[Xastir] New script: ads-b.pl for snagging airplane positions

[Curt Mills]

One more thing I wanted to mention: The altitudes reported via ADS-B (that
I've found so far) are using standardized barometric pressure of 1013.2 mb
for their altitude readings, same as used for airplane Flight Levels.

Two days ago planes were landing at the nearby airport at about 500'
(reported by ADS-B). Yesterday landings were at 1200'. The airport is
actually at 606'. Confused me until I read up on it and figured it out:
Barometric pressure changed by 21 mb in one day, which calculated to about
a 570' difference in reported altitude.

If I can find a WAAS/GPS reported position in the data to snag instead, I'd
rather parse and use that. So far I haven't found it in the port 30003 data.


On Thu, Feb 18, 2016 at 12:23 PM, Curt Mills <curt.we7u at gmail.com> wrote:

> Nice. Sounds like a fun project!
>
> All planes are required to have ADS-B transmitters (known as ADS-B OUT) by
> 2020 if they fly above 2500' (that height is probably U.S.-specific).
>
> Those that fly above 18k or outside the U.S. must have the 1090 MHz
> frequency. In the U.S. if you fly above 2500' but below 18k, you can use
> the 978 MHz frequency.
>
> I live and work near a county airport and have seen transmissions on both
> frequencies, but most is on 1090. I have dump978 attached to dump1090 port
> 30001 and sending packets into it, but don't know yet whether dump1090
> combines that input with its own when it sends decoded messages to port
> 30003, the port I'm pulling from. It does say that it combines them on port
> 30002, but that's the binary output port and I don't currently decode that.
>
> To test 978 I need to bring up dump1090 w/o any hardware, then use dump978
> w/hardware to send to dump1090 and see if I get anything out with my
> script. Been having too much fun listening on the 1090 frequency and don't
> want to stop long enough for that test! Particularly since the 978 packets
> are much less frequent. If anyone else tries this, let me know what you
> find out.
>
>
> On Thu, Feb 18, 2016 at 12:02 PM, Jason KG4WSV <kg4wsv at gmail.com> wrote:
>
>> On Thu, Feb 18, 2016 at 1:15 PM, Curt Mills <curt.we7u at gmail.com> wrote:
>>
>> > I added a new script today called "ads-b.pl".
>> >
>>
>> Cool! I'm getting my rocket tracking beagle bone black ground station
>> going, and this would be a nifty add-on.  Our waiver is to 24k', and it
>> will be interesting to see what goes on up there.
>>
>>
>> Thanks Curt!
>>
>> -Jason
>> kg4wsv
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>>
>
>
>
> --
> Curt, WE7U
> http://wetnet.net/~we7u
> http://www.sarguydigital.com
>



-- 
Curt, WE7U
http://wetnet.net/~we7u
http://www.sarguydigital.com