gmane.comp.hardware.usrp.e100

Re: USRP EMI Solution

Mark McCarron — 2013-05-19T00:11:45

The requirements are different, but how much EMI/RFI shielding do you think the box provides?

I can tell you now it would be around 1dB, if even that.  It really is as effective as tissue paper.  It may couple some near-field effects but not much.

Regards,

Mark McCarron

Date: Sat, 18 May 2013 19:24:04 -0400
Subject: Re: [USRP-users] USRP EMI Solution
From: hilbert3141-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org
To: mark.mccarron-SrPyuzuu+o61Qrn1Bg8BZw< at >public.gmane.org

The requirements of TEMPEST and the requirements of ordinary commercial EMC are very, very different.

Because a box doesn't meet TEMPEST says essentially *zero* about its suitability for ordinary commercial

  applications in the EMC realm.

I've been inside the photon-locked shielded room at NRAO, and other similar rooms.  Ordinary commercial gear
  *does not* need to meet those requirements.  At all.  Ever.

Open up a standard commercial-grade or ham-radio grade receiver/transceiver sometime.  You'll find that there's
  no extensive RF gas

Re: USRP EMI Solution

Mark McCarron — 2013-05-18T22:38:06

Hilbert,

I've designed EMI/RFI solutions and TEMPEST secure rooms to protect computing, comms and humans.  That box may as well be tissue paper.

Grounded means nothing other than general electrical safety (even then there are caveats to this).  An EMI/RFI shield extends a ground reference around an object.  That's not as easy as it sounds.

Regards,

Mark McCarron

Date: Sat, 18 May 2013 18:24:30 -0400
Subject: Re: [USRP-users] USRP EMI Solution
From: hilbert3141-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org
To: mark.mccarron-SrPyuzuu+o61Qrn1Bg8BZw< at >public.gmane.org

The metal is *grounded*.  It doesn't matter whether it's painted, or not.  The paint issue is along the seams in
  any type of cabinet.  Ideally, you want all the seams to be one continuous ground, and if you have a cabinet

  that fits-together mechanically, that's where you'll typically find RF gasket material between two non-painted
  surfaces.  But the paint, in and of itself, is irrelevant.

Certainly, if you're going to be operating any kind of

Re: USRP EMI Solution

Mark McCarron — 2013-05-18T21:58:53

That's not an EMI shield.  The metal is painted and would be effectively transparent to EMI/RFI.  What is required is a continuously conducting surface with proper sealed inputs and EMI gaskets.

Its incredibly hard to properly seal anything from EMI/RFI.

Regards,

Mark McCarron

Date: Sat, 18 May 2013 17:42:09 -0400
From: hilbert3141-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org
To: usrp-users-p6fHTpcPDZaz3Dx2OeFgIA< at >public.gmane.org
Subject: [USRP-users] USRP EMI Solution

Mark writes:

You mean, other than the one that comes with it?  The box is metallic, grounded, and most of the perforations in it are a tiny fraction of a wavelength up to a few GHz.  If I were

operating in high RF fields above about 3GHz, I might replace the fan grille with
some steel mesh.

The USB cable Ettus supplies includes a common-mode choke, as does the power cable.

For lower frequencies (below 50Mhz) adding more common-mode chokes to those cables will likely help, and they're available on eBay reasonably cheaply.

But, as far as

USRP EMI Solution

Hilbert Transform — 2013-05-18T21:42:09



You mean, other than the one that comes with it?  The box is metallic,
grounded, and most of the perforations in it are a tiny fraction of a
wavelength up to a few GHz.  If I were
operating in high RF fields above about 3GHz, I might replace the fan
grille with
some steel mesh.

The USB cable Ettus supplies includes a common-mode choke, as does the
power cable.

For lower frequencies (below 50Mhz) adding more common-mode chokes to those
cables will likely help, and they're available on eBay reasonably cheaply.

But, as far as I know, the existing steel cabinet was engineered to provide
EMI isolation, and given its material and construction, it can't help but
do so, due to physics...

USRP EMI Solution

Mark McCarron — 2013-05-18T21:09:39

Has anyone considered constructing an EMI shield box for the USRP?

