RES535 – 337 – DESCRIPTION 4 Compatibility analysis General In order to assess the performance of each requirement in the presence of noise and of the potential interference from other requirements using the same or adjacent channels, it is necessary to calculate the relevant reliability values. To this end, the Bureau will prepare suitable software, taking account of user requirements in terms of desired signal-to-noise and signal-to-interference ratios. Input data The schedule for a given season − this may be either an initial consolidated schedule (to permit assessment of those requirements which need coordination) or the High Frequency Broadcasting Schedule (to permit assessment of the likely performance of requirements during the relevant season). Methodology and data The software should use: – Recommendation ITU-R BS.705 for the calculation of antenna patterns; – Recommendation ITU-R P.533 for the prediction of the wanted field-strength values at each test point for each wanted requirement; – Recommendation ITU-R P.533 for the prediction of the potentially interfering field-strength values from all other co-channel or adjacent channel requirements at each test point for each wanted requirement; – Recommendation ITU-R BS.560 for adjacent channel RF protection ratios; – Recommendation ITU-R P.842 for the calculation of reliability values. The set of 911 test points (agreed at WARC HFBC-87) should be used, supplemented where necessary with test points based on a geographic grid. The software should calculate the wanted and unwanted field-strength values and the fading margins at each test point inside the required service area. The desired RF signal-to-noise and RF protection ratios should be user selectable, the default values being 34 dB and 17 dB (DSB-to-DSB co-channel case), respectively. In the case of digital emissions, the desired RF signal-to-noise ratios are as provided in the most recent version of Recommendation ITU-R BS.1615. The default values of RF protection ratio to be used by the Bureau for its compatibility analyses are given in Section 1 of the Annex to Resolution 543 (WRC-03). The dates for which a compatibility analysis is made should be user selectable, the default values being: – 0.5 month after the start of the season; – mid-point of the season; – 0.5 month before the end of the season.