
FASTRAK MANUAL
Rev. G
50
JUNE 2012
‘H’ – Hemisphere of Operation
Syntax:
H
station
,[p1],[p2],[p3]<>
or
H
station
<> to read back the current hemisphere selection
Description:
Because of the symmetry of the magnetic fields generated by the transmitter,
there are two mathematical solutions to each set of receiver data processed.
Therefore, only half of the total spatial sphere surrounding the transmitter is
practically used at any one time without experiencing an ambiguity (usually sign
flips) in the X, Y, Z measurements. This half sphere is referred to as the current
hemisphere. The chosen hemisphere is defined by an LOS (line-of-sight) vector
from the transmitter through a point at the zenith of the hemisphere, and is
specified by the LOS direction cosines.
Purpose:
Since the receiver(s) can only operate in one hemisphere at a time relative to the
transmitter, it is necessary to tell the FASTRAK system which side of the
transmitter they will be on, for each station. A “hemisphere tracking” option is
available, but important criteria must be met in order for it to work properly (see
pages that follow for more information). Identification of command parameters is
as follows.
station
the number of the station whose operational hemisphere is to be
modified.
p1 the x-component of a vector pointing in the direction of the
operational hemisphere. (Set to 0 to enable hemisphere tracking.)
p2 the y-component of a vector pointing in the direction of the
operational hemisphere. (Set to 0 to enable hemisphere tracking.)
p3 the z-component of a vector pointing in the direction of the
operational hemisphere. (Set to 0 to enable hemisphere tracking.)
If all of the optional parameters are set to 0, then hemisphere tracking will be
enabled for the specified station.
IMPORTANT NOTES ABOUT HEMISPHERE TRACKING:
“Hemisphere tracking” is a feature whereby the tracker can continuously modify
its operating hemisphere, given that it is started in a known, valid hemisphere.
1.
When this command (H1,0,0,0<>) is sent to the FASTRAK system, the
receiver of the specified station must be located in the currently set
hemisphere.
2.
‘^K’ – *Save Operational Configuration
) is sent to
the FASTRAK system while hemisphere tracking is enabled, the
currently