System Operating Margin

System Operating Margin

Distance: Miles Frequency: MHZ
Site 1:

Site 2:

Tx power dBm Tx power dBm
Rx Sensitivity dBm Rx sensitivity dBm
Antenna gain dBi Antenna gain dBi
Cable loss dB Cable loss dB


Free Space Loss: dB
Site1 to Site2 SOM: dB

Site2 to Site1 SOM: dB


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.