[USRP-users] USRP Noise

Farrukh Aziz farrukh59th at yahoo.com
Wed Sep 19 17:24:16 EDT 2012


Hi Josh, It was due to wrong data type selection. I was using 'float64' data type which was giving wrong result. It works fine with 'float' (in Matlab).
thanks
Farrukh Aziz Bhatti
Department of Electrical & Computer Engineering
University of Auckland



--- On Wed, 19/9/12, usrp-users-request at lists.ettus.com <usrp-users-request at lists.ettus.com> wrote:

From: usrp-users-request at lists.ettus.com <usrp-users-request at lists.ettus.com>
Subject: USRP-users Digest, Vol 25, Issue 16
To: usrp-users at lists.ettus.com
Received: Wednesday, 19 September, 2012, 9:00 PM

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Today's Topics:

   1. Getting started with usrp (Arjun Nadh)
   2. Re: Getting started with usrp (Nick Foster)
   3. Re: The right sample rate for USRP N210 (Deddi Hariprawira)
   4. E110 problem with OpenBTS (Altangerel Ganbold)
   5. USRP noise (Farrukh Aziz)
   6. Re: USRP noise (Josh Blum)
   7. 2 used USRPs for Sale (Vahid Behzadan)
   8. Transfer function Basic TX board ? (Per Zetterberg)
   9. N210 ADC & DAC sample rate (Rancid Fisch)
  10.  Transfer function Basic TX board ? (Per Zetterberg)


----------------------------------------------------------------------

Message: 1
Date: Wed, 19 Sep 2012 01:14:12 +0530
From: Arjun Nadh <arjunnadh at gmail.com>
To: usrp-users at lists.ettus.com
Subject: [USRP-users] Getting started with usrp
Message-ID:
    <CADaT_YgKzxWbWAJCjvTv15Tj-mxJSNFONVA-x0W94Ps+TmQEug at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Hi Guys
           There is some trouble in getting started with programming using
uhd.
Documentation is available for gnuradio.
    But the exact details for uhd are not available
Could some one please help me by saying where to start with?
I have ubuntu 11.10,with uhd installed.I use C++ API to interact with uhd.
My problem is I do not know about the various parameters,the form of
interaction between
usrp and host computer.i.e the stuff like metadata,or what are the steps in
setting up the
transmission/reception etc.
Thanks in advance
Arjun Nadh
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Message: 2
Date: Tue, 18 Sep 2012 12:45:59 -0700
From: Nick Foster <nick at ettus.com>
To: Arjun Nadh <arjunnadh at gmail.com>
Cc: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] Getting started with usrp
Message-ID:
    <CALALHJVK5KLZbw6y_huLXgpaBwD4cB=TpRciwJ_tNL42cOhMEQ at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Arjun,

The best place to start is with the examples in uhd/host/examples, and with
the documentation in uhd/host/docs. Once you're familiarized with those,
the mailing list is a good place to ask specific questions.

Best,
Nick

On Tue, Sep 18, 2012 at 12:44 PM, Arjun Nadh <arjunnadh at gmail.com> wrote:

> Hi Guys
>            There is some trouble in getting started with programming using
> uhd.
> Documentation is available for gnuradio.
>     But the exact details for uhd are not available
> Could some one please help me by saying where to start with?
> I have ubuntu 11.10,with uhd installed.I use C++ API to interact with uhd.
> My problem is I do not know about the various parameters,the form of
> interaction between
> usrp and host computer.i.e the stuff like metadata,or what are the steps
> in setting up the
> transmission/reception etc.
> Thanks in advance
> Arjun Nadh
>
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
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Message: 3
Date: Wed, 19 Sep 2012 09:08:11 +0700
From: Deddi Hariprawira <deddihp at gmail.com>
To: Nick Foster <nick at ettus.com>
Cc: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] The right sample rate for USRP N210
Message-ID:
    <CAD0oytL38PkmMuOCeVMwHW6QxtTT=Wg5Kb_fLJBR3RJq5aAqng at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

I think so,

Is there anyone in the list who have tried to run airprobe with N210 ?.

can you share the configuration ?.

