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Today's Topics:
1. The FPGA build is not compatible with the host code build
(Michel Burnand)
2. Re: UHD: What do the tx_metadata_t burst parameters mean?
(Raj Bhattacharjea)
3. FasTrack GRC Project (Derek Murphy)
4. Re: USRP captured data information (Raj Bhattacharjea)
5. Re: B210 over Network? (Raj Bhattacharjea)
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Message: 1
Date: Sat, 18 Apr 2015 20:33:52 +0200
From: Michel Burnand <[email protected]>
To: [email protected]
Subject: [USRP-users] The FPGA build is not compatible with the host
code build
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8; format=flowed
Hello Martin,
I have the same issue as Yue with my USRP2...
I have UHD_003.008.003-137-g2f760ac0 installed. Uploaded usrp2_fpga.bin
and usrp2_fw.bin, burned a SD card. No success at all...
The image file downloaded by uhd_images_downloader.py is:
uhd_images_003.008.003-130-g4ca383f7.zip
Thank you in advance for your help.
Michel, HB9DUG
---
L'absence de virus dans ce courrier ?lectronique a ?t? v?rifi?e par le logiciel
antivirus Avast.
http://www.avast.com
------------------------------
Message: 2
Date: Sat, 18 Apr 2015 15:32:23 -0400
From: Raj Bhattacharjea <[email protected]>
To: [email protected], [email protected]
Subject: Re: [USRP-users] UHD: What do the tx_metadata_t burst
parameters mean?
Message-ID:
<cap3eqje_7lrndme4jcstzusn73aokoio52rylgtowjvqvft...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Thank you for the references. Those examples give me a vague idea of what
these concepts mean. I certainly can't say I have a precise definition, or
understanding of how the behavior of UHD and/or the USRP will change with
different uses of the burst parameters. I'll carry on by experimentation
with the code and delving into the UHD source. I was hoping that there was
documentation, but it appears that there is not.
On Tue, Apr 14, 2015 at 3:27 PM, <[email protected]> wrote:
> I'd suggest looking at the source for tx_timed_samples.cpp and
> tx_bursts.cpp to get a feel for how this works, as well as tx_waveforms.cpp
>
>
>
>
>
>
> On 2015-04-14 15:00, Raj Bhattacharjea via USRP-users wrote:
>
> What is the meaning of various tx_metadata_t fields in UHD? The
> documentation is here:
>
> http://files.ettus.com/manual/structuhd_1_1tx__metadata__t.html
>
> This is API documentation explaining what functions and fields exist, but
> it does not tell me much about the concepts this API is implementing. Is
> there some document I'm missing that explains the concepts of metadata in
> UHD, how it is used, and what terms like time_spec and start_of_burst mean,
> precisely? When should a burst be considered to start? To stop? If I send
> 20 pulses of a carrier, each 20 microseconds long and separated by 10
> microseconds, then sleep for 1 second, then do it again, do I have one
> burst per second, or 20? What difference does this metadata even make, the
> samples still go out the TX port regardless of these flags, right? If I
> don't use the burst start and stop metadata correctly, will the state of
> the USRP be somehow invalid when I go to TX again later in my application?
>
> --
> Raj Bhattacharjea
> Georgia Institute of Technology
> School of Electrical and Computer Engineering
> http://www.prism.gatech.edu/~gtg037s/
> 404.894.7516
>
> _______________________________________________
> USRP-users mailing
> [email protected]http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
--
Raj Bhattacharjea
http://www.prism.gatech.edu/~gtg037s/
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Message: 3
Date: Sat, 18 Apr 2015 15:44:05 -0400
From: Derek Murphy <[email protected]>
To: [email protected]
Subject: [USRP-users] FasTrack GRC Project
Message-ID:
<CAPM65YikWoBYj=a352zL13wYJW_jc_kJuL7=PN7n6C6eWz=p...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
I've watched several videos of Balint conducting research into the FasTrack
passes and in one video he said he would publish all the code / grc files.
