System and method for demodulating an incoming signal
First Claim
1. A method for correlating an incoming signal with pseudonoise (PN) codes, comprising:
- receiving real/imaginary (I/Q) baseband samples in the I/Q domain;
converting the I/Q baseband samples to phase baseband samples;
generating, by a PN code generator, a PN code;
converting the PN code to PN phase data;
performing, by a correlator circuit, a correlation on the phase baseband samples using the PN phase data to generate correlated I/Q values, wherein performing the correlation includessubtracting the PN phase data from the phase baseband samples to generate a current residual signal,subtracting a correction value from the current residual signal to generate correlated phase values, wherein the correction value is one of;
a current frequency offset, an immediately previous residual signal, or an older residual signal generated prior to the immediately previous residual signal, andconverting the correlated phase values to the correlated I/Q values;
performing an adding operation on the correlated I/Q values to generate demodulated I/Q values;
converting the demodulated I/Q values into demodulated phase values;
performing, by a frequency correction circuit, a frequency correction operation on the demodulated phase values to generate frequency correction data;
converting the demodulated I/Q values into demodulated magnitude values; and
performing signal decoding and synchronization on the magnitude values to generate output data,wherein the operation of performing correlation on the phase baseband samples using the PN phase data is accomplished using scalar subtraction.
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Abstract
Methods and receiver circuits are provided for correlating an incoming signal with PN codes. An embodiment of the method includes receiving I/Q baseband samples in the I/Q domain; converting the I/Q baseband samples to phase baseband samples; generating a pseudonoise (PN) code; converting the PN code to PN phase data; performing a correlation on the phase baseband samples using the PN phase data to generate correlated I/Q values; performing an adding operation on the correlated I/Q values to generate demodulated I/Q values; converting the demodulated I/Q values into demodulated phase values; performing a frequency correction operation on the demodulated phase values to generate frequency correction data; converting the demodulated I/Q values into demodulated magnitude values; and performing signal decoding and synchronization on the magnitude values to generate output data. The operation of performing correlation on the phase baseband samples using the PN phase data is accomplished using scalar subtraction.
19 Citations
17 Claims
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1. A method for correlating an incoming signal with pseudonoise (PN) codes, comprising:
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receiving real/imaginary (I/Q) baseband samples in the I/Q domain; converting the I/Q baseband samples to phase baseband samples; generating, by a PN code generator, a PN code; converting the PN code to PN phase data; performing, by a correlator circuit, a correlation on the phase baseband samples using the PN phase data to generate correlated I/Q values, wherein performing the correlation includes subtracting the PN phase data from the phase baseband samples to generate a current residual signal, subtracting a correction value from the current residual signal to generate correlated phase values, wherein the correction value is one of;
a current frequency offset, an immediately previous residual signal, or an older residual signal generated prior to the immediately previous residual signal, andconverting the correlated phase values to the correlated I/Q values; performing an adding operation on the correlated I/Q values to generate demodulated I/Q values; converting the demodulated I/Q values into demodulated phase values; performing, by a frequency correction circuit, a frequency correction operation on the demodulated phase values to generate frequency correction data; converting the demodulated I/Q values into demodulated magnitude values; and performing signal decoding and synchronization on the magnitude values to generate output data, wherein the operation of performing correlation on the phase baseband samples using the PN phase data is accomplished using scalar subtraction. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A receiver circuit, comprising:
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a first conversion circuit configured to convert received real/imaginary (I/Q) baseband samples in the I/Q domain to phase baseband samples in the phase domain; a symbol buffer configured to store one symbol length of phase baseband samples; a pseudonoise (PN) code generator configured to generate a PN code; a correlator circuit configured to correlate one symbol length of the phase baseband samples with the PN code in the phase domain to generate correlated I/Q data using frequency correction data, wherein the correlator comprises N correlator sub-blocks connected in series with each other, an ith correlator sub-block including; an ith PN conversion circuit configured to convert the PN code to ith PN phase data, an ith PN subtractor configured to subtract the ith PN phase data from an ith portion of the phase baseband samples to generate an ith residual signal, an ith correction subtractor configured to subtract an ith correction value from the ith residual signal to generate an ith correlated phase value, and a phase conversion circuit configured to convert the ith correlated phase value to an ith correlated I/Q value, wherein the ith correction value is one of;
an ith frequency offset, an (i-1)th residual signal, or an (i-x)th residual signal,wherein i is an integer that varies from 1 to N, and wherein x is an integer greater than 1; an I/Q adder tree configured to perform an adding operation on the correlated I/Q data to generate demodulated I/Q data; a second conversion circuit configured to convert the demodulated I/Q data to demodulated magnitude data and demodulated phase data; a frequency correction circuit configured to generate the frequency correction data based on the demodulated phase data; and a symbol decode and synchronization circuit configured to generate decoded output data based on the demodulated magnitude data, wherein the correlator circuit is configured to correlate the phase baseband samples with the PN code using scalar subtraction. - View Dependent Claims (8, 9, 10, 11)
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12. A receiver circuit, comprising:
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means for receiving real/imaginary (I/Q) baseband samples in the I/Q domain; means for converting the I/Q baseband samples to phase baseband samples; means for generating a pseudonoise (PN) code; means for converting the PN code to PN phase data; means for performing a correlation on the phase baseband samples using the PN phase data to generate correlated I/Q values, wherein the means for performing a correlation further comprises; means for subtracting the PN phase data from the phase baseband samples to generate a current residual signal, means for subtracting a correction value from the current residual signal to generate correlated phase values, wherein the correction value is one of;
a current frequency offset, an immediately previous residual signal, or an older residual signal generated prior to the immediately previous residual signal, andmeans for converting the correlated phase values to the correlated I/Q values; means for performing an adding operation on the correlated I/Q values to generate demodulated I/Q values; means for converting the demodulated I/Q values into demodulated phase values; means for performing a frequency correction operation on the demodulated phase values to generate frequency correction data; means for converting the demodulated I/Q values into demodulated magnitude values; and means for performing signal decoding and synchronization on the magnitude values to generate output data, wherein the means for performing correlation on the phase baseband samples using the PN phase data is configured to perform the correlation using scalar subtraction. - View Dependent Claims (13, 14, 15, 16)
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17. A receiver circuit, comprising:
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means for receiving real/imaginary (I/Q) baseband samples in the I/Q domain; means for converting the I/Q baseband samples to phase baseband samples; means for generating a pseudonoise (PN) code; means for converting the PN code to PN phase data; means for performing a correlation on the phase baseband samples using the PN phase data to generate correlated I/Q values, wherein the means for performing a correlation is further configured to generate a plurality of sets of correlated I/Q values, and wherein the means for performing a correlation is further configured to perform the correlation using scalar subtraction; means for performing an adding operation on the correlated I/Q values to generate demodulated I/Q values; means for converting the demodulated I/Q values into demodulated phase values; means for performing a frequency correction operation on the demodulated phase values to generate frequency correction data, wherein the means for performing a frequency correction operation is further configured to convert the plurality of sets of correlated I/Q values to a plurality of sets of frequency correction data, and a final set of frequency correction data is selected to be a set of frequency correction data associated with a set of correlated I/Q values having a largest correlation magnitude; means for converting the demodulated I/Q values into demodulated magnitude values; and means for performing signal decoding and synchronization on the magnitude values to generate output data.
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Specification