Viavi 87339, Operation Manual

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Testing
4 -15
4.1.7.C Reacquisition (hot start)
The receiver has up-to-date almanac and ephemeris information, has not been turned off
for more than two hours and has not moved location more than 100m. In this scenario, the
receiver needs to obtain only timing information from each SV to return its position fix
location. Most modern GPS receivers return a position fix from a hot start condition within
0.5 to 20 seconds.
Perform the following steps for Reacquisition (hot start) TTF measurement.
STEP PROCEDURE
1. If connecting GPSG-1000 via Antenna Coupler, perform Antenna Coupler
Installation procedure Section 4.1.1. If directly connecting GPSG-1000 to GPS
receiver under test, proceed to step 2.
2. Perform Setup procedure Section 4.1.2.
3. Select Launch Bar tab to display launch bar. Select SV PRN function key to
display the SV PRN Function Window. The GPS SV’s in view will be displayed in a
table.
4. Turn ON all SV’s by selecting ON/OFF field to ON in each SV line and select
Apply. Select the close icon to close the Function Window.
5. On the Setup Simulation Function Window select PRN Signal drop down menu.
Select VARIABLE, this ensures the relative SV signal levels are set proportional
to the respective pseudo ranges.
6. Select RF Level and set to the receiver manufacturers TTFF RF level.
7. On the Simulation Function Window select the Run key to start the simulation.
Wait until a position fix is achieved and select the Stop Key.
8. Wait 60 seconds and then select Run key to restart simulation and measure the
Time to Fix (TTF).