[USRP-users] Video Stream using GRC as Physical Layer Flow Control Issues

[Sarah Tran via USRP-users]

Hi all,

My colleagues and I have created a GRC & C++ application that will send a 
real-time video stream over an X310+UBX-160. The physical layer is done in GRC 
and is a basic QPSK modem. The problem that we are running into is flow 
control. Anytime there is an underflow, it completely shuts the video stream 
down. Is there a way to receive feedback from GRC that says “Hey I need X more 
data bits in my buffer”, and we can pad our data with zeroes to fufill that?

Thank you,

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[USRP-users] RFNoC OFDM blocks error building FPGA image

[Sarah Tran via USRP-users]

Hi all,


I am trying to build a custom FPGA image for my X310 (daughterboards=UBX-160) 
using the uhd_image_builder gui and trying to use the following blocks:

fft

schmidl_cox

eq

ofdm_constellation_demapper


as the code is running and building, it always stops on this error:

'

[00:22:41] Current task: Logic Optimization +++ Current Phase: Finished
[00:22:41] Starting Connectivity Check Task
ERROR: [Opt 31-2] SRLC32E 
x300_core/inst_eq/inst_axi_wrapper/header_fifo/fifo_short/gen_srlc32e[64].srlc32e
 is missing a connection on D pin.
[00:22:51] Current task: Connectivity Check +++ Current Phase: Starting
[00:22:51] Current task: Connectivity Check +++ Current Phase: Finished
[00:22:51] Process terminated. Status: Failure


Warnings:   862
Critical Warnings:  36
Errors: 1

Makefile.x300.inc:111: recipe for target 'bin' failed
make[1]: *** [bin] Error 1
make[1]: Leaving directory '/home/lsop/rfnoc/fpga/usrp3/top/x300'
Makefile:119: recipe for target 'X310_RFNOC_HG' failed
make: *** [X310_RFNOC_HG] Error 2'

I can't seem to get it resolved, and I was wondering if there was a trick that 
someone else was able to use to get it to build. Any help or insight is 
appreciated.

Thank you,
Sarah

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[USRP-users] RFNoC X310 FPGA Image not Downloading

[Sarah Tran via USRP-users]

Hello all,

I am trying to use RFNoC on my X310. I started with a clean install of Ubuntu 
16.04 and I followed the instructions here:
https://kb.ettus.com/Getting_Started_with_RFNoC_Development

However when I get to the command of "uhd_images_downloader", it doesn't 
download any RFNOC images despite being pointed at to the UHD_VERSION = 
"4.0.0.rfnoc-devel-702-geec247b"
I have tried to manually download the uhd-images_4.0.0.rfnoc-devel-xxx- 
from the files.ettus.com/binaries/images page but none of them worked when I 
tried to run uhd_usrp_probe. They all have me an FPGA compatibility error. Is 
there somewhere else I can try to get the correct images with RFNOC for the 
X310? I also had the same issue when trying to use it for the E310. I saw a 
previous thread about it, but the link pointed to 
https://github.com/EttusResearch/fpga/tree/rfnoc-evel and I couldn't find any 
images for the X310 there either.

Thank you,

Sarah Leony

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[USRP-users] Unable to Install NI USRP Rio for Pcie Connectivity to X310

[Sarah Tran via USRP-users]

Hello all,



I am trying to connect my PC (intel core i7, 500gb HDD Ubuntu 18.04) with the 
X310 via PCIe. I have successfully installed UHD version 3.14 and am using gcc 
7.3 and I made sure my kernel was 64 bit (I ran uname -m and it returned 
x86_64).

For some reason I can't get nikal to build and this is the error I get (there 
is more but this is a snippet):



