Structural Health Monitoring Using Smart Sensors - ideals ...

The 1st block
Original signal
t
t last
current
t1+T2 - t last
tlast
N
l i
t1+T2
Resampled signal
t current
Figure 5.27. Resampling of the first block of data.
Resampling for
the i-th blcok
x prev
[n] x current
[n] x next
[n]
x’[n]
Original signal
t
t last
last, resample
t current
Resampled signal
t t N
1
current
last
N
t last
-t last, resample
1
fs
l i
Figure 5.28. Resampling of the i-th block of data (i>1).
t current
– t last
fs current
= --------------------------
N data
(5.23)
The sampling rate conversion by a factor
is determined by
L a
M r
is applied to the block of data. The factor
L a
= fs d s
M r
= fs current
d s
(5.24)
where d s
is the common denominator introduced to have the integer, L a
, in an
appropriate range. fs is the sampling rate after the rate conversion. l i
in Eq. (5.21) for the
first block of data is t ini
. For the subsequent blocks, l i
is determined by the time of the last
resampled signal of the previous block, . Because Eq. (5.21) requires xm in
t last,resample
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