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Today's Topics:
1. Re: NI2901 receive power (Rob Kossler)
2. Bringing N210 to USA - any issues ? (Jithesh Joshy)
3. Re: Bringing N210 to USA - any issues ? (Kyeong Su Shin)
4. Tuning time on E310 (Jessica Iwamoto)
5. Re: RFNoC syntax error in gnuradio's generated python file
(James Dunn)
6. Re: Tuning time on E310 (Marcus D. Leech)
7. Input signal for ADC is at high level (Muhammad Munir)
8. Re: Input signal for ADC is at high level (Marcus M?ller)
9. light weight direction finder (???)
10. Re: light weight direction finder (Marcus M?ller)
11. Re: Input signal for ADC is at high level (Muhammad Munir)
12. WBX board damaged, pre-amp U6 is not MGA62563? (Evert)
13. Re: Input signal for ADC is at high level (Marcus M?ller)
14. Re: WBX board damaged, pre-amp U6 is not MGA62563? (Marcus M?ller)
15. Re: Input signal for ADC is at high level (Marcus M?ller)
16. Re: Input signal for ADC is at high level (Muhammad Munir)
17. USRP X310 at 5.8GHz (chu li)
18. How to install USRP B200 image on Raspberry Pi 3 (Ankur Vora)
19. Re: USRP X310 at 5.8GHz (Marcus M?ller)
----------------------------------------------------------------------
Message: 1
Date: Tue, 18 Apr 2017 12:22:40 -0400
From: Rob Kossler <[email protected]>
To: emre g?ng?r <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] NI2901 receive power
Message-ID:
<cab__httwvg47hy1grnt98rdwgca1attur8u6s_c8a28nm8q...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Emre,
Make sure that the values that you send to the USRP sink are in the range
[-1,1] which is the normalized range that the sink expects. The sink will
then automatically multiply each value by 2^15 in order to send from the
D/A converter. Similarly, on the receive side, make sure that your
received samples are not reaching 1 or -1 because this indicates that the
A/D is producing values of 2^15 and -2^15 and likely means that you are
overdriving your A/D such that you need to add attenuation or reduce gain.
Regarding the low pass filter, keep in mind that although the USRP RF is a
5 GHz, the digital samples are downconverted to complex baseband, so it
makes sense to low pass filter the signal to see the power variation versus
time. Think of it like an envelope tracker where you are filtering the
envelope signal.
Rob
On Tue, Apr 18, 2017 at 11:56 AM, emre g?ng?r via USRP-users <
[email protected]> wrote:
> Hello,
>
> I sent my experiment in gnu radio, I use NI2901. I connect horn antennas
> to transmitter and reciver of Usrp. I have have high scattering obstacle
> (trihedral corner reflector) I am trying to measure power when there is
> corner reflector in front of antennas and without reflector.
>
> I take data from gnu radio and transfer it Matlab, I plot received data.
>
> As I said before I expect a bigger power change at graph. I dont mean I
> want to find absolute power in this way but I expect that these power
> values must be linearly related with power, but it is not.
>
> I didnt understand why are we using low pass filter for taking result.
> Because I sent signal with 5.1GHz center frequency. I also have no idea if
> received signal always be normalized between -1 and 1 how can I have an
> information related with voltage at the terminal of the antenna. In this
> experiment how should I adjust low pass filter parameters.
>
> Do you have any suggestion? How can I take correct power data by using gnu
> radio NI2901 and Matlab.
>
> I would be grateful if you can look at my experiment.
>
> Yours faithfully.
> Emre.
>
>
> 18 Nis 2017 02:16 tarihinde "Marcus D. Leech via USRP-users" <
> [email protected]> yazd?:
>
> On 04/17/2017 06:54 PM, emre g?ng?r via USRP-users wrote:
>
>> Hi again,
>>
>> How the signal amplitudes which varies around -1 and 1 can be related
>> with voltage at the antenna terminal. What represents high voltage or low
>> voltage. I used corner reflector which has rcs close to 1000, that means
>> received power must be x1000 when there is an corner reflextor in front of
>> the antenna when compared with without corner reflector case.
>>
>> That means the voltage at the antenna terminal is sqrt(1000).
>> But I measured this difference like x2 x3.
>> I used complex to mag square as you said and I also used low pass filter.
>> I could not understand logic of the low pass filter but it works as I said
>> at least I can see x2 x3 times difference at power.
>>
>> But they can not answer my questions.
>> I can list them again for better reading.
>>
>> 1. How can I interpret signal which varied around -1 and 1, how can it be
>> related to voltage?
>>
> Because real-world, AC signals (like radio waves) are the superposition of
> several sinusoids, all of which, when normalized, have instantaneous values
> in {-1,+1}. This is pretty basic. In Gnu Radio, signals are normalized
> into {-1.0,+1.0} you cannot know what they actually represent at the
> antenna terminals without *calibration*. This has already been
> mentioned.
>
>
>> 2. How should I choose cutoff frequency of the filter and transition
>> width of the filter, how it effects?
>>
> It's *YOUR* experiment--at what rate do you wish to measure power?
>
>
>
>> 3. Measurement not even close to theory. Why I can not take x1000 power
>> with corner reflector when compared to without corner reflector case.
>>
>> Best wishes.
>> Emre.
>>
>>
>> I can't answer this, because we have only a vague understanding of your
> experimental setup. Have you taken into account path-loss? And again,
> without
> calibration, you can only assume relative power. That is, if the
> received power increases by a factor of 2, your instantaneous voltage
> reading will increase
> by a factor of sqrt(2), etc. But for accuracy, you need to average
> these readings over several cycles--hence the low-pass filtering--I usually
> just use
> a single-pole IIR filter. But getting into a protracted discussion
> about why one filter is better than another for a specific purpose is best
> done on the
> discuss-gnuradio mailing list (and also, consulting on-line DSP forums,
> and cracking-open a few DSP textbooks).
