GLOBALSTAR PROPRIETARY AND CONFIDENTIAL INFORMATION
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document.
06/18/20
Subject to Change without Notice
P a g e | 75
4.6
24-bit location format
The 24-bit format used for latitude and longitude encodes 180 degrees of LATITUDE as a 24-bit (3-byte) signed integer
and 360 degrees of LONGITUDE as a 24-bit (3-byte) signed integer.
4.6.1
CALCULATING LATITUDE
Latitude may be calculated by converting the 3 encoded latitude bytes represented in hexadecimal to a decimal number
and multiplying this decimal integer by the DEGREES_PER_COUNT_LAT conversion factor.
DEGREES_PER_COUNT_LAT
= 90.0 / 2
23
Since the latitude is signed and can range from
–
90 to 90 degrees, if the above result is greater than or equal to 90
degrees, 180 must be subtracted from the result.
Negative Latitude corresponds to Latitude in the SOUTHERN Hemisphere.
Positive Latitude corresponds to Latitude in the NORTHERN Hemisphere.
Latitude Calculation Example:
24-bit latitude:
0x2AB69C (Hexadecimal)
This number converted to decimal (base 10) is: 2,799,260.
2,799,260 * (90.0 / 2
23
) = 30.032802
Since this result is less than 90 degrees, no subtraction is necessary.
30.032802 degrees = 30.032802 degrees NORTH
4.6.2
CALCULATING LONGITUDE
The longitude may be calculated by converting the 3 encoded longitude bytes represented in hexadecimal to a decimal
number. This decimal integer is multiplied by the DEGREES_PER_COUNT_LONG conversion factor.
DEGREES_PER_COUNT_LONG
= 180.0 / 2
23
If the above result is greater than or equal to 180 degrees, 360 must be subtracted from the result since the longitude is
signed and can range from
–
180 to 180 degrees.
Negative Longitude corresponds to Longitude in the WESTERN Hemisphere.
Positive Longitude corresponds to Longitude in the EASTERN Hemisphere.
Longitude Calculation Example:
24-bit longitude:
0xBFF46B (Hexadecimal)
