A method of transmitting digital information comprising: receiving a plurality of information bits representing audio information and/or data; encoding the information bits using low density parity check, LDPC, block coding to produce a composite lower-rate LDPC codeword and a plurality of higher-rate LDPC semi-codewords, wherein each higher-rate LDPC semi-codeword constitutes a valid LDPC codeword on its own, and wherein the lower-rate LDPC codeword is a composite codeword in that the higher-rate LDPC semi-codewords are partitions of the lower-rate LDPC codeword; dividing the information bits into main channel information and backup channel information, wherein the higher-rate LDPC semi-codewords comprise: a main LDPC semi-codeword representing main channel information and a backup LDPC semi-codeword representing backup channel information, wherein the main LDPC semi-codeword and the backup LDPC semi-codeword are non-overlapping partitions of the composite lower-rate LDPC codeword; a lower LDPC semi-codeword representing information to be transmitted on a lower sideband and an upper LDPC semi-codeword representing information to be transmitted on an upper sideband, wherein the lower LDPC semi-codeword and the upper LDPC semi-codeword are non-overlapping partitions of the composite lower-rate LDPC codeword; modulating at least one carrier signal with code bits of the semi-codewords, wherein the main channel information and the backup channel information is modulated on subcarriers in a lower sideband and in an upper sideband of an in-band on-channel radio signal; and transmitting the at least one carrier signal(s), wherein the main LDPC semi-codeword and the backup LDPC semi-codeword are transmitted one after the other, and wherein the lower LDPC semi-codeword and the upper LDPC semi-codeword are transmitted on the upper and lower sideband, respectively. receiving a plurality of information bits representing audio information and/or data; encoding the information bits using low density parity check, LDPC, block coding to produce a composite lower-rate LDPC codeword and a plurality of higher-rate LDPC semi-codewords, wherein each higher-rate LDPC semi-codeword constitutes a valid LDPC codeword on its own, and wherein the lower-rate LDPC codeword is a composite codeword in that the higher-rate LDPC semi-codewords are partitions of the lower-rate LDPC codeword; wherein each higher-rate LDPC semi-codeword constitutes a valid LDPC codeword on its own, and wherein the lower-rate LDPC codeword is a composite codeword in that the higher-rate LDPC semi-codewords are partitions of the lower-rate LDPC codeword; dividing the information bits into main channel information and backup channel information, wherein the higher-rate LDPC semi-codewords comprise: a main LDPC semi-codeword representing main channel information and a backup LDPC semi-codeword representing backup channel information, wherein the main LDPC semi-codeword and the backup LDPC semi-codeword are non-overlapping partitions of the composite lower-rate LDPC codeword; a lower LDPC semi-codeword representing information to be transmitted on a lower sideband and an upper LDPC semi-codeword representing information to be transmitted on an upper sideband, wherein the lower LDPC semi-codeword and the upper LDPC semi-codeword are non-overlapping partitions of the composite lower-rate LDPC codeword; a main LDPC semi-codeword representing main channel information and a backup LDPC semi-codeword representing backup channel information, wherein the main LDPC semi-codeword and the backup LDPC semi-codeword are non-overlapping partitions of the composite lower-rate LDPC codeword; a lower LDPC semi-codeword representing information to be transmitted on a lower sideband and an upper LDPC semi-codeword representing information to be transmitted on an upper sideband, wherein the lower LDPC semi-codeword and the upper LDPC semi-codeword are non-overlapping partitions of the composite lower-rate LDPC codeword; modulating at least one carrier signal with code bits of the semi-codewords, wherein the main channel information and the backup channel information is modulated on subcarriers in a lower sideband and in an upper sideband of an in-band on-channel radio signal; and transmitting the at least one carrier signal(s), wherein the main LDPC semi-codeword and the backup LDPC semi-codeword are transmitted one after the other, and wherein the lower LDPC semi-codeword and the upper LDPC semi-codeword are transmitted on the upper and lower sideband, respectively. wherein the main LDPC semi-codeword and the backup LDPC semi-codeword are transmitted one after the other, and wherein the lower LDPC semi-codeword and the upper LDPC semi-codeword are transmitted on the upper and lower sideband, respectively.