User's Manual

Fade margin calculations
SkyZhone 45 Installation Guide
21
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Fade margin calculations
The fade margin is the difference between the RSL and the receiver’s
threshold. Use the RSL as calculated in “Received Signal Level and link
budget”, and compare it to the receive threshold of the SkyZhone 45 radio
(-88 dBm for BER of10-8) The fade margin is the difference between the two
signal levels.
A fade margin of at least 20 dB is suggested for reliable performance, and
larger margins may be required over areas with water or thermal inversions.
Unit Frequencies
The SkyZhone 45 radios operate over two 100 MHz channels. The
SkyZhone 45 system divides each 100 MHz wide band into seventeen
overlapping sub-channels, each about 17 MHz wide. Spectrum reuse is
maximized and signal interference is minimized by changing sub-channels,
alternating polarization, and changing azimuth.
Each system has an “A” and “B” ODU. The radio with ODU variant “A”
transmits in the range of 5.725 to 5.825 GHz, and receives in the range 5.250
to 5.350 GHz. The “B” variant is the opposite, transmitting in the range 5.250
to 5.350 GHz and receiving at 5.725 to 5.825 GHz. This frequency split
allows full duplex communications.
Figure 6: SkyZhone 45 channel allocation
For information about channel center frequencies, see “Channel center
frequencies” on page 44.
Powering the units
The SkyZhone 45 system ODU receives power from the IDU. The IDU must
have access to a supply of appropriate power, either DC or AC. Do not
connect both AC power and DC power to the same IDU.
Power requirements are listed in Table 6 on page 16.