[Hackrf-dev] Visualising 1090 MHz ADS-B

[Chuck McManis]

Hi Andrew,

I don't know if you're coming at this from the Software side or the Radio
side but here is a good start:
https://www.elttam.com.au/blog/intro-sdr-and-rf-analysis/
That and watch *all* of the videos on the GreatScott Gadgets site

--Chuck


On Sat, Jul 8, 2017 at 6:17 PM, Andrew Rich <vk4tec at tech-software.net>
wrote:

> Ok I have just watched a video
>
> I is an amplitude sample in time
> Q is an amplitude sample in time
>
> They are just a little bit apart
>
> So what does an SDR program do with the I and Q ?
>
> How does it know when to start sweeping across the screen ?
>
> Sent from my iPhone
>
> > On 9 Jul 2017, at 11:01 am, Andrew Rich <vk4tec at tech-software.net>
> wrote:
> >
> > Ok my center frequency is 1090 MHz
> >
> > The on off rate is 1 MB/s I think from memory
> >
> > I have noticed the sampling rate determines the frequency span 10 MHz =
> 10 MHz
> >
> > So there is a stream of I and Q coming out
> >
> > What is I and Q telling me ?
> >
> > Is I how far along the scan it is ?
> >
> > And is Q telling me how big the signal
> > Is ?
> >
> > Would an IQ file contain a whole heap of scans ?
> >
> > I = X axis
> > Q = Y axis
> >
> > I would need to sample fast enough as to not miss an amplitude change I
> want to see
> >
> > I guess an IQ file is not plain text but 8 bit numbers packed ?
> >
> > Does it go IQIQIQIQ ?
> >
> > What relationship is I and Q to the center frequency ?
> >
> > I think the signal amplitude resolution is described as 8 or 12 bits ?
> >
> > So as the ADC is pumping out numbers, which it has no control over , it
> is just sampling the signal.
> >
> > Why does it not just out put values of amplitude ? Or is that what the I
> is about ?
> >
> > I am just trying to work out if I record 1090 MHz which is basically OOK
> on off keying, what would be contained in the file ?
> >
> > Am I right with the 8 bits , IQIQIQ ?
> >
> > Andy
> >
> > Sent from my iPhone
> >
> >>> On 9 Jul 2017, at 5:18 am, Cinaed Simson <cinaed.simson at gmail.com>
> wrote:
> >>>
> >>> On 07/08/2017 06:44 AM, Gregory Ratcliff wrote:
> >>> Great request!  I would like to see this also.
> >>>
> >>> Greg
> >>> Nz8r
> >>>
> >>> Sent from my iPad
> >>
> >> A flowgraph as in gnuradio?
> >>
> >> Don't know.
> >>
> >> How about a python script using qt and gnuradio?
> >>
> >> Try
> >>
> >>  https://github.com/bistromath/gr-air-modes
> >>
> >> You'll need to build it - might need a development environment.
> >>
> >> If you know what you're doing then you could probably build a flow graph
> >> from gr-air-modes python scripts.
> >>
> >> -- Cinaed
> >>
> >>
> >>
> >>
> >>
> >>
> >>>
> >>> On Jul 8, 2017, at 6:23 AM, <vk4tec at tech-software.net
> >>> <mailto:vk4tec at tech-software.net>> <vk4tec at tech-software.net
> >>> <mailto:vk4tec at tech-software.net>> wrote:
> >>>
> >>>> Hello Guys
> >>>>
> >>>>
> >>>>
> >>>> I have a hack rf, GNURadio and MacBook Pro
> >>>>
> >>>>
> >>>>
> >>>> Can someone point me towards a flow graph that would show me the
> >>>> pulses on 1090 MHz
> >>>>
> >>>>
> >>>>
> >>>> Showing the preamble and 56 and 112 bits please
> >>>>
> >>>>
> >>>>
> >>>> Andrew
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> HackRF-dev mailing list
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> greatscottgadgets.com>
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> >>>
> >>>
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> >>>
> >>
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>
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