help needed

[Maz]

Hi everyone,

I'm a student and need to import pdf files which show received data in a system and with mathcad get the bit error rate and other values for it.

.

HELP

[RichardJ]

Mathcad can't read a pdf file. If the data is in the file as text you should be able to copy and paste it into an input table. That depends on how it's formatted in the pdf file though. Can you post the file?

[Maz]

Thank you so much for your reply. What if I have the data in excel? (I've now put them in excel to make it work)

I'm sure I can enter it that way can't I? The problem is I am completely stumped

I would greatly appreciate your help.

[RichardJ]

Go to "Insert", "Data", "File Input", select your Excel file, select the worksheet, etc. If you want to change the worksheet later, right click on the File Input component, and select "Properties". You can use the submatrix function to remove the two header rows.

[Maz]

Thank you Richard,

Now I'm going to have to figure out how to use the data to create a graphs for the probability densities and we've been told to superimpose the graph over our data (no idea what the lecturer means by that) and then get the threshold voltage and then bit error rate and other data from there.

aaarrrggghhh I'm starting to feel really dumb

[RichardJ]

we've been told to superimpose the graph over our data (no idea what the lecturer means by that)

I'm sure that what is meant is that you should plot the functon for the probability density on the same graph as the data (i.e two curves on one graph).

[Maz]

Thanks again.

Well I guess I better figure all this out soon, or I fail my course.

[MikeArmstrong]

Well I guess I better figure all this out soon, or I fail my course.

NEVER USE THE F WORD.

Mike

[MikeArmstrong]

aaarrrggghhh I'm starting to feel really dumb

It is the weekend

Mike

[Maz]

Well Mike the problem is I only have the weekend to finish this and I have two exams next week too.

I've bitten off more than I can chew and am very afraid. I shouldn't have taken on this assignment I'm doing Power not Optical or Telecomms so now I'm suffering and am very very stuck

[MikeArmstrong]

Well Mike the problem is I only have the weekend to finish this and I have two exams next week too.

I've bitten off more than I can chew and am very afraid. I shouldn't have taken on this assignment I'm doing Power not Optical or Telecomms so now I'm suffering and am very very stuck

In that case, if you have any Mathcad issue's, post them in here and I'm sure myself and other members will do there best to help.

Mike

[Maz]

That would be very kind of you Mike.

What I'm trying to do is take received data from a excel file and import them into mathcad (which I've done)

then plot them, which I haven't managed to do yet.

Then I'm meant to superimposed that on to the probability distribution graphs. I don't know how to plot those either since mathcad constantly tells me that I haven't defined variables (but if I don't have values how am I to define them? I'm also meant to use either genfit or simplex optimization...

After all that I am meant to find the threshold voltage, bit error rate, Q factor, voltages, and variances. Hopefully I'll be able to get those from the equations, but that too keeps asking me to define everything.

I've been trying for ages and am still stuck

[Maz]

Could I also ask:

How do I plot the table I've imported from excel. I have no idea how to do it. I've been trying to find out for hours now.

There are two things I can't do:

first and therefore more importantly I can't give the columns variables

and second to plot it because of the first fact.

Thank you so much

[RichardJ]

Use the submatrix function to split the table into two vectors (you can dump the two header rows at the same time). Then put a graph on the page, and type the nesm of the x and y variables into the placeholders on the axes.

[Maz]

Use the submatrix function to split the table into two vectors (you can dump the two header rows at the same time). Then put a graph on the page, and type the nesm of the x and y variables into the placeholders on the axes.

Thank you sooooooooo much Richard. I finally managed to plot the stupid thing.

yeeey... only about a million more steps to go.

[MikeArmstrong]

Right, the best way to attack this is one problem at a time.

Can you post the Mathcad sheet where you have managed to insert the data.

Mike

[Maz]

I've only put in the first sheet Mike

then added the equations and some text

[MikeArmstrong]

The problem is that you have a lot of data scattered in a lot of sheets.

I would attack this problem by the using a scripted component as in the attached sheet. Have a look and see what you think.

Mike

[Maz]

wow that is amazing Mike.

I never would have thought of it. I did try to use readexcel, but was trying to do them one at a time and it wasn't really working anyway.

It would become much tidier, but if my lecturer wants to put in a new set of data to check that the programme is working, where would he have to do that from just enter a new excel file? Would it igmore the rest of the pages?

[MikeArmstrong]

wow that is amazing Mike.

I never would have thought of it. I did try to use readexcel, but was trying to do them one at a time and it wasn't really working anyway.

It would become much tidier, but if my lecturer wants to put in a new set of data to check that the programme is working, where would he have to do that from just enter a new excel file? Would it igmore the rest of the pages?

Firstly. I totally forgot about the READEXCEL function - that would do the same job.

Yes, your lecturer could change the Excel file. If the file was sent to him, remember he would have to change the path.

Mike

[MikeArmstrong]

Forgot to mention that M15 READEXCEL function doesn't work with Excel 2003 or lower.

Mike

[Maz]

Right thanks I'll keep that in mind.

[RichardJ]

This might get you going a bit.

[Maz]

Thank you Richard.

Yes I'm trying to use genfit now. Not going great, but trying my best

[Maz]

I'm quite confused about choosing the parametres for the matrix and why does one need to guess values?

[RichardJ]

I'm quite confused about choosing the parametres for the matrix

I'm not sure what you mean. Do you mean which parameters to choose, or do you mean how to calculate the derivative w.r.t those parameters?

why does one need to guess values?

The fit is a non-linear one (look up the linfit function to see what a linear function looks like) so it is not possible to calculate a numerical solution in one step. All non-linear solvers are iterative. You supply a starting point (the guess values), and they iteratively converge to a solution.

[Maz]

I'm not sure what you mean. Do you mean which parameters to choose, or do you mean how to calculate the derivative w.r.t those parameters?

Unfortunately both. I'm sorry I keep asking more questions, but this has turned in to such a difficult thing. I am struggling and the more I read all the examples online just confuse me more.

[RichardJ]

v is the independent variable, Ptot is the dependent variable. The parameters you don't know, and wish to find, are a, sigma, and v0. You need to find the derivatives w.r.t. those parameters. There are of course two of each, but the derivatives will have the same form in each case. You can find them by taking the derivative of P w.r.t each of those variables. Bear in mind that Mathcad has symbolic math capabilities, and can do this for you.

And I made a mistake in the worksheet I posted (oops!). There is no integral in the definition of P. The integral will give you the total probability between the integration limits, but you need the underlying probability density function (which also happens to be a built-in function in Mathcad.

[Maz]

Thank you Richard.