Peak-to-average power ratio reduction for hybrid FM HD radio transmission

A transmitter for reducing peak-to-average power ratio in an OFDM signal, the transmitter comprising:

• a modulator for modulating a set of subcarriers with a set of data symbol vectors including an OFDM symbol vector and an FM symbol vector to produce a modulated OFDM symbol and a modulated FM symbol;
• processing circuitry for combining the modulated OFDM symbol and the modulated FM symbol to produce a modulated hybrid symbol, limiting the magnitude of the modulated hybrid symbol to produce a first limited modulated hybrid symbol, demodulating the first limited modulated hybrid symbol to recover distorted QPSK constellations, constraining the distorted QPSK constellations recovered from the first limited modulated hybrid symbol to values greater than or equal to a minimum threshold value to produce constrained QPSK constellations in a hybrid symbol vector, demodulating the FM hybrid symbol to produce an FM symbol vector, subtracting the FM symbol vector from the hybrid symbol vector to produce an OFDM symbol vector, applying a mask to inactive subcarriers in the OFDM symbol vector, modulating the OFDM symbol vector to produce a modulated OFDM symbol, combining the modified modulated OFDM symbol vector with the modulated FM symbol to produce a modified modulated hybrid symbol, and outputting the modified modulated hybrid symbol;
• and
• an amplifier for amplifying the modified modulated hybrid symbol.