Nautel NX25, Руководство по эксплуатации и обслуживанию

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NX300 Operations and Maintenance Manual Operating the transmitter
Page 2-60 Issue 3.0 2012-11-01
Guidelines for selecting the DCC mode:
Observe the following guidelines when selecting the DCC mode for your application.
AMC mode (see Figure 2.40 on page 2-57 ) 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 asym-
metrical 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 not 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.