User's Manual

MDR2400-SR, MDR5800-SR and Orion 5825-SR
Issue 10 Page 27
3.2 Site Evaluation
When planning a site for a digital radio link, it is of the utmost importance that you take
the operational environment of the proposed site into account.
The combined effect of atmospheric environmental factors such as rain and lightning,
atmospheric attenuation, signal path obstruction, propagation fading, air temperature
gradients, ice build-up, wind and solar radiation can contribute towards reducing the
level of performance of the system. The 2.4 GHz and 5.8 GHz bands are not adversely
affected by rain, ice or snow. Severely cold and excessively warm climatic conditions
outside the scope of the operating temperature range can affect the function of the
system, especially the outdoor equipment (see Environmental Characteristics on page
52 of this manual).
Also, if masts are not sufficiently rigid, very strong winds can affect the antenna beam
alignment and Outdoor equipment reliability due to wind force build-up and/or vibration
of the mast-mounted equipment.
3.3 Multipath Effects
The effects of multipath propagation can influence the radio. Understanding these
effects will help when installing a radio link and maximise the reliability of the link.
Multipath fading occurs when the receiving antenna receives not only the direct signal
from the transmitting antenna but also a signal from the transmitting antenna that has
reflected off the ground or nearby obstacles. The reflected signal takes a longer path to
reach the receiver and acts as interference since it is not in-phase with the direct path
signal. The amplitude of the interference can be almost equal to that of the direct path
signal, thus degrading the performance of the link.
Multipath propagation is dependent on transmit frequency and the specific geometry of
the link such as antenna heights, distance between the antennas and the local terrain.
To counteract multipath propagation, the installer can change the frequency at which
the link operates or adjust the height of one or both of the antennas.
Figure 6. Multipath Effects.
User Data
MDR / Orion OU
M D R / O rio n IU
U s e r D a ta
MDR / Orion OU
MDR / Orion IU
D ire c t R F P a th
R e fle c tio n P a th