From: "address@hidden" <address@hidden>
To: address@hidden
Sent: Friday, December 21, 2012 6:00 PM
Subject: Discuss-gnuradio Digest, Vol 121, Issue 24
Send Discuss-gnuradio mailing list submissions to
address@hiddenTo subscribe or unsubscribe via the World Wide Web, visit
https://lists.gnu.org/mailman/listinfo/discuss-gnuradioor, via email, send a message with subject or body 'help' to
address@hiddenYou can reach the person managing the list at
address@hiddenWhen replying, please edit your Subject line so it is more specific
than "Re: Contents of Discuss-gnuradio digest..."
Today's
Topics:
1. PMR446 Receiver in GNU Radio Companion (Sajjad Safdar)
2. Re: PMR446 Receiver in GNU Radio Companion (Marcus D. Leech)
3. Re: gri_portaudio (Alan
Corey)
4. Re: PMR446 Receiver in GNU Radio Companion (Iain Young, G7III)
5. self-interference with wbx (Francois Quitin)
6. Re: self-interference with wbx (Marcus D. Leech)
7. Re: self-interference with wbx (Francois Quitin)
8. Re:
self-interference with wbx (Marcus D. Leech)
9. Re: self-interference with wbx (Matt Ettus)
----------------------------------------------------------------------
Message: 1
Date: Thu, 20 Dec 2012 09:52:38 -0800 (PST)
From: Sajjad Safdar <
address@hidden>
To: "
address@hidden" <
address@hidden>
Subject: [Discuss-gnuradio] PMR446 Receiver in GNU Radio Companion
Message-ID:
<
address@hidden>
Content-Type: text/plain; charset="us-ascii"
Hello,
I have build an PMR446 Receiver in GNU Radio Companion. I can detect the channel and also demodulate it, but the quality of the receiver is not that much good. I want to amplify my received signal, Anyone have suggestion how to do it.
Best Regards,
SAJJAD SAFDAR
MSc Communication Engineering
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/e3d513f8/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name:
Ptt_recieve.grc.png
Type:
image/png
Size: 95114 bytes
Desc: not available
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/e3d513f8/attachment.png>
------------------------------
Message: 2
Date: Thu, 20 Dec 2012 13:23:54 -0500
From: "Marcus D. Leech" <
address@hidden>
To:
address@hiddenSubject: Re: [Discuss-gnuradio] PMR446 Receiver in GNU Radio Companion
Message-ID: <
address@hidden>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
On 12/20/2012 12:52 PM, Sajjad Safdar
wrote:
> Hello,
>
> I have build an PMR446 Receiver in GNU Radio Companion. I can detect
> the channel and also demodulate it, but the quality of the receiver is
> not that much good. I want to amplify my received signal, Anyone have
> suggestion how to do it.
>
>
> Best Regards,
> SAJJAD SAFDAR
> MSc Communication Engineering
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
>
address@hidden>
https://lists.gnu.org/mailman/listinfo/discuss-gnuradioYou don't say what type of USRP you're using -- is a sample rate of 256k
supported on your USRP of choice?
Also, your RF is set
to 0, perhaps increase this some and see if
things
improve?
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/b53d942c/attachment.html>
------------------------------
Message: 3
Date: Thu, 20 Dec 2012 13:35:33 -0500
From: Alan Corey <
address@hidden>
To:
address@hiddenSubject: Re: [Discuss-gnuradio] gri_portaudio
Message-ID:
<
address@hidden>
Content-Type: text/plain; charset=ISO-8859-1
>> On Wed, Dec 19, 2012 at 7:59 PM, Tom Rondeau <
address@hidden> wrote:
>>
>>> we need to patch the script that looks for it.
This is vaguely similar to what happens under OpenBSD - PortAudio is
installed and working with other applications but Gnuradio doesn't
find it. I think your detection method needs work, but I
haven't
looked at how you're doing it.
In /usr/local/lib I have
libportaudio.a
libportaudio.la
libportaudio.so.1.0
This is a standard (for OpenBSD) installation and works with Audacity,
Fldigi,
etc.
