Artemis BP00707, Руководство пользователя

Страница: 45 / 72

45
5.7.5 Troubleshooting Coordinates
Sometimes coordinate values can be provided in ambiguous forms that hides their
format. In such cases think about the rules and range limits for Latitudes and
Longitude to help interpret them, for example…
 54 13 875
Artemis manager would not accept this as the third field is
seconds and so can only accept values up to 60.
It is more likely that a decimal place is missing and the value
should read “54 13.875” indicating a Degrees and decimal
minutes format.
If entered as a Latitude the value will be in the Northern
hemisphere, while a Longitude will specify the Eastern
hemisphere.
 093 42 23.5
This would have to be entered as a Longitude, as Latitude values
cannot exceed ±90°.
Artemis manager will ignore any leading zeroes on any of the
numeric fields.
 4916.45N
 12311.12W
Values in this type of format often come directly from GPS NMEA
serial strings.
Depending on the value type either the first two of three
characters should be interpreted as degrees, followed by two
characters and the decimals as the minutes…
4916.45N represents 49° 16.45’ N and should be entered as “49
16.45 N”.
12311.12W represents -123° 11.12’ E and could be entered as
either “123 11.12 W” or “-123 11.12 E”.
5.7.6 Useful Formula
A value expressed in Degrees, Minutes and Seconds component form can be converted
to Decimal Degrees using the following…
3600 60
S M
D DD
  
A value expressed as Decimal Degrees (DD) can be converted into its component
Degrees (D), Minutes (M) and Seconds (S) using the following equations…
 
 
 
60 mod 3600
60 mod 60
 
 

DD trunc S
DD trunc M
DD trunc D
Additionally the Decimal Minutes (DM) and Decimal Seconds values can be found by…
 
 
60 mod 3600
60 mod 60
 
 
DD DS
DD DM
Where…

DD
represents the absolute value of Decimal Degrees.

 
x trunc
is the truncation function (that removes the fraction part of a value).

mod
is the modulo operator, that finds the remainder of a division.