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 Rich On 22/09/2011, at 4:02, Nick Foster <n...@ettus.com> wrote: > 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 Rich <vk4...@tech-software.net> 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. > > 2. 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. > > 3. 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. > > 4. 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. > > 5. 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. > > > 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. > > 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 > > > > - Andrew - > > ----- Original Message ----- From: "Marcus D. Leech" <mle...@ripnet.com> > To: "Andrew Rich" <vk4...@tech-software.net> > Cc: <Discuss-gnuradio@gnu.org> > Sent: Thursday, September 22, 2011 1:47 AM > Subject: Re: GNU radio > > > On 21/09/2011 11:34 AM, Andrew Rich 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. > > > > > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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