[Hackrf-dev] Visualising 1090 MHz ADS-B

[Andrew Rich]

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
>>> 
>>> 
>>> 
>>> 
>>> 
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>> 
>> 
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> 
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