An interference removal technique, called Wavelet-Adaptive Interference Cancellation for Underdetermined Platforms (WAIC-UP), is provided to effectively eliminate stray magnetic field signals using multiple magnetometers, without requiring prior knowledge of the spectral content, location, or magnitude of the interference signals. WAIC-UP capitalizes on the distinct spectral properties of various interference signals and employs an analytical method to separate them from ambient magnetic field in the wavelet domain.