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Today's Topics:
1. Re: [EXTERNAL] Re: USRP B210: Filter Settings (Knee, Peter A)
2. Re: [EXTERNAL] USRP B210: Filter Settings (Marcus Leech)
3. Re: USRP N210 Spurious Signal (Jonathan Fox)
4. Re: USRP N210 Spurious Signal (Ian Buckley)
5. Re: USRP N210 Spurious Signal (Marcus Leech)
6. Re: USRP N210 Spurious Signal (Jonathan Fox)
7. Re: Send timed burst on N210 (Tim Newman)
8. Re: Send timed burst on N210 (John Malsbury)
9. Re: Send timed burst on N210 (Jason Harper)
10. PSK31 working / real world flow graph with USRP (Scott Dages)
11. Re: Send timed burst on N210 (Balint Seeber)
12. WBX/N200 cascade (Dan Sego)
13. Re: WBX/N200 cascade (Marcus D. Leech)
14. Re: PSK31 working / real world flow graph with USRP
(Marcus M?ller)
15. baseband signal using uhd_fft (Venkatesh Sandilya)
16. Re: baseband signal using uhd_fft (Marcus M?ller)
----------------------------------------------------------------------
Message: 1
Date: Wed, 26 Mar 2014 16:23:52 +0000
From: "Knee, Peter A" <[email protected]>
To: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] [EXTERNAL] Re: USRP B210: Filter Settings
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="us-ascii"
Marcus,
UHD version is 003.007.000-1-ga8caec5f. When I look into the images directory,
I only see a 003.006.002 tag. Do these images get rebuilt when the UHD is
updated or do I need to download new images?
Thanks,
Peter Knee
From: USRP-users [mailto:[email protected]] On Behalf Of
Marcus D. Leech
Sent: Tuesday, March 25, 2014 4:49 PM
To: [email protected]
Subject: [EXTERNAL] Re: [USRP-users] USRP B210: Filter Settings
All,
I'm having an issue with aliasing on the USRP B210. It seems that this issue
is only present at a sample rate of 16 MHz. The other tested rates (4 MHz, 8
MHz, 32 MHz) don't exhibit this issue. It seems as though the filters in the
AD9361 are potentially being bypassed or not set correctly based on the desired
sampling rate.
To test, we input a CW at a known frequency and tuned our device. As expected
we noticed a spike at the correct frequency. As we swept the CW outside of our
band of interest, we see it start to alias back into the band at virtually the
same power level. We don't see this issue at the other rates. Depending on
the nulls and sidelobes of the filters, we do occasionally see an alias of the
tone, but it is at least 40 dB below our tone.
Has anyone experienced similar behavior? How are the filters in the AD9361
set based on the sample rate?
I'd be happy to provide some screenshots and additional data to help track down
this issue.
Thanks,
Peter Knee
_______________________________________________
USRP-users mailing list
[email protected]<mailto:[email protected]>
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
What version of the UHD and firmware code are you running on your B210?
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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Message: 2
Date: Wed, 26 Mar 2014 16:30:28 +0000 (UTC)
From: Marcus Leech <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: [USRP-users] [EXTERNAL] USRP B210: Filter Settings
Message-ID: <244843981.7481.1395851429293.JavaMail.mail@webmail12>
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Message: 3
Date: Wed, 26 Mar 2014 14:33:04 -0400
From: Jonathan Fox <[email protected]>
To: Marcus Leech <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] USRP N210 Spurious Signal
Message-ID:
<capzrquzuoncq8axpbvqcu52jazrn0ejtb6zntzaj17kkwi5...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
So I turned the gain down to 0 (for TX, RX was already at 0) and still used
the same external attenuator (30 dB) for the USRP. Attached is the screen
shot with some those spurs still showing up below 1 GHz.
I am working on the Agilent Spectrum Analyzer now.
On Wed, Mar 26, 2014 at 10:27 AM, Marcus Leech <[email protected]> wrote:
> The reason to turn the RF gain down is to keep the power amplifier on the
> USRP linear, and the reason to use an attenuator is to keep the spectrum
> analyser linear...
