On 26/01/2023 09:02, claudio.franch...@tlrnet.eu wrote:
Hi, David,
the USRP 2901 is a dual channel RTX, so it can definitely receive two
different channels at the same time, i.e. two different (carrier)
frequencies. We just have to see the management through GNURadio, but
here I refer to those who are more experienced than me with the software.
In principle you can put a split downstream of the antenna and then go
on the two channel inputs, however keep in mind that with the splitter
you introduce a signal loss that can go from 3.5dB to 5dB or more,
depending on the splitter (3dB is anyway theoretical and unavoidable).
This means that, not only do you have the loss value of the splitter
on the signal level, but even more marked the fact that it worsens the
noise figure by the same amount. If the dynamics is enough it's fine,
otherwise it would be better to use separate antennas. Be careful not
to go into transmission on a channel if you use a splitter and a
single antenna!
Claudio
*From:* discuss-gnuradio-bounces+claudio.franchini=tlrnet...@gnu.org
<discuss-gnuradio-bounces+claudio.franchini=tlrnet...@gnu.org> *On
Behalf Of *David Dima
*Sent:* Thursday, January 26, 2023 9:33 AM
*To:* discuss-gnuradio@gnu.org
*Subject:* Dual-Frequency simultaneously receiver using one USRP 2901
Hi,
I am trying to simultaneously receive two signals from Galileo at
different frequencies (1176.45 MHz and 1575.42 MHz) using a single
antenna, a USRP 2901, and the GNU Radio Companion (GRC) software. I
would like to know if it is possible to do this with a single USRP,
that is, is the USRP able to receive two different frequencies at the
same time?
In the affirmative case, is it ok to just split the incoming signal
from the antenna with a splitter and connect it to two ports the USRP?
Many thanks in advance,
David
The USRP 2901 is the same as the USRP B210, and as such, uses an RF
Front End (RFFE) chip that has only a SINGLE
Local Oscillator in each direction. The chip (AD9361) is designed
for 2 x 2 MIMO applications where both channels are
mutually coherent and tuned to the same frequency.
So you can't tune that front-end chip to a different frequency for each
channel. What you CAN do, using manual
DDC tuning is have two narrower-band channels that aren't separated
by more than about 30MHz, and you tune
the RF hardware to half-way between your two channels. But in your
case, this won't work because your
channels are too far apart....
In terms of your splitter question--YES, this works just fine. I've even
used cheap Satellite TV splitters in such applications
without much issue--type-F to SMA adapters are readily available even
through Amazon.
