GSM IQ data capture

[waciuri]

Hi,

How do i make the Soft panel to display the required signal and not the noise floor? Cause after setting the configurations my expectation is the signal returned  is from the configurations. Forgive my ignorance.

Thanks.

[waciuri]

This fig is a soft panel for GSM Analysis signals. Can someone assist me to know whether what is been displayed is a real GSM signal waveform or it noise floor?

[B_Sherm]

Hello,

With the default settings we were able to create a loopback test with a VST. This is what the signals should look like below. The steps we took are also provided. 

1) Open the Generation Interactive Example for GSM/EDGE+ use the default settings. 

2) Open NI-RFSA. Make sure to choose IQ Power Edge Trigger.

3) Here is what the IQ data should look like in the Analysis Interactive Example for GSM/EDGE+

[shawn.t]

Waciuri,

Would you describe the physical connections in your system?  Do you have a cable connected directly from the VST RF out to RF in?  Is there some switching or filtering in between?

[waciuri]

Thanks for the reply.

My equipment is 5663E (signal generator 5652, Downconverter 5601,Digitizer 5622). 

Connections are like RF OUT -> LO IN, REF OUT2 -> CLK IN, IF OUT -> IF IN, and my GSM antenna to RF IN.

On the Soft Panels i tried as explained above but they are not responding equally. Check the images below

Generation interactive returns the error shown on choosing resource name. 

When you open the RFSA panel, it fails to open the device session.

If i run interactive on its own with default configurations it returns the error shown unless i pick waveform thats when it displays something like noise floor.see fig below

The image for my connections is as below

[B_Sherm]

The reason RFSA is saying No Device Session is because you have an open session with the device in the Generation Interactive Example. Your 5663E is only for acquiring signals. It cannot generate them.

In order to complete a loop back test you would need to have a piece of hardware that is capable of generating signals for the 5663E to read. I would suggest a hard wired connection over an antenna. That way me know the signal is making it to the 5663E. 

Please make sure that your device is configured correctly in MAX as well. Can you post screen shots of your MAX configuration of the 5652, 5601, and 5622. Just expand out all your devices in MAX and take a screen shot. 

Do you have a signal generator?

[waciuri]

Hi,

My MAX image is as follows

there are a few things i didnt understand:-

1. Are you asking whether i have a different signal generator outside the above setup(5652)?

2. What do you mean by a hard wired connection over the antenna?Please elaborate.

Thanks,

Moses.

[B_Sherm]

Moses,

1. Are you asking whether i have a different signal generator outside the above setup(5652)?

Yes. The 5662 is a LO (local oscillator) that the 5601 uses in order to downconvert the input signal. Do not think of the card individually because the three together only make 1 signal analyzer, the 5663E.

You can only acquire signals with your current setup. You will need other hardware to generate a signal for the 5663E to acquire.

2. What do you mean by a hard wired connection over the antenna?Please elaborate.

With the above being said, assuming you have other hardware to generate a signal, you would take a wire and connect RF out of a signal generator and wire the other end to the 5663E. Other than using two antennas, 

Does that help clear up a few things?

[waciuri]

Hi Brad,

That is well interpreted and i have the grasp now.

I dont have any other device- generator and only the analyzer cause my intention is to acquire GSM signal from the air and analyze them. 

Please guide me on this direction probably first using the Analysis interactive example to see whether the signals are been detected. If i try the spectrum as the fig below demonstrates. Could this mean GSM signal is been detected?

Thanks,

Moses.

[B_Sherm]

Moses,

Are you sure your antenna is able to capture data in this frequency band? There are antennas that are meant to be used with GSM data.You are not amplifying the information from you antenna and it could be buried in the noise floor. Our equipment is typically used to test if a signal is being generated properly. 

Without knowing information about the signal you are trying to receive, I do not know how to tell if you are receiving the correct data or not.