Operations and Maintenance Manual

VS300 Operations and Maintenance Manual Operating the transmitter
Page 2-62 Issue 10.0 2019-01-18
SCA tab: (see Figure 2.44)
• MPX SCA: Connector (J7:A for SCA1, J7:B for SCA2) for use with an externally gener-
ated 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 3.50 Vpp).
• 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 0.0 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).