Messages

1

General Discussion / Re: Mode A and Mode C

« on: February 19, 2016, 04:30:53 pm »

I see your point Wobblewing, but there are methods to verify the accuracy of an estimation. It doesn't have to be presented to the pilot unless let's say the estimation is within a 95% confidence interval.

Now I'm taking it to another level, but since radar locations are known, it is possible to listen on 1030 MHz for interrogation pulses to transponders with a second SDR and based on timing and geometry get a much more accurate position estimate of the aircraft.

There are technical solutions as long as there is a will!

EDIT: You can even run them on the same clock if you want thus maintaining phase coherence =)
http://www.rtl-sdr.com/passive-radar-dual-coherent-channel-rtl-sdr/

2

General Discussion / Re: Mode A and Mode C

« on: February 19, 2016, 12:03:18 am »

There are too many variable for this to be any use, if you ask me....
Results will be unreliable and possibly more useless than no result at all! :-)

Mode A and C detection is the only useful thing in Sweden if you are flying below FL300.

3

General Discussion / Re: FLARM protocol

« on: February 15, 2016, 03:56:21 pm »

Hello Admin.

One of the links that you removed was open linked straight from the flarm website.

4

General Discussion / Re: FLARM protocol

« on: February 15, 2016, 09:41:54 am »

I found it =)

(Post Edited)
I have removed the links posted here.
Flarm is a Proprietary system, I would rather not have links to their documents unless they are open.

5

General Discussion / Re: Mode A and Mode C

« on: February 15, 2016, 09:14:26 am »

So you don't want a beta tester that has access to an airplane and is willing to fly it up for you?

6

General Discussion / FLARM protocol

« on: February 15, 2016, 09:12:33 am »

Where can I find more details on the FLARM protocol that is used for communication with e.g. SkyDemon?

7

General Discussion / Re: Mode A and Mode C

« on: February 15, 2016, 07:57:17 am »

Sign me up for it =)

8

General Discussion / Mode A and Mode C

« on: February 14, 2016, 11:53:38 pm »

So I was wondering why Mode A and C transponders are not supported?

Given that you have an on-board GPS unit, and you know the RSSI from other Mode A and C transponders, and given that the aircraft is moving through the air, localization should be possible even for Mode A and C transponders by using a simple free-space path loss propagation model (the air doesn't have many reflectors anyway).

Slides 10 and 11 present a simple solution: http://www.eit.lth.se/fileadmin/eit/courses/etin10/2014/LectureA3_Positioning.pdf

E.g. the RSSI for the last X known positions could be used to estimate a static position, and since the other airplanes are moving through the air the next position could be estimated by adding the newest sample and discarding the oldest one (rolling estimation). Kalman filtering could also be applied to get rid of most of the errors.

/Dimitrios

9

General Discussion / Re: PilotAware Map

« on: February 14, 2016, 01:30:31 pm »

Added myself =)

Sad to see that I'm the first one in Sweden.