Whitening and Interleaving Operations for Modems
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
In a modem transmitter the data bit flow is split into fixed length groups of bits, each group of bits being used to define a symbol selected within a two-dimensional constellation of symbols and the components of the selected symbol are used to modulate quadrature component carriers. In a number of cases, the conversion from a group of bits to a symbol involves a convolutional encoding of predetermined bits of each group of bits, and then the encoded bits and the remaining non-encoded bits are used to address a ROM (read-only memory) providing the corresponding symbol coordinates. This symbol is then used to modulate carriers using, for instance, the DSB-QC techniques, before being transmitted over a transmission line toward the receiver.