Not receiving any fm signal

i ran marcus script, grc works fine. i ran many fm receivers but i
received only
white noise and no signal or sound. anyone has a working example for
n210 uhd?
thanks all
ahmad

On 20/09/11 07:15 AM, ahmad wrote:

i ran marcus script, grc works fine. i ran many fm receivers but i received only
white noise and no signal or sound. anyone has a working example for n210 uhd?
thanks all
ahmad

If you run a uhd_fft.py, tuned to the correct frequency, do you receive
a spectral plot that looks
“reasonable” ?


Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

Can I ask some questions about GNU radio ( I think I just did )

Is there a diffinative list of what GNU Radio can do ?

What modes does the GNU radio suite cover ?

Are there any experimental modes being used with GNU radio ?

Is it just the ease of experimentation that is the attraction ?

  • Andrew -

On 09/20/2011 06:14 PM, Andrew R. wrote:

Can I ask some questions about GNU radio ( I think I just did )

Is there a diffinative list of what GNU Radio can do ?
Well, there’s the Doxygen DOCs, which are more programmer-friendly than
for someone wanting to get a pithy overview.

http://gnuradio.org/doc/doxygen/index.html

And the www.gnuradio.org site in general has a fair amount of
information.

What modes does the GNU radio suite cover ?
A bunch. But keep in mind that Gnu Radio isn’t an end application,
but rather a DSP/SDR development environment for
developing end applications.

Applications are “strung together” from fundamental DSP building blocks,
like modulators, filters, etc. There’s a GUI-based application,
called “GRC” (GnuRadio Companion) which helps with that “stringing
together”, although one is also free to program using the
pre-defined blocks in either Python or C++. There is also a
mechanism for adding your own processing blocks, which are generally
written in C++, and interface to the rest of Gnu Radio using a formal
interface.

Are there any experimental modes being used with GNU radio ?
I huge fraction of the people using Gnu Radio are using it for
experimentation with communications protocols and new modulation
techniques. Some are students, using Gnu Radio to explore variants
of existing modulation schemes–OFDM, QAM, QPSK, etc.

Is it just the ease of experimentation that is the attraction ?

I guess that’s part of the attraction. And it’s free–both as in beer,
and “freedom”. It supports a growing number of SDR hardware
platforms as well, including the products from Ettus, and the FCD
from the UK. One of the Gnu-Radio based applications that I run
24x7 uses a PC sound card as an RF sampler for VLF radio.

Much of the “early” SDR hardware platforms out there, particularly those
targetted at the amateur-radio market, have a closed,
or nearly-closed API, and often you’re “locked in” to the
applications they provide. Which is fine if you think of an SDR
platform
as nothing more than a ham-radio “appliance”, with a PC GUI instead
of front-panel knobs.

But for those of us who think of SDR platforms as more-generic devices,
a “framework” like Gnu Radio is the perfect vehicle for
experimentation, research, testing, and even end-product “delivery”.
My own software-product, IRA, uses Gnu Radio underneath
to do about 80% of the signal-processing functions.


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

I was just looking at the N200

Do these hardware components have sensitivity figures ?

I am interested in passive RADAR

I have been using a 1090 MHz receiver and a cheap digital OSCilloscope
commaned under LINUX as a capture device.

I guess that is sort of what the hardware and software of an SDR does ?

My system is very slow

  • Andrew -

----- Original Message -----
From: “Marcus D. Leech” [email protected]
To: “Andrew R.” [email protected]; [email protected]
Sent: Wednesday, September 21, 2011 8:43 AM
Subject: Re: GNU radio

Hi Andrew,

Is there a diffinative list of what GNU Radio can do ?
It can do 99% of what RF spectrum can do today, de/modulation wise.
Have you tried youtube GNURadio or google on projects that you are
interested in?

What modes does the GNU radio suite cover ?
RF spectrum see http://www.ettus.com/order
Regarding de/modulation you must browse the source code
http://gnuradio.org/redmine/projects/gnuradio/wiki

Are there any experimental modes being used with GNU radio ?
I bet tons…sample
http://www.poes-weather.com/index.php?Itemid=50&option=com_content

Is it just the ease of experimentation that is the attraction ?
Yep, that too…

Patrik

----- Original Message -----
From: “Andrew R.” [email protected]
To: “Marcus D. Leech” [email protected]; [email protected]
Sent: Wednesday, September 21, 2011 1:14
Subject: [Discuss-gnuradio] GNU radio

On 21/09/2011 11:34 AM, Andrew R. wrote:

I was just looking at the N200

Do these hardware components have sensitivity figures ?
That depends entirely on the daughterboard you chose. Although most of
them have noise figures in the 4-5dB range at maximum gain.
If you’re just interested in RX in the 1090MHz range, I’d suggest the
DBS_RX2. Sensitivity is dominated by noise figure. If you need
lower noise figures you’ll have to put a band-specific LNA in front,
which is what I do for radio astronomy.

I am interested in passive RADAR

I have been using a 1090 MHz receiver and a cheap digital OSCilloscope
commaned under LINUX as a capture device.

I guess that is sort of what the hardware and software of an SDR does ?

My system is very slow

In an SDR, nearly-all the processing is done on the host computer, so
you need a fastish computer. Overall compute requirements
are roughly proportional to sample_rate * complexity-per-sample.

