Abstract
Spectral shaping codes are digital codes especially
designed in such a manner that their alphabets give rise to
predetermined frequency spectrum envelopes. This implies that
the signal energy of these alphabets will be concentrated into a
predetermined range of a given frequency spectrum. The design of
digital codes in the above mentioned fashion is done in order to
match specific channel constraints in the design of transmission,
multiplexing or storage systems. In certain applications it is
desirable that spectral shaping codes provide some error
correction capability or that they possess an increased robustness
to errors. These errors may be introduced during transmission,
processing or storage of digital information. In this paper, an
interleaving method is introduced to increase the robustness of DC
free codes toward burst errors whilst maintaining the spectral
shaping property of DC free codes. Interleaving when applied to a
coded communication system results in a reduction in the mean bit
error rate (BER) of coded bit streams.