An interleaved 5-binary to 2-octonary (5B20) block code is proposed to insert carrier and clock pilots in 64-QAM systems with a spectrum efficiency of about 4.5 bit/s/Hz. Its design is based on the rotated and scaled 64-QAM signal constellation. The spectral components of symbol sequences from this encoder are completely suppressed at DC and at the Nyquist frequency (NF).