USRP N210 and SBX transceiver will give you coverage of all those bands.

Matt

Maybe I can list my aims and you can tell me if GNU and N200 can do this
?

  1. Receive on 1030 MHz - BW not sure yet
  2. Receive on 1090 MHz - BW not sure yet
  3. Receive on 2700 - 2900 MHz - BW not sure yet
  4. Classify signals on these bands.
  5. Perform PPM decode - Pulse Position Decode on the 1090 MHz band

Using a hardware device and GNU radio

The computer would be a MAC MINI running openSUSE LINUX

or

MacBook PRO Laptop running LINUX

with either USB or Gigabit ethernet.

What would be the suggested software and hardware combinations ?

Can I use the N200 as a very basic spectrum analyser and a capture
device
( I guess the capture device would be just continuous)

I undestand what I want to do and I have started decoding singals on
1090
MHz already

I just want to turbo charge the process and make it as fast as my Mode S
1090 MHz receiver I have now, which is a 1090 MHz front end and FPGA

  • Andrew -

----- Original Message -----
From: “Marcus D. Leech” [email protected]
To: “Andrew R.” [email protected]
Cc: [email protected]
Sent: Thursday, September 22, 2011 1:47 AM
Subject: Re: GNU radio

Awesome thanks nick

Could you talk a bit about the decode ?

Do you have sort of loop ?

Starting from a first sample ?

Sent from my iPhone
Andrew R.

Nick,

could you give me a pointer to the schema of your decoder ?
It seems to me that was available somewhere but I didn’t manage to
retrieve it.
Thanks in advance

     *am*

Andrea, Andrew,

You’re best off reading the source code:
http://www.github.com/bistromath/gr-air-modes/

I also have a set of slides from the Gnuradio conference, but it doesn’t
go
into detail into the decoder itself:
http://www.nerdnetworks.org/~bistromath/adsb.pdf

PPM is pretty straightforward to decode. There’s a preamble detector
(air_modes_preamble.cc), which uses stream tags to mark possible valid
Mode
S packets, and a slicer (air_modes_slicer.cc) which gets bits out of it.
That’s all pushed through a message queue into the Python app, which
does
all the parsing, position decoding, etc.

Feel free to contact me personally with ADS-B- or gr-air-modes-specific
questions, that traffic probably doesn’t belong on the list.

–n

On Wed, Sep 21, 2011 at 11:35 AM, Andrea M. <

Andrew,

I’ve written a 1090MHz Mode S/ADS-B receiver for Gnuradio which can use
Ettus hardware (N200/N210, E100/E110, USRP1). It works pretty well (up
to

250nm range with line of sight). I’ll try to answer your questions inline
below as well.

On Wed, Sep 21, 2011 at 9:17 AM, Andrew R.
[email protected]wrote:

Maybe I can list my aims and you can tell me if GNU and N200 can do this ?

  1. Receive on 1030 MHz - BW not sure yet

Yes, up to 25MHz bandwidth with N200/N210. You’ll want to use WBX, SBX,
or
DBSRX2 as your daughterboard.

  1. Receive on 1090 MHz - BW not sure yet

Yes, up to 25MHz bandwidth with N200/N210. You’ll want to use WBX, SBX,
or
DBSRX2 as your daughterboard.

Keep in mind you will not be able to receive on 1030 and 1090
simultaneously
with a single board. I’m not sure if your application requires this. A
USRP1
plus two daughterboards, or two N200s in MIMO configuration would
accomplish
this.

  1. Receive on 2700 - 2900 MHz - BW not sure yet

Yes, up to 25MHz bandwidth with N200/N210. You’ll want to use SBX or
DBSRX2
as your daughterboard.

  1. Classify signals on these bands.

That’s totally up to you. Remember that a USRP will just give you
straight,
basically unprocessed digital RF samples from wherever in the spectrum
you
ask it to. The processing of those signals into something intelligible
is
your responsibility, and Gnuradio is a toolkit to make this, if not
easy, at
least easier than doing all your DSP from scratch.

For example, for 1090MHz PPM signals, if you create a dead-simple
Gnuradio
flowgraph which just does AM demod (complex-to-magnitude) on the input
samples, you’ll have a PPM signal that looks just like the output of
your
1090MHz front end. Further processing in Gnuradio can turn that into
intelligible Mode S data.

  1. Perform PPM decode - Pulse Position Decode on the 1090 MHz band

See the gr-air-modes package for an example of a Gnuradio receiver doing
just this. Might give you a good idea of what goes into a Gnuradio
flowgraph
since it’s a format you’re already pretty familiar with.

Either is fine. Recommend using an N200 + GigE.

What would be the suggested software and hardware combinations ?

Can I use the N200 as a very basic spectrum analyser and a capture device (
I guess the capture device would be just continuous)

If your bandwidth of interest is under 25MHz it will give you a good
spectrum analyzer display. You can “piece together” a wider spectrum by
re-tuning and capturing one 25MHz swath at a time.

I undestand what I want to do and I have started decoding singals on 1090
MHz already

I just want to turbo charge the process and make it as fast as my Mode S
1090 MHz receiver I have now, which is a 1090 MHz front end and FPGA

Depends on what you mean by “fast”. The N200 can get 25MHz of bandwidth
down
to the host, and since the Mode S waveform requires only 4Msps you’re
covered with room to spare.

–n

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