in the previous section. Also discussed in that sec-
tion were the three formats used for Lat/Lon data output. Data
may also be input in any of these three formats and the compute
will calculate the remaining two forms. This is a useful feature
if you need to convert from one format to another when using
different scale charts.
If you enter data as follows:
42.62 it will be accepted as format 1
Format 2 may be entered in any of these ways:
43/45.2 or 43:45.2 or 43,45.2 or 43 45.2
It does not matter if you type a , or a / or a space or a colon
as the delimiter, on the screen each of these forms would appear
as 43/45.2.
Format 3 allows the same delimiters and the data might be
entered as follows:
43/50/34.6 or 43:50:34.6 or 43,50,34.6 or 43 50 34.6
As before, no matter how you enter it, on the screen it will
look like the first example 43/50/34.6.
Once the Lat/Lon data is entered the Approximate Lat/Lon data is
temporarily changed to conform and the calculation is completed
for all of the secondaries in the chain.
MARNAV Documentation Page- 4
CAUTION! JUST BECAUSE THE COMPUTER TELLS YOU WHAT THE DELAY FOR
THAT POSITION WILL BE, IT MAY BE THAT YOU ARE SO FAR FROM A SEC-
ONDARY STATION THAT YOU MAY NOT BE ABLE TO RECEIVE IT!
As mentioned in the previous section, the INCLUDED CORRECTION
column will be discussed later.
Section IV
BEARING/DISTANCE
The Bearing/Distance option will calculate the heading from
point A to point B, it will give the distance in Nautical miles
and the reciprocal heading. (The heading from B to A). The
points may be specified in either Lat/Lon or Loran delays. One
may defined in one way while the second is defined in the other.
If, when the cursor is at the LOP1 (Delay 1 or Line of Position
1), you press the <ENTER> key the program assumes you will
specify the position in Lat/Lon coordinates. The cursor is then
positioned on the ENTER LATITUDE line.
If you enter either position in Loran delays the Lat/Lon posi-
tion is calculated; If, however, you enter the position in
Lat/Lon coordinates, the Loran delays will not be calculated.
This section should require no further discussion.
Section V
SPEED/TIME/DISTANCE
Little comment is required for this choice. The computer
calculates the relationship between these three variables. Enter
any two and it will calculate the third. Simply press <ENTER>
for the one you want the solution for. If the distance is in
Nautical miles, the speed given will be knots, or conversely if
speed is entered in knots, calculated distance will be in nauti-
cal miles. IF speed is miles per hour distance will be statute
miles.
If time is being calculated, the result is given in both Hours
and decimal hours as well as hours and minutes. If time is being
entered the same formats as discussed in Section III for degrees
and minutes, etc. hold for time, which may be entered in hours,
minutes and seconds using the same delimiters of "/" "," ":"
or space.
Section VI
GRI UTILITIES
The GRI Utilities allow you to enter data for a new Loran Chain,
let you edit all of the data for Loran Chains you already have
in files, provide an additional way to change the Initial GRI
(The GRI which comes up when you load the program), let you add
correction factors for each secondary and will print the data
file for any Loran Chain.
MARNAV Documentation Page- 5
When you select the EDIT option you have the choice of editing
the data currently in memory, reading a new GRI file for edit or
starting over to enter a new Loran Chain. Editing is straight
forward. You can move around the data screen using the arrow
keys. If you press the <ENTER> key the program accepts the entry
as it appears on the screen. To edit a data entry, the entire
entry must be retyped. When you have finished correcting the
data field, press <END> to return to the menu bar. If you are
satisfied with the field as it exists, move the cursor to WRITE
FILE-, press <ENTER> and the data will be written to disk.
If you selected the CHANGE GRI- option from the EDIT menu the
new data will replace the data you have been using. You can now
exit Edit and work in the new GRI or, you may want to edit that
data and write it to the files. If, at that time you want to
change back to the GRI you had previously, you will have to use
the CHANGE GRI- option again and call for the desired Chain.
