User`s guide

3 Working with Signals
3-50
•“Importing a Multichannel Frame-Based Signal” on page 3-68
Overlapping Buffers. In some cases it is useful to work with data that represents
overlapping sections of an original sample-based or frame-based signal. In
estimating the power spectrum of a signal, for example, it is often desirable to
compute the FFT of overlapping sections of data. Overlapping buffers are also
needed in computing statistics on a sliding window, or for adaptive filtering.
The
Buffer overlap parameter of the Buffer block specifies the number of
overlap points, L.
In the overlap case (L > 0), the frame period for the output is (M
o
-L)∗T
si
, where
T
si
is the input sample period and M
o
is the Buffer size.
Note Set the Buffer overlap parameter to a negative value to achieve output
frame rates slower than in the nonoverlapping case. The output frame period
is still T
si
∗(M
o
-L), but now with L < 0. Only the M
o
newest inputs are included
in the output buffer; the previous L inputs are discarded.
Example: Buffering Sample-Based Signals with Overlap. In the following model, a
four-channel sample-based signal with sample period 1 is buffered to a
frame-based signal with frame size 3 and frame period 2. Because of the
overlap, the input sample period is not conserved, and the output sample
period is 2/3.