 <11>Aug  8 08:53:49 nikal: ./arch/x86/include/asm/current.h:18:17: warning: 
passing argument 2 of 'get_user_pages' makes integer from pointer without a 
cast [-Wint-conversion]
<11>Aug  8 08:53:49 nikal:  #define current get_current()
<11>Aug  8 08:53:49 nikal:  ^
<11>Aug  8 08:53:49 nikal: 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:7021:37: note: in expansion of 
macro 'current'
<11>Aug  8 08:53:49 nikal: pinned = get_user_pages(current, current->mm,
<11>Aug  8 08:53:49 nikal:  ^~~
<11>Aug  8 08:53:49 nikal: In file included from 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:61:0:
<11>Aug  8 08:53:49 nikal: ./include/linux/mm.h:1398:6: note: expected 'long 
unsigned int' but argument is of type 'struct mm_struct *'
<11>Aug  8 08:53:49 nikal:  long get_user_pages(unsigned long start, unsigned 
long nr_pages,
<11>Aug  8 08:53:49 nikal:   ^~
<11>Aug  8 08:53:49 nikal: 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:7023:28: warning: passing 
argument 4 of 'get_user_pages' makes pointer from integer without a cast 
[-Wint-conversion]
<11>Aug  8 08:53:49 nikal: size,
<11>Aug  8 08:53:49 nikal: ^~~~
<11>Aug  8 08:53:49 nikal: In file included from 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:61:0:
<11>Aug  8 08:53:49 nikal: ./include/linux/mm.h:1398:6: note: expected 'struct 
page **' but argument is of type 'size_t {aka long unsigned int}'
<11>Aug  8 08:53:49 nikal:  long get_user_pages(unsigned long start, unsigned 
long nr_pages,
<11>Aug  8 08:53:49 nikal:   ^~
<11>Aug  8 08:53:49 nikal: 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:7024:28: warning: passing 
argument 5 of 'get_user_pages' makes pointer from integer without a cast 
[-Wint-conversion]
<11>Aug  8 08:53:49 nikal: flags & 
nNIKAL220_kPageListAccessModeWrite,
<11>Aug  8 08:53:49 nikal: ^
<11>Aug  8 08:53:49 nikal: In file included from 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:61:0:
<11>Aug  8 08:53:49 nikal: ./include/linux/mm.h:1398:6: note: expected 'struct 
vm_area_struct **' but argument is of type 'long unsigned int'
<11>Aug  8 08:53:49 nikal:  long get_user_pages(unsigned long start, unsigned 
long nr_pages,
<11>Aug  8 08:53:49 nikal:   ^~
<11>Aug  8 08:53:49 nikal: 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:7021:13: error: too many 
arguments to function 'get_user_pages'
<11>Aug  8 08:53:49 nikal: pinned = get_user_pages(current, current->mm,
<11>Aug  8 08:53:49 nikal:  ^~
<11>Aug  8 08:53:49 nikal: In file included from 
/var/lib/nikal/4.15.0-30-generic/nikal/nikal.c:61:0:
<11>Aug  8 08:53:49 nikal: ./include/linux/mm.h:1398:6: note: declared here
<11>Aug  8 08:53:49 nikal:  long get_user_pages(unsigned long start, unsigned 
long nr_pages,
<11>Aug  8 08:53:49 nikal:   ^~
<11>Aug  8 08:53:49 nikal: cc1: some warnings being treated as errors
<11>Aug  8 08:53:49 nikal: scripts/Makefile.build:339: recipe for target 
'/var/lib/nikal/4.15.0-30-generic/nikal/nikal.o' failed
<11>Aug  8 08:53:49 nikal: make[2]: *** 
[/var/lib/nikal/4.15.0-30-generic/nikal/nikal.o] Error 1
<11>Aug  8 08:53:49 nikal: Makefile:1552: recipe for target 
'_module_/var/lib/nikal/4.15.0-30-generic/nikal' failed
<11>Aug  8 08:53:49 nikal: make[1]: *** 
[_module_/var/lib/nikal/4.15.0-30-generic/nikal] Error 2
<11>Aug  8 08:53:49 nikal: Makefile:32: recipe for target 'nikal.ko' failed
<11>Aug  8 08:53:49 nikal: make: *** [nikal.ko] Error 2
<11>Aug  8 08:53:49 nikal: ERROR:  failed to build nikal
<11>Aug  8 08:53:49 nikal: ERROR:  NI-KAL update failed.
<11>Aug  8 08:53:49 nikal: ERROR:  make of nikal kernel module failed, not 
installing kernel module.
<11>Aug  8 08:53:49 nikal: ERROR:  updateNIDrivers should be called again after 
fixing the problem.
<11>Aug  8 08:53:49 nikal: ERROR:  Logging failure...
<11>Aug  8 08:53:52 nikal: ERROR:  Include the file /tmp/niSystemReport.out.gz 
when contacting
<11>Aug  8 08:53:52 nikal: ERROR:  National Instruments for support.
<11>Aug  8 08:53:52 nikal: ERROR: Update of National Instruments drivers failed.



