Hi,

 

The box is the first step; you also need to block the power supply line against 
any incoming RF, your 10.7 MHz IF out needs a low pass filter that cuts off all 
higher frequencies coming back in on this path, and your 433 MHz in needs to be 
shielded 100%, with some double shielded coax or semi rigid. 

 

The LO strays quite a bit, it is not a very good idea to have a second RX on 
the same frequency in one box...the fun with direct conversion receivers :-)

 

Ralph.

 

 

 

From: discuss-gnuradio-bounces+ralph=schmid....@gnu.org 
[mailto:discuss-gnuradio-bounces+ralph=schmid....@gnu.org] On Behalf Of Nemanja 
Savic
Sent: Tuesday, December 10, 2013 3:49 PM
To: GNURadio Discussion List
Subject: [Discuss-gnuradio] WBX Lo leakage to LFRX

 

Hi all,

As I described in one of my previousposts, I wanted to have several receiving 
paths for 434 MHz, and my USRP is equipped owith WBX and LFTX. So WBX is one, 
and for the other, I designed small RF frontend using TI's CC1000 that 
donwnconverts the signal to 10.7 MHz which can be used with LFRX. Now the 
problem is that i have like 30 - 40 dB spike in the spectrum of received signal 
at LFRX thata comes from the LO of the WBX. Is there any suggestion how to 
supress this signal, but first from phisycal point of few, and later if not 
possible trying to use some DSP manipulations. Namely, I packed new frontend in 
the alu box, so it's kind of shielded, but it didn't help that much.

Thanx,



-- 
Nemanja Savić 

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