>
>
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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Message: 2
Date: Tue, 18 Apr 2017 23:08:48 +0100
From: Jithesh Joshy <[email protected]>
To: [email protected]
Subject: [USRP-users] Bringing N210 to USA - any issues ?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
Hi ,
Just wanted to check if there is anything I need to be aware of when bringing
my N210 device with WBX daughter board (openBTS) to the USA?
Are there any restrictions in bringing and using it in USA?
Many thanks for any information
Kind Regards ,
Josh
------------------------------
Message: 3
Date: Tue, 18 Apr 2017 15:36:48 -0700
From: Kyeong Su Shin <[email protected]>
To: Ettus mail list <[email protected]>
Subject: Re: [USRP-users] Bringing N210 to USA - any issues ?
Message-ID:
<cagl0v3m66bir1i+xeuwm0el4vo9rmkzrq+bznpqhz0uuu-6...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Dear Jithesh Joshy:
You should check out the FCC regulations before operating the device (part
15, amateur, etc). I do not expect any problem in bringing it to the US.
Regards,
Kyeong Su Shin
On Tue, Apr 18, 2017 at 3:08 PM, Jithesh Joshy via USRP-users <
[email protected]> wrote:
>
> Hi ,
>
> Just wanted to check if there is anything I need to be aware of when
> bringing my N210 device with WBX daughter board (openBTS) to the USA?
>
> Are there any restrictions in bringing and using it in USA?
>
> Many thanks for any information
>
> Kind Regards ,
> Josh
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
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Message: 4
Date: Tue, 18 Apr 2017 22:50:27 +0000
From: Jessica Iwamoto <[email protected]>
To: usrp-users <[email protected]>
Subject: [USRP-users] Tuning time on E310
Message-ID:
<sn1pr09mb1008bf446a36008aa1a5d3069b...@sn1pr09mb1008.namprd09.prod.outlook.com>
Content-Type: text/plain; charset="us-ascii"
Hi all,
I am trying to quickly switch between rx frequencies on the E310 in network
mode, but I am observing some settling behavior on the order of 0.1s each time
I retune. I thought this behavior might be due to the time it takes to retune,
but 0.1s seems like a very large retuning time. Could this be because I am in
network mode or might there be something else slowing this down?
Thanks,
Jessica
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Message: 5
Date: Tue, 18 Apr 2017 16:34:37 -0700
From: James Dunn <[email protected]>
To: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] RFNoC syntax error in gnuradio's generated
python file
Message-ID:
<ca+viziqpgzac3jff9nyiey0zubnz7hpvyg6d+_46rqh+ywk...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hello,
This issue can be marked as resolved. After closer inspection of the XML
file of the Gnu Radio block, I was using an invalid <param> key.
Thank you,
James
On Tue, Apr 11, 2017 at 2:46 PM, James Dunn <[email protected]> wrote:
> Hello,
>
> I am following this guide:
> http://www.synchronouslabs.com/blog/creating-a-custom-
> rfnoc-block-with-using-xillinx-ip
>
> To create an RFNoC block from Xilinx IP. All goes successfully up until
> the point where I run the GRC application. When executing, I receive:
>
> Generating: '/root/rfnoc/src/gr-ettus/examples/rfnoc/rfnoc_hb_filter.py'
> Executing: /usr/bin/python2 -u /root/rfnoc/src/gr-ettus/
> examples/rfnoc/rfnoc_hb_filter.py
> File "/root/rfnoc/src/gr-ettus/examples/rfnoc/rfnoc_hb_filter.py", line
> 197
> self.filters_hbFilter_0 = Template error: filters.hbFilter(
> ^
> SyntaxError: invalid syntax
> >>> Done (return code 1)
>
> I have double-checked that the XML GRC model matches the one shown in the
> tutorial. What could cause this syntax error in the generated python script?
>
> I saw that someone had a similar issue on the master branch of gnu-radio ?
> the response was that it was a bug that was fixed in a recent merge of
> gnuradio:master. I did a git pull in the rfnoc/src/gnuradio repo, re-built
> the OOT module, and still get the same error.
> https://lists.gnu.org/archive/html/discuss-gnuradio/2017-01/msg00277.html
>
> Thank you for you assistance and best regards.
>
> James
>
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Message: 6
Date: Tue, 18 Apr 2017 21:27:14 -0400
From: "Marcus D. Leech" <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] Tuning time on E310
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"
On 04/18/2017 06:50 PM, Jessica Iwamoto via USRP-users wrote:
>
> Hi all,
>
> I am trying to quickly switch between rx frequencies on the E310 in
> network mode, but I am observing some settling behavior on the order
> of 0.1s each time I retune. I thought this behavior might be due to
> the time it takes to retune, but 0.1s seems like a very large retuning
> time. Could this be because I am in network mode or might there be
> something else slowing this down?
>
> Thanks,
>
> Jessica
>
>
>
Network mode will certainly add to the latency. But the AD9361 simply
doesn't re-tune very quickly. It has to do a fair amount of "song and
dance"
on every re-tune, so fast-hopping implementations that actually
re-tune the LO won't be able to do so very quickly. However, if you
just want to tune
around within the analog bandwidth of the AD9361, you can use more
complex tune_request_t structures to request DSP-based tuning, and leave
the LO alone.
http://files.ettus.com/manual/structuhd_1_1tune__request__t.html
And
https://files.ettus.com/manual/page_general.html#general_tuning_process
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Message: 7
Date: Wed, 19 Apr 2017 10:16:40 +0500
From: Muhammad Munir <[email protected]>
To: [email protected]
Subject: [USRP-users] Input signal for ADC is at high level
Message-ID:
<CACqj-HySYFv9WkNJRJE4iy97wr6yox7=k8hkjw70xe2l+nd...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Dear USRP-users,
I am using USRP N200 and LFRX daughter-board. I am getting a lot of
unwanted signals that are armonics of some other signal in that band. In
other words, I am getting harmonics of most of the signals. When I measured
the input level at RF of USRP, it was giving 900mV Vpp. By the datasheet of
USRP N200, the max input required is +15Dbm. I think the ADC is distorting
with this large input signal.