I found someone else who had this issue and it was resolved by upgrading gcc to 
4.9 or later and my gcc is already at 7.3 so I am not sure what else to do. Any 
insight would be appreciated. Thank you.



Sarah Tran
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[USRP-users] N310 printing 'S' when trying to use all 4 channels

[Sarah Tran via USRP-users]

Hi all,

So I recently posted about trying to figure out how to specify which channels I 
want. My goal is use all 4 channels of the N310 simultaneously. I used the 
subdev specification "A:0 B:0 C:0 D:0" in the Mb0 subdev spec input on the UHD 
sink block. None of the tx leds light up and I get a lot of 'S' on the console. 
I try each subdev individually, and they all work fine at sps of 12.5 Mhz. I am 
using the example program tx_ofdm.grc with the throttle blocks and ofdm 
transmitter blocks omitted and replaced by a UHD sink. I am using UHD 3.11.01. 
Any ideas on why this doesn't work or how to make it work?

Thank you,

Sarah

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Re: [USRP-users] N310 Subdevice Specification

[Sarah Tran via USRP-users]

Hi Nate,


Thank you for clarifying! I actually guessed and tried that subdev spec too, 
and while it got rid of the 'L's the 'S''s are still there and none of the leds 
come on. I am running at 12.5MHz. I am running the ofdm_tx.grx flowgraph and I 
made sure to get rid of the throttle block and replace the OFDM tranmitter 
block with the UHD sink block.


Thanks,


Sarah



From: Nate Temple <nate.tem...@ettus.com>
Sent: Monday, April 23, 2018 4:12 PM
To: Sarah Tran
Cc: usrp-users@lists.ettus.com
Subject: Re: [USRP-users] N310 Subdevice Specification

Hi Sarah,

For four channels on the N310 and UHD 3.11.0.1, the subdev spec will be  "A:0 
B:0 C:0 D:0".

What sample rate are you running at ?

Regards,
Nate Temple



On Mon, Apr 23, 2018 at 6:50 PM, Sarah Tran via USRP-users 
<usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com>> wrote:
Hi all,

I recently got the N310, and I got one of the example programs from gr-digital 
to run on it. However because I didn't specify a subdevice, it only uses one 
channel. I want to be able to TX on all 4 channels but I couldn't get the right 
subdevice specification syntax correct. I tried "A:0 B:0" just to get maybe two 
channels transmitting, but it just printed out a lot of 'S' and 'L's. I also 
tried the syntax for the E310 "A:A A:B" which didn't work either. I know this 
is just my error, but I can't find much documentation on the correct syntax to 
use! I am using UHD version 3.11 and GNU Radio 3.7.11.1. Any help is greatly 
appreciated!


-Sarah Leony


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[USRP-users] N310 Subdevice Specification

[Sarah Tran via USRP-users]

Hi all,

I recently got the N310, and I got one of the example programs from gr-digital 
to run on it. However because I didn’t specify a subdevice, it only uses one 
channel. I want to be able to TX on all 4 channels but I couldn’t get the right 
subdevice specification syntax correct. I tried “A:0 B:0” just to get maybe two 
channels transmitting, but it just printed out a lot of ‘S’ and ‘L’s. I also 
tried the syntax for the E310 “A:A A:B” which didn’t work either. I know this 
is just my error, but I can’t find much documentation on the correct syntax to 
use! I am using UHD version 3.11 and GNU Radio 3.7.11.1. Any help is greatly 
appreciated!


-Sarah Leony

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Re: [USRP-users] OFDM TX/RX BER Calculator and ofdm_tx underruns with x310

[Sarah Tran via USRP-users]

Hi Michael,

I just wanted to update you all on this problem. I spoke to Yang that posted 
the problem in here 
http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2017-March/023924.html.
 Her issue was that her USRP image was not the same as her version of uhd. I 
checked, and I updated the image for my X310. It fixed the issue! Thanks for 
your time.

-Sarah

From: Michael Dickens 
Sent: Friday, March 16, 2018 2:54 AM
To: Sarah Tran ; usrp-users@lists.ettus.com
Subject: Re: [USRP-users] OFDM TX/RX BER Calculator and ofdm_tx underruns with 
x310

Hi Sarah - You're welcome & the PER block sounds cool ... do you have a public 
repo where we can view the source? Well done!