Trying to use Jack audio as an alternative is giving shm errors but I
haven't followed them up. I could probably write a simple audio sink
easier than figuring out Jack audio's problem. I've written easily
half a dozen programs that use the native Audio for recording. Don't
know much about Linux sound though. And yes, having multiple sound
layers is common in Linux, FreeeBSD and OpenBSD. I decided to learn
the native, bottom layer, which in OpenBSD (and probably NetBSD) is
just called Audio. Supposedly based on Sun audio.
There's a main parameter struct containing 2 member structs (for
record and play), and an ioctl that writes them to the sound card.
After that you can open() the sound card and read and write the same
as if it were a binary file. Very simple.
Alan
------------------------------
Message: 4
Date: Thu, 20 Dec
2012 21:58:18 +0000
From: "Iain Young, G7III" <
address@hidden>
To: "
address@hidden" <
address@hidden>
Subject: Re: [Discuss-gnuradio] PMR446 Receiver in GNU Radio Companion
Message-ID: <
address@hidden>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 20/12/12 17:52, Sajjad Safdar wrote:
> I have build an PMR446 Receiver in GNU Radio Companion. I can detect the
> channel and also demodulate it, but
the quality of the receiver is not
> that much good. I want to amplify my received signal, Anyone have
>
suggestion how to do it.
If I read your flowgraph correctly. Your sample rates are not aligned
You have 256k coming out of your USRP [See Martin's reply on this]
You then decimate that by 5, which gives 51.2k, but your NBFM receive
is expecting 44k1.
You then feed that 44k1 out to a standard squelch that is expecting to
be fed at 32k, which you then send onto an audio sink expecting 44k1,
and a EX GUI FFT sink expecting 256k
And as Martin mentioned, you have 0 db Gain. Increase that to 20 or 25
for testing.
I'm actually surprised that it managed to detect and demodulate anything
with those values, although your basic flowgraph is fine. Do you not get
lots of underflows and overflows, as well as a slowly updating FFT ?
If it were me, I'd grab 250k of B/W off the USRP, Use a LPF instead of
a BPF, Decimate by 5 (to 50k), then use a rational resampler to get to
44k1 (or just get the
rational resampler to go from 250k to 44k1), then
do the NBFM receive
Note NBFM receive block can do *some* resampling, but it has to have
the quadrature rate divisible by the audio rate (eg 88k2 and 44k1 are
fine, but 44k1 and 250k are not), so you might want a rational
resampler block that will do just about any two B/Ws, although takes
more CPU
Iain
------------------------------
Message: 5
Date: Thu, 20 Dec 2012 16:40:08 -0800
From: "Francois Quitin" <
address@hidden>
To: <
address@hidden>, <
address@hidden>
Subject: [Discuss-gnuradio] self-interference with
wbx
Message-ID: <address@hidden>
Content-Type: text/plain; charset="us-ascii"
Dear List,
I am using a USRP-2 with a WBX daughterboard that is operating in full
duplex mode. Both the Tx and Rx gain are cranked up to their maximum values
(tx gain 25 dB, rx gain 30 dB). The Tx and Rx frequencies are about 70 MHz
apart (Tx->964 MHz and Rx->892MHz). I'm having a little trouble with the
self-interference:
- when the Tx chain is sending periodic packets (with 0s in
between), this creates very high noise in my Rx chain (up to 0.01 on
gnuradio companion scope)
- when the Tx chain is sending a continuous pilot tone, there is no
noise in my Rx chain (noise is lower than 0.0005 on gnuradio companion
scope)
I would like that, when transmitting periodic packets, the noise
would be as
low as when transmitting a continuous pilot tone. I understand that periodic
packets would create noise in a wider band than the periodic tone, but
still, my Tx and Rx frequencies are very far apart. Is there some automatic
gain in the USRP that is playing tricks here? If so, is there a way to solve
this?