I have not found any of those posted.
I was wondering if anyone has the grc file he is referring to. I am also
interested in learning about how to send a signal to interrogate the
FasTrack and then have the usrp receive the response and parse the result.
I'm working on make a grc project to do this but I am fairly new to GRC /
SDRs. I've done the basic FM receiver / FM transmitter. I also have a HAM
license and have listed to HF using an upconverter.
Thanks for the help
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Message: 4
Date: Sat, 18 Apr 2015 16:19:20 -0400
From: Raj Bhattacharjea <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] USRP captured data information
Message-ID:
<CAP3eQJddn_4_QjG+QX7AaD0GrvO=mysjxcdbbqrqhjw+bfe...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
With your mention of curve fitting and RSSI, I had a strong suspicion you
were doing some practical channel measurements and modeling. Here are some
pointers that might help you.
What we call power in a signal is proportional to a time-average of the
square of the signal. See here:
https://en.wikipedia.org/wiki/Spectral_density#Power_spectral_density
I say proportional because to get actual real world units like Watts of RF
power at an arbitrary receiver antenna, there must be extra factors
included like pi and the intrinsic impedance of free-space, and you have to
back out the effect of the receiver antenna including radiation efficiency
and impedance.
To go from USRP measurements to something proportional to power, you can
form the complex baseband in Matlab using something like this: X = I+1j*Q,
assuming I and Q are the I and Q samples, respectively. Now abs(X).^2 must
be time-averaged over some window of time, which looks something like
conv(abs(X).^2,ones(1,N)/N,'valid'), where N is the number of samples over
which you want to time-average. That would give you a signal that is
proportional to the the average power in the original signal (over N-sample
windows). This is something akin to RSSI, and you could move around your
antennas and measure the power in various locations and do your curve
fitting and come up with path loss exponents and variances, etc.
You could reasonably also fix the unknown constant of proportionality in
the system through calibration: cable connect a TX to an RX, transmit your
waveform at a known level, measure the RX power, and record that as the
reference level. Then, divide all further measurements by that reference
value. Alternately, if you work in path loss, then the absolute power
levels drop out because you form the difference between transmitted and
received power.
--
Raj Bhattacharjea
http://www.prism.gatech.edu/~gtg037s/
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Message: 5
Date: Sat, 18 Apr 2015 17:36:06 -0400
From: Raj Bhattacharjea <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] B210 over Network?
Message-ID:
<cap3eqjfgaxmmc2vacdh4h3-m9p8gzkew2s9knm-upolae8+...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
There is no built in functionality to do this kind of thing in UHD. It
would be great if Ettus provided a daemon that handled talking to the B210
over USB and looked like an available USRP over the network (just like an N
series). I see why they don't though: 1 GBPS of network bandwidth can't
keep up with the 54 MSamps/s @ sc16 (32 bits per complex sample) that the
B210 is capable of. Lower sample rates or lower bit resolution (sc8) are
possibilities however, and I second the use of the rx_samples_to_udp
example file for those cases.
Here's some stuff we are doing in this same vein, I hope these details
maybe help you out. We have B210s connected to Gigabyte BRIX machines
instead of NUCs, but only because the BRIX is available with a decent
graphics processor in a NUC-like form factor. For spectrum visualization
remotely, we use the GPU + gr-fosphor to crunch the FFTs and then encode a
video stream using the CPU + ffmpeg, and send this video stream over UDP to
the client. In my simple tests, the datarate of such a video with no
compression is an order of magnitude less than the raw datarate of a 20-30
MSamp/s IQ data stream. With compression, the video bitrate is of course
even lower. Other modes we're working on include remote recording and
playback of samples. The "B210 server" and the consuming client
applications are Python code and network sockets are used for all
communications between machines.
--
Raj Bhattacharjea
http://www.prism.gatech.edu/~gtg037s/
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