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-3.4 8. Rain attenuation: - As the water droplets scatters and absorbs radiation the effect of
es on increasing with the increase of frequencies i.e. it is more in 13 GHz system
GHz
stance
likely size of rain cell i.e. by space diversity.
in 1+1
traffic, called
es, cost of the
version of the same signal are transmitted at different time
instance which is useful for forward error correction.
2. Frequency diversity: - A parallel stem is provided 1+1 so that both systems should
s of frequencies. This method is providing both
ent as well as frequency diversity so it is expensive. This technique a high order of
fect both frequencies.
ps. Each site is provided with
st path
7
rain go
compared to 4 and 6
Formula A (dB) = 0.0308 f – 0.1872R, R - Rain rate at that location = ------------
Where f = operating frequency within 10-15 GHz
This rain attenuation can be reduced by interconnecting two stations separated by di
greater than
9, Diversity: - If channel is affected by loading then second channel will take load here
configuration, Parallel system is provided so that two systems can carry the same
equipment/ frequency diversity. As it is required two sets of equipment/ frequenci
equipment is more. Signal is spread out over a large frequency band width.
Types of diversity: -
1. Time diversity: - Multiple
sy
carry the same traffic. It requires two set
equipm
reliability as fading is least likely to af
Fig. 7-16
3. Space diversity: - It is applicable in W/B system for larger ho
two Antennas. Main antenna at station A transmits signals of all frequencies, at station B signal
received by both antennas main and space diversity which will detect the signal with lowe
loss between two sites.
X
X
X
X
RCC1
RCC 2
CONBINER
O/P
TR
I/P
TR
X
X
X
X
X
X
X
X
RX 1
RX 2
O/P
Tx
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