My question is, what happens to the spectrum of a signal when ADC distorts
a signal? I searched a lot but could not get a satisfied answer. For
example, if I am receiving a spectrum of 5MHz and ADC is producing
harmonics. At what frequencies do I get harmonics as there are 5M
frequencies with different power levels?
Regards:
Munir
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Message: 8
Date: Wed, 19 Apr 2017 08:31:00 +0200
From: Marcus M?ller <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] Input signal for ADC is at high level
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"
Hi Munir,
that's an interesting question, and there's multiple ways to derive an
answer. Sadly, I'm running short on time and can't do one in depth, so
here's what you might want to consider:
The spectrum of a clipped cosine depends on the amount of clipping. To
illustrate this, let's first assume our system clips at +- 1.
There's two extreme cases: Feeding a system with a cosine of frequency
$f_0$ of such an amplitude that we get
1. no clipping at all, or
2. the system is always clipping
The trivial case is 1., where we immediately know the spectrum,
$\frac12\left(\delta(f_0-f)+\delta(f_0+f)\right)$.
In case 2., we get a simple square wave. The spectrum of a square wave
is also known, it contains every /odd/ ($n=2m+1,\,\,m\in\mathbb Z$)
harmonic (i.e. components at $f=nf_0$), weigthed inversely to the order
of that harmonic ($\frac 1n$).
But what happens in between?
Well, let's consider the point where we adjust the cosine's amplitude so
that it clips exactly half of the time.
Then, what we get is the cosine minus an error term. That error term is
the product of at shifted, scaled square wave, taking either the value 0
(when the signal is currently not clipping) or 1 (when the signal is
currently clipping) and the original tone. (I'd make a drawing, but I'm
out of time.)
Now, that square wave has a different frequeny: its period is half of
that of the original tone, so it has it's frequency components at $f=
n\frac{f_0}2$. Since we have multiplied that (modified) square wave with
the cosine to get the error term, the error term's spectrum is the
convolution of this spectrum with the cosine spectrum (which luckily
doesn't add new terms).
These are the easy cases. For everything that's not always, never, or
half of the time clipping, you can't simply represent the error term
with a square wave that's equal times on and off. You'd have to
understand this "clipping mask" as kind of a PWM-type signal ? with the
usual derivation from an infinite sum of rect functions in time, via an
infinite sum of sincs in frequency domain to a discrete spectrum.
"Discrete Spectrum" is an important point here: since whatever you do to
clip a periodic function will always be periodic, your spectrum will be
discrete.
However, don't forget that you're only observing a finite amount of time
in practical applications. So, if you do a 256-point FFT to estimate the
PSD, it might not be quite as discrete-looking as you'd like.
Best regards,
Marcus
On 19.04.2017 07:16, Muhammad Munir via USRP-users wrote:
> Dear USRP-users,
> I am using USRP N200 and LFRX daughter-board. I am getting a lot of
> unwanted signals that are armonics of some other signal in that band.
> In other words, I am getting harmonics of most of the signals. When I
> measured the input level at RF of USRP, it was giving 900mV Vpp. By
> the datasheet of USRP N200, the max input required is +15Dbm. I think
> the ADC is distorting with this large input signal.
> My question is, what happens to the spectrum of a signal when ADC
> distorts a signal? I searched a lot but could not get a satisfied
> answer. For example, if I am receiving a spectrum of 5MHz and ADC is
> producing harmonics. At what frequencies do I get harmonics as there
> are 5M frequencies with different power levels?
>
> Regards:
> Munir
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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Message: 9
Date: Wed, 19 Apr 2017 15:39:01 +0900
From: ??? <[email protected]>
To: [email protected] <[email protected]>
Subject: [USRP-users] light weight direction finder
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Hi all
I'm planning L-band direction finding system with MUSIC algorithm
In this mission we need 3 or 4 channel cohirent receiver
I found N200 seriese have Synchronization and MIMO Capability
Also X300 series have linear array direction finding example
Our another requirement is weight, no good with N/X series
Here is my question Is it possible synchronize multiple B200 series?
Or any other recomendation?
Thanks
Kim taeyeong
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Message: 10
Date: Wed, 19 Apr 2017 09:37:03 +0200
From: Marcus M?ller <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] light weight direction finder
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Hi Kim taeyeong,
the B2xx series can be made coherent by supplying an external PPS and 10
MHz signal. That would also add weight.
But the relative phase will be random after every tune.
If you need reproducible 4-channel coherent receivers with reproducible
(==calibrateable) phase relations, you'd probably look at the X3x0 + 2x
TwinRX daughterboards. You could replace the sturdy aluminium case with
your own enclosure.
Best regards,
Marcus
On 19.04.2017 08:39, ??? via USRP-users wrote:
>
> Hi all
>
>
>
> I'm planning L-band direction finding system with MUSIC algorithm.
>
> In this mission we need 3 or 4 channel cohirent receiver.
>
> I found N200 seriese have Synchronization and MIMO Capability.
>
> Also X300 series have linear array direction finding example.
>
>
>
> Our another requirement is weight, no good with N/X series.