As for your other question: Have you tried updating to the latest UHD release 
(3.11)? That might fix the issue "out of the box" ... and if not, try building 
from source via the latest GIT master branch. Even though 3.10 isn't really 
that old, it's old enough that updating might fix the issue. If not, then 
please provide the startup info from UHD to show its version & build, along 
with some code / specifics on how to replicate your issue & we'll definitely 
take a look & see what we can do.

Cheers! - MLD

On Thu, Mar 15, 2018, at 6:19 PM, Sarah Tran wrote:

I was able to make a PER block and it turns out I was dropping some packets, so 
when I took into account those dropped packets when I performed the BER, I was 
in a much better place 10e-2. Thank you for the explanation and help!



I had another question. I was previously using the N210 for this, and have 
since upgraded to the X310. However I get severe underruns (I tried the WBX and 
UBX-160 daughtercards). No matter what samp rate I use (from 400kHz to 10 MHz), 
I get lots of U’s printed on my console and then the X310 stops transmitting 
and freezes. I saw a previous thread that mentioned it was a problem with the 
UHD 3.10 code (which I am running), but didn’t say how it was fixed. (See 
http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2017-March/023924.html).
 Do you have any idea what the problem could be? I also put a null source 
instead of file source and changed the uhd sink to a probe+message debug, and 
it looks like my rates are good 2e7. The N210 works great and the X310 will 
transmit other data at the same rates, but not the ofdm_tx code.

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Re: [USRP-users] OFDM TX/RX BER Calculator and ofdm_tx underruns with x310

[Sarah Tran via USRP-users]

Hi Michael,



Here is the public repo with the custom block source code: 
https://st...@code.oceanit.com/stran/gr-per.git . The block is called Ansect 
Per ('Ansect' is the name of my own project I am using it for and 'per' stands 
for packet error rate). The source code is under /lib/ansect_per_impl.cc. 
Warning: I am not a programmer or GNU Radio savvy person, so I apologize in 
advance if my code is weird :). I kind of hacked something together that 
worked, but I hope it is useful to someone else! The README explains more.



I updated UHD to 3.11 and now I don't get underruns and it doesn't freeze, but 
whatever is being sent through the radio isn't correct still. Essentially the 
tx LED comes on and the frequency spectrum looks good from the tx side, but the 
rx side gets garbled data (detects a lot of invalid packets I am using an X310 
with two UBX-160 daughterboards, I also tried the WBX daughterboards which gave 
the same output. My version of GNU Radio is 3.7.11. ). I use the same computer 
to run the same code but using an N210 with a UBX-40 daughterboard, and I get 
the correct packet data (ofdm frequency spectrum looks great and good packets) 
on the rx side (using another computer + N210 to run rx_ofdm.py). This is the 
output from when I run tx_ofdm.py:


./tx_ofdm.py
Gtk-Message: Failed to load module "overlay-scrollbar"
[INFO] [UHD] linux; GNU C++ version 5.4.0 20160609; Boost_105800; 
UHD_3.11.0.1-3-g8bb15ee1
[INFO] [X300] X300 initialization sequence...
[INFO] [X300] Determining maximum frame size...
[INFO] [X300] Maximum frame size: 1472 bytes.
[INFO] [X300] Setup basic communication...
[INFO] [X300] Loading values from EEPROM...
[INFO] [X300] Setup RF frontend clocking...
[INFO] [X300] Radio 1x clock:200
[INFO] [RFNOC DMA FIFO] Running BIST for FIFO 0...
[INFO] [RFNOC DMA FIFO] BIST passed (Throughput: 1318 MB/s)
[INFO] [RFNOC DMA FIFO] Running BIST for FIFO 1...
[INFO] [RFNOC DMA FIFO] BIST passed (Throughput: 1309 MB/s)
[WARNING] [RFNOC] [0/Radio_0] defines 2 input buffer sizes, but 1 input ports
[INFO] [RFNOC RADIO] Register loopback test passed
[INFO] [RFNOC RADIO] Register loopback test passed
[WARNING] [RFNOC] [0/Radio_1] defines 2 input buffer sizes, but 1 input ports
[INFO] [RFNOC RADIO] Register loopback test passed
[INFO] [RFNOC RADIO] Register loopback test passed
[INFO] [CORES] Performing timer loopback test...
[INFO] [CORES] Timer loopback test passed
[INFO] [CORES] Performing timer loopback test...
[INFO] [CORES] Timer loopback test passed

I use the tx_ofdm code and take out the channel model, OFDM receiver, and Tag 
debug blocks. Instead I replace it with a UHD Sink block that has a samp rate 
of 1e6, center freq of 1.412e9, gain of 30 (absolute), tx/rx antenna, and 
bandwidth of 250kHz. When I hook up a frequency spectrum analyzer to the X310, 
I don't get the frequency response of the ofdm that I expect, but the same code 
will work for the N210. If you need more information to replicate the problem, 
please let me know!

