Receive channel ADC Noise

I am trying to capture Analog Backscattered data from RFID tags.
Essentially I am transmitting a continuous wave of 915 MHz and receiving
the backscatter signal at the same frequency on the receive channel.
However, I am seeing a large amount of Noise (profile similar to white
noise). My parameters are as follows:

  1. Frequency of Transmission: 915 MHz
  2. ADC Sampling Rate=64 MHz (Default) which is decimated by a factor of
  3. rx_gain=25
  4. Amplify block on the transmit side is being varied from 300 to 30000.

Could anybody advice me on the parameters which affect the ADC noise
profile of the USRP. Which parameters should I be concerned if I am
looking to capture weal signals.

Any help in this matter would be greatly appreciated.

Thanks and Regards,
Vamsi Talla
Graduate Student
University of Washington, Seattle