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From: SamU on 21 Feb 2010 23:57
Hi everyone,

So I have two data sets recorded at different sampling frequencies. I interpolated one sample from 100Hz to 200Hz, to give me two data sets at 200Hz. I have a problem in that the two data sets have a different amount of numbers in them. One has 202, and the other has 223. Is there a way in signal processing to either interpolate or decimate the numbers to get the samples the same length? Thus normalising the data, in my case, to gait cycle percentage?

Thanks again,

Sam.
From: Jan Simon on 22 Feb 2010 11:45
Dear SamU!

> So I have two data sets recorded at different sampling frequencies. I interpolated one sample from 100Hz to 200Hz, to give me two data sets at 200Hz. I have a problem in that the two data sets have a different amount of numbers in them. One has 202, and the other has 223. Is there a way in signal processing to either interpolate or decimate the numbers to get the samples the same length? Thus normalising the data, in my case, to gait cycle percentage?

You can interpolate the data to get exactly 101 data points using INTERP1.

Kind regards, Jan
From: Rune Allnor on 22 Feb 2010 11:59
On 22 Feb, 15:57, SamU <samuel.ur...(a)unn.ac.uk> wrote:
> Hi everyone,
>
> So I have two data sets recorded at different sampling frequencies. I interpolated one sample from 100Hz to 200Hz, to give me two data sets at 200Hz.. I have a problem in that the two data sets have a different amount of numbers in them. One has 202, and the other has 223. Is there a way in signal processing to either interpolate or decimate the numbers to get the samples the same length? Thus normalising the data, in my case, to gait cycle percentage?

If the signals are sampled at the same rate and are of different
length, then the reason is that the data sets are of different
durations.

The only way to match up the data durations is to

1) Extract a subsequence from the longer data set, thus
wasting measured data

2) Extrapolate the shorter data set, thus introducing
errors and artefacts.

Those are the choises you have, if you insist on matching up
the data sequences.

Rune
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