Demodulator for signal which is frequency modulated by digital data
AssigneeThomson-CSF
InventorJean P. Dehaene
Life of this patent
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Abstract
In a device comprising a linear frequency demodulator, the demodulation threshold is improved for demodulation of signals which have been modulated by a digital data item and have an energy line at the carrier frequency. To this end, the received modulated signal is not applied directly to the demodulator but added within an adder circuit to a signal corresponding to the carrier-frequency line which is obtained by means of a carrier recovery circuit. The output signal of the adder circuit is applied to the input of the linear frequency demodulator.
Claims2
A device for demodulating a modulated signal resulting from frequency modulation of a carrier by a digital data item and having a spectral line at the carrier frequency, wherein said device comprises:
- an adder circuit having a first input for receiving the modulated signal, a second input and an output,
- carrier recovery means for receiving the modulated signal and having one output coupled to the second input of the adder circuit;
- and a linear frequency demodulator having one input coupled to the output of the adder circuit.
Dependencies are inferred from the claim text.