Thanks for your time,

Sarah





From: Michael Dickens 
Sent: Friday, March 16, 2018 2:54 AM
To: Sarah Tran ; usrp-users@lists.ettus.com
Subject: Re: [USRP-users] OFDM TX/RX BER Calculator and ofdm_tx underruns with 
x310



Hi Sarah - You're welcome & the PER block sounds cool ... do you have a public 
repo where we can view the source? Well done!



As for your other question: Have you tried updating to the latest UHD release 
(3.11)? That might fix the issue "out of the box" ... and if not, try building 
from source via the latest GIT master branch. Even though 3.10 isn't really 
that old, it's old enough that updating might fix the issue. If not, then 
please provide the startup info from UHD to show its version & build, along 
with some code / specifics on how to replicate your issue & we'll definitely 
take a look & see what we can do.



Cheers! - MLD



On Thu, Mar 15, 2018, at 6:19 PM, Sarah Tran wrote:

I was able to make a PER block and it turns out I was dropping some packets, so 
when I took into account those dropped packets when I performed the BER, I was 
in a much better place 10e-2. Thank you for the explanation and help!



I had another question. I was previously using the N210 for this, and have 
since upgraded to the X310. However I get severe underruns (I tried the WBX and 
UBX-160 daughtercards). No matter what samp rate I use (from 400kHz to 10 MHz), 
I get lots of U's printed on my console and then the X310 stops transmitting 
and freezes. I saw a previous thread that mentioned it was a problem with the 
UHD 3.10 code (which I am running), but didn't say how it was fixed. (See 
http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2017-March/023924.html).
 Do you have any idea what the problem could be? I also put a null source 
instead of file source and changed the uhd sink to a probe+message debug, and 
it looks like my rates are good 2e7. The N210 works great and 

Re: [USRP-users] OFDM TX/RX BER Calculator and ofdm_tx underruns with x310

[Sarah Tran via USRP-users]

Hi Michael,

I was able to make a PER block and it turns out I was dropping some packets, so 
when I took into account those dropped packets when I performed the BER, I was 
in a much better place 10e-2. Thank you for the explanation and help!

I had another question. I was previously using the N210 for this, and have 
since upgraded to the X310. However I get severe underruns (I tried the WBX and 
UBX-160 daughtercards). No matter what samp rate I use (from 400kHz to 10 MHz), 
I get lots of U’s printed on my console and then the X310 stops transmitting 
and freezes. I saw a previous thread that mentioned it was a problem with the 
UHD 3.10 code (which I am running), but didn’t say how it was fixed. (See 
http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2017-March/023924.html).
 Do you have any idea what the problem could be? I also put a null source 
instead of file source and changed the uhd sink to a probe+message debug, and 
it looks like my rates are good 2e7. The N210 works great and the X310 will 
transmit other data at the same rates, but not the ofdm_tx code.

Thank you!

Sarah

From: Michael Dickens 
Sent: Thursday, March 8, 2018 6:12 AM
To: Sarah Tran ; usrp-users@lists.ettus.com
Subject: Re: [USRP-users] OFDM TX/RX BER Calculator

Hi Sarah - Glad you're heading down a positive path.

The header data is removed from the raw data being decoded, but added as 
meta-data on the stream. This meta-data is optionally printed out by GR OFDM 
and/or various Qt displays. Once the header has been verified (via CRC8), it is 
no longer part of the raw OFDM symbol data.

Cheers! - MLD

On Wed, Mar 7, 2018, at 9:11 PM, Sarah Tran wrote:

Thank you for your quick response! I wanted the payload to be QPSK modulated. I 
put a QT Range blocks in for the gain settings on the ofdm_tx and ofdm_rx 
flowgraphs. I still can’t seem to get any better than 20% BER though, but I 
think the advice about doing a PER calculator is pointing me in the right 
direction as a lost packet would definitely screw up the BER. So thank you very 
much for the advice!!



