RES535 – 333 – The software should calculate the field-strength values and the fading margins at each test point inside the required service area for each of the frequency bands declared to be available, taking account of the relevant transmitting antenna characteristics for each frequency band. The desired RF signal-to-noise ratio should be user selectable with a default value of 34 dB in the case of double sideband (DSB) or as provided in the most recent version of Recommendation ITU-R BS.1615, as appropriate, in the case of digital emissions. The dates for which calculations are 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. The times for which calculations are made should be user selectable, the default values being: – 30 min past the hour in which the requirement starts; – 30 min past each successive hour until the hour in which the requirement stops. Software output data For rapid assessment of suitable frequency bands, the software should calculate: – the basic service reliability for each available frequency band and for the relevant test points from the set of 911 test points; – the basic area reliability for each available frequency band and for the relevant test points from the set of 911 test points. In order to provide information about the geographic distribution of wanted signal values within the required service area, additional results should be available from the software: – a listing should be available giving, for each of the available frequency bands, the basic circuit reliability (BCR) for each of the test points (from the set of 911 test points) inside the required service area. In some cases, a graphical display of the BCR values throughout the required service area may be desirable. These values should be calculated at test points at 2° intervals of latitude and longitude throughout the required service area. The BCR values should be displayed graphically as a set of coloured or hatched “pixels” scaled in steps of 10%. It should be noted that: – reliability values relate to the use of a single frequency band; – reliability values are a function of the desired RF signal-to-noise ratio (user selectable); – the field-strength values should be calculated by the supplied software on the user’s own computer hardware. The software supplied should calculate the relevant reliability values based on these field-strength values and the user-supplied desired RF signal-to-noise values.