Indoor noise measurements in medium wave band

Updated reference indoor radio noise values in the medium wave band are provided. The results are based on an extensive trial: 339 locations in buildings located in two cities in the north of Spain gathering data at frequencies of 630, 675, 1035, 1242, and 1620 kHz. The increase in absolute noise levels as well as location variability values has been found significant if they are compared to values reported in ITU-R P.372 and other recently published values for measurements outdoors. These results are essential for planning upcoming digital broadcasting services (In Band On Channel HD-RADIO and Digital Radio Mondiale) to receivers located indoors. Provided is a prediction formula as a function of the frequency obtained from measurements by multiple regressions, differentiating households from office buildings, where noise levels have been found noticeably higher.