Diadem - Data reduction timestamp problem

[SukramNotna]

Hi together,

try to find the best way to reduce my tons of tdms-data 🙂

Situation: Many TDMS-File appended to one file. Then the next step is the data reduction of that file with e.g. an interval width of 100 building the 1st value & min & max value. That produces three channels with the data. So far so good.

BUT the problem is now: If I compare the min/max channel with the original channel I see that the time stamps are NOT matching! The min/max channel includes the correct values but the timestamp is not correct. That couldnt be correct or something is here wrong?!

Does anybody know what is beyond?

Thanks,

Markus

[AndreasK]

>> The min/max channel includes the correct values but the timestamp is not correct

Could you explain what this means?

• Is there a resolution issue?
• What differs?
• How is calculation done?
• Can you provide example data?

[SukramNotna]

---

@AndreasK wrote:

>> The min/max channel includes the correct values but the timestamp is not correct

Could you explain what this means?

• Is there a resolution issue?
• What differs?
• How is calculation done?
• Can you provide example data?

---

Ok, let me explain from the beginning and make an example. I have a channel of voltage values with an index of 100. And a channel for the time. The 100 time values have not a constant distance between. It is around 1sec but it differ a bit from 1 to 2 sec.

Alright - now I want to reduce that data of 100 values. For example give me the maximum of each 10 values. (data reduction possibility at the diadem navigator). That creates a channel of 10 values and of course a smaller file size.

It is done correctly - the diadem function of datareduction captures the maximum out of it. But if you compare then the timestamp of that found maximum (in the 10 values channel) with the original file (with 100 values) the absolute timestamp is not the same!

For example at the 01.01.2017 at 12:00:00 there is a maximum at the original 100 values-file which was found and picked. The reduced file with 10 values have e.g. 12:00:01 or 11:00:59 or whatever. That's what I mean and cant explain why there is a shift here.

[AndreasK]

Could you provide example data and a little script showing the effect.

Which version of DIAdem are you using?

[SukramNotna]

Honestly it is to much data but here you can see what I mean. There is no script behind only in the NAVIGATOR - right click - data reduction.

The red graph is the original data with many data points. The green one is the reduced one and captures every 100 values of the red graph the maximum. U can see that it takes the maximum values but shiftet in the time-axis! And it is changing...the shift is not always the same. Only systematic what I see the green (maximum chanel) is shifted to the right at the time axis. The minimum found values (not shown here) are shifted to the left.

By the way - after reducing the green original channel - the new two reduced channels (min&max) have new time channels but that's clear I think.

[AndreasK]

Now I got it. I assume it is a missunderstanding.

Time_Min and Time_Max are not the position of the Minimum/Maximum but the start and the end of the interval by means of [time_min-time_max].

So there is no shift but it is a matter of the choosen X-Axis.

This is done because when reducing huge amounts of data a single point is normally displayed by a line between min and max value on a given time interval.

[SukramNotna]

But what can I do if I want to see the real time of the MAX-Event? Here I cant trust in the time of the max-event...but I want to know that info 🙂

---

[AndreasK]

I assume the Reduction is not the right method for this. You need "Peek find" or "Event match" functionality.

[SukramNotna]

But the data reduction was my main intension. I have too much data to work with...

[AndreasK]

How about using "Resampling"?

ChnResampleFreqBased

After the complete append mode is finished.