Synchronous Time Averaging

[hyin]

Hi all,

I wish to do synchronous time averaging where the signal is acquired if the trigger function detects a rising pulse from a tachometer.

My problem is when I add the current signal and previous signal together, there is no signal output after the add function.

I'm using a shift register to accumulate signals for every iteration.

Can anybody help me in solving this?

Thank you.

Regards,

Hyin

[GerdW]

Hi Hyin,

adding something to an empty array results in an empty array...

You have to initialize your shift register (or use a case structure to handle the initial iteration). Right now your VI will start with an uninitialized (and thus "empty") shift register!

[hyin]

Hi Gerd,

I thought when I add an array with an empty array will result in the array itself. How come it can become zero?

Can I know how to initialize the shift register? I try to add a constant outside of the loop, but it doesn't work as well.

[GerdW]

Hi Hyin,

adding arrays with different size (=length) will result in an array with the smaller size of both the input arrays, so adding with an empty array will always yield in an empty array...

You should use a case structure to avoid adding in the first iteration!

[hyin]

Hi Gerd,

I add a case structure to pass the signal out when the iteration number is zero, and add the signal when the iteration number more than zero, and it works well.

Now I can do time averaging alrd.

Thank you very much!

I wish to ask one more question.

I tried to use the "time averaging function" in the signal express before and it doesn't do the right averaging. I mean it doesn't synchronize the signals when it perform the averaging.

Do you know why? 

[GerdW]

Hi Hyin,

I don't use SignalExpress, maybe you should ask in that forum?