>
>
>
> on Mar 26, 2014, *Jonathan Fox* <[email protected]> wrote:
>
>
> On Wed, Mar 26, 2014 at 5:24 AM, Ralph A. Schmid, dk5ras <[email protected]
> > wrote:
>
>> Did you try using an external attenuator? Maybe the analyzer is
>> overdriven...
>>
>>
>> Ralph.
>>
>>
>>
>>
>>
>> *From:* USRP-users [mailto:[email protected]] *On
>> Behalf Of *Jonathan Fox
>> *Sent:* Tuesday, March 25, 2014 11:44 PM
>> *To:* [email protected]
>> *Subject:* [USRP-users] USRP N210 Spurious Signal
>>
>>
>>
>> A colleague and I were sending out simple signals from the USRP with GNU
>> Radio to our spectrum analyzer through SMA cables rated for RF use.
>>
>>
>>
>> Basically, two cosine signals of the same amplitude (0.4) at 1 MHz and 3
>> MHz, added together and transmitted at 1 GHz from a USRP N210 with WBX
>> daughterboard (see usrp_tone.png for flow graph). The sampling rate was the
>> same for all blocks, 25 MS/s. The systctl -w net.core.rmem_max=50000000 was
>> set ahead of time and no grc prompt came up about it for this run. No U's
>> or any other character codes when running. The USRP sink block is at max
>> gain, 20 dB.
>>
>>
>>
>> The issue we are having as the other image attached shows, is we have our
>> two signals and a lot run off spurs showing up on our Spectrum Analyzer.
>> These spurs have a reduced amplitude of over -30 dBm in comparison to our
>> two cosine signals which are around 0.76 dBm.
>>
>>
>>
>> I am not nearly as experienced as my colleague is but he is as stumped as
>> much as I am concerning this. Has anyone encountered an issue like this
>> before?
>>
>>
>>
>> Thanks,
>>
>>
>>
>> Jon
>>
>
>
> I have used both the Agilent internal attenuator for the
> standalone analyzer and an external for when I followed Marcus' advice on
> reduced signal amplitude and feed into another USRP to use GNU Radio's
> Visual FFT (the analyzer was in use by another).
>
> Marcus has recommended that I turn the gain down, so I will try that next,
> although I am tempted to also use an external attenuator on the spectrum
> analyzer.
>
> Thanks,
>
> Jon
>
> ------------------------------
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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Message: 4
Date: Wed, 26 Mar 2014 11:43:44 -0700
From: Ian Buckley <[email protected]>
To: Jonathan Fox <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] USRP N210 Spurious Signal
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"
Maybe I'm missing something but that looks like a classic case of IQ imbalance
in a direct conversion radio.
On Mar 26, 2014, at 11:33 AM, Jonathan Fox <[email protected]> wrote:
> So I turned the gain down to 0 (for TX, RX was already at 0) and still used
> the same external attenuator (30 dB) for the USRP. Attached is the screen
> shot with some those spurs still showing up below 1 GHz.
>
> I am working on the Agilent Spectrum Analyzer now.
>
> On Wed, Mar 26, 2014 at 10:27 AM, Marcus Leech <[email protected]> wrote:
> The reason to turn the RF gain down is to keep the power amplifier on the
> USRP linear, and the reason to use an attenuator is to keep the spectrum
> analyser linear...
>
>
>
> on Mar 26, 2014, Jonathan Fox <[email protected]> wrote:
>
> On Wed, Mar 26, 2014 at 5:24 AM, Ralph A. Schmid, dk5ras <[email protected]>
> wrote:
> Did you try using an external attenuator? Maybe the analyzer is overdriven?
>
>
> Ralph.
