4.2.3 Protection ratio This mode is identical to the “sensitivity” mode since the only difference is that the Blocking value (relative to the noise floor) is provided in dB. The software processes the information using exactly the same method to obtain the value of the receiver attenuation (see  A8.7 ). The function block Protection Ratio ( Df ) that you entered represents the protection ratio, i.e. the ratio of maximum acceptable level of interfering signal to the wanted signal level, at a given frequency separation. In this case SEAMCAT calculates the receiver attenuation a VLR ( Df ) to be applied to the interfering signal by using the following expression (see Figure 105): (Eq. 24)                                                  Figure 105: Mean iRSS blocking in case of Protection-ratio mode