VECTOR MODULATION MODE
3-49
Modulation fading
The signal generator is able to simulate the effects of fading in a transmission system. Pressing the
[Fading Control]
key on the
Sig Gen
menu causes the
Vector Modulation Fading Control
menu
shown in Fig. 3-49 to be displayed.
LOCAL
Fading
Disabled
Rayleigh
Fading
Rician
Fading
Direct
Doppler
Doppler
Speed
Path
Ratio
C0852
Vector Modulation Fading Control
Doppler Speed
: 0 Hz
Direct Path Doppler : 0 Hz
Path Ratio
: 0 dB
(Direct/Scattered)
Fading Control: RAYLEIGH
Fig. 3-49 Vector modulation: Fading control menu showing Rayleigh fading selected
Select between the two types of fading by pressing the
[Rayleigh Fading]
or
[Rician Fading]
key.
Doppler speed for Rayleigh fading and the scattered path for Rician fading can be entered using
the
[Doppler Speed]
key.
To set the direct/scattered path ratio for Rician fading, press the
[Path Ratio]
key, enter the path
ratio in dB (positive or negative) and terminate the entry with the [dB] key. The direct path
doppler speed for Rician fading can be entered using the
[Direct Doppler]
key. The entered value
must be within a factor of 2 of the scattered path doppler.
When not required the fading may be disabled using the
[Fading Disabled]
key.
When Rayleigh fading is enabled the direct path doppler and the path ratio settings are
ignored.
When fading is enabled the DCFM control of the main instrument synthesizer is used, hence
when first enabled, or during an IQ selfcal, a nulling operation occurs. This ensures
accurate carrier frequency output. The legend:
*** DCFM NULLING ***
appears briefly on the display.
Menu exit
Press [SIG GEN] to return to the
Sig Gen
menu where further selections may be made.