If you are entering data for a new Loran Chain, latitude and
longitude data must be entered in the degree and decimal degree
mode only. Double check all of your entries carefully because an
error here produces erroneous output. When all the data has been
entered, write the data to disk using the WRITE FILE- option.
When you want to change the Initial GRI, select that option from
the Utilities menu bar. The cursor will move to the upper left
portion of the screen. You then enter the new GRI designation,
along with the Latitude and Longitude quadrants you will be
working in. (See Section II). When you press <ENTER> after the
longitude quadrant selection, the new GRI file will be read.
After that whenever you start the program, the data for the Ini-
tial GRI will be loaded automatically.
SECTION VII
CORRECTION FACTOR
Loran calculations and their accuracy depend on the propagation
velocity of radio waves. Unfortunately the propagation velocity
is not the same over all types of terrain so the delay time to a
given point may be slightly different than it is to another
point whose distance from the secondary station is exactly the
same. While the errors incurred are not large, they can lead to
position errors of one quarter to one third of a mile.
If you get the exact geographic location of some fixed object
such as a bridge, a building or a point of land you can calcu-
late the theoretical Loran delays for that point. If you now
measure the actual delays to that point using a Loran, the dif-
ference between the calculated delays and the measured delays
can be entered as correction factors.
MARNAV Documentation Page- 6
These correction factors will be approximately correct for all
Loran data in the general area where they were determined. These
correction factors will have a negative value because the propa-
gation velocity of radio waves is decreased by surface
anomalies. These correction factors may be entered for each sec-
ondary using the editor in the GRI UTILITIES mode. It is this
propagation velocity problem that results in the Absolute Posi-
tion Error in Lorans even though Repeatable Accuracy may be as
little as 50 feet. The correction factors help to resolve this
difficulty when precise positioning is important.
Do not use the chart position of markers or bouys from marine
charts since their geographic position is often significantly
different from their position on the chart. Land based points
whose position is determined by surveys are more suitable for
calculating correction factors.
Section VIII
HARD COPY-OFF or ON
It is often convenient to have a hard copy of your conversions
or, more often, the calculations of heading and distance. This
is especially true when you are planning a boat cruise since you
can plan your entire trip in the comfort of your home or office
and have a printout of the results. The HARD COPY OFF/ON option
of the main menu toggles the printer on and off whenever the
cursor is positioned at this choice and you press <ENTER>. After
each of your conversions or calculations, the results are auto-
matically printed.
MARNAV Documentation Page- 7
PROGRAM REGISTRATION
The distribution of MARNAV.EXE by shareware vendors and other
distributors of user supported software is hereby authorized.
MARNAV.EXE is copyrighted software and is not placed in the
public domain but rather is entered in the Shareware market so
that potential users may insure that it meets their needs.
The registration fee for the program is a only $35.00. Reg-
istered users will automatically receive software support and
notice of any program enhancements. Any future new versions will
be made available to registered users for a nominal fee.
PLEASE SHOW YOUR SUPPORT FOR THE SHAREWARE CONCEPT BY SUBMITTING
THE REGISTRATION FEE. WE ENCOURAGE YOU TO SHARE COPIES OF THIS
SOFTWARE PLUS THE DOCUMENTATION FILE WITH OTHERS WHO MIGHT FIND
IT USEFUL.
______________________________________________________________
Registration Form
MARNAV.EXE
Name ____________________________________________
Street __________________________________________
City/State ______________________________________
Please enclose the $35.00 registration fee and mail to:
C & E Associates
119 Placid Drive
Fort Myers, FL
33919
Thank you for you support,
Ed Panner
MARNAV
C & E ASSOCIATES
119 PLACID DRIVE
FORT MYERS, FLA.
33919
MARNAV 1.0 DOCUMENTATION
SECTION I
INTRODUCTION
There is an increasing need for software which will convert
Latitude/Longitude data to LORAN-C delay coordinates and
vice-versa for the purpose of adding LORAN-C data to the many
charts and maps, both land and marine which are published with-
out this information. In addition to the LORAN-Geographic
conversion, MARNAV also provides a means of calculating all
delays for a given geographic location thus allowing a shift to
another slave in the event of technical difficulty or as a means
of double checking a position.
