The value is determined separately for the two control points from the product of the K-factor fM and the basic MUF. The lower value is taken as the operational MUF for the whole path. = · MHz (31) fM K fBM The K-factor is used to calculate the operational MUF from the basic MUF fM fBM: (32) where: : value of for a time corresponding to local noon fBM,noon fBM : lowest value of which occurs during 24 hours. fBM,min fBM and are in Table 3. The azimuth angle of the great-circle path is determined at the centre W, X Y of the whole path; this angle is used to linearly interpolate the angle between the East-West and NorthSouth values. TABLE 3 Values of and used for the determination W, X Y of the correction factor K W X Y East-West 0.1 1.2 0.6 0.2 0.2 0.4 5.3.2 Determination of the fL The LUF is strongly influenced by non-deviative absorption. HF waves are absorbed by penetrating the D-Layer. For the determination of the LUF, the path is divided into equal hops in length nL dL (none longer than 3 000 km). The penetration points are determined by assuming a fixed reflection height of 300 km and a penetration height of 90 km (two penetration points per hop). The is calculated by equation (33): fL MHz (33) number of penetration points 2nL m: sun spot number which does not saturate for high values and can exceed 160 R12: : zenith angle which can be calculated by the following equation: (34) declination (radians) δ: geographical latitude of the penetration point (radians) mth φm: hour angle (radians). The solar declination, can be approximated by the subsolar latitude for the middle of the month δ, (sx) from Table 4:
The value fM is determined separately for the two control points from the product of the K-factor and the basic MUF. The lower value is taken as the operational MUF for the whole path. fM = K · fBM MHz (31) The K-factor is used to calculate the operational MUF fM from the basic MUF fBM: (32) where: fBM,noon : value of fBM for a time corresponding to local noon fBM,min : lowest value of fBM which occurs during 24 hours. W, X and Y are in Table 3. The azimuth angle of the great-circle path is determined at the centre of the whole path; this angle is used to linearly interpolate the angle between the East-West and NorthSouth values. TABLE 3 Values of W, X and Y used for the determination of the correction factor K W X Y East-West 0.1 1.2 0.6 0.2 0.2 0.4 5.3.2 Determination of the fL The LUF is strongly influenced by non-deviative absorption. HF waves are absorbed by penetrating the D-Layer. For the determination of the LUF, the path is divided into nL equal hops dL in length (none longer than 3 000 km). The penetration points are determined by assuming a fixed reflection height of 300 km and a penetration height of 90 km (two penetration points per hop). The fL is calculated by equation (33): MHz (33) m: number of penetration points 2nL R12: sun spot number which does not saturate for high values and can exceed 160 : zenith angle which can be calculated by the following equation: (34) δ: declination (radians) φm: geographical latitude of the mth penetration point (radians) hour angle (radians). The solar declination, δ, can be approximated by the subsolar latitude for the middle of the month (sx) from Table 4:
R-REC-P.533-13-201507-I!!MSW-E.docx