Re: [Discuss-gnuradio] Comparison between GNU Radio and FlexRadio

[Ben Hoyt]

Also, a couple more questions about the USRP daughterboards (showing my radio ignorance here!):

The BasicRX (from the schematics) looks like it's just a transformer and a 300MHz low-pass filter. Is the transformer for impedance matching, or does it serve other purposes as well?

All "the literature" notes that you should have an RF front end before the BasicRX board. There's an example at http://www.gnuradio.nl/pascal/BasicHFfront.html put together by the gnuradio.nl folks.

Is this kind of RF amplifier/filter required so that you've got some decent-sized voltages to sample in the band you're sampling? The reason I ask is because I read somewhere that the purpose of SDR is to sample "as close to the antenna as possible", and at least for HF frequencies, an RF front end seems like an unnecessary analog step.

Thanks,

Ben.