Tektronix SPG8000 Technical Reference page 74

REF button menu
62
ACQUIRE GPS POSITION. This menu item appears only when Option GPS is
installed and GPS Signal is the selected reference source. Press the ENTER
button to erase the saved position, and then reacquire and save a new averaged
position. Note that the GPS signal quality might indicate low or no signal during
this process.
NOTE.
The module must make 60, 1 second GPS readings with at least four
satellites to acquire the position. How long this takes depends on various
conditions. If there are less than four satellites, a reading cannot be taken.
GPS SIGNAL WARNING. This menu item appears only when Option GPS is
installed and GPS Signal is the selected reference source. This function provides
a warning that the antenna signal has degraded. Set this level below the normal
range experienced as a function of time of day, weather, or other variables. To
configure the output warning, use the REF button menu. (See page 57, REF
button menu.) Use the left (◄) or right (►) arrow button to select the FOM
(quality of the GPS signal) value that will trigger warning indicators. (See page 2,
Figures of Merit (FOM).)
SPG8000 Technical Reference