tricky graphing question

[PFITZ]

Hi all,

I have a set of data which has been generated by a DAQ card, which is
essentially a 50Hz sine wave, I was sampling at 1KHz, so I have
exactly 20 data points per period.

My frequency & phase are constant but my amplitude and duty cycle are
variable. Currently I have thousands of Y values and each one
corresponds to a unique X(time) value corresponding to each subsequent
millisecond.

What I would like to do is view my data in such a way as it is
superimposing each 20 datapoint period of my sine wave on top of the
previous one, ie after every 20 datapoints, I'd like the graph to
begin from zero again.

So that my graph would consist of 1-20 on the X scale, and have
hundreds of individual data series, each of 20 datapoints.

Is there any graphing option to allow this in excel?

Thanks

PFITZ

 

[GerryGerry]

I'm a little unclear from your description as to how the data is currently
laid out, by assuming it is a long list of values pairs (time in col. A and
value in col. B), you could use the folowing formula to display the data in
a more 'rectangular' form:
=INDIRECT("B" & (COLUMN()-1)*20 + ROW())
place this to the left of the data and copy this down 20 row then copy
across as many columns as needed. You can then use the newly created table
as the basis for a multi line graph

 

[GerryGerry]

I should have said place the formula to the RIGHT of the data

 

[PFITZ]

Hi Gerry,

Yes that's how I've the data arranged, do I need to modify your
formula in any way?

It doesn't seem to do what I expect, although it is doing something.
It seems to be repeating the same values after a while.

 

[GerryGerry]

Before it starts repeating is it getting it right? also at what point does
it repeat


Hi Gerry,

Yes that's how I've the data arranged, do I need to modify your
formula in any way?

It doesn't seem to do what I expect, although it is doing something.
It seems to be repeating the same values after a while.

 

[PFITZ]

It's repeating every 60 values. That will do me though, being able to
see 3 cycles might be more benficial.

 

[GerryGerry]

I've just tried it out myself, and seems to work fine. I can't think why it
should repeat after 60 values (3 columns worth). Perhaps others here can
offer an explanation/solution.

I'm glad it's useful anyway.

Regards Gerry

It's repeating every 60 values. That will do me though, being able to
see 3 cycles might be more benficial.