Nautel NX15, Operation And Maintenance Manual

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NX15/NX25 Operations and Maintenance Manual Operating the transmitter
Issue 6.0 2019-01-31 Page 2-63
Guidelines for selecting the DCC mode:
Observe the following guidelines when selecting the DCC mode for your application.
AMC mode (see Figure 2.43 on page 2-61 ) should work well for most broadcasters and is
generally recommended if you have an IBOC transmission. It has several advantages over the
other modes:
• It tends to save the most power when used with a heavily processed audio signal and
asymmetrical modulation.
• It does not affect the modulation depths of the received signal, so the station’s sound
should not change.
• It performs the reduction in power in such a way that it tends to be masked by the
audio.
If AMC is not being used, consider DAM mode as a second choice, although the power savings
will be significantly less. If the station is operating with less audio processing, or has more
silent periods, the DAM algorithms will tend to save more power. However, the basic DAM
characteristic will impact the audio quality of the station. In IBOC mode, DAM will
significantly reduce the audio quality of the station as it will increase the impact of the IBOC
on the analog. It may also make it more difficult for the transmitter to meet the spectral mask,
by making the transmitter operate at a much higher modulation depth and effectively
increasing the level of the digital carriers relative to the analog.