>
> Here is my question. Is it possible synchronize multiple B200 series?
>
> Or any other recomendation?
>
>
>
> Thanks
>
> Kim taeyeong
>
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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Message: 11
Date: Wed, 19 Apr 2017 14:23:40 +0500
From: Muhammad Munir <[email protected]>
To: Marcus M?ller <[email protected]>,
[email protected]
Subject: Re: [USRP-users] Input signal for ADC is at high level
Message-ID:
<CACqj-HwVB6aNEgHQUnaR=1gnsentf+ntuiukk5iqc2krlgr...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi Marcus,
Thank you. It was very helpful answer. You talked about a single frequency
cosine wave. I would like to ask that if a time domain signal contains a
lot of frequencies (say 1MHz to 6MHz) with different amplitudes, it
produces a cosine wave with varying amplitude. The clipping will occur at
the high peaks only which means that the clipping effect is not same for a
complete signal duration. What are the considerations to analyse this kind
of signal?
Regards:
Munir
On Wed, Apr 19, 2017 at 11:31 AM, Marcus M?ller via USRP-users <
[email protected]> wrote:
> Hi Munir,
>
> that's an interesting question, and there's multiple ways to derive an
> answer. Sadly, I'm running short on time and can't do one in depth, so
> here's what you might want to consider:
>
> The spectrum of a clipped cosine depends on the amount of clipping. To
> illustrate this, let's first assume our system clips at +- 1.
>
> There's two extreme cases: Feeding a system with a cosine of frequency [image:
> $f_0$] of such an amplitude that we get
>
> 1. no clipping at all, or
> 2. the system is always clipping
>
> The trivial case is 1., where we immediately know the spectrum, [image:
> $\frac12\left(\delta(f_0-f)+\delta(f_0+f)\right)$].
>
> In case 2., we get a simple square wave. The spectrum of a square wave is
> also known, it contains every *odd* ([image: $n=2m+1,\,\,m\in\mathbb Z$])
> harmonic (i.e. components at [image: $f=nf_0$]), weigthed inversely to
> the order of that harmonic ([image: $\frac 1n$]).
>
> But what happens in between?
>
> Well, let's consider the point where we adjust the cosine's amplitude so
> that it clips exactly half of the time.
>
> Then, what we get is the cosine minus an error term. That error term is
> the product of at shifted, scaled square wave, taking either the value 0
> (when the signal is currently not clipping) or 1 (when the signal is
> currently clipping) and the original tone. (I'd make a drawing, but I'm out
> of time.)
>
> Now, that square wave has a different frequeny: its period is half of that
> of the original tone, so it has it's frequency components at [image: $f=
> n\frac{f_0}2$]. Since we have multiplied that (modified) square wave with
> the cosine to get the error term, the error term's spectrum is the
> convolution of this spectrum with the cosine spectrum (which luckily
> doesn't add new terms).
>
> These are the easy cases. For everything that's not always, never, or half
> of the time clipping, you can't simply represent the error term with a
> square wave that's equal times on and off. You'd have to understand this
> "clipping mask" as kind of a PWM-type signal ? with the usual derivation
> from an infinite sum of rect functions in time, via an infinite sum of
> sincs in frequency domain to a discrete spectrum.
>
> "Discrete Spectrum" is an important point here: since whatever you do to
> clip a periodic function will always be periodic, your spectrum will be
> discrete.
>
> However, don't forget that you're only observing a finite amount of time
> in practical applications. So, if you do a 256-point FFT to estimate the
> PSD, it might not be quite as discrete-looking as you'd like.
> Best regards,
> Marcus
>
>
> On 19.04.2017 07:16, Muhammad Munir via USRP-users wrote:
>
> Dear USRP-users,
> I am using USRP N200 and LFRX daughter-board. I am getting a lot of
> unwanted signals that are armonics of some other signal in that band. In
> other words, I am getting harmonics of most of the signals. When I measured
> the input level at RF of USRP, it was giving 900mV Vpp. By the datasheet of
> USRP N200, the max input required is +15Dbm. I think the ADC is distorting
> with this large input signal.
> My question is, what happens to the spectrum of a signal when ADC distorts
> a signal? I searched a lot but could not get a satisfied answer. For
> example, if I am receiving a spectrum of 5MHz and ADC is producing
> harmonics. At what frequencies do I get harmonics as there are 5M
> frequencies with different power levels?
>
> Regards:
> Munir
>
>
> _______________________________________________
> USRP-users mailing
> [email protected]http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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------------------------------
Message: 12
Date: Wed, 19 Apr 2017 11:43:23 +0200
From: Evert <[email protected]>
To: [email protected]
Subject: [USRP-users] WBX board damaged, pre-amp U6 is not MGA62563?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8; format=flowed
Hello gents,
I have an WBX board with faillures. I repaired most of the damage ( done
by another ).
The only strange issue is that on the WBX_fe board there is an U6, in
the schematics refered to as an MGA6x563.
This is under the assumption that this is an MGA62563 low noise hemt
pre-amp with bias.
However, my board has the bias pin tied the pin down to ground. In other
words, there is no bias.
I replaced the broken U6 ( whatever type it is ) by an mga62563 and end
up with negative gain. ( since there is no bias pin on the board ).
The SMD marking on the original chip was 62F and not 62x.
The schematic on:
http://files.ettus.com/schematics/wbx/wbx_fe.pdf
says clearly that there must be a bias pin on the board. On my board
there is no bias pin ( directly grounded ).
Also, there is no bias resistor R68 on the board as well.
According to the datasheet of the MGA62563 the device will directly die
with 0V bias.
Ofcourse there is vcc 3.3 volt on the supply pins.
Anyone a clue which chip this should be?
