RECOMMENDATION ITU-R F.1491-2 - Error performance objectives for real digital radio links used in the national ... ANNEX 1 - Examples of calculation for real links ANNEX 2 - Error performance events for different SDH radio-relay link configurations 1 Introduction 2 Link-end points are path end-points with and without frequency diversity 3 Link end-points are SDH multiplex section (MS) end-points 3.1 One hop MS without frequency diversity protection 3.2 One hop MS with frequency diversity protection 4 Link end-points are SDH regenerator section (RS) end-points 4.1 One hop RS without frequency diversity protection 4.2 RS with frequency diversity protection switching 4.3 Multihop RS without frequency diversity protection 5 Link end-points are combinations from the previous ones