Nautel GV3.5, Operation & Maintenance Manual, Page: 84 / 251

GV5/GV3.5 OPERATIONS & MAINTENANCE MANUAL OPERATING THE TRANSMITTER
VERSION 0.2 2014-07-23 PAGE 3.2.67
Figure 3.2.46: Presets - SCA
SCA - (see Figure 3.2.46
)
:
 MPX SCA: Connector (J7:A for SCA1, J7:B for SCA2) for use with an externally generated SCA;
select
Enabled
or
Disabled.
When enabled, all the selections listed below are active.
 Input Level: signal level that represents 10% modulation. Enter a value between 1 and
5 V p-p (typically 2.83 V p-p).
 SCA Reduction : Attenuation applied to the SCA input; set between 0 and 20% (used to reduce
the modulation level of the main audio when SCAs are enabled; typically, for every 2% of SCA
modulation, the main audio modulation must be reduced by 1%).
 Internal SCA1/2 : Enable or disable the appropriate internal SCA ( SCA1 or SCA2 ). When enabled,
the settings listed below are active for the associated SCA signal (1 or 2).
 SCA1 or SCA2 Injection Level: enter value between 0 and 20% (typically 10%); this level is
added to the composite baseband signal.
 SCA1 or SCA2 Frequency: enter value between 20 and 100 kHz (typically set to 67 kHz or
92 kHz).
 SCA1 or SCA 2 Input Level: enter value between -12 and +12 dBu, which represents the input
voltage level that yields 10% modulation (typically 4.7 dBu).
 SCA1 or SCA2 Lowpass Filter: select Enabled (applies 7.5 kHz low-pass filter to audio input)
or Disabled.
 SCA1 or SCA2 Preemphasis: select 0 us, 50 us, 75 us or 150 us.
 SCA1 or SCA2 Mode: select FM (frequency modulated sub-carrier, typical) or DSB-SC (double
side band suppressed carrier).