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delayseq

Delay or advance sequence

Syntax

shifted_data = delayseq(data,DELAY)
shifted_data = delayseq(data,DELAY,Fs)

Description

shifted_data = delayseq(data,DELAY) delays or advances the input data by DELAY samples. Negative values of DELAY advance data, while positive values delay data. Noninteger values of DELAY represent fractional delays or advances. In this case, the function interpolates. How the delayseq function operates on the columns of data depends on the dimensions of data and DELAY:

  • If DELAY is a scalar, the function applies that shift to each column of data.

  • If DELAY is a vector whose length equals the number of columns of data, the function shifts each column by the corresponding vector entry.

  • If DELAY is a vector and data has one column, the function shifts data by each entry in DELAY independently. The number of columns in shifted_data is the vector length of DELAY. The kth column of shifted_data is the result of shifting data by DELAY(k).

shifted_data = delayseq(data,DELAY,Fs) specifies DELAY in seconds. Fs is the sampling frequency of data. If DELAY is not divisible by the reciprocal of the sampling frequency, delayseq interpolates to implement a fractional delay or advance of data.

Input Arguments

data

Vector or matrix of real or complex data. This argument supports single and double precision.

DELAY

Amount by which to delay or advance the input. If you specify the optional Fs argument, DELAY is in seconds; otherwise, DELAY is in samples. This argument supports single and double precision.

Fs

Sampling frequency of the data in hertz. If you specify this argument, the function assumes DELAY is in seconds. This argument supports single and double precision.

Default: 1

Output Arguments

shifted_data

Result of delaying or advancing the data. shifted_data has the same number of rows as data, with appropriate truncations or zero padding.

Examples

collapse all

Delay a cosine signal an integral number of samples.

fs = 1.0e4;
t = 0:1/fs:0.005;
signal = cos(2*pi*1000*t)';

Set the delay to 0.5 ms or 5 samples.

shifted_signal = delayseq(signal,0.5e-3,fs);

Plot the original and delayed signals.

subplot(2,1,1)
plot(t.*1000,signal)
title('Input')
subplot(2,1,2)
plot(t.*1000,shifted_signal)
title('0.5-msec delay')
xlabel('msec')

Delay a 1 kHz cosine signal by a fractional number of samples. Assume a sampling rate of 10 kHz.

fs = 1e4;
t = 0:1/fs:0.005;
signal = cos(2*pi*1000*t)';

Set the delay to 0.25 ms or 2.5 samples.

delayed_signal = delayseq(signal,0.25e-3,fs);

Plot the original signal (blue) and delayed (red) signals.

plot(t.*1000,signal)
title('Delayed Signal')
hold on
plot(t.*1000,delayed_signal,'r')
axis([0 5 -1.1 1.1])
xlabel('msec')
legend('Original Signal','Delayed Signal')
hold off

The values of the delayed signal amplitudes differ from the original signal due to the interpolation used in implementing the fractional delay.

Extended Capabilities

Introduced in R2011a