Re: [Discuss-gnuradio] X310 with 2 WBX in full duplex

Hi,

I've installed the correct uhd/gnuradio/gr-ettus packages now, and constructed the attached flow graph. However, the application hangs up after a second or so. Underflow warnings also appear almost immediately after the flow starts.

Image of flow graph and error attached. GRC file also attached.

An earlier email mentioned:

====

Also you may get underflows depending on your
sample rate, in my case these were solved by moving the bpsk transmit
chain to fabric (RFNoC) as the host was not fast enough to generate
samples otherwise.

====

However my sampling rate is pretty low. 1Msps. With 2xN210 I can support ~5Msps tx+rx on this PC.

Any ideas on whats going on, and how to fix it?

Also, what are DUC input/out rates? What should the "analog bandwidth" be set to? Same as sampling rate or 0, or something else?

Thank you,

Thanks for the pointers. I'll look into them soon. I've temporarily moved to another setup. Will report back when I come back the this one.

Thanks,

From: Michael Carosino <address@hidden>
Sent: Friday, November 3, 2017 3:38:37 PM
To: Bakshi, Arjun
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] X310 with 2 WBX in full duplex

Hi,

I don't believe you need to install Xilinx/vivado/etc - that's only needed if you want to create your own rfnoc blocks (like I did for the transmitter, but ideally you avoid this as its a lot of work!).

You should simply need the UHD rfnoc_devel branch installed w/gnuradio and use the image downloader to download the precompiled image for usrp_x310_fpga_HG and flash it to the x310. (usrp_x310_fpga_HG contains 2x DDC, 2x DUC, 2x Radios, and 1x DMAFIFO which is all you should need per my previous pictures).

For instructions, see https://kb.ettus.com/Getting_Started_with_RFNoC_Development#Testing_the_default_FPGA_image_and_building_from_existing_blocks and also flashing instructions here http://files.ettus.com/manual/page_usrp_x3x0.html#x3x0_load_fpga_imgs

On Fri, Nov 3, 2017 at 8:42 AM, Bakshi, Arjun <address@hidden> wrote:

Thanks for the quick reply, Michael. I looked into installing RFNoC and thats going to need vivado/xilinx, and a bunch of other stuff.

Trouble is that I don't have +20GB to spare needed for its installation. Is there any way around it? What are the bare minimum options required? I tried installing the Vivado Lab Solutions instead, but I guess thats not enough as I couldn't get ettus's fpga software to build after just that.

Install options image attached.

Thanks,

AB

From: Michael Carosino <address@hidden>
Sent: Thursday, November 2, 2017 10:21:52 PM
To: Bakshi, Arjun
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] X310 with 2 WBX in full duplex

Hi,

I've successfully gotten the two tx-rx setup on an x310 you've
described but I did it somewhat differently. Instead of using the usrp
source/sink blocks I ended up using the RFNoC blocks - the main reason
for this is because a USRP Sink block is made up of the following
RFNoC blocks: RFNoC DMAFIFO -> RFNoC DUC -> RFNoC Radio. It turns out
that the DMAFIFO included by the USRP Sink block has a default depth
size of 32MB and this results in multiple seconds of delays for the
sample rates I was using (Ettus includes this fifo due to some flow
control latencies in their protocol that they use for transport
between the USRP and host over ethernet).

Anyways, by manually creating the radio chain in RFNoC as described
above, you can adjust the default depth size of the DMAFIFO. By
playing around I found that a depth of 2^20 = 1.04MB worked well. It
is also of note that if you do this method you need four total radio
blocks - 2 for transmit and 2 for receive (for some reason the
multi-channel selection in the rfnoc radio block did not work, this
method does however).

I would also run 'ethtool -G eth0 rx 4096' to ensure packets aren't
dropped in your NIC. Also you may get underflows depending on your
sample rate, in my case these were solved by moving the bpsk transmit
chain to fabric (RFNoC) as the host was not fast enough to generate
samples otherwise.

Finally, you will probably experience occasional errors on flow graph
startup about synchronization errors (timeout waiting for PLL to lock,
backend sync failed, unexpected fifo depth), retrying to run the
flowgraph (sometimes it takes a few tries) will usually get it
running. I've spoken to Ettus about this and they are tracking this
issue so hopefully its solved soon.

Attached a picture of transmit/receive configuration in RFNoC.

regards,
Michael

On Thu, Nov 2, 2017 at 7:12 PM, Bakshi, Arjun
<address@hidden> wrote:
> Few mistakes I caught after sending it. Center frequencies I had chosen were
> out of range for WBX. Fixed now. Also, image file now has proper extension.
>
>
> Thank you,
>
>
> AB
>
> ________________________________
> From: Bakshi, Arjun
> Sent: Thursday, November 2, 2017 9:38:48 PM
> To: address@hidden
> Subject: X310 with 2 WBX in full duplex
>
>
> Hi,
>
>
> I'm trying to get two Tx-Rx links running with an X310 with two WBX
> daughterboards in it. I've used multi-channel USRP source/sink blocks, but
> I'm experiencing latency (L) errors with the connection, and then the
> application (GRC) hangs. I've attached an image of my USRP source/sink
> blocks. I'm connected to the X310 with a 1GB ethernet connection.
>
>
> Can anyone point out the reason/mistake? Also, is the sub-device spec
> correct? Followed instructions for WBX from here:
> https://www.ettus.com/content/files/kb/application_note_frontends_subdevices_antenna_ports.pdf

RX DSP Chain 1 Logic DDC ADC SMA RXB - Ettus Research

www.ettus.com

Default Sub-Device and Antenna Specifications UHD will automatically select a sub-device and antenna specification if they are not specified by you.

>
> My goal:
>
> I want to have a Tx-Rx link in freq F1 and another in freq F2 at the same
> time. One daughterboard TXes in F1 and RXes in F2, while other TXes in F2
> and RXes in F1. Is this possible with the equipment I have?
>
>
> Thank you,
>
>
> AB
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

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>

From:	Bakshi, Arjun
Subject:	Re: [Discuss-gnuradio] X310 with 2 WBX in full duplex
Date:	Sun, 19 Nov 2017 00:53:47 +0000