SWCtruncated

function [U] = SWCtruncated(t,Wtrue,Signal) Used to get the harmonic component (amplitude and phase) of the Signal at frequency Wtrue

Extracts the harmonic component of the Signal at angular frequency Wtrue. Can be used as sinusoid amplitude and phase estimator if frequency is known or as a narrowband filter extracting particular frequency component from the signal. Equivalent to Fourier transform, just frequency is not limited to Fourier bins.

Uses sine wave correlation (SWC). More details in:

L.Svilainis, et al. The Automated Complex Impedance Measurement System. Electronics and Electrical Engineering. 2007. Nr. 4(76),pp. 59-62. Available at: http://eejournal.ktu.lt/index.php/elt/article/view/10720

Other m-files required: none

Subfunctions: none

MAT-files required: none

Authors: Linas Svilainis

Kaunas University of Technology, Dept. of Electronics Engineering,

Kaunas, Lithuania

email address: [e-mail]

December 2006; Last revision: 10-Jul-2018

Copyright: Linas Svilainis

Syntax: [U] = SWCtruncated(t,Wtrue,Signal)

Inputs:

Signal - (1,N) array of sampled signal values

t - time axis,(1,N) array, must be same length as Signal

Wtrue - angular frequency for estimation (2*pi*F)

Outputs:

U - measured complex amplitude of the sinusoid

Notes:

The more periods you record the better is noise or other frequencies rejection, the better estimation accuracy;

Recond length is truncated to aproximately fit the integer number of frequency Wtrue periods;

Time axis t must be sampled equally;

Example (TestSWC)

clear all

fsampl=100e6;%sampling frequency is 100MHz

f0=1.3012e6;%sinusoid frequency is 1.3012MHz

phi=30/180*pi;%sinusoid phase is 30deg

Um=0.141;%sinusoid amplitude is 0.141V

N=100;%record length is 1000 samples

%make time axis:

t=(0:(N-1))/fsampl;

%generate test signal:

MySignal=Um*cos(2*pi*f0*t+phi);

%add some noise:

MySignal=MySignal+0.01*randn(1,N);

%estimate signal amplitude and phase:

Uest = SWCtruncated(t,2*pi*f0,MySignal);

Umag=abs(Uest)

Uph_rad=angle(Uest)

Uph_deg=Uph_rad/pi*180

%plot the raw signal and estimated harmonic component:

figure(1)

plot(t*1e6,MySignal,'r',t*1e6,Umag*cos(2*pi*f0*t+Uph_rad),'k')

xlabel('Time, us')

ylabel('Amplitude, V')

grid on

axis tight