I did have another question though regarding the metadata that still has me 
confused. If the header data is taken out of the payload, why does it still 
show up when I put a time sink after the payload gettings decoded (after the 
constellation decoder/stream CR32 blocks)? It plots the decoded bits as well as 
the packet num, carrier_offset, etc. Did I put my time sink in the wrong place?
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Re: [USRP-users] OFDM TX/RX BER Calculator

[Sarah Tran via USRP-users]

Hi Michael,

Thank you for your quick response! I wanted the payload to be QPSK modulated. I 
put a QT Range blocks in for the gain settings on the ofdm_tx and ofdm_rx 
flowgraphs. I still can’t seem to get any better than 20% BER though, but I 
think the advice about doing a PER calculator is pointing me in the right 
direction as a lost packet would definitely screw up the BER. So thank you very 
much for the advice!!

I did have another question though regarding the metadata that still has me 
confused. If the header data is taken out of the payload, why does it still 
show up when I put a time sink after the payload gettings decoded (after the 
constellation decoder/stream CR32 blocks)? It plots the decoded bits as well as 
the packet num, carrier_offset, etc. Did I put my time sink in the wrong place?

Thank you!
Sarah

From: Michael Dickens [mailto:michael.dick...@ettus.com]
Sent: Tuesday, March 6, 2018 5:24 PM
To: Sarah Tran <st...@oceanit.com>; usrp-users@lists.ettus.com
Subject: Re: [USRP-users] OFDM TX/RX BER Calculator

Hi Sarah - A few things to note on using the default GR OFDM using real SDR 
devices that could be relevant here:

* tx data amplification: This needs to be such that the data heading to UHD 
doesn't saturate on conversion. You can visually see this if you look at the 
raw Rx signal ... it will look mostly like OFDM in the center but then have 
significant side bands. With too little Tx data amplification, the signal will 
look very OFDM, but it might end up with the average signal peaks being not far 
enough above the noise floor. The Tx data amp value depends on which 
constellation you're using for the payload. An easy way to see all of this is 
to use a graphical slider to set this value & then watch the raw Rx signal.

* rx data amplification: You generally want this "high", but you can play with 
this value to see what works best. This value generally isn't as critical as 
the Tx data amp value.

* Since OFDM sends data in packets, you really care about the Packet Error Rate 
(PER). Lose 1 packet, and you've lost a bunch of bits. The OFDM Rx uses the tag 
"packet_num" to show successful packet receipt, and increments this value by 1 
for each packet detected but invalid (whether in the meta-data header or in the 
payload). So you should be able to create a PER block that just watches for 
skips in the Rx "packet_num" tag.

* The meta-data you mention is the header, which is indeed inserted into the 
OFDM signal. It is removed on Rx, so it should not be the cause of your issues.

* It sounds almost as if the OFDM Rx is losing sync after 20% of the data is 
received, for some reason. Usually Rx sync is lost because the USRP's Tx gain 
isn't high enough, and so the Rx signal's "SNR" isn't high enough to always 
meet the sync's criteria. Maybe try playing with the USRP Tx gain & see if that 
helps.

I';m sure there are other things relevant here, but these are the ones that 
come to mind. Hope this helps! - MLD

On Tue, Mar 6, 2018, at 3:53 PM, Sarah Tran via USRP-users wrote:

I am trying to use the ofdm_tx.grc and ofdm_rx.grc to transmit data from one 
N210 controlled by a host to another N210 controlled by a separate host. 
Eventually I want to build an 8x8 MIMO system using OFDMA. I want to verify 
that the correct data is being received so I sent all of the decoded payload 
data into a file sink. The file I sent has 10e6 random samples from 0-255 being 
stored into bytes. I received at least 5x that amount to ensure that I got all 
the data. I imported the received data and the known sent data into Matlab and 
performed the cross-correlation. The figure looks kind of okay as it showed 
multiple peaks (see figure below). However when I went to actually calculate 
the BER, I never got more than 20% of the correct bits. It was behaving 
strangely as 20% of the bits would be correct in a row, and then after that it 
would just be completely wrong. I know the ofdm_tx.grc graphs inserts metadata 
into the signal, and my theory is that the meta data is also being decoded and 
it won’t match exactly what was sent in the file because of the extra 
information. My understanding might be completely off, so if anyone can clarify 
it would be greatly appreciated! I just want to be able to have a way that 
calculates the BER between what is transmitted and what is received. Thank you 
for your time!!

