Remedying low densities of ONEs in transmission and reception of digital television signals

摘要

In a DTV transmitter the bits of shortened BCH codewords that exhibit undesirably low densities of ONEs are ONEs' complemented before being further coded, and used to modulate carrier waves. In a DTV receiver the further coding is decoded after demodulation. The results of such decoding are processed to recover successive shortened BCH codewords, some of which are in TRUE form and others of which have had their bits ONEs' complemented. Each shortened BCH codeword is extended to full length with ZEROs, and decoding is attempted. Successful decoding confirms that the shortened BCH codeword was received in TRUE form. If decoding is unsuccessful, the bits of the shortened BCH codeword as received are ONEs' complemented, extended to full length with ZEROs, and decoding is attempted. Successful decoding confirms that the shortened BCH codeword was received in ONEs' complemented form and has subsequently been converted to TRUE form.

主权项

1. Receiver apparatus for digital television signals that transmit via an orthogonal frequency-division modulated carrier wave of electromagnetic energy successive shortened Reed-Solomon (RS) codewords encoding respective lateral-data packets, selected ones of which shortened RS codewords have had their bits ONEs' complemented, said receiver apparatus comprising:
a tuner for converting a selected orthogonal frequency-division modulated carrier wave of electromagnetic energy modulated in accordance with a digital television signal to a baseband digital television signal; a decoder for decoding forward-error-correction coding of bits of said baseband digital television signal, thus to recover byte-interleaved shortened RS codewords, selected ones of which shortened RS codewords were transmitted after having had their bits ONEs' complemented; a byte de-interleaver for de-interleaving said byte-interleaved shortened RS codewords, thus to recover successive shortened RS codewords, selected ones of which were transmitted after having had their bits ONEs' complemented; RS decoding apparatus configured for determining whether each of said successive shortened RS codewords was transmitted after said having had its bits ONEs' complemented, attempting to decode each of said successive shortened RS codewords to reproduce with possible corrections of any erroneous bytes therein a respective lateral-data packet coded within each of said successive shortened RS codewords whether or not that said successive shortened RS codeword had the bits thereof ONEs' complemented before its transmission, and determining which ones of said respective lateral-data packets as so reproduced are correct for being free of any detectable byte errors in bytes thereof; and further receiving apparatus for utilizing ones of said lateral-data packets as so reproduced by said RS decoding apparatus, including at least those that are determined to be correct.