Regards,

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overflow on E100 over HDMI

Robyn Colopy — 2013-05-18T00:33:22

Hi folks,

I got an E100 recently and since I'm pretty new at GNURadio I'm trying
to do some quick sanity checks using a monitor before switching to
ssh. Right now I just have a USRP Source going into a QT GUI Time
Sink. I've brought the FPGA clock down to 16M and the sampling to 31
kHz and I've tried a couple different settings on the GUI update rate.
Nothing seems to slow it down enough to prevent overflow.

I was hoping someone might be able to point me to some documentation
regarding the lowest achievable sampling rate, or if that's still not
slow enough, a hint on how to perform finite rx/tx instead of
continuous.

Thanks for your help!
Robyn

Re: B100 Transmitting At Power On???

Matt Ettus — 2013-05-17T04:12:32

It is not transmitting.  Before the FPGA is loaded, the LEDs connected to
the FPGA are all on.

Matt


On Thu, May 16, 2013 at 8:17 PM, Mark McCarron <mark.mccarron-SrPyuzuu+o61Qrn1Bg8BZw< at >public.gmane.org>wrote:

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B100 Transmitting At Power On???

Mark McCarron — 2013-05-17T03:17:32

I have noticed that the B100, when initially powered up, reports it is transmitting.  The three lights on the left-hand column are lit and the bottom one on the right.

The LEDs lit are:

A,C,E
F

Is that normal?

Regards,

Mark McCarron       _______________________________________________
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Re: USRP B100 and USB 3.0

Matt Ettus — 2013-05-16T04:46:17

Mark,

We are always working on new products, and will have some to announce soon.
 As for "options" for owners of current products, I am not sure what you
mean.  The B100 will continue to function and be fully supported by Ettus
Research long after any new products are released.

The USRP1 was released on January 1st, 2005, more than 8 years ago.  We are
still supporting them, and people are still using them (and even buying new
ones!) despite our subsequent release of the USRP2, N200, N210, B100, E100,
and E110.  We fully intend for that pattern to continue.

Matt Ettus



On Wed, May 15, 2013 at 11:59 AM, Mark McCarron <mark.mccarron-SrPyuzuu+o61Qrn1Bg8BZw< at >public.gmane.org>wrote:

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Re: Sending data to USRP2 with Simulink, without Buffer Overflow

Mike McLernon — 2013-05-16T02:33:34

Hi Ken,

Do you plan to use GNU Radio or MATLAB/Simulink?

Mike

________________________________________
From: USRP-users [usrp-users-bounces-p6fHTpcPDZaz3Dx2OeFgIA< at >public.gmane.org] on behalf of Ken [alexcaundy-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org]
Sent: Wednesday, May 15, 2013 6:02 PM
To: usrp-users-p6fHTpcPDZaz3Dx2OeFgIA< at >public.gmane.org
Subject: Re: [USRP-users] Sending data to USRP2 with Simulink,  without Buffer Overflow

Mike McLernon <Mike.McLernon< at >...> writes:

USRP Rx block?
Overflow
width of 40kHz.
file, output it via soundcard, with a
to the RX.
and it worked fine !
overflow at the USRP2 input.
USRP2 ?

Hello to anyone who can help me out. I am a total stranger, when it comes to
using GNU and SDR. I am interested in playing with a complete transmit and
receive OFDM model that can be ported into USRP. I don't mind giving my e-
mail. I would also like to put convolutional or permutation codding in the
model.
Ken

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Re: Sending data to USRP2 with Simulink,without Buffer Overflow

Ken — 2013-05-15T22:02:10

USRP Rx block?
Overflow
width of 40kHz.
file, output it via soundcard, with a
to the RX.
and it worked fine !
overflow at the USRP2 input.
USRP2 ?


Hello to anyone who can help me out. I am a total stranger, when it comes to  
using GNU and SDR. I am interested in playing with a complete transmit and 
receive OFDM model that can be ported into USRP. I don't mind giving my e-
mail. I would also like to put convolutional or permutation codding in the 
model. 
Ken

USRP B100 and USB 3.0

Mark McCarron — 2013-05-15T18:59:26

Does anyone know if there are any plans to update the B100 to USB 3.0?

If so, does anyone know what options will exist for current B100 owners?