>
>
>
> From: USRP-users [mailto:[email protected]] On Behalf Of
> Jonathan Fox
> Sent: Tuesday, March 25, 2014 11:44 PM
> To: [email protected]
> Subject: [USRP-users] USRP N210 Spurious Signal
>
>
> A colleague and I were sending out simple signals from the USRP with GNU
> Radio to our spectrum analyzer through SMA cables rated for RF use.
>
>
> Basically, two cosine signals of the same amplitude (0.4) at 1 MHz and 3 MHz,
> added together and transmitted at 1 GHz from a USRP N210 with WBX
> daughterboard (see usrp_tone.png for flow graph). The sampling rate was the
> same for all blocks, 25 MS/s. The systctl -w net.core.rmem_max=50000000 was
> set ahead of time and no grc prompt came up about it for this run. No U's or
> any other character codes when running. The USRP sink block is at max gain,
> 20 dB.
>
>
> The issue we are having as the other image attached shows, is we have our two
> signals and a lot run off spurs showing up on our Spectrum Analyzer. These
> spurs have a reduced amplitude of over -30 dBm in comparison to our two
> cosine signals which are around 0.76 dBm.
>
>
> I am not nearly as experienced as my colleague is but he is as stumped as
> much as I am concerning this. Has anyone encountered an issue like this
> before?
>
>
> Thanks,
>
>
> Jon
>
>
>
> I have used both the Agilent internal attenuator for the standalone analyzer
> and an external for when I followed Marcus' advice on reduced signal
> amplitude and feed into another USRP to use GNU Radio's Visual FFT (the
> analyzer was in use by another).
>
> Marcus has recommended that I turn the gain down, so I will try that next,
> although I am tempted to also use an external attenuator on the spectrum
> analyzer.
>
> Thanks,
>
> Jon
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
> <Screenshot-Usrp Tone.png>_______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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Message: 5
Date: Wed, 26 Mar 2014 18:50:15 +0000 (UTC)
From: Marcus Leech <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: [USRP-users] USRP N210 Spurious Signal
Message-ID: <1594415634.9471.1395859815283.JavaMail.mail@webmail12>
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Message: 6
Date: Wed, 26 Mar 2014 15:36:00 -0400
From: Jonathan Fox <[email protected]>
To: Marcus Leech <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] USRP N210 Spurious Signal
Message-ID:
<capzrquy3bwoz-kalnggow+nr3xamqvxmigrzykmed4veyuo...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
No, in fact the thought never crossed my mind.
I am learning how to use the utility now.
On Wed, Mar 26, 2014 at 2:50 PM, Marcus Leech <[email protected]> wrote:
> yes, that could easily be it. I was focussed purely on the non-linearity
> possibilities.
>
> Jonathan, have you run the iq_bal utilities on this box with this card?
>
>
>
> on Mar 26, 2014, *Ian Buckley* <[email protected]> wrote:
>
> Maybe I'm missing something but that looks like a classic case of IQ
> imbalance in a direct conversion radio.
>
> On Mar 26, 2014, at 11:33 AM, Jonathan Fox <[email protected]>
> wrote:
>
> So I turned the gain down to 0 (for TX, RX was already at 0) and still
> used the same external attenuator (30 dB) for the USRP. Attached is the
> screen shot with some those spurs still showing up below 1 GHz.
>
> I am working on the Agilent Spectrum Analyzer now.
>
> On Wed, Mar 26, 2014 at 10:27 AM, Marcus Leech <[email protected]> wrote:
>
>> The reason to turn the RF gain down is to keep the power amplifier on the
>> USRP linear, and the reason to use an attenuator is to keep the spectrum
>> analyser linear...
>>
>>
>>
>> on Mar 26, 2014, *Jonathan Fox* <[email protected]> wrote:
>>
>>
>> On Wed, Mar 26, 2014 at 5:24 AM, Ralph A. Schmid, dk5ras <
>> [email protected]> wrote:
>>
>>> Did you try using an external attenuator? Maybe the analyzer is
>>> overdriven...
>>>
>>>
>>> Ralph.
