Method and apparatus for estimating power of first adjacent analog FM interference in an in-band on-channel (IBOC) communication system

Abstract

A method and apparatus are disclosed for estimating the power of the first adjacent FM interference and for using the estimated power to identify the number of OFDM bins that are at least partially corrupted by the first adjacent FM interference. The number of corrupted bins, Ncorr, is obtained based on measurements of the power of each of the first adjacent FM analog interference, Ik, and the power of the background noise, Nk, of the digital side bands. The power measurements, together with the known slope of the first adjacent FM analog interference, is used to identify when the power of the measured background level equals the prorated power of the slope. All of the bins that fall below a threshold value are determined to be at least partially corrupted. The FFT output provides the power of the first adjacent FM analog interference, Ik, measured, for example, at ±200 kHz, and the power of the background noise, Nk, of each of the digital side bands, measured, for example, at 130 kHz and −130 kHz. In a hard-masking implementation, the corrupted bins are discarded (set to zero) and in a soft-masking implementation, the partially corrupted bins are scaled according to the interference slope before further processing, for example, by the Viterbi decoder.

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