Nautel XR12, Руководство по предварительной установке

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XR12 Transmitter Pre-installation Manual Other considerations
Issue 0.17 2005-08-31 Page 7-1
Section 7: Other considerations
This section describes other considerations regarding the XR12 transmitter.
• External RF drive source
• External RF drive source - see page 7-1
Also review considerations associated with XR12 accessories. See “Accessories” on page 10-1 .
External RF drive source
You can apply an externally generated RF drive (carrier frequency only or digital broadcast phase
modulated carrier) to the exciter interface board. This replaces the internal carrier frequency
oscillator for one or both exciters (A/B).
The external RF drive must:
• be the carrier frequency (ƒc), within ± 5 Hz or 5 parts per million (ppm), whichever is
greater, when it is not being modulated
• have a peak-to-peak amplitude of between 5.0 V and 12 V (sine wave or square wave)
• be phase modulated, with no other modulation
• be spectrally pure when it is not being modulated.
Note: There is only one external RF drive input. If you use it for both exciters, duplicate the RF
drive source (main/standby), and incorporate an automatic changeover circuit to select the standby
source if the main source fails.
Note: Any signal connected to the phase input may affect the transmitter’s RF output. To comply
with regulatory limits on emissions, ensure that the RF drive source is acceptable.