>>>
>>>
>>>
>>> *From:* USRP-users [mailto:[email protected]] *On
>>> Behalf Of *Jonathan Fox
>>> *Sent:* Tuesday, March 25, 2014 11:44 PM
>>> *To:* [email protected]
>>> *Subject:* [USRP-users] USRP N210 Spurious Signal
>>>
>>>
>>> A colleague and I were sending out simple signals from the USRP with GNU
>>> Radio to our spectrum analyzer through SMA cables rated for RF use.
>>>
>>>
>>> Basically, two cosine signals of the same amplitude (0.4) at 1 MHz and 3
>>> MHz, added together and transmitted at 1 GHz from a USRP N210 with WBX
>>> daughterboard (see usrp_tone.png for flow graph). The sampling rate was the
>>> same for all blocks, 25 MS/s. The systctl -w net.core.rmem_max=50000000 was
>>> set ahead of time and no grc prompt came up about it for this run. No U's
>>> or any other character codes when running. The USRP sink block is at max
>>> gain, 20 dB.
>>>
>>>
>>> The issue we are having as the other image attached shows, is we have
>>> our two signals and a lot run off spurs showing up on our Spectrum
>>> Analyzer. These spurs have a reduced amplitude of over -30 dBm in
>>> comparison to our two cosine signals which are around 0.76 dBm.
>>>
>>>
>>> I am not nearly as experienced as my colleague is but he is as stumped
>>> as much as I am concerning this. Has anyone encountered an issue like this
>>> before?
>>>
>>>
>>> Thanks,
>>>
>>>
>>> Jon
>>>
>>
>>
>> I have used both the Agilent internal attenuator for the
>> standalone analyzer and an external for when I followed Marcus' advice on
>> reduced signal amplitude and feed into another USRP to use GNU Radio's
>> Visual FFT (the analyzer was in use by another).
>>
>> Marcus has recommended that I turn the gain down, so I will try that
>> next, although I am tempted to also use an external attenuator on the
>> spectrum analyzer.
>>
>> Thanks,
>>
>> Jon
>> ------------------------------
>>
>> _______________________________________________
>> USRP-users mailing list
>> [email protected]
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>> <Screenshot-Usrp Tone.png>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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Message: 7
Date: Wed, 26 Mar 2014 12:01:10 -0800
From: Tim Newman <[email protected]>
To: Jason Harper <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] Send timed burst on N210
Message-ID:
<cakbqcwqjjv16mgvylargp2r9513quousaavrhtmzap3n46p...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Anyone, anyone? I would also like to know the answer to this. How can the
power amp just be left on to avoid this? Or is this not something that is
suppose to be happening?
Tim
On Mon, Mar 24, 2014 at 5:37 AM, Jason Harper <[email protected]>wrote:
> John,
>
> Any thoughts on the screen shots that I passed along?
>
> Thanks for any help you can provide!
>
> Jason
>
> On 03/12/2014 10:39 AM, Jason Harper wrote:
>
> Attached are the screen shots of the time domain plots. The blue line is
> instantaneous power and red is the average power. The spike appears to be
> at the first sample or very close to first sample of the zero-pad.
>
> Jason
>
>
> On 03/11/2014 04:47 PM, John Malsbury wrote:
>
> Pad or ramp-up/down is recommended to properly flush the filters on the
> transmit chain. Ramp-up/down reduces spurious emissions compared to an
> instantaneous amplitude change.
>
> Could you send a screen shot of the timed domain plots? Does the spike
> occur at the first sample of the zero-pad?
>
> -John
>
>
> On Tue, Mar 11, 2014 at 10:38 AM, Jason Harper <[email protected]>wrote:
>
>> I am running into an issue sending a timed burst. Using the tx_streamer
>> class, I am sending a timed burst at the correct time in the future;
>> however, when looking at the signal in the time domain there is a clear
>> ramp up period. I have zero padded the beginning of the burst and sent the
>> new burst earlier in time to account for the zero-padding. This appears to
>> work and no more ramp up is seen but the time-domain shows a spike which I
>> assume is the power amplifier turning on. Does anyone know of a way to
>> avoid this ramping period when sending a time burst? Is there a way to
>> leave the power amplifier on to avoid this?