Any input is appreciated,
Thanks a lot,
Francois
PS: for our application, we had to turn the DUC cordic off. But even with
the DUC cordic enabled, I still observe similar trends, so I don' suppose
that would matter. We also had to put the Clock source to "external" to
avoid the automatic clock correction (but again, putting it to "Default"
didn't change a thing).
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/73efab0d/attachment.html>
------------------------------
Message: 6
Date: Thu, 20 Dec 2012 19:51:41 -0500
From: "Marcus D. Leech" <
address@hidden>
To:
address@hiddenSubject: Re: [Discuss-gnuradio] self-interference with wbx
Message-ID: <
address@hidden>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
> Dear List,
>
> I am
using a USRP-2 with a WBX daughterboard that is operating in full
>
duplex mode. Both the Tx and Rx gain are cranked up to their maximum
> values (tx gain 25 dB, rx gain 30 dB). The Tx and Rx frequencies are
> about 70 MHz apart (Tx->964 MHz and Rx->892MHz). I'm having a little
> trouble with the self-interference:
>
> -when the Tx chain is sending periodic packets (with 0s in between),
> this creates very high noise in my Rx chain (up to 0.01 on gnuradio
> companion scope)
>
> -when the Tx chain is sending a continuous pilot tone, there is no
> noise in my Rx chain (noise is lower than 0.0005 on gnuradio companion
> scope)
>
> I would like that, when transmitting periodic packets, the noise would
> be as low as when transmitting a continuous pilot tone. I understand
> that periodic packets would create noise in a wider band than the
> periodic tone, but still, my Tx and Rx frequencies are very far
apart.
> Is there some automatic gain in the USRP that is playing tricks here?
> If so, is there a way to solve this?
>
> Any input is appreciated,
>
> Thanks a lot,
>
> Francois
>
> PS: for our application, we had to turn the DUC cordic off. But even
> with the DUC cordic enabled, I still observe similar trends, so I don'
> suppose that would matter. We also had to put the Clock source to
> "external" to avoid the automatic clock correction (but again, putting
> it to "Default" didn't change a thing).
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
>
address@hidden>
https://lists.gnu.org/mailman/listinfo/discuss-gnuradioI a fully-engineered full-duplex system, there'll be a duplexor to
provide better isolation (70-80dB) for the RX gain an mixer. Your RX
front-end is
"seeing" all of the TX energy you're transmitting, and very likely
being drive into non-linear operating territory -- just because your
mixer is tuned
70Mhz away from the TX, *does not mean* that your RX LNA is "tuned"
only to your tuned frequency. You might able to get away with just using
a notch for your TX frequency in front of your RX, but without some
actual RF plumbing/systems-engineering, you'll run into "desense" issues
like
this.
Any such duplexing arrangements are clearly, *necessarily* application
specific. Which is why there's no duplexor or other filters on the
daughtercards.
Since they're used for a
*huge* variety of applications, there's no
way to engineer them to always "do the right thing" regardless of
application.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/1566d5bc/attachment.html>
------------------------------
Message: 7
Date: Thu, 20 Dec 2012 17:00:38 -0800
From: "Francois Quitin" <
address@hidden>
To: "'Marcus D. Leech'" <
address@hidden>,
<
address@hidden>
Subject: Re: [Discuss-gnuradio] self-interference with wbx
Message-ID: <address@hidden>
Content-Type: text/plain; charset="iso-8859-1"
Hi Marcus,
Thanks for your answer. I do expect some of the Tx power to leak into my Rx
chain, and my application can live with that. What I don?t understand, is
why this power is much higher when transmitting packets than when
transmitting a continuous tone.
