Direct-path filtering of DAB waveform from PCL receiver target channel

Signal space projection techniques are introduced to filter the direct-path signal component from the passive coherent location (PCL) receiver target channel. Filter performance is characterised using ambiguity function analysis of the digital audio broadcast (DAB) waveform, considered here as a PCL waveform of opportunity. For ideal DAB phase reference synchronisation, the direct-path component is perfectly eliminated. For non-ideal phase synchronisation, the direct-path component is sufficiently attenuated to permit target detection; approximately 22 dB of direct-path signal attenuation is demonstrated.