Transmitter With Forward Error Correction Coding for Hybrid AM In-Band On-Channel Digital Audio Broadcasting Systems

A transmitter for broadcasting an AM compatible digital audio broadcasting signal, the transmitter comprising:

• means for producing an analog modulated carrier signal centrally positioned in a radio channel, wherein the analog modulated carrier signal is modulated by an analog signal;
• means for producing a plurality of digitally modulated subcarrier signals in the radio channel, wherein the digitally modulated subcarrier signals are modulated using complementary pattern-mapped trellis code modulation including a code mapped to overlapping partitions;
• and
• means for broadcasting the analog modulated signal and the plurality of digitally modulated subcarrier signals;
• wherein in a first operating mode the analog modulated carrier signal and the plurality of digitally modulated subcarrier signals are in a 20 kHz channel and the analog modulated signal is delayed with respect to the plurality of digitally modulated subcarrier signals, and in a second operating mode the analog modulated carrier signal and the plurality of digitally modulated subcarrier signals are in a 30 kHz channel and a first group of the plurality of digitally modulated subcarrier signals are delayed with respect to a second group of the plurality of digitally modulated subcarrier signals.

A transmitter for broadcasting an AM compatible digital audio broadcasting signal, the transmitter comprising:

• an analog modulator for producing an analog modulated carrier signal centrally positioned in a radio channel, wherein the analog modulated carrier signal is modulated by an analog signal;
• means for producing a first plurality of subcarrier signals in a first portion of the radio channel and a second plurality of subcarrier signals in a second portion of the radio channel, wherein the first and second pluralities of subcarrier signals are complementary modulated subcarrier signals and have a power spectral density below the analog modulated carrier by a first margin;
• means for producing a third plurality of subcarrier signals in a third portion of the radio channel and a fourth plurality of subcarrier signals in a fourth portion of the radio channel, wherein the third and fourth pluralities of subcarrier signals are complementary modulated subcarrier signals and have a power spectral density below the analog modulated carrier by a second margin;
• means for producing a fifth plurality of subcarrier signals in a fifth portion of the radio channel and a sixth plurality of subcarrier signals in a sixth portion of the radio channel, wherein the fifth and sixth pluralities of subcarrier signals have a power spectral density below the analog modulated carrier by a third margin;
• wherein the first, second, third, fourth, fifth and sixth pluralities of subcarrier signals are modulated by one or more digital signals, the first margin is larger than the second margin, and the second margin is larger than the third margin;
• and
• means for transmitting the first, second, third, fourth, fifth and sixth pluralities of subcarrier signals.