S parameters

[labvieew]

hi first of all i'm so happy that i found this forum
i hope some can help me

my graduation project is to with the use of GPIB and labview
a agilent dso6000 scope and a ESG44xx signal genrator ( i not at the lab so cant remember the exact serial number)
implement/code/write a system to measure the S-paramaters
from a blackbox/filter/amplifier

the first part is done i connected the scope and the SigGen to the pc
and installed their drivers works .
at least the example programs the ones they came with the drivers work.

i am not that good at programming
is there any example programs , tutorials where i can learn to develop such system

I have to plot the S parameters dB vs Frequency 

 

thx

[Burban]

Since you have found the instrument driver and the included examples for both the signal generator and the scope, I would suggest looking further at those.  There are many other LabVIEW shipping examples that will help you with the rest of the LabVIEW programming.

To my knowledge, there is not a specific tutorial or training about S parameters on ni.com.

Also, this is the forum you should be posting in for this issue.  Instrument Control (GPIB, Serial, VISA, IVI)

[labvieew]

Now i'm kinda stuck bought a book labview for everyone learned the basics 

its just to make a program to obtain the frequency response

with signal generator ,  scope and UUT 

and save the Transfer function 

OK i found an example program how to do frequency response in Labview

can configure the signal generator to required parameters(frequency and amplutude)

and can view the scopes screen on labview

are there any specific examples/tutorials to obtain this response with signal generator(as a hardware) and a scope (also as a hardware)

or even close examples 

how to i combine these all 

for example do i need signalexpress?

 advices?

can anyone guide me ?

[Burban]

I'm uncertain as to what you mean by "(as a hardware)" but I'm guessing you are not currently using your actual instruments and instead are using LabVIEW to generate a signal in software and using some form of graph or chart to display the data from that.

I've attached a screenshot of where to find example programs for controlling your scope and signal generator after you have installed the project style instrument drivers for your instruments.  Since you have indicated that you have already installed the instrument drivers, I won't explain that further.

After you are comfortable with using those examples, try modifying them for your application.  To combine them, you will program a VI in LabVIEW that has VI's from both of these instrument drivers as well as other VI's that accomplish the other tasks that you require.  This will require understanding the instrument driver examples provided as well as how LabVIEW works.  There will not be a example that combines all of these elements into an application similar to yours.  LabVIEW is an engineering tool; not an out of the box solution.

For more information on Instrument Control, take a look at the Developer Zone article, Instrument Control Fundamentals: Main Page.  It links to many useful resources for learning about how to do instrument control with LabVIEW.

You will not need SignalExpress.  SignalExpress is an alternative environment for instrument control, data acquisition, etc and will not likely be used in this application if you are already using LabVIEW.

[labvieew]

Hi Burban

OK i already analyzed the VIs from the drivers

figured out that i can't use the output of the signal generator in the execution of the program or can i ? How ?

 when it can be done  the FRF(frequency response function) fits perfect to the solution 

i wrote a program ( has small error the  error out is missing driver is not installed on this PC I'm not at the lab)

which also works between 1-80MHz 100steps

generate and read continuously

the resulting frequency response is at -45dB

but after 85MHz the scope can't read the inputs

signal generator Max 3GHz scope Max 1GHz

now this is a big problem 

timeout for the scope is 10seconds (even same error after i changed it to 100seconds)after that gives error and continues to the next freq and same error goes on

am i on the right way?

is this program logically correct for frequency response ?

thx

[Dennis_Knutson]

I don't understand what you mean by 'use the output of the signal generator in the execution of the program '. You are using the output of the signal generator now.

You can do quite a bit to clean up the program. Move all of the instrument initialization functions to outside the loop. There is no point in running this over and over again. All that you want inside the loop is a function to set the frequency and acquire the waveform. That means that you also place the close and error queries outside the loop and execute them only when the loop finishes. You will also want to connect the error out of the set frequency function to the error in of the acquire waveform function so that the acquisition is performed after the frequency is adjusted.

Instead of using the auto setup feature of the scope, you may need to explicitly set the timebase and other parameters. If you can't find a setting that will accomadate the entire frequency range you are inputting, a change during the sweep (i.e. with a case statement looking at the freq of the signal generator) may be appropriate.

[labvieew]

hi Burban and Dennis Knutson

i would like to thank u both

problem solved 

Now the system is fully functional  and works properly

after i took all of the instrument initialization functions to outside the loop

the system worked much faster and more accurate

to adjust the level of the scope wasnt necessary

again thanks a lot

zir_green