Setting up the real time gps signal – Agilent Technologies E8267D PSG User Manual
Page 230
216
Chapter 8
GPS Modulation (Option 409)
Real Time GPS
Setting Up the Real Time GPS Signal
If the signal generator is in the factory-defined preset mode, (
Utility
>
Power On/Preset
>
Preset Normal User
to
Normal) a basic GPS signal is automatically set up when you press the
Preset
key. Perform step 2 and steps 6
through 8 to generate a signal at the RF OUTPUT connector. To set up a signal using additional features of
the GPS personality, complete this procedure starting with step 1.
1. Press
Preset
.
2. Press
Mode
>
More (1 of 2)
>
GPS
>
Real Time GPS
.
3. Press
Satellite ID
>
8
>
Enter
.
4. Press
Doppler Shift
>
2.5
>
kHz.
5. Press
Data Mode Enc TLM
to Enc.
6. Press
Data
>
PN Sequence
>
PN15
.
7. Press
Real-time GPS Off On
to On.
8. Press the
Frequency
hardkey. Using the numeric keypad, set the signal generator RF output frequency to
1.57542 GHz (L1 carrier frequency).
9. Press the
Amplitude
hardkey. Using the numeric keypad, set the signal generator RF output amplitude to
120 dBm.
10. Turn the RF output on by pressing the
RF On/Off
hardkey on the signal generator front panel.
The real-time GPS signal is now available at the signal generator RF OUTPUT connector.
shows what the signal generator display should like after all steps have been completed. Notice the
GPS
, I/Q, and RF ON annunciators are on and the parameter settings for the signal are displayed in the
status area of the signal generator display.
This procedure sets up a GPS signal that incorporates a subframe structure using 10 words, each with 24 raw
data bits and 6 parity bits computed from the data source. The signal generator created this subframe
structure when you selected Enc as the data mode and a PN15 sequence as the data type. The PN15 sequence
was encoded with the C/A code at 50 bps. Using factory preset settings, the C/A chip rate is 1.023 Mcps
with a clock reference of 10.23 Mcps. A 2.5 kHz doppler shift simulates the relative motion of the satellite
with respect to the receiver. For more information on the GPS option, refer to