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[USRP-users] OFDM TX/RX BER Calculator

[Sarah Tran via USRP-users]

Hi all,

I am trying to use the ofdm_tx.grc and ofdm_rx.grc to transmit data from one 
N210 controlled by a host to another N210 controlled by a separate host. 
Eventually I want to build an 8x8 MIMO system using OFDMA. I want to verify 
that the correct data is being received so I sent all of the decoded payload 
data into a file sink. The file I sent has 10e6 random samples from 0-255 being 
stored into bytes. I received at least 5x that amount to ensure that I got all 
the data. I imported the received data and the known sent data into Matlab and 
performed the cross-correlation. The figure looks kind of okay as it showed 
multiple peaks (see figure below). However when I went to actually calculate 
the BER, I never got more than 20% of the correct bits. It was behaving 
strangely as 20% of the bits would be correct in a row, and then after that it 
would just be completely wrong. I know the ofdm_tx.grc graphs inserts metadata 
into the signal, and my theory is that the meta data is also being decoded and 
it won’t match exactly what was sent in the file because of the extra 
information. My understanding might be completely off, so if anyone can clarify 
it would be greatly appreciated! I just want to be able to have a way that 
calculates the BER between what is transmitted and what is received.

Thank you for your time!!

[cid:image002.jpg@01D3B539.503832E0]

Sarah Tran
Electrical Engineer
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Re: [USRP-users] Passing Messages as Commands to UHD Sink

[Sarah Tran via USRP-users]

Hi Martin,

Thank you for verifying my code I was able to put in debugging printf 
statements, and was able to figure out what was wrong (although I couldn't get 
the GR logging statements like debug to show). The message was indeed getting 
to the UHD sink, but I realized that I needed to also specify the parameter for 
lo_offset otherwise the key 'freq' just sets the lo_offset to 0. I was using 
Bastian's gr-ieee802-11 library, and I didn't realize the way that he tunes his 
center freq is different than just uhd.tune_request(target_freq, lo_offset). He 
actually uses uhd.tune_request(target_freq, rf_freq=freq-lo_offset, 
rf_freq_policy = uhd.tune_request.POLICY_MANUAL). So I modified the code like 
below:

::uhd::tune_request_t request;
request.target_freq = freq;
request.rf_freq_policy = ::uhd::tune_request_t::POLICY_MANUAL;
request.rf_freq = rx_freq - lo_offset;
new_tune_reqest = ::uhd::tune_request_t(request);
.
.
_update_curr_tune_req(new_tune_reqest, chan);

That did the trick. Thank you for your help.

-Sarah


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Subject: USRP-users Digest, Vol 89, Issue 21

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Today's Topics:

   1. Re: UHD Converter for X310 series with unsupported data
  format (Kei Nguyen)
   2. Re: Help on UHD Python API installation (Zhongyuan Zhao)
   3. Re: Help on UHD Python API installation (Zhongyuan Zhao)
   4. Using both sides of an NI USRP-2953R (da...@daryllee.com)
   5. Re: UHD Converter for X310 series with unsupported data
  format (Martin Braun)
   6. Re: Help on UHD Python API installation (Martin Braun)
   7. Re: Using both sides of an NI USRP-2953R (Martin Braun)
   8. Re: 2 B210 synchronous problem (Martin Braun)
   9. Re: USRP with different GPSDO (Martin Braun)
  10. Re: Passing Messages as Commands to UHD Sink (Martin Braun)
  11. Re: use 2 DDC chain of N210 with SBX (Martin Braun)
  12. Re: transmit underrun in dual 10Gige X310 config (Martin Braun)
  13. Re: [RFNoC] uhd_usrp_probe fails and throws uhd::lookup_error
  (Adam Kurisko)
  14. Re: [RFNoC] uhd_usrp_probe fails and throws uhd::lookup_error
  (Martin Braun)
  15. [UHD] Dependency changes: MSVC and Vivado (Martin Braun)
  16. Re: [RFNoC] uhd_usrp_probe fails and throws uhd::lookup_error
  (Adam Kurisko)
  17. Re: [RFNoC] uhd_usrp_probe fails and throws uhd::lookup_error
  (Martin Braun)
  18. [UHD] Changes to uhd_images_downloader (Martin Braun)
  19. uhd error with new version (Dang tien Vo-Huu)
  20. Re: 2 B210 synchronous problem (Piotr Krysik)
  21. Re: [RFNoC] uhd_usrp_probe fails and throws uhd::lookup_error
  (EJ Kreinar)
  22. Re: use 2 DDC chain of N210 with SBX (omid saeedy)
  23. Re: [RFNoC] uhd_usrp_probe fails and throws uhd::lookup_error
  (Adam Kurisko)


