Power level of the received signal and SNR

The SNR or S/ N (Signal-to-Noise Ratio) parameter is given in decibels (dB). It describes the ratio at the frequency in question.

The speed rate of wireless link depends on the power level of the received signal and its ratio to the noise. Even well -balanced radio link will be useless in case of high noise level. We have no influence on ambient electromagnetic noise level. The noise includes all unwanted radio signals that can deteriorate operation of wireless link or even make it idle. If the interference is in the working channel, even high power level of the received signal will not protect us against decrease of transfer rate.


Unexpected transmission interruptions and/or large number of lost packets can indicate decrease of SNR, e.g. some interference has occurred.
However, the most frequent reasons of SNR decrease are: water -soaked RF cable connecting the RF device with the antenna (e.g. due to damaged sheath), water -soaked connector(s), moved antenna (especially in the case of offset or parabolic antenna with narrow half -power beamwidth), mechanical damage of the antenna. The diagnostic testing of the installation has to be started with inspection of the physical condition of these elements. The quality of the components used is vital for reliability and longevity of every installation.

The problem with interferences is more difficult to tackle. It may be a "competing" service provider using the same or close channel. The countermeasures include:

* change to other, free channel
* change of polarization of the antennas
* use of client antennas with narrower beamwidth
* increase of RF power levels
* change to more powerful antennas

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