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In this calculation mode the function block_{Max Interf Signal} (Df) that you entered represents the absolute power level (in dBm) of maximum interfering signal (maximum acceptable interfering power), which might be tolerated by the receiver at a given frequency separation (see Figure 12).

In this case SEAMCAT calculates the receiver attenuation, Attenuation (Df), to be applied to the interfering signal by using the following expression:

       Attenuation(Df) = block_{Max Interf Signal} (Df) (dBm) - sens_VLR (dBm) + C/(N+I) (dB) – I/N (dB)                 (Eq. 23)

where:

• Df = (f_ILT - f_VLR) is the frequency separation;
• sens_VLR is the sensitivity of the VLR (dBm) as defined in the simulation scenario.

To achieve a realistic value, you may define the sensitivity (sens_VLR) as (see the figure below):

Sensitivity = Noise Floor + C/(N+I)                                                              

Sensitivity = -110 dBm + 16 = -94 dBm

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Figure 107: Setting up the sensitivity in SEAMCAT

Then the attenuation may be evaluated:

Attenuation (Df ) = 40 + 94 + 16 - 0 = 150 dB                  

iRSS_blocking = Interfering Signal Level (f it )= -54.5 - 150 = -204.5 dBm        

This can be checked by running a simulation and displaying the iRSS_blocking in case of Sensitivity mode calculated by SEAMCAT see Figure 108.

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Figure 108: Mean iRSS_blocking in case of Sensitivity mode