Br
Evert Verduin
------------------------------
Message: 13
Date: Wed, 19 Apr 2017 12:02:02 +0200
From: Marcus M?ller <[email protected]>
To: Muhammad Munir <[email protected]>,[email protected]
Subject: Re: [USRP-users] Input signal for ADC is at high level
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Well, the theory gets a bit more ugly if you're not dealing with a single
cosine.
A mathematical tool here is to understand clipping as a function of the input
value (as opposed to my simple case, where you could just consider it as a
function of time). You can then find a description of that function in terms
that make the Fourier transform easier.
Typically, this would be very similar to what we do to model intermodulation
that happens on exponential nonlinearities, I.e. I'd recommend reading up on
how semiconductor mixers mathematically work to have the tools to approximate
the clipper e.g. as power series, and then figure out where your modulation
products end up.
As a general rule of thumb: you'll get a lot of intermodulation between
basically all frequencies in your signal. That means that you'll probably see
things get a lot "wider" in spectrum, and also, assuming sufficiently many
moments of this process are random, and sufficiently uncorrelated as well as
sufficiently similar, you'll end up with things that resemble Gaussians (CLT).
But that is more of a gut feeling, and really depends on your signal model.
Best regards,
Marcus
Am 19. April 2017 11:23:40 MESZ schrieb Muhammad Munir <[email protected]>:
>Hi Marcus,
>Thank you. It was very helpful answer. You talked about a single
>frequency
>cosine wave. I would like to ask that if a time domain signal contains
>a
>lot of frequencies (say 1MHz to 6MHz) with different amplitudes, it
>produces a cosine wave with varying amplitude. The clipping will occur
>at
>the high peaks only which means that the clipping effect is not same
>for a
>complete signal duration. What are the considerations to analyse this
>kind
>of signal?
>
>Regards:
>Munir
>
>On Wed, Apr 19, 2017 at 11:31 AM, Marcus M?ller via USRP-users <
>[email protected]> wrote:
>
>> Hi Munir,
>>
>> that's an interesting question, and there's multiple ways to derive
>an
>> answer. Sadly, I'm running short on time and can't do one in depth,
>so
>> here's what you might want to consider:
>>
>> The spectrum of a clipped cosine depends on the amount of clipping.
>To
>> illustrate this, let's first assume our system clips at +- 1.
>>
>> There's two extreme cases: Feeding a system with a cosine of
>frequency [image:
>> $f_0$] of such an amplitude that we get
>>
>> 1. no clipping at all, or
>> 2. the system is always clipping
>>
>> The trivial case is 1., where we immediately know the spectrum,
>[image:
>> $\frac12\left(\delta(f_0-f)+\delta(f_0+f)\right)$].
>>
>> In case 2., we get a simple square wave. The spectrum of a square
>wave is
>> also known, it contains every *odd* ([image: $n=2m+1,\,\,m\in\mathbb
>Z$])
>> harmonic (i.e. components at [image: $f=nf_0$]), weigthed inversely
>to
>> the order of that harmonic ([image: $\frac 1n$]).
>>
>> But what happens in between?
>>
>> Well, let's consider the point where we adjust the cosine's amplitude
>so
>> that it clips exactly half of the time.
>>
>> Then, what we get is the cosine minus an error term. That error term
>is
>> the product of at shifted, scaled square wave, taking either the
>value 0
>> (when the signal is currently not clipping) or 1 (when the signal is
>> currently clipping) and the original tone. (I'd make a drawing, but
>I'm out
>> of time.)
>>
>> Now, that square wave has a different frequeny: its period is half of
>that
>> of the original tone, so it has it's frequency components at [image:
>$f=
>> n\frac{f_0}2$]. Since we have multiplied that (modified) square wave
>with
>> the cosine to get the error term, the error term's spectrum is the
>> convolution of this spectrum with the cosine spectrum (which luckily
>> doesn't add new terms).
>>
>> These are the easy cases. For everything that's not always, never, or
>half
>> of the time clipping, you can't simply represent the error term with
>a
>> square wave that's equal times on and off. You'd have to understand
>this
>> "clipping mask" as kind of a PWM-type signal ? with the usual
>derivation
>> from an infinite sum of rect functions in time, via an infinite sum
>of
>> sincs in frequency domain to a discrete spectrum.
>>
>> "Discrete Spectrum" is an important point here: since whatever you do
>to
>> clip a periodic function will always be periodic, your spectrum will
>be
>> discrete.
>>
>> However, don't forget that you're only observing a finite amount of
>time
>> in practical applications. So, if you do a 256-point FFT to estimate
>the
>> PSD, it might not be quite as discrete-looking as you'd like.
>> Best regards,
>> Marcus
>>
>>
>> On 19.04.2017 07:16, Muhammad Munir via USRP-users wrote:
>>
>> Dear USRP-users,
>> I am using USRP N200 and LFRX daughter-board. I am getting a lot of
>> unwanted signals that are armonics of some other signal in that band.
>In
>> other words, I am getting harmonics of most of the signals. When I
>measured
>> the input level at RF of USRP, it was giving 900mV Vpp. By the
>datasheet of
>> USRP N200, the max input required is +15Dbm. I think the ADC is
>distorting
>> with this large input signal.
>> My question is, what happens to the spectrum of a signal when ADC
>distorts
>> a signal? I searched a lot but could not get a satisfied answer. For
>> example, if I am receiving a spectrum of 5MHz and ADC is producing
>> harmonics. At what frequencies do I get harmonics as there are 5M
>> frequencies with different power levels?
