Longley–Rice model

The Longley–Rice model (LR) is a radio propagation model: a method for predicting the attenuation of radio signals for a telecommunication link in the frequency range of 20 MHz to 20 GHz. The Longley–Rice model (LR) is a radio propagation model: a method for predicting the attenuation of radio signals for a telecommunication link in the frequency range of 20 MHz to 20 GHz. Longley-Rice is also known as the irregular terrain model (ITM). It was created by scientists Anita Longley and Phil Rice of the then Central Radio Propagation Laboratory in Boulder, CO for the needs of frequency planning in television broadcasting in the United States in the 1960s and was extensively used for preparing the tables of channel allocations for VHF/UHF broadcasting there. LR has two parts: a model for predictions over an area and a model for point-to-point link predictions. A description of the method was published by the U.S. government under the title 'Prediction of tropospheric radio transmission loss over irregular terrain. A computer method-1968', A. G. Longley and P. L. Rice, ESSA Tech. Rep. ERL 79-ITS 67, U.S. Government Printing Office, Washington, DC, July 1968. This document followed on an earlier publication titled 'Transmission loss predictions for tropospheric communication circuits', P.L. Rice, Volume I & II, National Bureau of Standards, Tech. Note 101.