Adtran TRC4305 Manual Do Utilizador
Section 2, Microwave Path Engineering Basics
TRACER 4305 System Manual
14
© 2002 ADTRAN, Inc.
612804305L1A-1A
1.
LINE-OF-SITE
The TRACER 4305 system is designed for operation in the 5725 MHz to 5825 MHz unlicensed National
Information Infrastructure (U-NII) frequency band. Radio wave propagation in this band exhibits
microwave characteristics, which are ideally suited for point-to-point, line-of-sight communications.
Line-of-sight essentially requires that the transmitting antenna and receiving antenna are able to “see” each
other, and that the straight-line path between the two antennas is free of any obstructions, such as
buildings, trees, mountains, and, in longer paths, even the curvature of the earth.
Information Infrastructure (U-NII) frequency band. Radio wave propagation in this band exhibits
microwave characteristics, which are ideally suited for point-to-point, line-of-sight communications.
Line-of-sight essentially requires that the transmitting antenna and receiving antenna are able to “see” each
other, and that the straight-line path between the two antennas is free of any obstructions, such as
buildings, trees, mountains, and, in longer paths, even the curvature of the earth.
2.
DECIBELS
The received signal power equation is often expressed in a decibel (dB) format, which turns the power
multiplication and division operations into addition and subtraction operations. In general, any quantity
can be expressed in decibels. If the quantity (x) is a power level, the decibel equivalent is defined as
multiplication and division operations into addition and subtraction operations. In general, any quantity
can be expressed in decibels. If the quantity (x) is a power level, the decibel equivalent is defined as
If the quantity x is referenced to a milliwatt (mW), then the decibel-milliwatt (dBm) is used instead of a
generic decibel.
generic decibel.
3.
RECEIVER POWER
The radio frequency (RF) signal power that is available at the input to the receiving TRACER 4305 system
is the next parameter of interest in analyzing a wireless path. Per FCC 15.407 rules, the TRACER 4305 is
permitted a maximum output power level of 100 mW, which is equivalent to 20 dBm. This output signal
will be attenuated and distorted by various factors, all of which will degrade the original signal and affect
the signal strength and quality as sensed by the receiving unit. A simplified power budget analysis is
beneficial to perform after verifying a suitable line-of-sight path to determine if the microwave path is
suitable, even for ideal, non-distorted signals.
is the next parameter of interest in analyzing a wireless path. Per FCC 15.407 rules, the TRACER 4305 is
permitted a maximum output power level of 100 mW, which is equivalent to 20 dBm. This output signal
will be attenuated and distorted by various factors, all of which will degrade the original signal and affect
the signal strength and quality as sensed by the receiving unit. A simplified power budget analysis is
beneficial to perform after verifying a suitable line-of-sight path to determine if the microwave path is
suitable, even for ideal, non-distorted signals.
The equation relating received signal power to the other microwave parameters is
Point-to-Point
Wireless communication from a single site to another
individual site. Contrast with point-to-multipoint
individual site. Contrast with point-to-multipoint
Line-of-Sight
An unobstructed, direct path exists between the
transmitting and the receiving antennas.
transmitting and the receiving antennas.
x
dB
10 log
10
x
( )
⋅
=
(dB)
x
dBm
10 log
10
x
1mW
-------------
⋅
=
(dBm)
P
R
P
T
G
T
G
R
λ
2
4
π
( )
2
d
2
L
---------------------------
=
(watts, W)