Bandwidth
Channel widths used for transmitting.
Measure frequency
By default, the Radio loopback is measured with the current frequency of the transmitter. Measure-
ment can be performed with the frequency of the receiver. Both results may differ slightly because
the antenna parameters are frequency dependent.
Mute peer TX
The deactivation of Peer station transmission during measurement (not to interfere with the meas-
urement).
TX to RX isolation
The result of the Radio loopback measurement is given as the ratio between the levels of the
transmitted and received signal. The ratio is given as a logarithmic value in [dB]. The higher the
number, the better the antenna quality. Here are the thresholds for evaluating the results:
• less than 40 dB - insufficient
• from 40 dB to 45 dB - reasonable
• more than 45 dB - good
Note
Possible reasons for isolation ratio lower than 45 dB are listed below. They are ordered
according the probability of occurrence. Typical methods of repair are described as well:
• Silicon grease in the waveguide => clean the antenna waveguide and the neck of the
unit
• Antenna for another frequency band => check the type of antenna and replace it with a
suitable one
• Frozen (dewy) antenna => after climatic conditions improvement everything returns to
original values (antenna heating would eliminate that - quite useful in mountainous areas)
• Reflective (metal) surface near the antenna (even outside of the Fresnel zone) => change
of antenna position
• Mechanically damaged antenna dish or radome => inspection of the antenna, cleaning
or replacement of the radome
• Lost mirror at the end of a waveguide inside the antenna => inspection of the antenna
interior, its repair or replacement
• Damaged polarization transducer inside the unit => repair of the unit at the manufacturer
(this never occurred, yet)
Fig. 5.47: Menu Tools > Live data > Radio loopback result
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