>>
>> Thanks,
>> Jason
>>
>> _______________________________________________
>> 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: 8
Date: Wed, 26 Mar 2014 13:04:14 -0700
From: John Malsbury <[email protected]>
To: Jason Harper <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] Send timed burst on N210
Message-ID:
<can5wegqa+cy+dmhn2m7homdt8+st0bkchjzphxk0g1ejw92...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Jason,
Can you clarify what device you are seeing this on?
-John
On Tue, Mar 11, 2014 at 10:38 AM, Jason Harper <[email protected]>wrote:
> I am running into an issue sending a timed burst. Using the tx_streamer
> class, I am sending a timed burst at the correct time in the future;
> however, when looking at the signal in the time domain there is a clear
> ramp up period. I have zero padded the beginning of the burst and sent the
> new burst earlier in time to account for the zero-padding. This appears to
> work and no more ramp up is seen but the time-domain shows a spike which I
> assume is the power amplifier turning on. Does anyone know of a way to
> avoid this ramping period when sending a time burst? Is there a way to
> leave the power amplifier on to avoid this?
>
> Thanks,
> Jason
>
> _______________________________________________
> 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, 26 Mar 2014 16:29:49 -0400
From: Jason Harper <[email protected]>
To: John Malsbury <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] Send timed burst on N210
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
I am seeing this on an N210 with SBX. I thought it might be an SBX
issue so I have also tried using a CBX card and it required even more
zero-padding to have a clean signal.
Jason
On 03/26/2014 04:04 PM, John Malsbury wrote:
> Jason,
>
> Can you clarify what device you are seeing this on?
>
> -John
>
>
> On Tue, Mar 11, 2014 at 10:38 AM, Jason Harper
> <[email protected] <mailto:[email protected]>> wrote:
>
> I am running into an issue sending a timed burst. Using the
> tx_streamer class, I am sending a timed burst at the correct time
> in the future; however, when looking at the signal in the time
> domain there is a clear ramp up period. I have zero padded the
> beginning of the burst and sent the new burst earlier in time to
> account for the zero-padding. This appears to work and no more
> ramp up is seen but the time-domain shows a spike which I assume
> is the power amplifier turning on. Does anyone know of a way to
> avoid this ramping period when sending a time burst? Is there a
> way to leave the power amplifier on to avoid this?
>
> Thanks,
> Jason
>
> _______________________________________________
> USRP-users mailing list
> [email protected] <mailto:[email protected]>
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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Message: 10
Date: Wed, 26 Mar 2014 16:57:53 -0400
From: Scott Dages <[email protected]>
To: [email protected]
Subject: [USRP-users] PSK31 working / real world flow graph with USRP
Message-ID:
<CAP8PMe7cqC-wXbT-st=vwqtucwracmqfp+pzgypabjhhrho...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Does anyone have a working "real world" PSK31 receiver (GRC Flow Graph) for
the USRP 200? Ideally it would decode varicode and output text.
Scott
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Message: 11
Date: Wed, 26 Mar 2014 15:18:38 -0700
From: Balint Seeber <[email protected]>
To: Jason Harper <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] Send timed burst on N210
Message-ID:
<capcb_2od3vzix1cslvbwzwl9ukvsw8dthrwoeduj-hqwkp2...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi Jason,
If you wish, you can fiddle with the ATR registers. E.g. for SBX have a
look at the function 'update_atr' (line 255 in latest
host/lib/usrp/dboard/db_sbx_common.cpp).
You'll note that there are multiple sections/states - when the radio is in
idle/RX/TX/full-duplex.
