Installation Manual

Tsunami MP.11a Antenna Installation Guide
CALCULATIONS
Availability of the microwave path is a prediction of the percent of time that the link operates without
producing an excessive bit error rate (BER) due to multipath fading. In the absence of direct interference,
availability is affected by the following:
▪ Path length
▪ Fade margin
▪ Frequency
▪ Terrain (smooth, average, mountainous)
▪ Climate (dry, temperate, humid)
Depending upon the type of information carried over the link and the overall network design redundancy, you
may want to design for a specific availability rate. For example, if the data or voice traffic carried by the radio
is critical, the link can be designed for a very high availability rate (for example, 99.999% or 5.3 minutes of
predicted outage per year).
Availability can be improved by increasing the fade margin either by making the path shorter or by using the
higher gain antennas in conjunction with lower loss transmission line (using a higher quality transmission
line, shortening the length, or both).
Calculating Received Signal Level and Link Budget
Use the following formula to estimate the received signal level (RSL):
RSL (dBm) = P
out
- L
1
+ G
1
+ G
2
- L
2
- L
p
where:
P
out
is the transmitter output power (in dBm)
L
1
is the total loss of all transmission elements between the antenna and the RF Unit on one
side of the link (in dB)
G
1
is the gain of the antenna on one side of the link (in dB)
G
2
is the gain of the antenna on the opposite side of the link (in dB)
L
2
is the total loss of all transmission elements between the antenna and the RF Unit on the
opposite side of the link (in dB)
L
p
is the Path loss, defined by:Lp (dB) = 96.6 + 20 log
10
F + 20 log
10
D
where:
F is the Frequency of the radio system in GHz (5.8 in the case of this model)
D is the Distance of the path in miles
See the following figure for a visual representation of the elements of this equation.
Chapter 2. Determining Range and Clearance 20
CPN 65756 Issue Date: 01 August 2003