Thanks,


On Tue, Sep 18, 2012 at 10:40 PM, Nick Foster <nick at ettus.com> wrote:

> N210 uses a 100Msps native clock rate, so you should pick a sample rate
> which is a factor of 100e6. I don't know what rate gsm_receive.py is
> expecting, so I can't advise you what particular rate you should be using.
>
> --n
>
> On Tue, Sep 18, 2012 at 1:35 AM, Deddi Hariprawira <deddihp at gmail.com>wrote:
>
>> Hi List,
>>
>> I have a problem of using airprobe gsm-receiver.
>> I am using N210 USRP.
>>
>> I am assuming that the clock reference of N210 is 64 MHz and decimation
>> rate is 112 so i put the following script to run
>>
>> sudo uhd_rx_cfile -g 0 --samp-rate 571428.571429 -f 945400000 mypipe
>>
>> But when I decode it using
>>
>> gsm_receive.py -I mypipe -d 112
>>
>> it prints
>> sch.c:260 ERR: conv_decode 11
>> sch.c:260 ERR: conv_decode 11
>> sch.c:260 ERR: conv_decode 10
>> sch.c:260 ERR: conv_decode
>>
>> What is the right sample rate for USRP N210 ?.
>>
>> Thanks,
>>
>>
>> _______________________________________________
>> USRP-users mailing list
>> USRP-users at lists.ettus.com
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>
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Message: 4
Date: Wed, 19 Sep 2012 13:53:48 +0800
From: Altangerel Ganbold <altangerel.g at mobicom.mn>
To: <usrp-users at lists.ettus.com>
Subject: [USRP-users] E110 problem with OpenBTS
Message-ID: <50595DEC.1010903 at mobicom.mn>
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed

Hi all,

I am doing some experiment with USRP E110 device. My goal is to build 
GSM network and register mobile to that network. OpenBTS v2.8 is 
installed on the device and every components running without any error. 
5060,5062,5063, and 5064 UDP ports are open and listening. Even though 
my mobile phone can't find the OpenBTS network. I am using GSM SIM card 
of local carrier. I did not find anything serious from log files.
To build GSM network with E110 device, what software should be installed 
and how it should be configured? If only OpenBTS is required, what 
should I check? Help me with this issue, please.


Regards,
Altangerel



------------------------------

Message: 5
Date: Wed, 19 Sep 2012 01:01:49 -0700 (PDT)
From: Farrukh Aziz <farrukh59th at yahoo.com>
To: USRP user forum <usrp-users at lists.ettus.com>
Subject: [USRP-users] USRP noise
Message-ID:
    <1348041709.19023.YahooMailClassic at web161302.mail.bf1.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

Hi, I am using USRP N210. I have recorded the USRP noise on the PC and it looks bizarrehttp://tinypic.com/view.php?pic=21acyl2&s=6?
I have examined several noise measurements and they are similar to this shown in link. During the measurements I ensured that there were no impulses arising on the Fourier plot and the spectrum was pretty flat. I record the complex samples as two floating points to have good resolution. I understand that due to filtering USRP noise may not be pure AWGN, but what I see here is unacceptable. Is it due to the low resolution that cannot distinguish samples at such low values?
I would be extremely grateful for any clarifications.
Farrukh Aziz Bhatti

Department of Electrical & Computer Engineering
University of Auckland

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Message: 6
Date: Wed, 19 Sep 2012 05:19:17 -0400
From: Josh Blum <josh at ettus.com>
To: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] USRP noise
Message-ID: <50598E15.8080309 at ettus.com>
Content-Type: text/plain; charset=ISO-8859-1



On 09/19/2012 04:01 AM, Farrukh Aziz wrote:
> Hi, I am using USRP N210. I have recorded the USRP noise on the PC
> and it looks bizarrehttp://tinypic.com/view.php?pic=21acyl2&s=6 I
> have examined several noise measurements and they are similar to this
> shown in link. During the measurements I ensured that there were no
> impulses arising on the Fourier plot and the spectrum was pretty
> flat. I record the complex samples as two floating points to have
> good resolution. I understand that due to filtering USRP noise may
> not be pure AWGN, but what I see here is unacceptable. Is it due to
> the low resolution that cannot distinguish samples at such low
> values? I would be extremely grateful for any clarifications. Farrukh
> Aziz Bhatti
> 

Can you share the data type of the samples and what the plot scaling
means? The plots are showing 1.0*10^-21, but the smallest sample value
possible is 1.0/32767 when using complex floats.

-josh

> Department of Electrical & Computer Engineering University of
> Auckland
> 
> 
> 
> 
> _______________________________________________ USRP-users mailing
> list USRP-users at lists.ettus.com 
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
> 



------------------------------

Message: 7
Date: Wed, 19 Sep 2012 04:41:10 -0700 (PDT)
From: Vahid Behzadan <vbehzadan at yahoo.com>
To: "discuss-gnuradio at gnu.org" <discuss-gnuradio at gnu.org>,
    "usrp-users at lists.ettus.com" <usrp-users at lists.ettus.com>
Subject: [USRP-users] 2 used USRPs for Sale
Message-ID:
    <1348054870.30125.YahooMailNeo at web125703.mail.ne1.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

Hi All,

I know that many of the users are looking for used USRPs, so I thought I'd let you know that?I have listed 2 of my USRP 1s for sale on ebay. One is equipped with a 52MHz clock required for running OpenBTS and the other one is unaltered. I prefer to ship to the UK only, but if you are elsewhere in Europe I can consider other destinations as well. Take a look at these listings if you are interested and let me know if you have any questions.

