Proxim TSUNAMI CPN 65756B User Manual

1.  Start with the transmit power and the number of the channel to be used.  From the output power tables 

2.  Subtract the total loss of all transmission elements between the antenna and the radio on one side of the 

3.  Add the dBi of the antenna you will be using.  The total is the EIRP (equivalent isotropically radiated 

power). 

4.  Determine your link budget from the Distance and Path Loss table,  For example, if the distance between 

the two radios is approximately 5 km, the link budget would be 121.  (Note that this is the value for 4.8 

km, which is closest to the actual value.) 

5.  Add the gain of the antenna on the second side of the link. 

6.  Subtract the total loss of all transmission elements between the antenna and the radio on the second 

side of the link.  The result is the Received Signal Level (RSL). 

7.  From the Receiver Sensitivity in Table 2 on page 23, find the dBm value for the data rate used for the 

link. 

8.  Add the “Minimum SNR for a Good Link” value of the data rate in use to the Receiver Sensitivity level. 

9.  Subtract this value from the Received Signal Level; this is the Fade Margin. 

▪ 

The RSL must be higher than the Receiver Sensitivity plus the minimum SNR for a good link.  See Table 

3 on page 23, to have a working link with no excessive errors.  The amount of Fade Margin indicates the 

reliability of the link; the more Fade Margin, the more reliable the link. 

▪ 

The path loss must be smaller than the link budget minus the minimum required fade margin.  The 

maximum ranges cause the path loss plus the fade margin to be the same as the link budget. 

 

The results of this link budget calculation are very important for determining any potential problems during 

installation.  If you have calculated the expected RSL, you can verify that it has been achieved during 

installation and troubleshooting, if necessary. 

In the USA and Canada, this model radio can be installed with any gain directional antennas, as there is no  

Effective Isotropic Radiated Power (EIRP) limit for the application of these systems for fixed point-to-point 

applications.  In other countries, EIRP limits may apply.   

In the case of EIRP limits, use the lesser of either (P

out

 - L

1

+ G

1

) or the EIRP limit within the previous 

equation.  You should check this equation in both directions to assure legal application. 

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