Hi ,
just one comment : the interrogation is periodic and stable.. the request
is transmitted by a rotating antenna turning at constant speed. If you can
get the direct path to the interrogation system, you may estimate the
round-trip time and then when the interrogation pulse is sent
sylvain
2014-02-17 16:46 GMT+01:00 Allan Healy <allan.healy121(a)gmail.com>om>:
Hi Pete
Thanks for the reply. Yeah I can see the MODE C transmissions with the
rtl_adsb alright but I don't know how to see the interrogation
transmissions from an SSR. Like you said there are many decoders available
for MODE S. Hopefully my supervisor will understand the gravitas of the
project and will accept MODE S as a suitable solution. Still I will try do
some more research. If I am successful I will provide my solution to this
forum. Thanks again.
Allan
On 17 Feb 2014, at 15:31, Pete Zaitcev <zaitcev(a)kotori.zaitcev.us> wrote:
On Mon, 17 Feb 2014 14:57:44 +0000
Allan Healy <allan.healy121(a)gmail.com> wrote:
> My name is Allan an I am currently working on my final year project
> for college. The idea is to create a radar system that interprets
> MODE C interrogation signals and replies by aircraft and SSR and
> with this information determine where these airplanes are in your
vicinity.
I never heard of anyone being able to do that so far. Mode S is easy
and there's any number of 1090 Extended Squitter receivers and decoders
out there, but Mode C relies on the illumination by the radar to
trigger the transmission. Since you cannot know where the radar
is pointing and when the impulse started (and sometimes not where
the radar is located), you cannot link Mode C squitter with the
particular
primary target.
You can receive Mode C with rtl_adsb and have a look at 56-bit packets,
but they are completely useless for an independent ground station.
Some people nowadays play with a concept of building a something
like interferometer from 3 or 4 receivers, but nobody has succeeded
thus far, as far as I know.
-- Pete