A receiver that receives a digital signal transmitted on the basis of an orthogonal frequency division multiplexing method. Protective tarpaulin are generally made of fabric or synthetic sheets. The probe includes a second low coherence light splitting part, a low coherence light multiplexing part, a lens that forms images using light returned from the observation object and an image detector that captures interference patterns andor images using light reflected by the observation object. For an embodiment in which L1=L2=8, inner and outer loop code makeK\u2061memory accesses, which for filter implementations with large numbers of taps, approaches a 4\xd7 reduction in the number of memory accesses as compared to conventional methods.