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Today's Topics:
1. Re: Question about basic daughterboard with UHD (Josh Blum)
2. J/F 12 number for USRP2/WBX? (Feng Andrew Ge)
3. GPSDO (Matthew Singer)
4. Large and Fast Disk Storage for Multiple USRPs (Khalid Jamil)
5. Re: Large and Fast Disk Storage for Multiple USRPs
(Farhad Abdolian)
6. Re: GPSDO (Josh Blum)
7. Re: Severe DC offset ([email protected])
8. Realtime AGC ([email protected])
9. Re: Severe DC offset (Matt Ettus)
----------------------------------------------------------------------
Message: 1
Date: Mon, 28 Mar 2011 10:03:49 -0700
From: Josh Blum <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] Question about basic daughterboard with UHD
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
On 03/28/2011 02:25 AM, Per Zetterberg wrote:
> Hi Josh and List,
>
> Can I use the two SMA inputs as the I and Q channels of a direct
> downconversion receiver ?
>
Indeed: Specify that you want to use the AB subdevice (this is also the
default)
usrp->set_rx_subdev_spec(":AB")
http://www.ettus.com/uhd_docs/manual/html/dboards.html#basic-rx-and-and-lfrx
-Josh
------------------------------
Message: 2
Date: Mon, 28 Mar 2011 14:00:23 -0400
From: Feng Andrew Ge <[email protected]>
To: [email protected], [email protected]
Subject: [USRP-users] J/F 12 number for USRP2/WBX?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi, all,
Does any person happen to know whether USRP2/WBX has been given a J/F 12
application number yet?
I'd greatly appreciate if you have information about this?
Regards,
Andrew
------------------------------
Message: 3
Date: Mon, 28 Mar 2011 19:03:04 +0000
From: Matthew Singer <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [USRP-users] GPSDO
Message-ID:
<148568767c61c14b862119cc5401532c0aa...@eceexchange.ece.eastcor.com>
Content-Type: text/plain; charset="us-ascii"
Any example of using this from the UHD available?
------------------------------
Message: 4
Date: Mon, 28 Mar 2011 22:26:20 +0300
From: Khalid Jamil <[email protected]>
To: [email protected]
Subject: [USRP-users] Large and Fast Disk Storage for Multiple USRPs
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
Hello,
I have eight USRP N210s running synchronously. I want to store their data to
a disk storage for later processing on a computer. Can anyone help me in
finding the right solution that can handle all this data without any loss?
We are talking about 8 x 1 GigE.
Any help or pointers will be appreciated.
Thanks,
Khalid.
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Message: 5
Date: Mon, 28 Mar 2011 13:15:22 -0700 (PDT)
From: Farhad Abdolian <[email protected]>
To: Khalid Jamil <[email protected]>, [email protected]
Subject: Re: [USRP-users] Large and Fast Disk Storage for Multiple
USRPs
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
Hi Khalid,
The fastest drive I am aware of is Plextor M2S Series that support SATA-III at
around 330MB/s write speed. You have to study and see if your computer supports
multiple SATA-III at max speed or not. The one I am using is a GigaByte
GA-EX58A that theoretically supports 750MB/s on each SATA-III channels, but I
never had the need to test it yet.
Best regards,
Farhad
________________________________
From: Khalid Jamil <[email protected]>
To: [email protected]
Sent: Mon, March 28, 2011 9:26:20 PM
Subject: [USRP-users] Large and Fast Disk Storage for Multiple USRPs
Hello,
I have eight USRP N210s running synchronously. I want to store their data to a
disk storage for later processing on a computer. Can anyone help me in finding
the right solution that can handle all this data without any loss? We are
talking about 8 x 1 GigE.
Any help or pointers will be appreciated.
Thanks,
Khalid.
-------------- next part --------------
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------------------------------
Message: 6
Date: Mon, 28 Mar 2011 13:35:07 -0700
From: Josh Blum <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] GPSDO
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
On 03/28/2011 12:03 PM, Matthew Singer wrote:
>
> Any example of using this from the UHD available?
>
>
Can you be more specific?
To use the 10mhz ref do
usrp->set_clock_config(uhd::clock_config_t::external());
http://www.ettus.com/uhd_docs/doxygen/html/classuhd_1_1usrp_1_1multi__usrp.html#aceddf575752fda1a8cc75513a1178fd9
To sync the time do either
usrp->set_time_unknown_pps(time)
-- OR --
usrp->set_time_next_pps(time)
http://www.ettus.com/uhd_docs/doxygen/html/classuhd_1_1usrp_1_1multi__usrp.html#a413014bf3aea4a8ea2d268b4a3b390e9
http://www.ettus.com/uhd_docs/doxygen/html/classuhd_1_1usrp_1_1multi__usrp.html#aaa80cd6ee4b3c1bf52afb9c3ef02f64d
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
------------------------------
Message: 7
Date: Tue, 29 Mar 2011 11:10:06 -0400
From: [email protected]
To: [email protected]
Cc: [email protected], [email protected]
Subject: Re: [USRP-users] Severe DC offset
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
format="flowed"
Lately there's been a lot of traffic about spectral issues with the USRP2.
I'd like to share my experience.
We've been building an 80211.g compliant transceiver using the USRP.
