Nautel XR6, Руководство по предварительной установке

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XR6/XR3 Pre-installation Manual RF output requirements
Issue 3.0 2009-07-15 Page 8-3
Antenna system
Ensure that the antenna system meets or exceeds the standards specified in EIA Standard TR-101-A,
paragraph 8(b), with a normal impedance of 50 ohms at the carrier frequency. The transmitter will
operate with a maximum VSWR of 1.5:1, or with sideband VSWRs of up to 2:1 when the carrier
frequency impedance is 50 ohms. However, overall system performance degrades as the VSWR
increases.
Advances in digital modulation schemes like IBOC and DRM systems require better performance
from antenna systems. To ensure the proper operation during digital broadcasting, ensure that the
VSWR does not exceed 1.4:1 at the carrier frequency ±15 kHz.
In order to achieve the proper sideband symmetry (Hermitian symmetry) needed for IBOC
operation, you may need to adjust the tuning of the antenna system to balance the impedances at the
sidebands. You must perform a full impedance sweep of the antenna system before broadcasting
IBOC. This requires information about phase versus frequency for Hermitian symmetry at the power
amplifier. The information will be provided with the transmitter at time of shipment. For information
about your transmitter’s RF phase, contact Nautel Customer Support.