Adtran TRC3202 用户手册
TRACER 2210/3202 System Manual
Section 2, Microwave Path Engineering Basics
61280012L1-1A
© 2002 ADTRAN, Inc.
17
3.
RECEIVER POWER
The radio frequency (RF) signal power that is available at the input to the receiving TRACER 2210/3202
system is the next parameter of interest in analyzing a wireless path. Per FCC 15.247 rules, the TRACER
3202 RIU is allowed to output a maximum 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.
system is the next parameter of interest in analyzing a wireless path. Per FCC 15.247 rules, the TRACER
3202 RIU is allowed to output a maximum 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
where the variables in the equation are defined as
P
R
received power (Watts)
P
T
transmitted power (100 mW for TRACER 2210/3202)
G
T
transmit antenna gain
G
R
receive antenna gain
λ
carrier wavelength ( c / ƒ ) (meters)
d
path distance (meters)
L
other losses (RF coaxial cable, etc.)
As previously mentioned, the transmitted power is limited for the 5.8 GHz ISM band to a maximum of
20 dBm. The actual transmit and receive antenna gain values are strictly dependent upon the physical
characteristics of the antennas installed for each link. Typical gains are between 20 and 30 dB. For
example, a 4 foot diameter, flat panel C-band antenna from a popular antenna manufacturer advertises a
gain of 23.5 dB. The carrier wavelength is the physical wavelength of the main RF carrier being used for
communication, and is usually approximated at the center frequency of the band, which is 5787.5 MHz.
This gives a wavelength of 5.18 cm.
20 dBm. The actual transmit and receive antenna gain values are strictly dependent upon the physical
characteristics of the antennas installed for each link. Typical gains are between 20 and 30 dB. For
example, a 4 foot diameter, flat panel C-band antenna from a popular antenna manufacturer advertises a
gain of 23.5 dB. The carrier wavelength is the physical wavelength of the main RF carrier being used for
communication, and is usually approximated at the center frequency of the band, which is 5787.5 MHz.
This gives a wavelength of 5.18 cm.
The path distance is simply the physical distance between the transmit and receive antennas. For the
TRACER 2210/3202 these distances can range up to 30 miles. The final parameter L incorporates all other
signal power losses in the microwave link, most of which are caused by antenna feed, or coaxial cables
used to connect the TRACER 3202 N-type connector to the antenna connector. Since the TRACER 3202
is a mast-mounted device, the antenna feed losses are minimized by requiring only short runs of coaxial
cable.
TRACER 2210/3202 these distances can range up to 30 miles. The final parameter L incorporates all other
signal power losses in the microwave link, most of which are caused by antenna feed, or coaxial cables
used to connect the TRACER 3202 N-type connector to the antenna connector. Since the TRACER 3202
is a mast-mounted device, the antenna feed losses are minimized by requiring only short runs of coaxial
cable.
P
R
P
T
G
T
G
R
λ
2
4
π
( )
2
d
2
L
---------------------------
=
(watts, W)