|From:||Marcus D. Leech|
|Subject:||Re: [Discuss-gnuradio] self-interference with wbx|
|Date:||Thu, 20 Dec 2012 19:51:41 -0500|
|User-agent:||Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:18.104.22.168) Gecko/20111108 Fedora/3.1.16-1.fc14 Thunderbird/3.1.16|
I a fully-engineered full-duplex system, there'll be a duplexor to provide better isolation (70-80dB) for the RX gain an mixer. Your RX front-end is
"seeing" all of the TX energy you're transmitting, and very likely being drive into non-linear operating territory -- just because your mixer is tuned
70Mhz away from the TX, *does not mean* that your RX LNA is "tuned" only to your tuned frequency. You might able to get away with just using
a notch for your TX frequency in front of your RX, but without some actual RF plumbing/systems-engineering, you'll run into "desense" issues like
Any such duplexing arrangements are clearly, *necessarily* application specific. Which is why there's no duplexor or other filters on the daughtercards.
Since they're used for a *huge* variety of applications, there's no way to engineer them to always "do the right thing" regardless of application.
-- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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