Man-Made Noise Level Measurements of the UHF Radio Environment

Manmade noise level measurements have been made of the UHF radio environment over a four month period in Ottawa. The ambient or antenna noise temperature, Ta, has been measured at a number of sites typical of business, residential and rural areas at five frequencies between 600 MHz and 950 MHz. In addition to those made in the urban core, business measurements have also been made on a 4-lane divided highway and on a main arterial road. For each of the areas a minimum of 1800 measurements have been combined to form a cumulative probability distribution which shows the time and location variability of the noise. The highly skewed shape of the distributions, especially those from the business areas, show that the UHF radio environment is composed of a basic background level upon which is superimposed a highly variable man-made level from vehicle ignition noise. This information is important for use in the design of UHF mobile communication systems.