Francois
De : discuss-gnuradio-bounces+fquitin=
address@hidden[mailto:discuss-gnuradio-bounces+fquitin=
address@hidden] De la part de
Marcus D. Leech
Envoy? : jeudi 20 d?cembre 2012 16:52
? :
address@hiddenObjet : Re: [Discuss-gnuradio] self-interference with wbx
Dear List,
I am using a USRP-2 with a WBX daughterboard that is operating in full
duplex mode. Both the Tx and Rx gain are cranked up to their maximum values
(tx gain 25 dB, rx gain 30 dB). The Tx and Rx frequencies are about 70 MHz
apart (Tx->964 MHz and Rx->892MHz). I?m having a little trouble with the
self-interference:
when the Tx chain is sending periodic packets (with 0s in between),
this
creates very high noise in my Rx chain (up to 0.01 on gnuradio companion
scope)
when the Tx chain is sending a continuous pilot tone, there is no noise in
my Rx chain (noise is
lower than 0.0005 on gnuradio companion scope)
I would like that, when transmitting periodic packets, the noise would be as
low as when transmitting a continuous pilot tone. I understand that periodic
packets would create noise in a wider band than the periodic tone, but
still, my Tx and Rx frequencies are very far apart. Is there some automatic
gain in the USRP that is playing tricks here? If so, is there a way to solve
this?
Any input is appreciated,
Thanks a lot,
Francois
PS: for our application, we had to turn the DUC cordic off. But even with
the DUC cordic enabled, I still observe similar trends, so I don? suppose
that would matter. We also had to put the Clock source to ?external? to
avoid the automatic clock correction (but again, putting it to ?Default?
didn?t change a thing).
_______________________________________________
Discuss-gnuradio mailing list
address@hiddenhttps://lists.gnu.org/mailman/listinfo/discuss-gnuradioI a fully-engineered full-duplex system, there'll be a duplexor to provide
better isolation (70-80dB) for the RX gain an mixer. Your RX front-end is
"seeing" all of the TX energy you're transmitting, and very likely being
drive into non-linear operating territory -- just because your mixer is
tuned
70Mhz away from the TX, *does not mean* that your RX LNA is "tuned" only
to your tuned frequency. You might able to get away with just using
a notch for your TX frequency in front of your RX, but without some
actual
RF plumbing/systems-engineering, you'll
run into "desense" issues like
this.
Any such duplexing arrangements are clearly, *necessarily* application
specific. Which is why there's no duplexor or other filters on the
daughtercards.
Since they're used for a *huge* variety of applications, there's no way to
engineer them to always "do the right thing" regardless of application.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/5d60dd06/attachment.html>
------------------------------
Message: 8
Date: Thu, 20 Dec
2012 20:30:15 -0500
From: "Marcus D. Leech" <
address@hidden>
To: Francois Quitin <
address@hidden>, "
address@hidden"
<
address@hidden>
Subject: Re: [Discuss-gnuradio] self-interference with wbx
Message-ID: <
address@hidden>
Content-Type: text/plain; charset="iso-8859-1";
Format="flowed"
> Hi Marcus,
>
> Thanks for your answer. I do expect some of the Tx power to leak into
> my Rx chain, and my application
can live with that. What I don't
> understand, is why this power is much higher when transmitting packets
> than when transmitting a continuous tone.
>
> Francois
>
Just different spectral signature.
Seriously, if you are TXing 70Mhz away from RX, and the antennae are
more-or-less co-located, your RX is going to be overloaded. RF amplifiers
don't like that.
Again, properly-engineered full-duplex RF systems use a duplexor for
precisely this reason.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/d65dddc8/attachment.html>
------------------------------
Message: 9
Date: Thu, 20 Dec 2012 17:41:05 -0800
From: Matt Ettus <
address@hidden>
To: Francois Quitin <
address@hidden>
Cc: GNURadio <
address@hidden>
Subject: Re: [Discuss-gnuradio] self-interference with wbx
Message-ID:
<CAN=1kn-e0RB+=g-91MAKL_ix0PCi=G1q0FdK3Hf763p=
address@hidden>
Content-Type: text/plain; charset="windows-1252"
One possible reason is that your transmitted signal may have a
wider
spectrum than you think due to the intermittent nature and or intermod.
You should look at the spectrum of the output signal and make sure you are
not transmitting wider than you think. Rapid on-off keying of the
transmitted signal without ramping up and down at the beginning and end
will create spectral noise. This is why most standards like bluetooth and
802.11 specify amplitude ramp functions.