All LORAN-C Chains for which data is currently available
have been included in MARNAV. The chain data used is based on
information from the UNITED STATES COAST GUARD, Department of
Transportation as published in COMDTINST-M16562.3 (Old CG-462).
The following constants were used for all algorithms in the
MARNAV Program. Signal propagation velocity used is the velocity
of light in free space 299,792,458 meters/sec.., sea water con-
ductivity 5.0 mhos/meter, 0.01745329251993889 radians/degree.
All calculations and data in double precision. Calculations nec-
essarily assume an all water path.
In addition to LORAN-C Geographic conversions, MARNAV also
provides the ability to navigate from one pair of LORAN-C delays
to another pair within the same chain. In cruise planning,
waypoint data is generally listed during the planning stage and
since these data are already available it is convenient to use
them for calculating heading and distance information. In addi-
tion it is also possible to calculate heading and distance
information from Latitude/Longitude data over a rhumb line
course. These programs do not parallel programs available within
typical LORAN-C units available today since those computer navi-
gation features calculate from measured delays at present
position.
Since the Navigation solutions are available it only seemed
logical to include a Time/Speed/Distance function. The simplest
data entry scheme appeared to be the query for each entry with a
calculated result for the one not entered.
MARNAV Documentation Page- 2
MARNAV has a data base of thirteen files, one for each of the
thirteen chains world wide. The Shareware version is distributed
with only one of these, the Great Lakes Chain (GRI 8970) which
will let you try all of the programs features. In addition to
these data files, one file is maintained to indicate the Active
Chain (The chain you are currently using). When you first bring
up MARNAV, it will read this active chain file and then the data
for the indicated chain. It is necessary that the program and
all of the data files be kept in the same directory since the
program looks for its data files in whatever directory you were
in when you first brought up the program!
The first screen gives the title and copyright data as well as a
message indicating what Active GRI data has been loaded. At the
bottom of the screen is the main menu. You will be able to
return to this menu from virtually anywhere in the program by
pressing the <HOME> key. In some cases you may also use the <M>
key as indicated on the screen at that time. Each of the menu
selections will be discussed below. Use the arrow keys to move
around the menu selections. When the blinking cursor is at the
end of any menu selection, the <RETURN> key will select that
menu choice.
Section II
LORAN >> LAT/LON-
As the menu suggests, when you make this choice, the program
will convert Loran delay data to Latitude/Longitude position.
You may enter delay data for any two secondaries. The program
will not only calculate and report your Latitude/Longitude posi-
tion but will also calculate the remaining secondary delays for
that position. This may at times be very useful since secondar-
ies do fail and it may be necessary to choose another.
A number of comments are in order at this point. Since Loran
positioning depends on the intersection of two Hyperbolic delay
lines, there are two valid intersections with the same delays.
These are usually far enough apart so they do not confuse the
user but the computer does not know which one you are interested
in and so may well calculate the other position. To avoid this,
it is necessary to provide the computer with an approximate
latitude and longitude position. Generally anything within a few
hundred miles is close enough. (2 to 3 degrees) Those are the
numbers appearing at the top right of this screen. The Active
GRI and these numbers may be changed by pressing <END> in the
conversion routines, from the master menu or by using the utili-
ties and that will be discussed in a later section.
Notice that the Latitude/Longitude data is printed in three
formats: Degrees and decimal Degrees; Degrees, Minutes and deci-
mal Minutes; Degrees, Minutes, Seconds and decimal Seconds. This
is done since different charts and maps have grids given in any
one of these three formats depending on the scale.
MARNAV Documentation Page- 3
In normal geographic position data, West Longitude and South
Latitude are negative values. In order to avoid the inconve-
nience of worrying about the sign of these numbers, the quadrant
data near the top center of the screen defines the quadrants
which are defined with positive values. For example, the United
States is in the North latitude quadrant and the West Longitude
quadrant. Consequently, these Lat/Lon numbers are given as posi-
tive values. The quadrants selected may also be changed in the
same way as are the approximate latitude and longitude by press-
ing the <END> key in the conversion routines.
