what is the maximum sample rate for USRP receiver can simulink process it?

Hello, I downloaded the USRP® Support Package from Communications System Toolbox. Connect the USRP2 to the computer and made the required settings. Tried an existing example of sdruFMMono and it works. But when I tried to receive DVB-T signal with center frequency 474MHz and the bandwidth 8 MHz. I couldn't do that and the results that I couldn't separate between the noise and the signal(they had the same level). I upload the received signal here. Please Can some one help me in this. May be the problem the simulink USRP receiver block can't take high sample rate of 20 MHz? what is the maximum sample rate for USRP receiver can simulink process it? How to solve this problem

Thank you for your help