Double-channel Cancellation Method for Mitigating DPI in PCL

One of the major problems in PCL applications is the direct path interference (DPI). The reflected signal from the target is received at the background of this interference; the target would be buried under the sidelobes of the DPI in the receiver circuit. Conventional solution to this problem is the use of an adaptive antenna, steering null towards the interference. Unfortunately this technology is not always effective. For PCL system based on FM radio the null depth obtained is not enough. This paper proposes a technique of DPI suppression based on double channel cancellation, the full formulation is provided and discussed in detail, it indicates equalization and normalization is necessary before cancellation. At last the cancellation experiment is also considered