Browse Prior Art Database

Notched Channel Codes Conversion

IP.com Disclosure Number: IPCOM000047260D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Siegel, PH: AUTHOR

Abstract

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).

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Notched Channel Codes Conversion

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). Original: 1 1 -1 1 -1 -1 -1 1

Converted: 1 -1 -1 -1 -1 1 -1 -1 This modification of the codestream effects the notch shift. NRZI Codes (ZM) A similar conversion will shift the DC notch in the ZM spectrum to a notch at F/2. The converter differs from the NRZ notch converter because NRZI codes have symbols 0 and 1, with 0 corresponding to no change in polarity in the write current waveform, and 1 corresponding to a change (transition) in polarity. The principle underlying the two conversions is, however, the same. The NRZI notch converter adds 1 (modulo 2) to each bit in the NRZI codestream. That is, it changes each 0 to a 1, and each 1 to a
0. An example of NR...