3
rd
Generation Rack-
Mount RDMS™
141
Quasonix, Inc.
If there are two channels, and the Combiner is set to On, the Modulation Scaling is NOT linked. Modulation Scaling
for channel one and channel two functions independently.
When the RDMS™ has a good lock on the target transmitter, Modulation Scaling should be set to Hold.
Mod Scaling should be turned off when a new generation, digitally synthesized transmitter is the source. Digitally
synthesized transmitters do not have a variable deviation sensitivity adjustment, and as such are not subject to
inaccurate modulation index settings
Acquire mode has two states: Armed and Triggered. When Modulation Scaling is set to Acquire, the state is set to
Armed. In Armed state, modulation scaling operates continuously.
If the receiver is locked and the delta h (the change in modulation index) has settled below the delta h threshold for
the specified settling time, the state changes to Triggered and the eye pattern turns green. In Triggered mode, the
estimated h (modulation index) is monitored but the scale is not updated.
If delta h goes above the delta h threshold and settles again, the receiver is still locked, and the Eb/N0 at the settling
point is higher than the last settling point, the current scaling is updated with the new estimate.
There is no transition from Triggered back to Armed except for setting the mode to Acquire again.
4.5.3.5.3 Mod Scale Index
The Mod Scale Index option allows the operator to manually set the modulation scale index. This enables the
receiver to operate at the optimum range of modulation desired by the user.
When modulation scale index is set via the front panel of the receiver, the Modulation Scaling option is
simultaneously changed to Hold. The Hold notation includes the new index number that the operator has chosen.
To change the Modulation Scale Index in the
Browser
, ensure that the Modulation Index Scaling Mode is set to
Hold. If it isn’t, the Modulation Scale In
dex field is set to
read only
, as shown in Figure 239. Use the steps in section
4.5.3.5.1 to set and save the scaling mode. When the scaling mode is saved as Hold, the Mod Scale Index field
changes to an editable field, as shown in Figure 240. Type the desired scale index in the field or use the up/down
scroll arrows to change the value. The valid modulation scale index range is 0.350 to 8.000.
If the held index number is to be retained following a power-off cycle of the rack, then turn on Mod Persist from the
Main Menu. Refer to section 4.4.2.13, Modulation Persistence.
Figure 239: Advanced PCMFM Settings Window, Modulation Scale Index Current Value, Read Only
