[Discuss-gnuradio] Guide: Understanding the various relationship of gain, decimation and offset values in the captured file USRP.

Hi everyone,
  I am a bit trying to understand the relationship of the gain,offset and decimation parameter in the USRP and
what it reflects in the capturing of the files ... If i want to get a proper output of a particular frequency with proper
output how can i adjust them.
Althou i do realise my question / doubt may be a bit different or may be unrealistic and the way i asked my
question may be a bit Ambigious.. please do tolerate it and also ask me if so , so that i can make it more clearer....

Thanks guys in advance....