//set the TX atr regs that change with antenna setting
this->get_iface()->set_atr_reg(dboard_iface::UNIT_TX, \
dboard_iface::ATR_REG_RX_ONLY, 0 | tx_lo_lpf_en \
| tx_ld_led | tx_ant_led | TX_POWER_UP | TX_MIXER_DIS \
| ((_rx_ant != "RX2")? ANT_RX : ANT_TX));
Is the one you'll be interested in I believe (assuming you're receiving
when you're not transmitting a burst, otherwise also change the
corresponding ATR_REG_IDLE state for UNIT_TX). Try changing TX_MIXER_DIS to
TX_MIXER_ENB and see what happens.
Before you make the change, though, check if you notice the spike in your
screenshot with your TX gain set to 0. Once you've made the change, keep
both gains low while you experiment, and slowly take it up to the values
where you've been operating.
Also, as John said, padding the end (ideally with ramp down and zeroes) is
important to flush the TX chain - otherwise you'll have old samples turning
up at the beginning of the next burst. For N-series, I've found that at
minimum 16 samples should be sufficient.
Kind regards,
Balint
On Wed, Mar 26, 2014 at 1:29 PM, Jason Harper <[email protected]>wrote:
> I am seeing this on an N210 with SBX. I thought it might be an SBX issue
> so I have also tried using a CBX card and it required even more
> zero-padding to have a clean signal.
>
> Jason
>
>
> On 03/26/2014 04:04 PM, John Malsbury wrote:
>
> Jason,
>
> Can you clarify what device you are seeing this on?
>
> -John
>
>
> On Tue, Mar 11, 2014 at 10:38 AM, Jason Harper <[email protected]>wrote:
>
>> I am running into an issue sending a timed burst. Using the tx_streamer
>> class, I am sending a timed burst at the correct time in the future;
>> however, when looking at the signal in the time domain there is a clear
>> ramp up period. I have zero padded the beginning of the burst and sent the
>> new burst earlier in time to account for the zero-padding. This appears to
>> work and no more ramp up is seen but the time-domain shows a spike which I
>> assume is the power amplifier turning on. Does anyone know of a way to
>> avoid this ramping period when sending a time burst? Is there a way to
>> leave the power amplifier on to avoid this?
>>
>> Thanks,
>> Jason
>>
>> _______________________________________________
>> USRP-users mailing list
>> [email protected]
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>
>
>
> _______________________________________________
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> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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Message: 12
Date: Wed, 26 Mar 2014 19:19:01 -0700
From: Dan Sego <[email protected]>
To: [email protected]
Subject: [USRP-users] WBX/N200 cascade
Message-ID:
<calgevjt4jvh2wcbvcsecp9860ajc3rwepy8gmtovhn_+drf...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Greetings. Is anyone aware of an RF cascade for the WBX? I have a bistatic
radar application where I need to confirm that the WBX/N200- has sufficient
gain, or whether an additional amplifier may be necessary. Also I have been
looking, without success, for the ADC model number in the N200.
cheers. Dan Sego
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Message: 13
Date: Wed, 26 Mar 2014 22:32:38 -0400
From: "Marcus D. Leech" <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] WBX/N200 cascade
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
On 03/26/2014 10:19 PM, Dan Sego wrote:
> Greetings. Is anyone aware of an RF cascade for the WBX? I have a
> bistatic radar application where I need to confirm that the WBX/N200-
> has sufficient gain, or whether an additional amplifier may be
> necessary. Also I have been looking, without success, for the ADC
> model number in the N200.
> cheers. Dan Sego
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
http://files.ettus.com/schematics
Are you talking about RF power output? it maxes out at about +20dBm.
The noise figure of the RX input is about 5-8dB, depending on frequency,
at maximum RF gain.
Unless you have lower noise figure requirements, or your RX antenna is
at the end of a long cable from the USRP, you shouldn't need any extra
gain. The SFDR of the ADC in the N200 is about 80dB or so.
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Message: 14
Date: Thu, 27 Mar 2014 12:25:16 +0100
From: Marcus M?ller <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] PSK31 working / real world flow graph with
USRP
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
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Hi Scott,
http://sdradventure.wordpress.com/2011/10/15/gnuradio-psk31-decoder-part-2/
might be of interest, although it will not work with the current
version of GNU Radio (3.7).
