50 lines
1.6 KiB
Matlab
50 lines
1.6 KiB
Matlab
function [dataOut, fdTarget, samplePosTarget] = suqareShapeFreqEst(dataIn, interp, fs, fmin, fmax, fd)
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%suqareShapeFreqEst - 利用星座图的集中程度在一定频率范围内使用频率步进估计方波成形信号的频偏
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%
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% data - input complex data, row vector
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% dataLen - data length
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% interp - interpolation rate
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% fs - sampling rate, in Herts
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% fmin - minimum estimation frequency, in Herts
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% fmax - maximum estimation frequency, in Herts
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% fd - estimation frequency step, in Herts
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% dimension
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[dataLen,channelNum] = size(dataIn);
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freqList = fmin:fd:fmax;
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freqNum = length(freqList);
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varRecord = zeros(freqNum,interp);
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dataOut = zeros(dataLen/interp,channelNum);
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fdTarget = zeros(channelNum,1);
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samplePosTarget = zeros(channelNum,1);
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for channel = 1:channelNum
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for freq = 1:freqNum
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% carrier
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cxr = exp(-1i*2*pi*freqList(freq)/fs*(0:dataLen-1)');
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% apply frequency shift onto input data
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seqRx = dataIn(:,channel).*cxr;
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for samplePos = 0:interp-1
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seqRxDown = downsample(seqRx,interp,samplePos); % 下采样
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seqRxDownQuaterOne = abs(real(seqRxDown)) + 1i*abs(imag(seqRxDown)); % 集中到第一象限
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varRecord(freq,samplePos+1) = var(seqRxDownQuaterOne);
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end
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end
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[fdIndex, samplePosIndex] = find(varRecord==min(min(varRecord)));
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fdTarget(channel) = freqList(fdIndex);
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samplePosTarget(channel) = samplePosIndex-1;
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cxrTarget = exp(-1i*2*pi*fdTarget(channel)/fs*(0:dataLen-1)');
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seqRxTarget = dataIn(:,channel).*cxrTarget;
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dataOut(:,channel) = downsample(seqRxTarget,interp,samplePosTarget(channel));
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end
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end |