Communications, Radar & Electronic Warfare (201.. - Index of

VHF to SHF Radio Prediction 181within it. It was principally an urban model, but corrections were added for suburbanand rural environments. The initial model was based on measurementsbetween 150 and 1500 MHz, but the COST 23 1 model extended this to 2000 MHzto account for newer mobile phone frequencies. The original loss equation for urbanenvironments is:L =69.55 + 26.1610glOf - 13.821ogehBs - a(hMS) + (44.9 - 6 .551ogehBS)log lOdwheref is the frequency in MHz.a is a coefficient for the height of the mobile station.hBs is the height of the base station.hMs is the height of the mobile.d is distance in km.Again, this model is terrain independent and provides a generic model to assessrelatively short-range results. It works out the horizon, but some have added diffractionmodelling to extend its range.As well as mobile phone applications, the model can be used for other applicationsthat closely approximate the conditions for which the model was originally developed.This includes assessing the performance of mobile phones used to trigger RCIEDs andthe jammers designed to counter them.10.4. 3 ITU-R P. 1546The ITU-R P. 1546 model is an extension of the ITU-R P. 370 model, which hasbeen used for years to assess long-range interference including cross-borderapplications to assess interference into other countries. Both of these models areintended for interference assessment rather than detailed network design, and theyare both of the same form with the 1546 model including more data input,including clutter options.The models are intended for ranges of 10-10 000 km for transmitters between37.5 and 1200 metres, and for receiving antennas of 10 metres above height althoughcorrections can be added to modify receiver antenna heights. The models werederived from measurements taken over long periods and as such, they take intoaccount not only normal propagation conditions but also variations around themedian loss values. The loss values are presented in graphical format that can bedigitised for computer calculations. These graphs describe median loss for 50% oflocations and time percentages of 50, 10 and 1 % of the time, with losses lower for thesmaller time percentages.