User`s guide

3 Working with Signals
3-28
Example: Buffering with Alteration of the Signal. In the model below, a signal with a
sample period of 0.125 seconds is rebuffered from a frame size of 8 to a frame
size of 16 with an overlap of 4.
The relation for the output frame period for the Buffer block is
which indicates that T
fo
should be (16-4)∗0.125, or 1.5 seconds, as confirmed by
the second Probe block. The sample period of the signal at the output of the
Buffer block is no longer 0.125 seconds, but rather 0.0938 seconds (i.e., 1.5/16).
Thus, both the signal’s data and the signal’s sample period have been altered
by the buffering operation.
Avoiding Unintended Rate Conversions
The previous sections discussed a number of the blocks that are responsible for
rate conversions. It is important to be aware of where in a model these rate
conversions are taking place; in a few cases, unintentional rate conversions can
produce misleading results. The following pair of examples illustrate how
unintended rate conversion can occur:
•“Example 1: No Rate Conversion”
•“Example 2: Unintended Rate Conversion”
Example 1: No Rate Conversion. The model below plots the magnitude FFT of a
signal composed of two sine waves, with frequencies of 1 Hz and 2 Hz.
T
fo
M
o
L–()T
si
=