If the entered delays are unrealistically far from the Approxi-
mate Lat/Lon entries you will get a message:
NO USEFUL SOLUTION-CHECK INPUT DATA".
Press any key to
return to the Main Menu.
We will defer discussion of the "INCLUDED CORRECTION" column
until the Utilities are discussed in a later section.
Section III
LAT/LON >> LORAN
This menu choice lets you convert Lat/Lon data to Loran delays.
The Quadrant data and the Approximate Lat/Lon have already been
discussed in the previous section. Also discussed in that sec-
tion were the three formats used for Lat/Lon data output. Data
may also be input in any of these three formats and the compute
will calculate the remaining two forms. This is a useful feature
if you need to convert from one format to another when using
different scale charts.
If you enter data as follows:
42.62 it will be accepted as format 1
Format 2 may be entered in any of these ways:
43/45.2 or 43:45.2 or 43,45.2 or 43 45.2
It does not matter if you type a , or a / or a space or a colon
as the delimiter, on the screen each of these forms would appear
as 43/45.2.
Format 3 allows the same delimiters and the data might be
entered as follows:
43/50/34.6 or 43:50:34.6 or 43,50,34.6 or 43 50 34.6
As before, no matter how you enter it, on the screen it will
look like the first example 43/50/34.6.
Once the Lat/Lon data is entered the Approximate Lat/Lon data is
temporarily changed to conform and the calculation is completed
for all of the secondaries in the chain.
MARNAV Documentation Page- 4
CAUTION! JUST BECAUSE THE COMPUTER TELLS YOU WHAT THE DELAY FOR
THAT POSITION WILL BE, IT MAY BE THAT YOU ARE SO FAR FROM A SEC-
ONDARY STATION THAT YOU MAY NOT BE ABLE TO RECEIVE IT!
As mentioned in the previous section, the INCLUDED CORRECTION
column will be discussed later.
Section IV
BEARING/DISTANCE
The Bearing/Distance option will calculate the heading from
point A to point B, it will give the distance in Nautical miles
and the reciprocal heading. (The heading from B to A). The
points may be specified in either Lat/Lon or Loran delays. One
may defined in one way while the second is defined in the other.
If, when the cursor is at the LOP1 (Delay 1 or Line of Position
1), you press the <ENTER> key the program assumes you will
specify the position in Lat/Lon coordinates. The cursor is then
positioned on the ENTER LATITUDE line.
If you enter either position in Loran delays the Lat/Lon posi-
tion is calculated; If, however, you enter the position in
Lat/Lon coordinates, the Loran delays will not be calculated.
This section should require no further discussion.
Section V
SPEED/TIME/DISTANCE
Little comment is required for this choice. The computer
calculates the relationship between these three variables. Enter
any two and it will calculate the third. Simply press <ENTER>
for the one you want the solution for. If the distance is in
Nautical miles, the speed given will be knots, or conversely if
speed is entered in knots, calculated distance will be in nauti-
cal miles. IF speed is miles per hour distance will be statute
miles.
If time is being calculated, the result is given in both Hours
and decimal hours as well as hours and minutes. If time is being
entered the same formats as discussed in Section III for degrees
and minutes, etc. hold for time, which may be entered in hours,
minutes and seconds using the same delimiters of "/" "," ":"
or space.
Section VI
GRI UTILITIES
The GRI Utilities allow you to enter data for a new Loran Chain,
let you edit all of the data for Loran Chains you already have
in files, provide an additional way to change the Initial GRI
(The GRI which comes up when you load the program), let you add
correction factors for each secondary and will print the data
file for any Loran Chain.
MARNAV Documentation Page- 5
When you select the EDIT option you have the choice of editing
the data currently in memory, reading a new GRI file for edit or
starting over to enter a new Loran Chain. Editing is straight
forward. You can move around the data screen using the arrow
keys. If you press the <ENTER> key the program accepts the entry
as it appears on the screen. To edit a data entry, the entire
entry must be retyped. When you have finished correcting the
data field, press <END> to return to the menu bar. If you are
satisfied with the field as it exists, you must move the cursor
to WRITE FILE-, press <ENTER> and the data will be written to
disk.