>>
>> Regards:
>> Munir
>>
>>
>> _______________________________________________
>> USRP-users mailing
>[email protected]http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>>
>> _______________________________________________
>> USRP-users mailing list
>> [email protected]
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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------------------------------
Message: 14
Date: Wed, 19 Apr 2017 12:08:36 +0200
From: Marcus M?ller <[email protected]>
To: Evert <[email protected]>,[email protected]
Subject: Re: [USRP-users] WBX board damaged, pre-amp U6 is not
MGA62563?
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Hi Evert,
Could you tell us which hardware revision this is?
I think you're right, this should be an MGA62563, but I'd have to check.
Best regards,
Marcus
Am 19. April 2017 11:43:23 MESZ schrieb Evert via USRP-users
<[email protected]>:
>Hello gents,
>
>I have an WBX board with faillures. I repaired most of the damage (
>done
>by another ).
>
>The only strange issue is that on the WBX_fe board there is an U6, in
>the schematics refered to as an MGA6x563.
>
>This is under the assumption that this is an MGA62563 low noise hemt
>pre-amp with bias.
>
>However, my board has the bias pin tied the pin down to ground. In
>other
>words, there is no bias.
>
>I replaced the broken U6 ( whatever type it is ) by an mga62563 and end
>
>up with negative gain. ( since there is no bias pin on the board ).
>
>The SMD marking on the original chip was 62F and not 62x.
>
>
>The schematic on:
>
>http://files.ettus.com/schematics/wbx/wbx_fe.pdf
>
>says clearly that there must be a bias pin on the board. On my board
>there is no bias pin ( directly grounded ).
>Also, there is no bias resistor R68 on the board as well.
>According to the datasheet of the MGA62563 the device will directly die
>
>with 0V bias.
>
>
>Ofcourse there is vcc 3.3 volt on the supply pins.
>
>
>Anyone a clue which chip this should be?
>
>
>Br
>
>Evert Verduin
>
>_______________________________________________
>USRP-users mailing list
>[email protected]
>http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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------------------------------
Message: 15
Date: Wed, 19 Apr 2017 13:06:08 +0200
From: Marcus M?ller <[email protected]>
To: Muhammad Munir <[email protected]>, [email protected]
Subject: Re: [USRP-users] Input signal for ADC is at high level
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
By the way, that would be something incredibly simple to simulate!
I'd recommend recording your non-clipping signal (by having a lot of
external attenuation in the signal path), and then using GNU Radio to
simulate clipping. I'd just recommend writing your own python block and
using out[:] = numpy.clip(in[:], -1,1) .
Best regards,
Marcus
On 04/19/2017 12:02 PM, Marcus M?ller wrote:
> Well, the theory gets a bit more ugly if you're not dealing with a
> single cosine.
>
> A mathematical tool here is to understand clipping as a function of
> the input value (as opposed to my simple case, where you could just
> consider it as a function of time). You can then find a description of
> that function in terms that make the Fourier transform easier.
>
> Typically, this would be very similar to what we do to model
> intermodulation that happens on exponential nonlinearities, I.e. I'd
> recommend reading up on how semiconductor mixers mathematically work
> to have the tools to approximate the clipper e.g. as power series, and
> then figure out where your modulation products end up.
>
> As a general rule of thumb: you'll get a lot of intermodulation
> between basically all frequencies in your signal. That means that
> you'll probably see things get a lot "wider" in spectrum, and also,
> assuming sufficiently many moments of this process are random, and
> sufficiently uncorrelated as well as sufficiently similar, you'll end
> up with things that resemble Gaussians (CLT). But that is more of a
> gut feeling, and really depends on your signal model.
>
> Best regards,
> Marcus
>
>
>
> Am 19. April 2017 11:23:40 MESZ schrieb Muhammad Munir
> <[email protected]>:
>
> Hi Marcus,
> Thank you. It was very helpful answer. You talked about a single
> frequency cosine wave. I would like to ask that if a time domain
> signal contains a lot of frequencies (say 1MHz to 6MHz) with
> different amplitudes, it produces a cosine wave with varying
> amplitude. The clipping will occur at the high peaks only which
> means that the clipping effect is not same for a complete signal
> duration. What are the considerations to analyse this kind of signal?
>
> Regards:
> Munir
>
> On Wed, Apr 19, 2017 at 11:31 AM, Marcus M?ller via USRP-users
> <[email protected] <mailto:[email protected]>>
> wrote:
>
> Hi Munir,
>
> that's an interesting question, and there's multiple ways to
> derive an answer. Sadly, I'm running short on time and can't
> do one in depth, so here's what you might want to consider:
>
> The spectrum of a clipped cosine depends on the amount of
> clipping. To illustrate this, let's first assume our system
> clips at +- 1.
>
> There's two extreme cases: Feeding a system with a cosine of
> frequency $f_0$ of such an amplitude that we get
>
> 1. no clipping at all, or
> 2. the system is always clipping
>
> The trivial case is 1., where we immediately know the
> spectrum, $\frac12\left(\delta(f_0-f)+\delta(f_0+f)\right)$.
>
> In case 2., we get a simple square wave. The spectrum of a
> square wave is also known, it contains every /odd/
> ($n=2m+1,\,\,m\in\mathbb Z$) harmonic (i.e. components at
> $f=nf_0$), weigthed inversely to the order of that harmonic
> ($\frac 1n$).
>
> But what happens in between?
>
> Well, let's consider the point where we adjust the cosine's
> amplitude so that it clips exactly half of the time.
>
> Then, what we get is the cosine minus an error term. That
> error term is the product of at shifted, scaled square wave,
> taking either the value 0 (when the signal is currently not
> clipping) or 1 (when the signal is currently clipping) and the
> original tone. (I'd make a drawing, but I'm out of time.)
