rms 公式 有效值_信号的有效值(RMS)估计

% Root Mean Square Value

function [retval] = rms1(sig)

N = 20;

for k = 1 : length(sig)/N - 1

sig_sum = sum(sig((k-1)*N+1 : k*N));

squ_sum = sum(sig((k-1)*N+1 : k*N).**2);

retval(k) = sqrt(squ_sum/N);

end

endfunction

% Root Mean Square Value of AC

function [retval] = rms2(sig)

N = 20;

for k = 1 : length(sig)/N - 1

sig_sum = sum(sig((k-1)*N+1 : k*N));

squ_sum = sum((sig((k-1)*N+1 : k*N) .- sig_sum/N).**2);

retval(k) = sqrt(squ_sum/N);

end

endfunction

% Root Mean Square Value of AC

function [retval] = rms3(sig)

N = 20;

for k = 1 : length(sig)/N - 1

sig_sum = sum(sig((k-1)*N+1 : k*N));

squ_sum = sum(sig((k-1)*N+1 : k*N).**2);

retval(k) = sqrt((squ_sum - sig_sum)/N);

end

endfunction

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Fs = 1e5;

N = 1000;

t = [0 : 1/Fs : (N-1)/Fs];

x = 2 * 1.414 * cos(2*pi*25e3*t) .+ 2 * 1.414 * cos(2*pi*10e3*t) + 1.0;

figure;

subplot(2,2,1)

plot(x(1:50));

grid on;

subplot(2,2,2);

plot(rms1(x));

grid on;

subplot(2,2,3);

plot(rms2(x));

grid on;

subplot(2,2,4);

plot(rms3(x));

grid on;