If you selected the CHANGE GRI- option from the EDIT menu the
new data will replace the data you have been using so you can
edit that data and write it to the files. When you exit the EDIT
routines, the computer will automatically load the Initial GRI
file.
If you are entering data for a new Loran Chain, latitude and
longitude data must be entered in the degree and decimal degree
mode only. Double check all of your entries carefully because an
error here produces erroneous output. When all the data has been
entered, write the data to disk using the WRITE FILE- option.
When you want to change the Initial GRI, select that option from
the Utilities menu bar. The cursor will move to the upper left
portion of the screen. You then enter the new GRI designation,
along with the Latitude and Longitude quadrants you will be
working in. (See Section II). When you press <ENTER> after the
longitude quadrant selection, the new GRI file will be read.
After that whenever you start the program, the data for the Ini-
tial GRI will be loaded automatically.
SECTION VII
CORRECTION FACTOR
Loran calculations and their accuracy depend on the propagation
velocity of radio waves. Unfortunately the propagation velocity
is not the same over all types of terrain so the delay time to a
given point may be slightly different than it is to another
point whose distance from the secondary station is exactly the
same. While the errors incurred are not large, they can lead to
position errors of one quarter to one third of a mile.
If you get the exact geographic location of some fixed object
such as a bridge, a building or a point of land you can calcu-
late the theoretical Loran delays for that point. If you now
measure the actual delays to that point using a Loran, the dif-
ference between the calculated delays and the measured delays
can be entered as correction factors.
MARNAV Documentation Page- 6
These correction factors will be approximately correct for all
Loran data in the general area where they were determined. These
correction factors will have a negative value because the propa-
gation velocity of radio waves is decreased by surface
anomalies. These correction factors may be entered for each sec-
ondary using the editor in the GRI UTILITIES mode. It is this
propagation velocity problem that results in the Absolute Posi-
tion Error in Lorans even though Repeatable Accuracy may be as
little as 50 feet. The correction factors help to resolve this
difficulty when precise positioning is important.
Do not use the chart position of markers or bouys from marine
charts since their geographic position is often significantly
different from their position on the chart. Land based points
whose position is determined by surveys are more suitable for
calculating correction factors.
Section VIII
HARD COPY-OFF or ON
It is often convenient to have a hard copy of your conversions
or, more often, the calculations of heading and distance. This
is especially true when you are planning a boat cruise since you
can plan your entire trip in the comfort of your home or office
and have a printout of the results. The HARD COPY OFF/ON option
of the main menu toggles the printer on and off whenever the
cursor is positioned at this choice and you press <ENTER>. After
each of your conversions or calculations, the results are auto-
matically printed.
MARNAV Documentation Page- 7
PROGRAM REGISTRATION
The distribution of MARNAV.EXE by shareware vendors and other
distributors of user supported software is hereby authorized.
MARNAV.EXE is copyrighted software and is not placed in the
public domain but rather is entered in the Shareware market so
that potential users may insure that it meets their needs.
The registration fee for the program is a only $35.00. Reg-
istered users will automatically receive software support and
notice of any program enhancements. Any future new versions will
be made available to registered users for a nominal fee.
PLEASE SHOW YOUR SUPPORT FOR THE SHAREWARE CONCEPT BY SUBMITTING
THE REGISTRATION FEE. WE ENCOURAGE YOU TO SHARE COPIES OF THIS
SOFTWARE PLUS THE DOCUMENTATION FILE WITH OTHERS WHO MIGHT FIND
IT USEFUL.
______________________________________________________________
Registration Form
MARNAV.EXE
Name ____________________________________________
Street __________________________________________
City/State ______________________________________
Please enclose the $35.00 registration fee and mail to:
C & E Associates
119 Placid Drive
Fort Myers, FL
33919
Thank you for your support,
Ed Panner