>
> Now, that square wave has a different frequeny: its period is
> half of that of the original tone, so it has it's frequency
> components at $f= n\frac{f_0}2$. Since we have multiplied that
> (modified) square wave with the cosine to get the error term,
> the error term's spectrum is the convolution of this spectrum
> with the cosine spectrum (which luckily doesn't add new terms).
>
> These are the easy cases. For everything that's not always,
> never, or half of the time clipping, you can't simply
> represent the error term with a square wave that's equal times
> on and off. You'd have to understand this "clipping mask" as
> kind of a PWM-type signal ? with the usual derivation from an
> infinite sum of rect functions in time, via an infinite sum of
> sincs in frequency domain to a discrete spectrum.
>
> "Discrete Spectrum" is an important point here: since whatever
> you do to clip a periodic function will always be periodic,
> your spectrum will be discrete.
>
> However, don't forget that you're only observing a finite
> amount of time in practical applications. So, if you do a
> 256-point FFT to estimate the PSD, it might not be quite as
> discrete-looking as you'd like.
>
> Best regards,
> Marcus
>
>
> On 19.04.2017 07:16, Muhammad Munir via USRP-users wrote:
>> Dear USRP-users,
>> I am using USRP N200 and LFRX daughter-board. I am getting a
>> lot of unwanted signals that are armonics of some other
>> signal in that band. In other words, I am getting harmonics
>> of most of the signals. When I measured the input level at RF
>> of USRP, it was giving 900mV Vpp. By the datasheet of USRP
>> N200, the max input required is +15Dbm. I think the ADC is
>> distorting with this large input signal.
>> My question is, what happens to the spectrum of a signal when
>> ADC distorts a signal? I searched a lot but could not get a
>> satisfied answer. For example, if I am receiving a spectrum
>> of 5MHz and ADC is producing harmonics. At what frequencies
>> do I get harmonics as there are 5M frequencies with different
>> power levels?
>>
>> Regards:
>> Munir
>>
>>
>> _______________________________________________
>> USRP-users mailing list
>> [email protected] <mailto:[email protected]>
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>> <http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com>
> _______________________________________________ USRP-users
> mailing list [email protected]
> <mailto:[email protected]>
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> <http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com>
>
>
> -- Sent from my Android device with K-9 Mail. Please excuse my brevity.
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------------------------------
Message: 16
Date: Wed, 19 Apr 2017 16:26:01 +0500
From: Muhammad Munir <[email protected]>
To: Marcus M?ller <[email protected]>
Cc: [email protected]
Subject: Re: [USRP-users] Input signal for ADC is at high level
Message-ID:
<CACqj-HyLYS+o-knZNo-sR1Gx79jZCzyPC0=ehn+tiry02++...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi Marcus,
Thanks a lot. It has directed me to a new way of thinking.
Now, I will try to first simulate it in MATLAB/Gnuradio by generating
known signals and then I will deal with my real time signals. I need to use
low gain amplifier or attenuate it, but it is always good to understand the
effect of each problem you are facing and then finding the solution.
Regards:
Munir
On Wed, Apr 19, 2017 at 4:06 PM, Marcus M?ller <[email protected]>
wrote:
> By the way, that would be something incredibly simple to simulate!
> I'd recommend recording your non-clipping signal (by having a lot of
> external attenuation in the signal path), and then using GNU Radio to
> simulate clipping. I'd just recommend writing your own python block and
> using out[:] = numpy.clip(in[:], -1,1) .
>
> Best regards,
> Marcus
>
> On 04/19/2017 12:02 PM, Marcus M?ller wrote:
>
> Well, the theory gets a bit more ugly if you're not dealing with a single
> cosine.
>
> A mathematical tool here is to understand clipping as a function of the
> input value (as opposed to my simple case, where you could just consider it
> as a function of time). You can then find a description of that function in
> terms that make the Fourier transform easier.
>
> Typically, this would be very similar to what we do to model
> intermodulation that happens on exponential nonlinearities, I.e. I'd
> recommend reading up on how semiconductor mixers mathematically work to
> have the tools to approximate the clipper e.g. as power series, and then
> figure out where your modulation products end up.
>
> As a general rule of thumb: you'll get a lot of intermodulation between
> basically all frequencies in your signal. That means that you'll probably
> see things get a lot "wider" in spectrum, and also, assuming sufficiently
> many moments of this process are random, and sufficiently uncorrelated as
> well as sufficiently similar, you'll end up with things that resemble
> Gaussians (CLT). But that is more of a gut feeling, and really depends on
> your signal model.
>
> Best regards,
> Marcus
>
>
>
> Am 19. April 2017 11:23:40 MESZ schrieb Muhammad Munir
> <[email protected]> <[email protected]>:
>>
>> Hi Marcus,
>> Thank you. It was very helpful answer. You talked about a single
>> frequency cosine wave. I would like to ask that if a time domain signal
>> contains a lot of frequencies (say 1MHz to 6MHz) with different amplitudes,
>> it produces a cosine wave with varying amplitude. The clipping will occur
>> at the high peaks only which means that the clipping effect is not same for
>> a complete signal duration. What are the considerations to analyse this
>> kind of signal?
>>
>> Regards:
>> Munir
>>
>> On Wed, Apr 19, 2017 at 11:31 AM, Marcus M?ller via USRP-users <
>> [email protected]> wrote:
>>
>>> Hi Munir,
>>>
>>> that's an interesting question, and there's multiple ways to derive an
>>> answer. Sadly, I'm running short on time and can't do one in depth, so
>>> here's what you might want to consider:
>>>
>>> The spectrum of a clipped cosine depends on the amount of clipping. To
>>> illustrate this, let's first assume our system clips at +- 1.
