Trip, The circulator idea is interesting. Thanks for the link. I did not understand the difference between a diplexer and a duplexer. The link you sent has a great explanation of this. It would seem that a duplexor is what I want, but I could not tell if a duplexer can be used in full duplex mode (i.e. send and receive at the same time). My power needs are very low. I am thinking that maybe a combiner/splitter has enough isolation to do what I need. Again, thank you for the quick response. I believe I learned something today :)
- ken > On Sep 5, 2017, at 5:07 PM, Humphries, James R. <humphrie...@ornl.gov> wrote: > > And I guess the other question would be if there is a circulator that you can > buy at that low of frequency. I'm not sure that I have seen one, but never > actually looked. > > -Trip > > > -----Original Message----- > From: USRP-users [mailto:usrp-users-boun...@lists.ettus.com] On Behalf Of > Humphries, James R. via USRP-users > Sent: Tuesday, September 5, 2017 5:00 PM > To: Ken M Erney <gsmmobile...@gmail.com> > Cc: usrp-users@lists.ettus.com > Subject: Re: [USRP-users] 50 Ohm terminator on LFTX board > > 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 _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