Basically, you should be able to just use GNU Radio's DPSK Demod right
after your UHD Source block and would be getting 0's and 1's out of
that, which, using the python dict from aforementioned website (or
from the first part of that article,
http://sdradventure.wordpress.com/2011/10/15/gnuradio-psk31-decoder-part-1/
, to be more precise), can be varicode decoded.
Wrapping the varicode decoding in a GNU Radio block and combining it
with the DBPSK demod into a hierarchical block would make a great
out-of-tree module!
So:
Happy hacking,
Marcus
On 26.03.2014 21:57, Scott Dages wrote:
> Does anyone have a working "real world" PSK31 receiver (GRC Flow
> Graph) for the USRP 200? Ideally it would decode varicode and
> output text.
>
> Scott
>
>
>
> _______________________________________________ USRP-users mailing
> list [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
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Message: 15
Date: Thu, 27 Mar 2014 11:42:22 -0400
From: Venkatesh Sandilya <[email protected]>
To: usrp-users <[email protected]>
Subject: [USRP-users] baseband signal using uhd_fft
Message-ID:
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Content-Type: text/plain; charset="iso-8859-1"
Hello
I have a USRP N200 connected to to an external receive antenna (CF at
1090MHz) and the N200 has a DBSRX2 daughter board. I am looking at the
spectrum analyser display using the uhd_fft tool of gnuradio. I used the -S
option for the uhd_fft program (uhd_fft -f 1090M -s 25M -S) to get the
oscilloscope display and both images are attached.
In the spectrum analyser display, I see a spike at 1100MHz (besides the
one at 1090 which I see every time a TCAS burst was detected) and I believe
that would be the 11th harmonic of the master clock (100 MHz). Is there a
way to suppress that?
Is there a way to look at the baseband signal like I would in a regular
oscilloscope. Just curious if anybody has tried that since the oscilloscope
display isn't of much help for me or it may be that I am not using it
right.
Thanks for the help.
Venkatesh
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Message: 16
Date: Thu, 27 Mar 2014 16:51:09 +0100
From: Marcus M?ller <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] baseband signal using uhd_fft
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
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Hi Venkatesh,
you can use a notch filter to eliminate these very narrowband noises
if you click together a uhd source - filter - qt gui flow graph in the
gnuradio-companion program.
However, all my alarm bells are ringing: The console in the background
of your screenshot is filled with 'D's. This is *NOT* ok, see
http://files.ettus.com/uhd_docs/manual/html/general.html#overflow-underflow-notes
25Msam/s *is* quite a computational load. Actually, it is too much for
many PCs and laptops. Reduce that until you don't see 'D' anymore.
Otherwise, your sample stream will have a holes, and your received
signal is not really usable, and its spectrum will be distorted.
Greetings,
Marcus
On 27.03.2014 16:42, Venkatesh Sandilya wrote:
> Hello
>
> I have a USRP N200 connected to to an external receive antenna (CF
> at 1090MHz) and the N200 has a DBSRX2 daughter board. I am looking
> at the spectrum analyser display using the uhd_fft tool of
> gnuradio. I used the -S option for the uhd_fft program (uhd_fft -f
> 1090M -s 25M -S) to get the oscilloscope display and both images
> are attached.
>
> In the spectrum analyser display, I see a spike at 1100MHz
> (besides the one at 1090 which I see every time a TCAS burst was
> detected) and I believe that would be the 11th harmonic of the
> master clock (100 MHz). Is there a way to suppress that?
>
> Is there a way to look at the baseband signal like I would in a
> regular oscilloscope. Just curious if anybody has tried that since
> the oscilloscope display isn't of much help for me or it may be
> that I am not using it right.
>
> Thanks for the help.
>
> Venkatesh
>
>
>
> _______________________________________________ USRP-users mailing
> list [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
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