Hey Ken, Are you thinking of something like a circulator?
https://www.microwaves101.com/encyclopedias/circulators -Trip -----Original Message----- From: USRP-users [mailto:usrp-users-boun...@lists.ettus.com] On Behalf Of Ken M Erney via USRP-users Sent: Tuesday, September 5, 2017 4:47 PM To: usrp-users@lists.ettus.com Subject: Re: [USRP-users] 50 Ohm terminator on LFTX board Here is another question for the RF folks out there. I have a device that is sending a signal over a coax cable at about 8 MHz while receiving a signal over the same cable at around 3 MHz (both HF). I have an N210 with both LFRX and LFTX boards installed. Attached to the coax is a filter and DC block. The filter blocks 0 to 1.7 MHz and passes 1.8 to 54 MHz. What I wanted to do is take the output from the filter, split it, and send one feed to the LFRX and one feed to the LFTX. I am then going to use gnu-radio to send (at 3 MHz) and receive (at 8 MHz). My initial thought was to use a splitter but this setup would basically create a loop-back between the TX and RX boards on the N210. I next thought of a duplexer, but I could not find anything that would split out 3 and 8 Mhz. My question is… is this even possible? If it is, what do I need to put between the TX and RX side of the N210 to prevent the TX signal going directly into the RX port? The setup looks something like this: |—— (LFRX) ———(8 Mhz)———| N210 | |——(y-cable)——| (filter/block) |——— (signal coax 50 ohm) |—— (LFTX) ———(3 Mhz)———| In this diagram, what would I used on the RX and TX ports on the N210 to prevent the loop-back condition? The frequencies (i.e. 8 and 3) are not exact, so I can’t really use a hardware filter (I assume). I could use a software filter in gnu-radio, but I was not sure about what might happen in this scenario (i.e. loopback). One possible idea is to put an attenuator just before the LFRX board like the one supplied in the N210 loopback kit (i.e. 30db, 0-6Ghz) but I assume this would reduce the power of the receive signal as well. Noob here, so my apologies if these are simple questions. I could not find much via google on this. Thanks _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