Matt
On Thu, Dec 20, 2012 at 5:00 PM, Francois Quitin <
address@hidden> wrote:
> Hi Marcus, ****
>
> ** **
>
> Thanks for your answer. I do expect some of the Tx power to leak into my
> Rx chain, and my application can live with that. What I don?t understand,
> is why this power is much higher when transmitting packets than when
>
transmitting a continuous tone.
****
>
> ** **
>
> Francois****
>
> ** **
>
> *De :* discuss-gnuradio-bounces+fquitin=
address@hidden [mailto:discus
> s-gnuradio-bounces+fquitin=
address@hidden] *De la part de* Marcus D.
> Leech
> *Envoy? :* jeudi 20 d?cembre 2012 16:52
> *? :*
address@hidden> *Objet :* Re: [Discuss-gnuradio] self-interference with wbx****
>
> ** **
>
> Dear List, ****
>
> ****
>
> I am using a USRP-2 with a WBX daughterboard that is operating in full
> duplex mode. Both the Tx and Rx gain are
cranked up to their maximum values
> (tx gain 25 dB, rx gain 30 dB). The Tx and Rx
frequencies are about 70 MHz
> apart (Tx->964 MHz and Rx->892MHz). I?m having a little trouble with the
> self-interference: ****
>
> when the Tx chain is sending periodic packets (with 0s in between), this
> creates very high noise in my Rx chain (up to 0.01 on gnuradio companion
> scope)****
>
> when the Tx chain is sending a continuous pilot tone, there is no noise in
> my Rx chain (noise is lower than 0.0005 on gnuradio companion scope)****
>
> ****
>
> I would like that, when transmitting periodic packets, the noise would be
> as low as when transmitting a continuous pilot tone. I understand that
> periodic packets would create noise in a wider band than the periodic tone,
> but still, my Tx and Rx frequencies are very far apart. Is there some
> automatic gain in the USRP that is playing tricks here? If so, is there a
> way
to solve this? ****
>
> ****
>
> Any input is appreciated, ****
>
> Thanks a lot, ****
>
> ****
>
> Francois****
>
> ****
>
> PS: for our application, we had to turn the DUC cordic off. But even with
> the DUC cordic enabled, I still observe similar trends, so I don? suppose
> that would matter. We also had to put the Clock source to ?external? to
> avoid the automatic clock correction (but again, putting it to ?Default?
> didn?t change a thing). ****
>
> ** **
>
> ** **
>
> _______________________________________________****
>
> Discuss-gnuradio mailing list****
>
>
address@hidden****
>
>
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio****>
> I a fully-engineered full-duplex system, there'll be a duplexor to provide
> better isolation (70-80dB) for the RX gain an mixer. Your RX front-end is
> "seeing" all of the TX energy you're transmitting, and very likely being
> drive into non-linear operating territory -- just because your mixer is
> tuned
> 70Mhz away from the TX, *does not mean* that your RX LNA is "tuned" only
> to your tuned frequency. You might able to get away with just using
> a notch for your TX frequency in front of your RX, but without some
> actual RF plumbing/systems-engineering, you'll run into "desense" issues
> like
> this.
>
> Any such duplexing arrangements are clearly, *necessarily* application
>
specific. Which is why there's no duplexor or other
filters on the
> daughtercards.
> Since they're used for a *huge* variety of applications, there's no way
> to engineer them to always "do the right thing" regardless of application.
>
>
>
>
> ****
>
> -- ****
>
> Marcus Leech****
>
> Principal Investigator****
>
> Shirleys Bay Radio Astronomy Consortium****
>
>
http://www.sbrac.org****>
>
> _______________________________________________
> Discuss-gnuradio mailing list
>
address@hidden>
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>
>
-------------- next part --------------
An HTML
attachment was scrubbed...
URL: <
http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20121220/b5faedec/attachment.html>
------------------------------
_______________________________________________
Discuss-gnuradio mailing list
address@hiddenhttps://lists.gnu.org/mailman/listinfo/discuss-gnuradioEnd of Discuss-gnuradio Digest, Vol 121, Issue 24
*************************************************
Overdamped.png
Underdamped.png