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.