Sunday, September 23, 2007

IBOC Interference Calculations

The procedure outlined here is intended to estimate the impact on the nighttime groundwave coverage of a Canadian AM station from a U.S. AM IBOC station located on a 1st adjacent channel. Although it is not the only situation that may cause interference, 1st adjacent IBOC is the dominant source of nighttime problems, due to the strength of nighttime skywave and the fact that most of the digital power resides in the 1st adjacent channels. Nearly all of the power that gets dumped into the adjacent channels is in the primary digital sidebands, which are located between 10 and 15 kHz from the carrier frequency of the IBOC station.