Hi Jonathan,
Most of this information relates to the subdevice specification and
channel number mapping, described on this manual page.
https://files.ettus.com/manual/page_configuration.html#config_subdev
If you run uhd_usrp_probe you'll see a description of the available
radio hardware for your specific configuration. An X310 has two
daughterboard slots, A and B. The TwinRX has two receivers, 0 and 1. The
complete subdevice spec for your radio is thus "A:0 A:1 B:0 B:1". These
are channels [0,1,2,3] in UHD, and thus up into GNU Radio. These (in my
experience) map by default to Antennas [RFA TX/RX, RFA RX2, RFB TX/RX,
RFB RX2]. (more on that at the end)
1) The default channel used in a single channel streaming case is
Channel 0, mapped to subdevice A:0 using antenna RFA TX/RX.
A different single channel can be addressed in (at least) two ways. You
can change the order of the subdevice spec (Making a headache for
yourself), or change the channel mapping. I would manually specify the
default subdevice spec (to make it explicit and clear) as "A:0 A:1 B:0
B:1" and then under "Channels" in GNU Radio, specify the array "[2]" for
instance to say that the single channel is the "2" index of the
subdevice spec, aka B:0. There's no problem sourcing data from any
particular subset of channels.
Discussed in
https://files.ettus.com/manual/page_multiple.html#multiple_channumbers
2) By two receivers I assume you mean two X310s. This manual page talks
about the basics, and not basics, of working with device/motherboard
indexes in addition to the subdevice spec. The antenna connectors in the
GNU Radio tab are indexed by channel number, so once you've selected
your subdevice spec (for sanity's sake really do keep the same on all
the devices) and your channel map array (select which receivers are in
use, and which order the user channel numbers map to those receivers)
the antenna list should make sense.
https://files.ettus.com/manual/page_multiple.html
IE: Two X310s with two TwinRX each, both specified in the same GNU Radio
USRP Source block. Subdev default "A:0 A:1 B:0 B:1", Channel map
[0,2,4,6] would use every other receiver from the 8 available. MB0 A:0
B:0, MB1 A:0 B:0. Changing the antenna selector for channel index 2
would change it for MB1 A:0.
Yes, you must select 2 motherboards and should supply both IP addresses
or device argument IDs in the USRP Source block.
3) No, but yes. You can put a single TwinRX in either slot. Mixing with
other daughterboard types might now be supported, but was not for a long
time, check with NI Support on the latest. If you put the TwinRX in the
B slot you will have receivers B:0 B:1 available. Run uhd_usrp_probe to
see this in detail. I'm nearly positive that the unknown daughterboard
in side A will not be prefered in the UHD default channel selection, but
am not 100% sure, so check the behavior on the bench. If you manually
specify the subdev spec as "B:0 B:1" then channel 0 (default) will
definitely be the first TwinRX receiver.
Regards,
Derek
Bits to Volts Ltd
On 12/9/2021 7:06 AM, Jonathan Pratt wrote:
Hi all
We have an X310 with 2 x TWIN RX radios in it.
We want to set up a GNU radio flow for this setup but not sure exactly how
connections are mapped.
1. If we create a block (UHD: USRP source) with only one channel, which
receiver is the data coming from - in particular which antenna is being used
with the normal connection of left Twin RX (looking from the front) Antenna 1
to RF A TX/RX and Antenna 2 to RFA RX2; and for the right Twin RX Antenna 1 to
RFB RX/TX and Antenna A RFB RX2. The presumption is that it is RFA TX/RX but we
would like to be certain. Is it possible to address a different receiver as a
single channel? Is there a problem with only sourcing data from less than all
of the receivers? The reason for doing this is because we can't get enough data
from the X310 with all receivers being polled so we want to focus on a single
receiver output if possible
2. If there are two receivers and the block is configured for four channels do
the antenna connections in the RF Options tab refer to the connections of the
specific radios? Does the MB option on the General tab need to be set to 2 for
this to work properly?
3. If we install only one of the Twin RX boards, does it matter which position
(RFA or RFB) that we install the board?
Is there some link that contains this kind of information?
Thanks
Kind regards
Jonathan Pratt
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