ez question: How to calculate bandwidth? (Photo included)

[sunson29]

Dear friends, 

Allow me to ask one elementary school question.   How to use the given IQ rate at Tx, to calucate the bandwidth at Rx ?  

I am using 2 usrp rio, one is Tx (in built example: niUSRP EX PSK Rx), another one is Rx made myself.  To save your time, what I have is here, but plz check the photos as well.

In photo 1,  Tx IQ rate is 1M,   the Rx shows bandwidth is 0.0002 X 10^9  

In photo 2,  Tx IQ rate is 5M,   the Rx shows bandwidth is 0.001 X 10^9  

In photo 3,  Tx IQ rate is 10M, the Rx shows bandwidth is 0.002 X 10^9  

So, how to calculate it by using the IQ rate at TX ?  I thought the bandwidth = 1  / T. I know the IQ rate is already in frequency domain,   but, e.g. in the photo 1,  if rate is 1M (10^6) , why the bandwidth is not 1M, instead of 2M (0.0002 X 10^9  ). There is the 2 factor in all case of photo 1,2,3.    I do know this is dumb question, but could you someone give me detail how to calculate , if there are any link I could read, please link here.  Thank you so much for your advice.

[wiebe@CARYA]

The data in the IQ data determines the width of the signal. If your IQ data is a sine wave, you'll get a very narrow peak. If you'd send a square wave, you get a wide peak. The IQ bandwidth is just the maximum bandwidth...

The IQ data that is calculated might be effected by the bandwidth you choose. There might be aliasing, clipping, etc.. Just a thought ...

Not sure I learned stuff like this at elementary school...