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Today's Topics:
1. Example code for a pair of TwinRXs (d.des)
2. Re: Example code for a pair of TwinRXs (Marcus D. Leech)
3. Re: Example code for a pair of TwinRXs (d.des)
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Message: 1
Date: Sat, 17 Sep 2016 18:51:31 +0000
From: "d.des" <d....@sbcglobal.net>
To: usrp-users@lists.ettus.com
Subject: [USRP-users] Example code for a pair of TwinRXs
Message-ID: <1474138291.3491.24.ca...@sbcglobal.net>
Content-Type: text/plain; charset="UTF-8"
I just installed two TwinRXs in an X310 for use in a 4-channel
interferometer. ?I'm looking forward to the "zero-drift/offset/phase
jitter setup" promised by Marcus on this list in an August 5th post.
?Derek Kozel posted on August 22nd that there were some UHD examples in
development at that time and that a GNU Radio flowgraph would be
available the next day. ?Are these available and if so can you point me
to them? ?I think that most of the necessary commands are described in
the August 22nd discussion but a listing of all the setup commands
(e.g. set_rx_lo_source, set_rx_lo_export, ...) in order to get four
time- and phase-synchronous channels would be a huge help. ?It wouldn't
have to be as elaborate as an updated rx_multi_samples, although that
would be great
Our previous 4-channel system required two X310s and an additional off-
board radio that generated a calibration pulse once per second to deal
with the random startup phase and drift caused by issues with the LO
discipline mechanism. ?Am I correct in assuming that when fed four
identical signals a pair of TwinRXs side-by-side in a single X310 will
produce four identical phases without random offsets or calibration?
?The discussion on September 5th ("TwinRX Phase Offset) has me a little
concerned. ?Are the latest git master branch uhd and fpga images likely
to produce four channels with the correct phase relationship? ?I'm not
set up to compile FPGA code.
Thanks,
Dave
------------------------------
Message: 2
Date: Sat, 17 Sep 2016 14:57:09 -0400
From: "Marcus D. Leech" <mle...@ripnet.com>
To: usrp-users@lists.ettus.com
Subject: Re: [USRP-users] Example code for a pair of TwinRXs
Message-ID: <57dd9205.3020...@ripnet.com>
Content-Type: text/plain; charset=utf-8; format=flowed
On 09/17/2016 02:51 PM, d.des via USRP-users wrote:
> I just installed two TwinRXs in an X310 for use in a 4-channel
> interferometer. I'm looking forward to the "zero-drift/offset/phase
> jitter setup" promised by Marcus on this list in an August 5th post.
> Derek Kozel posted on August 22nd that there were some UHD examples in
> development at that time and that a GNU Radio flowgraph would be
> available the next day. Are these available and if so can you point me
> to them? I think that most of the necessary commands are described in
> the August 22nd discussion but a listing of all the setup commands
> (e.g. set_rx_lo_source, set_rx_lo_export, ...) in order to get four
> time- and phase-synchronous channels would be a huge help. It wouldn't
> have to be as elaborate as an updated rx_multi_samples, although that
> would be great
>
>
> Our previous 4-channel system required two X310s and an additional off-
> board radio that generated a calibration pulse once per second to deal
> with the random startup phase and drift caused by issues with the LO
> discipline mechanism. Am I correct in assuming that when fed four
> identical signals a pair of TwinRXs side-by-side in a single X310 will
> produce four identical phases without random offsets or calibration?
> The discussion on September 5th ("TwinRX Phase Offset) has me a little
> concerned. Are the latest git master branch uhd and fpga images likely
> to produce four channels with the correct phase relationship? I'm not
> set up to compile FPGA code.
>
> Thanks,
> Dave
>
Derek Kozel is your "man" on this, and he and most of the Ettus R&D team
have been away this week at GRCon.
You should be able to use independent-LO+timed-commands to achieve phase
synchronization, but better is shared-LO
mode, which is somewhat complicated, and Derek can probably provide
an example flow-graph when he gets back
from GRCon.
What type of interferometer? For astronomy, or something else?
------------------------------
Message: 3
Date: Sat, 17 Sep 2016 19:17:03 +0000
From: "d.des" <d....@sbcglobal.net>
To: "usrp-users@lists.ettus.com" <usrp-users@lists.ettus.com>
Subject: Re: [USRP-users] Example code for a pair of TwinRXs
Message-ID: <1474139823.4120.9.ca...@sbcglobal.net>
Content-Type: text/plain; charset="UTF-8"
> Derek Kozel is your "man" on this, and he and most of the Ettus R&D
team have been away this week at GRCon.
> You should be able to use independent-LO+timed-commands to achieve
phase synchronization, but better is shared-LO mode, which is somewhat
complicated, and Derek can probably provide an example flow-graph when
he gets back from GRCon.
Shared-LO seems like the right answer, so specific instructions for
setting that up would be good. ?I use the uhd API without Gnuradio but
could probably pull what I need from a flow graph if that's easiest.
>What type of interferometer?????For astronomy, or something else?
It's for angle of arrival logging of pulsed signals.
------------------------------
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