The empirical troposcatter model in Section 4.4 (Propagation by tropospheric scatter) of Recommendation ITU-R P.1812-7, taken from Recommendation ITU-R P.617-5, was fitted to over-the-horizon measurement data for path distances greater than 66 km with scatter angles exceeding 2.6 mrad eq. (82). Recent validations showed that for shorter distances, with smaller scatter angles, the troposcatter model can introduce significant errors in the total basic transmission loss. For this reason, users are advised to revert to using the troposcatter model from Recommendation ITU-R P.1812-6 for the calculation of the Lbs parameter (eq. (44)).
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