We had initially noticed that with the firmware/hardware we got out of
gnuradio head couldn't decode packets because of a large DC offset,
which was dominating the our FFT spectra. We could see the spectral
signature of the 80211 packet, but it was being crushed by this high
power offset. Similarly we had trouble transmitting.
It turns out that the lo offset was, at least partly, to blame for our
problems. Since we need 20Mhz spectrum, we need to set the
default_lo_offset in the db_rfx_2400_tx and db_rfx_2400_rx to
~12Mhz to ensure that the db_tune does the right thing - namely sets
the baseband frequency and lo_offset frequency to be outside the
80211.g spectral envelope. Of course, this has other implications,
like interfering with other bands, but I guess we'll deal with these
problems moving forward. However, with the correct lo offset, we can
at least receive and transmit 802.11g packets with commodity devices,
using the USRP2 and XUPv5.
If you want to get a measure of the "damage" caused by this problem,
the spectrum diagrams I attached earlier do show the magnitude of the
DC offset that we were measuring post FFT in our 80211 receiver.
Hopefully this is useful others.
-Elliott
Quoting [email protected]:
> I'm trying to decode 80211.g packets using the USRP2 and the XUPV5.
>
> When I use the old USRP2 code (not the UHD build, but code obtained
> off of gnuradio head), I don't receive packets. This appears to be
> caused by enormous power in the DC band. When I collect similar
> traces using UHD code, I see no such DC offset and I can decode
> packets without issue.
>
> I'm wondering what could have happened to cause this discrepancy.
> The DSP code appears to be the same between the two FPGA builds.
> My current belief is that something changed in the software
> configuration during the move to UHD.
>
> Is there some kind of software post-processing going on in the new
> build? Do I need to manually remove the DC offset using the the
> dcoffset registers in the rx dsp block?
>
> I have attached power spectra showing the difference between UHD and
> the old code load.
>
> -Kermin
>
------------------------------
Message: 8
Date: Tue, 29 Mar 2011 11:45:47 -0400
From: [email protected]
To: [email protected]
Subject: [USRP-users] Realtime AGC
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
format="flowed"
Does anyone have experience rigging real-time AGC for the RX side of
USRP2? Advice and observations are appreciated.
-Elliott
------------------------------
Message: 9
Date: Tue, 29 Mar 2011 09:42:50 -0700
From: Matt Ettus <[email protected]>
To: [email protected]
Cc: [email protected], [email protected]
Subject: Re: [USRP-users] Severe DC offset
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
Elliott,
I would like to help you with this, but in order to do that, I need some
more information. Please tell me:
1 - UHD or old style drivers?
2 - GNU Radio or some other software package?
3 - Is the DC offset you see on the receive side?
4 - Is this a two-way system or receive only?
5 - Is your transmitter running at the same time as the receiver?
6 - What frequency is the TX? The RX?
7 - What are your gain settings?
8 - What is the amplitude of the DC offset you see?
Matt
On 03/29/2011 08:10 AM, [email protected] wrote:
> Lately there's been a lot of traffic about spectral issues with the USRP2.
>
> I'd like to share my experience.
>
> We've been building an 80211.g compliant transceiver using the USRP. We
> had initially noticed that with the firmware/hardware we got out of
> gnuradio head couldn't decode packets because of a large DC offset,
> which was dominating the our FFT spectra. We could see the spectral
> signature of the 80211 packet, but it was being crushed by this high
> power offset. Similarly we had trouble transmitting.
>
> It turns out that the lo offset was, at least partly, to blame for our
> problems. Since we need 20Mhz spectrum, we need to set the
> default_lo_offset in the db_rfx_2400_tx and db_rfx_2400_rx to ~12Mhz
> to ensure that the db_tune does the right thing - namely sets the
> baseband frequency and lo_offset frequency to be outside the 80211.g
> spectral envelope. Of course, this has other implications, like
> interfering with other bands, but I guess we'll deal with these problems
> moving forward. However, with the correct lo offset, we can at least
> receive and transmit 802.11g packets with commodity devices, using the
> USRP2 and XUPv5.
>
> If you want to get a measure of the "damage" caused by this problem, the
> spectrum diagrams I attached earlier do show the magnitude of the DC
> offset that we were measuring post FFT in our 80211 receiver.
>
> Hopefully this is useful others.
>
> -Elliott
>
>
>
> Quoting [email protected]:
>
>> I'm trying to decode 80211.g packets using the USRP2 and the XUPV5.
>>
>> When I use the old USRP2 code (not the UHD build, but code obtained
>> off of gnuradio head), I don't receive packets. This appears to be
>> caused by enormous power in the DC band. When I collect similar
>> traces using UHD code, I see no such DC offset and I can decode
>> packets without issue.
>>
>> I'm wondering what could have happened to cause this discrepancy.
>> The DSP code appears to be the same between the two FPGA builds. My
>> current belief is that something changed in the software
>> configuration during the move to UHD.
>>
>> Is there some kind of software post-processing going on in the new
>> build? Do I need to manually remove the DC offset using the the
>> dcoffset registers in the rx dsp block?
>>
>> I have attached power spectra showing the difference between UHD and
>> the old code load.
>>
>> -Kermin
>>
>
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
------------------------------
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