Demodulating modulated signals
AssigneeNordic Semiconductor ASA
InventorDaniel Ryan
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Abstract
An apparatus for demodulating a frequency-modulated signal comprises a joint frequency-offset & modulation-index estimator, and a signal demodulator. The joint estimator receives data representative of a preamble portion of the signal, modulated with predetermined preamble data. It jointly determines a frequency-offset estimate and a modulation-index estimate by using an optimization process that minimizes a cost function that is a function of the received data and that is parameterised by a frequency-offset parameter and by a modulation-index parameter. The signal demodulator receives data representative of a message portion of the signal, modulated with message data, and uses the frequency-offset estimate to demodulate the message.
Claims20
An apparatus for demodulating a frequency-modulated signal, the apparatus comprising:
- a joint frequency-offset and modulation-index estimator;
- and
- a signal demodulator,
- wherein the joint frequency-offset and modulation-index estimator is configured to:
- receive data representative of a preamble portion of the frequency-modulated signal, wherein the preamble portion is modulated with predetermined preamble data;
- and
- jointly determining a frequency-offset estimate and a modulation-index estimate by using the received data to perform an optimization process, wherein the optimization process minimizes a cost function that is a function of the received data and that is parameterised by a frequency-offset parameter and by a modulation-index parameter,
- and wherein the signal demodulator is configured to:
- receive data representative of a message portion of the frequency-modulated signal, wherein the message portion is modulated with message data;
- and
- use the frequency-offset estimate to demodulate the message.
A method of demodulating a frequency-modulated signal, the method comprising:
- receiving data representative of a preamble portion of the frequency-modulated signal, wherein the preamble portion is modulated with predetermined preamble data;
- jointly determining a frequency-offset estimate and a modulation-index estimate by using the received data to perform an optimization process, wherein the optimization process minimizes a cost function that is a function of the received data and that is parameterised by a frequency-offset parameter and by a modulation-index parameter;
- receiving data representative of a message portion of the frequency-modulated signal, wherein the message portion is modulated with message data;
- and
- using the frequency-offset estimate when demodulating the message portion.
Dependencies are inferred from the claim text.