--

Message: 1
Date: Tue, 23 Jan 2018 12:13:48 -0500
From: Kei Nguyen 
To: usrp-users@lists.ettus.com
Subject: Re: [USRP-users] UHD Converter for X310 series with
unsupported data format
Message-ID:

[USRP-users] Passing Messages as Commands to UHD Sink

[Sarah Tran via USRP-users]

Hi All,

I would like to change the center freq of my UHD Sink depending on who the 
receiver is. So I wrote a custom block that will read what the destination mac 
address is for a packet, and send a message to change the center freq based on 
what destination address it is. This is the format for how I write the message:

{
   message_port_register_out(PDU_PORT_ID);
}
.
.
.
   command = pmt::make_dict();
   command = pmt::dict_add(command, pmt::mp(“freq”), 
pmt::mp(2.412e9));
   command = pmt::dict_add(command, pmt::mp(“chan”), pmt::mp(0));
   message_port_pub(PDU_PORT_ID, command);

I saw from other mailing list posts, that this was the syntax they used, but I 
can’t get it to actually the center frequency. Is there something I am doing 
wrong? I am using uhd version 3.10 and GRC version 3.7.11.1.

Thank you!!
-Sarah Leony

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[USRP-users] Phase Alignment of Multiple X310s

[Sarah Tran via USRP-users]

Hi everyone!

I was wondering if anyone knew if it was possible to phase align more than 2 
X310s (with UBX daughterboard) to form a coherent array? I know that 2x2 MIMO 
is possible using a single X310, but I want to be able to sync 4 of them. I 
thought I read somewhere that it was dependent on the daughterboard, but I 
can’t find that thread anywhere.

Thanks for all the help!



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Email: st...@oceanit.com
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[USRP-users] TCP/IP can't ping using N210

[Sarah Tran via USRP-users]

Hi everyone!


I am trying to use the example tunnel.py in 
~/gnuradio/gr-digital/examples/ofdm. I have two N210's connected to two 
separate Linux computers, and I am using the following settings:


Machine A (TX):

sudo ./tunnel.py --freq 5e9 --verbose

opened another terminal

sudo ifconfig gr0 192.168.200.1


Machine B (RX):

sudo ./tunnel.py --freq 5e9 --verbose

opened another terminal

sudo ifconfig gr0 192.168.200.2


Unfortunately when I try to ping either machine, it does not work. Does anyone 
have any idea where I could be going wrong? Or am i missing something? I have 
seen others ask similar questions in the past, but it doesn't look like it has 
gotten resolved yet.


Thank you for your time!


-Sarah Leony
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[USRP-users] TXRX_loopback_to_file problem with USRP N210 and MIMO

[Sarah Tran via USRP-users]

Hello!



I am trying to use 2 N210's connected by a MIMO cable to execute the uhd 
example program txrx_loopback_to_file. I have one host machine and would like 
one SDR to transmit the signal and the other SDR to receive it to a file. I 
would like to eventually modify the code so that I can make a bit error rate 
tester between the two N210's, but I was trying to get the threading to work 
first.



I have the args: --tx-args="addr=192.168.10.2" --rx-args="addr=192.168.10.3" 
--type="float" --nsamps=1e6 --tx-rate=5e6 --rx-rate=5e6 --tx-freq=900e6 
--rx-freq=900e6 --tx-ant="TX/RX" --rx-ant="TX/RX" --ref="mimo" 
--wave-type="SINE" --wave-freq="2000"



I am using matlab to convert the binary file "usrp_samples.dat" into a complex 
array and I plot the results. I have attached the plot.



The results I get from the receive function do not resemble a sine wave; it 
looks more like noise. I have 50 db (50 ohm) attenuation inline with the cable 
that is connecting the two usrps (I am not actually transmitting over the air). 
However when I run the code, I see that LED's indicating that they are 
transmitting and receiving as they should, but the results are not what is 
expected.



I am fairly new to usrp and C++, so any help or direction as to what could be 
the problem would be greatly appreciated. Thank you for your time!



-Sarah Leony

Electrical Engineer
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