I was thinking a switch would get moved to the RX port of the circulator, which would see the TX power reduced by 20dB. Then into a switch that switched the RX port of the circulator between a 50 ohm load and the RX port.
Sent from my iPhone > On Apr 19, 2021, at 5:13 PM, Brendan Horsfield > <[email protected]> wrote: > > > Martin, Marcus, > > I don't see how adding a circulator will protect the Rx port of the USRP > without blocking the signal from the CubeSat as well. > > Are you transmitting and receiving on different frequencies? If so, you could > insert a filter between the Rx port and the switch to block the Tx > frequencies. > > On the other hand, if your Tx and Rx signals are in the same band, you can > add a second switch in cascade with the first one to increase the Tx-Rx > isolation. You can keep adding switches if necessary, until your isolation > target is met. > > Regards, > Brendan. > >> On Mon, 19 Apr 2021, 23:52 Marcus D. Leech, <[email protected]> wrote: >> On 04/19/2021 09:49 AM, Martin Elfvelin wrote: >>> Thank you for your input. Do you suggest adding a circulator to the system >>> or rather replacing the switch with a circulator? >>> >>> Best regards, >>> Martin >> I'd say add a circulator in addition to your switch. >>> >>> On Mon, Apr 19, 2021 at 3:43 PM Marcus D Leech <[email protected]> >>> wrote: >>>> A circulator can give you an additional 20dB isolation. >>>> >>>> Putting 5d!m into the RX2 port will likely destroy the RX amplifier in the >>>> AD9361. >>>> >>>> Sent from my iPhone >>>> >>>> > On Apr 19, 2021, at 9:12 AM, Martin Elfvelin via USRP-users >>>> > <[email protected]> wrote: >>>> > >>>> > >>>> > Hello all, >>>> > >>>> > I am planning on using a USRP B200 in a half-duplex communication system >>>> > to communicate with a CubeSat. The TX/RX port will be used for >>>> > transmitting and the RX2 port for receiving. The transmitting port will >>>> > be connected to a power amplifier with a 60W output, this will in turn >>>> > connect to an RF switch which will switch between the TX/RX >>>> > (transmitting) and RX2 (receiving). The RF switch has an isolation of >>>> > ~40-43 dB which means from the 47.78 dBm transmitted we will have >>>> > roughly 5-8 dBm reflected to RX2. Since the SDR is only rated to receive >>>> > maximum 0 dBm I'm wondering if someone has any ideas on how to handle >>>> > this. I'm unsure if this power will simply fry the board and I should >>>> > implement a power limiter or if there are other workarounds. >>>> > >>>> > Appreciate any help you can provide. >>>> > Best regards, >>>> > Martin Elfvelin >>>> > _______________________________________________ >>>> > USRP-users mailing list -- [email protected] >>>> > To unsubscribe send an email to [email protected] >> >> _______________________________________________ >> USRP-users mailing list -- [email protected] >> To unsubscribe send an email to [email protected]
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