Ettus Research USRP Software Defined Radio DBSRX2 RFX1200:
http://www.ebay.co.uk/itm/221127259077?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649#ht_483wt_1418?



Ettus USRP 1 Software Radio for use with OpenBTS 2.6:
http://www.ebay.co.uk/itm/221127267689?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649#ht_500wt_1414?

 
?
Vahid Behzadan
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Message: 8
Date: Wed, 19 Sep 2012 12:27:37 +0000
From: Per Zetterberg <perz at kth.se>
To: "usrp-users at lists.ettus.com" <usrp-users at lists.ettus.com>
Subject: [USRP-users] Transfer function Basic TX board ?
Message-ID: <0E84A17EEB8CD04BA9F33C99FB201FFC406830D4 at EXDB4.ug.kth.se>
Content-Type: text/plain; charset="us-ascii"

Hi,

We are looking at the Basic TX with USRP N210. When we generate a sinusoid the amplitude is -22.72dBm at 250kHz, -12.78dBm at 1MHZ and -8.63dBm@ 10MHz (the amplitude was 16000 in digital base-band ( unsigned short), UHD driver and a small program). This is perfectly fine with regards to the specification of the Basic TX board. 

We then removed the components on the board and measured directly on the DAC output. The characteristic was still the same. We had suspected the transformer created the high-pass characteristic.

Could somebody please explain why we get this result? Is there some high-pass filtering going on on the FPGA?

BR/
Per


------------------------------

Message: 9
Date: Wed, 19 Sep 2012 15:06:33 +0200
From: Rancid Fisch <rancid.fisch at gmail.com>
To: usrp-users at lists.ettus.com
Subject: [USRP-users] N210 ADC & DAC sample rate
Message-ID:
    <CAOMgnsE-een28LSXwEGDPYH=F5FXGYnKOCeQuPOQa7m2gB6wwA at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Greetings USRP experts of the world,

The block diagram (
https://www.ettus.com/content/files/06983_Ettus_N200-210_DS_Flyer_HR_1.pdf),
shows that the sample rate of the ADC is 100 MS/s, that the sample rate of
the DAC is 400 MS/s, and that both ADC and DAC are fed with the same clock
(ADC/DAC Clock).

Firstly, please confirm the following:

   - the sample rate of the ADC is *fixed *at 100 MS/s
   - the sample rate of the DAC is *fixed *at 400 MS/s
   - both ADC and DAC are fed with the *same *clock (ADC/DAC Clock)

Secondly, using the above (or their corrected versions) as working
assumptions, how does one set the decimation of the Digital Down-Converter
(DDC) and the interpolation of the Digital Up-Converter (DUC) so that
different sampling rates can be used?

Thirdly, as you can gather, I am struggling to come to grasps with the
basic method of operation. Therefore, if anyone could post some sort of
introductory text that explains, perhaps with the use of a diagram or two,
how the sampling, clocking and sampling conversion works within the USRP,
then I would be very happy [?].

Thanks.

-- 
__________
Rancid Fisch

mailto:rancid.fisch at gmail.com <rancid.fisch at gmail.com>
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Message: 10
Date: Wed, 19 Sep 2012 13:42:02 +0000
From: Per Zetterberg <perz at kth.se>
To: "usrp-users at lists.ettus.com" <usrp-users at lists.ettus.com>
Subject: [USRP-users]  Transfer function Basic TX board ?
Message-ID: <0E84A17EEB8CD04BA9F33C99FB201FFC406831D4 at EXDB4.ug.kth.se>
Content-Type: text/plain; charset="us-ascii"


Hi,

We are looking at the Basic TX with USRP N210. When we generate a sinusoid the amplitude is -22.72dBm at 250kHz, -12.78dBm at 1MHZ and -8.63dBm@ 10MHz (the amplitude was 16000 in digital base-band ( unsigned short), UHD driver and a small program). This is perfectly fine with regards to the specification of the Basic TX board.

We then removed the components on the board and measured directly on the DAC output. The characteristic was still the same. We had suspected the transformer created the high-pass characteristic.

Could somebody please explain why we get this result? Is there some high-pass filtering going on on the FPGA?

BR/
Per



------------------------------

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