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@gmail.com:
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@kotori.zaitcev.us wrote:
On Mon, 17 Feb 2014 14:57:44 +0000 Allan Healy allan.healy121@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