Measurements of atmospheric noise levels

Two separate standard equipments have been simultaneously used for the measurement of atmospheric radio noise parameters at Ibadan (7°N, 6°E) during the spring and summer seasons of 1958 to 1961. The first was designed by the Department of Scientific and Industrial Research of Great Britain (D.S.I.R.) for obtaining, by manual operation, the amplitude probability distribution of noise envelopes from which noise parameters may be derived. The second equipment is an automatic noise recorder (ARN-2) designed by the Central Radio Propagation Laboratories of the United States of America (C.R.P.L.). Values of atmospheric noise power and other noise parameters have been directly obtained from the equipment. It is shown that both equipments can be operated to provide consistent and reliable values of atmospheric noise parameters in a tropical area. Comparisons of the results of noise power and r.m.s./average ratios at chosen frequencies (113 kc/s, 11 Mc/s and 20 Mc/s) indicate that the discrepancies are significant only at 20 Mc/s and that at this frequency station interference is the major source of error on the C.R.P.L. equipment.