Method for reducing the out-of-band emission in AM transmitters for digital transmission
AssigneeDeutsche Telekom AG
InventorsDietmar Rudolph, Andreas Schaefer
Life of this patent
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Abstract
A method for reducing out-of-band emission in an AM transmitter for digital transmission includes generating, from a digital modulation signal, an amplitude signal and a phase-modulated radio frequency signal configured to control the AM transmitter. A digital modulation process is used in which a hole is formed around a 0/0 point so that a zero crossing is avoided by a substantial margin in a vector diagram representation. Thereby a respective bandwidth of the amplitude signal and the phase-modulated radio frequency signal is limited so that the out-of-band emission decreases as a function of a shoulder distance achievable by the AM transmitter at a rate where a spectrum mask is not exceeded.
Claims10
A method for reducing out-of-band emission in an amplitude modulation (AM) transmitter for digital transmission, the method comprising:
- generating, from a digital modulation signal, an amplitude signal and a phase-modulated radio frequency signal configured to control the AM transmitter;
- and
- using a digital modulation process in which a hole is formed around a 0/0 point so that a zero crossing is avoided by a substantial margin in a vector diagram representation so as to limit a respective bandwidth of the amplitude signal and the phase-modulated radio frequency signal so that the out-of-band emission decreases as a function of a shoulder distance achievable by the AM transmitter at a rate where a spectrum mask is not exceeded.
Dependencies are inferred from the claim text.