Apparatus for determining a frequency offset error and receiver based thereon
AssigneeST-Ericsson SA
InventorRoland Egon Ryter
Life of this patent
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Abstract
The apparatus (20) for determining a frequency offset error comprises an input (24.1) for receiving a digitally coded frequency demodulated signal (demod Ip2). The frequency demodulated signal (demod Ip2) is processed by digital means (35) for performing a correlation, and by digital means (36) for performing a minimum-maximum evaluation. In order to determine whether a conflation criterion and a minimum-maximum criterion are fulfilled, the apparatus (20) comprises digital processing means (38) to calculate the current offset of the frequency demodulated signal (demod Ip2) and to cancel the current offset if both criteria are fulfilled.
Claims41
Apparatus for determining a frequency offset error, comprising an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled,
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled, and
- digital processing means for calculating a current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled, wherein the digital means for performing the minimum-maximum evaluation determines whether expected peaks of positive and negative half-waves of the frequency demodulated signal have predefined distances.
A receiver comprising:
- an apparatus for determining a frequency offset error, the apparatus including:
- an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by,
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled, and
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled, said apparatus further comprising digital processing means to calculate the current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled, wherein the digital means for performing the minimum-maximum evaluation determines whether expected peaks of positive and negative half-waves of the frequency demodulated signal have predefined distances.
Apparatus for determining a frequency offset error, comprising an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled, wherein the digital means for performing a correlation comprise a correlator, a peak detector and a comparator,
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled, and
- digital processing means for calculating a current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled.
Apparatus for determining a frequency offset error, comprising an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled,
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled, wherein the digital means for performing a minimum-maximum evaluation comprise two subtractors and two comparator, and
- digital processing means for calculating a current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled.
Apparatus for determining a frequency offset error, comprising an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled,
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled, and
- digital processing means for calculating a current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled, wherein the digital processing means comprise an average detector, an offset register, and an offset compensator to subtract the current offset stored in the offset register from the frequency demodulated signal.
Apparatus for determining a frequency offset error, comprising an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled,
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled,
- digital processing means for calculating the current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled, and
- two comparators serving as limiters followed by building blocks arranged to extract said frequency demodulated signal from a frequency shift keyed modulated signal.
Apparatus for determining a frequency offset error, comprising an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled,
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled,
- digital processing means for calculating the current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled, and
- wherein the digital means for performing a correlation correlates the frequency demodulated signal with a time-limited sine wave signal, and determines whether the result of this correlation exceeds a certain threshold.
Apparatus for determining a frequency offset error, comprising an input for receiving a digitally coded frequency demodulated signal, said frequency demodulated signal being processed by
- digital means for performing a correlation in order to determine whether a correlation criterion is fulfilled,
- digital means for performing a minimum-maximum evaluation in order to determine whether a minimum-maximum criterion are fulfilled,
- digital processing means for calculating the current offset of the frequency demodulated signal and to cancel the current offset if both criteria are fulfilled, and
- wherein the digital means for performing a minimum-maximum evaluation calculates two subtractions in order to compare four received symbols with corresponding amplitudes.
Dependencies are inferred from the claim text.