Specifications

IntroductionGPS and Assisted GPS
21Operating Manual 1171.5248.12 ─ 15
Enable this mode, if a simulation of realistic GPS scenario of up to 4 configurable GPS
satellites per baseband and flexible simulation time is required. The signal will be calcu-
lated for the selected fixed or moving location. Simulation of moving receiver requires
option Assisted GPS R&S SMx/AMU-K65.
1. Execute "Set To Default" to adjust the instrument's settings to a standard set of oper-
ating conditions.
2. Select the required "RF Band".
3. Adjust the output frequency of the instrument to the frequency selected with the
parameter "RF Band":
a) for RF instruments, select "Set to Default RF and Level" or
b) select the FREQ key to set the frequency in the header of the instrument.
4. Set the parameters "Simulation Mode" to "Localization Mode".
5. Set the "Localization Mode" to "Auto SV Selection".
6. Select and configure a static predefined or user-defined "Geographic Location" or a
moving receiver.
7. Use the "Select Almanac File" function and choose an almanac file.
The navigation message will be extracted from this almanac file.
8. Adjust the "Date" and the simulation time ("GPS Mean Time"). Any simulation time
in the week span can be selected. However, only the period between the Time of
Almanac (TOA) and TOA+3.5 days ensures to lead to a receiver fix.
9. Choose the generation of GPS signal of 4 or 8 satellites.
10. Adjust the required "Satellite Elevation Mask" and set the elevation mask of the GPS
receiver to this value.
11. Set the GPS "State" to ON to enable the GPS signal generation.
The R&S Signal Generator generates a realistic GPS signal for 4 or 8 satellites' con-
stellation, calculated to fulfill the minimum PDOP criteria. The selected satellites are
displayed in the "Satellite Configurations" dialog. Most of the parameters are read-
only; the satellite parameters can be additionally reconfigured to simulate multipath
effects for instance (see also chapter 2.8.2, "Generating Multipath Scenar-
ios", on page 20).
Open the Real-Time S.P.O.T. display to show the position of the active and inactive
satellites. The current values of the parameters "PDOP", "HDOP", "Receiver Loca-
tion", "Time of Simulation" and "Elapsed Time" are also displayed.
If a moving receiver had been configured, the "Real-Time S.P.O.T." displays the ideal
trajectory the receiver should have.
2.8.4 Generating GPS Signal with Satellite Handover (Localization Mode
Auto SV Selection and Update)
(for R&S SMx/AMU instruments only)
Typical Workflows