| 摘要 |
<p>A converted digital signal is provided in NRZI code with a DC component of zero and with a maximum of four bits between level transitions in the signal by dividing the base digital signal into eight-bit base words, each of which is then converted into a ten-bit word signal that has 1024 (210) possible combinations, of which there are 193 that begin with no more than two digital zeros, end with no more than one digital zero, have no more than three consecutive digital zeros anywhere else, and have a DC component of zero when NRZI coded, and each of which is used to represent one eight-bit base word. Each of the remaining 63 of the total 256 (28) base words is converted into a secondary ten-bit combination having a "convention" DC component of +2 or -2. The number of level transitions in the converted, NRZI-coded digital signal are detected up to the end of the ten-bit combination immediately preceding the next secondary combination and, depending on the number of level changes, the first bit of the next secondary combination is provided to give it a convention DC component, thereby eliminating the DC component in that portion of the signal.</p> |
