Note1: The S.O.M. must be calculated both ways (Site1 to Site2 and Site2 to Site1). Consider the
lowest of the 2 values as the link’s S.O.M. 

Note2: The radio Rx sensitivity relies on the desired connection speed. The radio Tx power is ussually configurable. Check the radio specifications and current settings prior to S.O.M. calculation. 

SOM is a measure in dB of the signal loss your system can with stand before it degrades to the error rate specified at your Receiver Sensitivity threshold. A minimum 20 dB SOM is recommended and many systems are designed with 30 dB+ due to additional circumstances such as inadequate Fresnel clearance, desensitization, intermod etc.