Regards,

Mark McCarron       _______________________________________________
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Re: Frequency Offsets for USRP -N210

mahaveer gupta — 2013-05-15T17:39:53

Thats a good point. Simulations could be helpful, also will measure the
frequency offset over a larger sample size (like 1024). In general my
expectation is that the offset should not vary much except for temperature
of the daughterboard, if it gets heated up


On Wed, May 15, 2013 at 1:30 PM, Matt Ettus <matt-+aYTwkv1SeIAvxtiuMwx3w< at >public.gmane.org> wrote:

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Re: Frequency Offsets for USRP -N210

Matt Ettus — 2013-05-15T17:30:04

32 samples is a very short time to measure frequency.  Have you measured in
the same way on simulated data with comparable noise levels?

Matt


On Wed, May 15, 2013 at 9:35 AM, mahaveer gupta <mgupta1616-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org>wrote:

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Re: Frequency Offsets for USRP -N210

mahaveer gupta — 2013-05-15T16:35:39

the mean angle difference between 32 samples (half preamble) which is
output by ofdm_sync_pn was around 5 degrees. The standard deviation was
around 2-.2.5 degrees

Thanks


On Wed, May 15, 2013 at 12:24 PM, Matt Ettus <matt-+aYTwkv1SeIAvxtiuMwx3w< at >public.gmane.org> wrote:

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Re: Frequency Offsets for USRP -N210

Matt Ettus — 2013-05-15T16:24:49

Yes, but what are the frequency errors you are seeing?


On Wed, May 15, 2013 at 9:22 AM, mahaveer gupta <mgupta1616-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org>wrote:

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Re: Frequency Offsets for USRP -N210

mahaveer gupta — 2013-05-15T16:22:50

Hi Matt,

the estimation is done once in 240 samples at 1Mhz, 2.4Ghz band. The FFT
size is 64

Thanks


On Wed, May 15, 2013 at 12:02 PM, Matt Ettus <matt-+aYTwkv1SeIAvxtiuMwx3w< at >public.gmane.org> wrote:

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Re: Frequency Offsets for USRP -N210

Matt Ettus — 2013-05-15T16:02:41

The estimator has its own error.  What size are the changes you are seeing?

Matt


On Tue, May 14, 2013 at 11:03 PM, mahaveer gupta <mgupta1616-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org>wrote:

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Testbench for usrp2

Purush — 2013-05-15T09:20:01

I am USRP newbie. I am trying to get a first hands on experience in adding
few registers into the FPGA and reading them back into the host machine.

I am using USRP2 and using the main branch of UHD.

To start with I am just adding registers into the "u2_core.v" and making
changes into the firmware of ZPU. I added to the code to write
"sr_my_regs_ctrl->params_b
= 0xffffffff;"  to the zpu code (in the u2_init.c file) and generated the
rom file. As described in :

http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2011-March/000886.html

I renamed the generated ROM file to "flash.rom" and moved it to the
testbench folder.

I am using a mixed language simulator (i.e. ModelSim) to simulate the
design and see the register being written. I understand that the testbench
found in the "testbench/single_u2_sim.v" is outdated and needs to be
changed to remove some obvious library errors generated due to FIFO
libraries. As discussed in the message exchanges by the post:

http://lists.ettus.com/pipermail/usrp-us

Frequency Offsets for USRP -N210

mahaveer gupta — 2013-05-15T06:03:19

Hello,

The frequency offset computed for a a pair of USRP-N210's comes out to
be different every time

Frequency offsets usually vary in longer timescales but I get completely
non-correlated values every time I make transmissions between a
transmitter-receiver pair.

When I sent back-to-back packets, the offset estimation from different
preambles deviate as big as 30-40%. Is this the expected behavior? Will
appreciate if somebody can help me figure out whats going on here?

Wondering whether there is a way to calibrate the USRP such that the
frequency offset does not vary in shorter time-scales


Thanks,
M
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Re: QPSK Demodulator using GRC

Robert Watson — 2013-05-14T14:08:04

Hi,

Check the note in the documentation on thread priority scheduling...
http://files.ettus.com/uhd_docs/manual/html/general.html#threading-notes

R.


On 14 May 2013 13:20, ZaInzAiN Jj <zain_zain_jj-/E1597aS9LQAvxtiuMwx3w< at >public.gmane.org> wrote:

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