Notched Channel Codes Conversion
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
This invention relates to a method for converting a NRZI code having a DC notch to a NRZI code with a F/2 notch, F being the bit clocking frequency. The method steps comprise changing the polarity of alternate bits in the source codestream, and K-way interleaving of the NRZI codestream with a notch at F/n, yielding a codestream with notch F/kn. In this method, a NRZ code designed to have a notch at DC can be converted to a NRZ code with a notch at F/2. By interleaving, this code can be applied wherever a pilot signal could be inserted in the notch. NRZ codes The NRZ notch converter, which shifts the spectral notch from DC to F/2, changes the polarity of alternate bits in the codestream. An example of NRZ codestream is shown below, along with the converted codestream (Fig. 1).