Abstract: A method of transmitting digital data by radio signals in orthogonal frequency division multiplex (OFDM). Digital data is divided into error protection classes and the power level of the digital data is altered according to the particular error protection class. In addition to the data thus altered, error protection class data is transmitted in a separate logic channel. By using this error protection class data, a reception device is able to reverse this change in power level and perform a correct demodulation. The error protection class data is generated on the basis of the number, length and transmission reliability of the error protection classes and on the basis of transmission parameters. The digital data, divided into frames, is first assigned to services, and then these services are assigned to a corresponding error protection class.

Abstract: A broadband multi-frequency-block Extended Digital Audio Broadcasting X-DAB) transmission method for the interference-free transmission of value-added services at a high data rate to mobile receivers within an analog television channel. At least two simultaneously-broadcast adjacent X-DAB frequency blocks in a single-frequency network are provided. A digital input data stream is multiplexed onto the frequency blocks, with the input data steam being source-coded according to the service content of the input data stream. The input data stream is separated into a plurality of individual dens streams, with the individual data steams each having a respective quality of service importance and being distributed according to the respective quality of service importance among the at least two frequency blocks.

Abstract: A method of transmitting digital data by radio signals in orthogonal frequency division multiplex (OFDM). Digital data is divided into error protection classes and the power level of the digital data is altered according to the particular error protection class. In addition to the data thus altered, error protection class data is transmitted in a separate logic channel. By using this error protection class data, a reception device is able to reverse this change in power level and perform a correct demodulation. The error protection class data is generated on the basis of the number, length and transmission reliability of the error protection classes and on the basis of transmission parameters. The digital data, divided into frames, is first assigned to services, and then these services are assigned to a corresponding error protection class.

Abstract: An improved DAB transmission system with which a higher net data rate can be achieved while maintaining the same system quality, or the same system quality can be achieved with a much lower signal-to-noise ratio on the receiver side at the same net data rate. A symbol mapper is connected directly downstream from a convolution encoder instead of to the block generator; as in the case of prior DAB systems. A multi-stage channel encoder, to which the data substreams of a source data stream are distributed, is used. The source data stream is processed on the complex symbol level and not on the bit level, as in the case of prior DAB systems.

Abstract: A method for transmitting digitally coded data of a radio program (A) is proposed, in which the digitally coded data are modulated by a modulation method, in particular by OFDM. The data are modulated to at least one carrier wave. The data are transmitted in a transmission frame. The method is characterized in that the data of a radio program (A) are transmitted, with at least one repetition, and then are evaluated in common. In this process the complex values (20, 21), which have been furnished by the demodulator circuit (53), are added together.

Abstract: A novel receiver for subcarriers in a radio broadcasting system is described, in which the characteristic frequency of the mixing oscillator is varied under program control. An incoming signal from antenna 1 passes through an input stage 2 to a mixing stage 3. Mixing stage 3 receives the output of an oscillator 4. The output of the mixing stage passes into an intermediate frequency filter stage 5, which preferably includes A/D converters 13 and demultiplexers 14. Stage 5 feeds a plurality of demodulators 6, which may include equalizers 12. Buffer memories 7 store information from demodulated subcarrier signals, and feed an evaluation unit 8. Evaluation unit 8 has a first output which drives a speaker 9 and a second output which is applied to a memory 11. A control unit 10, connected to the output of memory 11, controls the frequency generated by mixing oscillator 4.