T-45C TS, ADV & IUT ENG-24
GINA Operating Characteristics
B.
Ranging and triangulation
1.
Distance from satellites is determined using
pseudo-ranging
NOTE: Pseudo-ranging is a measurement of the
time a satellite signal takes to arrive at a receiver
2.
An optimum satellite array (technically termed a
constellation) for triangulation is one (1) satellite
directly above receiver; three (3) to the sides, each
separated by 120 degrees spacing
C.
Standard Positioning Service (SPS)
1.
Provided to all users
2.
Horizontal positioning accuracy of 100 meters with
95% probability; to 300 meters with a 99.99%
3.
Signal is unencrypted
4.
Modulated error signal is purposely induced
INSTRUCTOR NOTES
At the time of this writing, it was recently announced that the
U.S. government will be taking steps over the next 8-10 years
to up-grade the accuracy of GPS signals provided to civilian
users. Additionally, new satellites will be launched that contain
more available frequencies and other improvements for both
military and civilian use. The modulated error signal will be
removed. Government intent is to equate the increased SPS
accuracy with what is now available to the U.S. military and
other approved users.
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