>>>
>>> There's two extreme cases: Feeding a system with a cosine of frequency
>>> [image:
>>> $f_0$] of such an amplitude that we get
>>>
>>> 1. no clipping at all, or
>>> 2. the system is always clipping
>>>
>>> The trivial case is 1., where we immediately know the spectrum, [image:
>>> $\frac12\left(\delta(f_0-f)+\delta(f_0+f)\right)$].
>>>
>>> In case 2., we get a simple square wave. The spectrum of a square wave
>>> is also known, it contains every *odd* ([image: $n=2m+1,\,\,m\in\mathbb
>>> Z$]) harmonic (i.e. components at [image: $f=nf_0$]), weigthed
>>> inversely to the order of that harmonic ([image: $\frac 1n$]).
>>>
>>> But what happens in between?
>>>
>>> Well, let's consider the point where we adjust the cosine's amplitude so
>>> that it clips exactly half of the time.
>>>
>>> Then, what we get is the cosine minus an error term. That error term is
>>> the product of at shifted, scaled square wave, taking either the value 0
>>> (when the signal is currently not clipping) or 1 (when the signal is
>>> currently clipping) and the original tone. (I'd make a drawing, but I'm out
>>> of time.)
>>>
>>> Now, that square wave has a different frequeny: its period is half of
>>> that of the original tone, so it has it's frequency components at [image:
>>> $f= n\frac{f_0}2$]. Since we have multiplied that (modified) square
>>> wave with the cosine to get the error term, the error term's spectrum is
>>> the convolution of this spectrum with the cosine spectrum (which luckily
>>> doesn't add new terms).
>>>
>>> These are the easy cases. For everything that's not always, never, or
>>> half of the time clipping, you can't simply represent the error term with a
>>> square wave that's equal times on and off. You'd have to understand this
>>> "clipping mask" as kind of a PWM-type signal ? with the usual derivation
>>> from an infinite sum of rect functions in time, via an infinite sum of
>>> sincs in frequency domain to a discrete spectrum.
>>>
>>> "Discrete Spectrum" is an important point here: since whatever you do to
>>> clip a periodic function will always be periodic, your spectrum will be
>>> discrete.
>>>
>>> However, don't forget that you're only observing a finite amount of time
>>> in practical applications. So, if you do a 256-point FFT to estimate the
>>> PSD, it might not be quite as discrete-looking as you'd like.
>>> Best regards,
>>> Marcus
>>>
>>>
>>> On 19.04.2017 07:16, Muhammad Munir via USRP-users wrote:
>>>
>>> Dear USRP-users,
>>> I am using USRP N200 and LFRX daughter-board. I am getting a lot of
>>> unwanted signals that are armonics of some other signal in that band. In
>>> other words, I am getting harmonics of most of the signals. When I measured
>>> the input level at RF of USRP, it was giving 900mV Vpp. By the datasheet of
>>> USRP N200, the max input required is +15Dbm. I think the ADC is distorting
>>> with this large input signal.
>>> My question is, what happens to the spectrum of a signal when ADC
>>> distorts a signal? I searched a lot but could not get a satisfied answer.
>>> For example, if I am receiving a spectrum of 5MHz and ADC is producing
>>> harmonics. At what frequencies do I get harmonics as there are 5M
>>> frequencies with different power levels?
>>>
>>> Regards:
>>> Munir
>>>
>>>
>>> _______________________________________________
>>> USRP-users mailing
>>> [email protected]http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>
>>> _______________________________________________ USRP-users mailing list
>>> [email protected] http://lists.ettus.com/mailman
>>> /listinfo/usrp-users_lists.ettus.com
>>
>> -- Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
>
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Message: 17
Date: Tue, 18 Apr 2017 10:08:06 +0000
From: chu li <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [USRP-users] USRP X310 at 5.8GHz
Message-ID:
<hkxpr03mb2312fa1a097288f69cc56c03af...@hkxpr03mb2312.apcprd03.prod.outlook.com>
Content-Type: text/plain; charset="gb2312"
Hello,
I am trying to transmit ofdm data from a file at 50MS/s using the USRP X310
with CBX 120, when I transmit at 2.45 GHz, I got a good signal, but at 5.8GHz,
the signal is weakened, even use cable transmission, the result is the same.
Anybody knows the reasons?
I use uhd 003.009.003 and 10Gigabit Ethernet.
Best regards,
Li
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Message: 18
Date: Wed, 19 Apr 2017 09:32:31 -0400
From: Ankur Vora <[email protected]>
To: [email protected]
Subject: [USRP-users] How to install USRP B200 image on Raspberry Pi 3
Message-ID:
<camfxtedhb75es+brbdvpjiir-7wfdpzuvvspepw855qlyqe...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi ,
I am able to install GNU Radio on Raspbery Pi3 with Raspbian OS but when I
try to download image it doesnt installed. Can somebody help me how to
install USRP B200 image that will work on Raspberry Pi.
Thanks,
Ankur
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Message: 19
Date: Wed, 19 Apr 2017 17:51:27 +0200
From: Marcus M?ller <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] USRP X310 at 5.8GHz
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"
Dear Li,
weakened, by how many dB? Notice that our boards are not calibrated, and
will exhibit different gain at different frequencies; compare the TX
performance data from
https://files.ettus.com/performance_data
Best regards,
Marcus
On 04/18/2017 12:08 PM, chu li via USRP-users wrote:
> Hello,
>
> I am trying to transmit ofdm data from a file at 50MS/s using the USRP
> X310 with CBX 120, when I transmit at 2.45 GHz, I got a good signal,
> but at 5.8GHz, the signal is weakened, even use cable transmission,
> the result is the same. Anybody knows the reasons?
>
> I use uhd 003.009.003 and 10Gigabit Ethernet.
>
> Best regards,
> Li
>
>
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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Subject: Digest Footer
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End of USRP-users Digest, Vol 80, Issue 19
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