You may choose the protection criteria to be used in the calculation of the probability of interference and the type of interference to be considered (unwanted and/or blocking).
Using the unwanted mode, it is possible to derive the C/I:
dRSS/iRSSunwanted = -53.5- (-77.5) = 24 dB
Since the resulting C/I is above the protection criteria (19 dB), the probability of interference calculated by SEAMCAT (Interference calculation) is equal to 0 (see Figure 100 (a)).
The same conclusion is reached by using the C/(N+I) criteria. It should be noted that SEAMCAT performs a consistency check (ANNEX 19:) between the interference criteria (ANNEX 3:).
It is also possible to derive the (N+I)/N= -77.5-(-100)= 22.5 (since I>>N). Since the (I+N)/N which is obtained is above the protection criteria (3 dB), the probability of interference calculated by SEAMCAT (Interference calculation) is equal to 1 (see Figure 100(b)).
The same conclusion is reached by using the I/N criteria.
| (a) |  |
|---|---|
| (b) |  |
Figure 101: Probability of interference considering the impact of the receiver blocking response for
(a) C/I and (b) (N+I)/N
Then, by taking into account the sum of the two signal types, the probability of interference becomes equal to 1 (due to the unwanted emissions) (see Figure 102)
Figure 102: Probability of interference considering the impact of unwanted emissions and
the receiver blocking response