Hi Michal, Thank you for asking the question - I was thinking about this too last night (actually this morning) while I was trying to catch up on some sleep, but my brain wouldn't stop ticking over :) Can't be sure of the effect as datasheets aren't public, but I will experiment with narrowing the bandwidth. The 'IFfilter' function in the E4000 tuner code is made up of a massive if/else block that sets various register values by checking the input IF-BW values from <= 2150 to > 5500, so it appears to support a wide range (despite the convenience 'E4000_BANDWIDTH_HZ' enum in the header). Will post findings a little later, unless someone beats me to it :) Kind regards, Balint PS: "Software-Defined Radio For $11" on Slashdot! http://hardware.slashdot.org/story/12/03/31/1914217/software-defined-radio-f or-11 PPS: I've been working to improve the GNU Radio Source block and Windows plugin with generous feedback from the community. Grab them here if you wish: http://wiki.spench.net/wiki/gr-baz#rtl_source_c http://wiki.spench.net/wiki/USRP_Interfaces