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cyoung / stratux

Aviation weather and traffic receiver based on RTL-SDR.
BSD 3-Clause "New" or "Revised" License
1.06k stars 362 forks source link

Support for UAT Ownship anonymous mode #754

Open Camlock opened 5 years ago

Camlock commented 5 years ago

  1. Stratux version: 1.4r5

  2. Stratux config:

    SDR

    • [ ] single
    • [x] dual

    GPS

    • [x] yes
    • [ ] no type: u-blox 7

    AHRS

    • [x] yes
    • [ ] no

    power source: panel or wall wort

    usb cable: 1 meter

  3. EFB app and version: (e.g., WingX Pro7 8.6.2) Foreflight

    EFB platform: (e.g., iOS 9.2) 12.01

    EFB hardware: (e.g., iPad Mini 2) 9.7" 6th gen and Mini 4

  4. Description of your issue IMO, this next year will be a wave of UAT out installs (likely uAvionics). UAT features an option for flight privacy. Anonymous mode offers a random non-assigned temporary ICAO for that flight.
    Requesting some consideration on how to make anonymous own ship go smoothly. Consider. a button on the settings page for anonymous mode. When activated, during taxi, the strongest received ADS-B in is used as a candidate ICAO own ship. If the ADS-B in position and the rPi position are within 10 meters, same heading, plus or minus 10 degrees, then candidate ICAO is assigned own ship.
    IIRC, startup of the ADS-B out includes a few seconds of non-anonymous transmission, so a very strong signal that drops, and a strong "VFR" immediately following could be tagged as a candidate own ship also.
    There are likely a few ways to accomplish correct own ship for each flight. When stratus and foreflight "know" own ship, it should be possible to minimize nuisance traffic warnings. If possible, enable "Replay Logs", reproduce the problem, and provide a copy of the logs in http://192.168.10.1/logs/stratux/ and http://192.168.10.1/logs/stratux.log.

cyoung commented 5 years ago

Detecting Mode-C ownship was tested extensively with the SDRs and found not possible, since the receiver often saturated with the strong signal.

This should be possible with the new UAT radio (v3).

Camlock commented 5 years ago

Thanks for the comment. It seems if there is saturation, then the less strong general traffic would be problematic, no? If a nearby strong signal is causing havoc, then perhaps an argument for a top mounted receiving antenna when out antenna is underneath. A general update. Up until this last weekend, the ownship and anonymous mode was working well with Foreflight and Stratux. This last weekend, our area had a very strong high pressure system. When broadcasting anonymous, I'd often get a ghost ship 700 feet below me. So the GDL82 UAT is sharing pressure altitude, a pressure that normally occurs at lower elevations. Guessing here, but perhaps Stratux or Foreflight had an algorithm comparing pressure altitude to a Stratux installed WAAS GPS altitude, and when they were so different, concluded that it can't be ownship, it must be an airplane below me. Conjecture on my part... I haven't dug into the inner workings enough to understand what parts Stratux does versus Foreflight. Insight appreciated.

cyoung commented 5 years ago

I don't know exactly, but I think ForeFlight does try to detect ownship based on altitude. I've experienced the same as you, when GPS and pressure altitude are quite different then the ghost target shows up more often.

jzeevi commented 5 years ago

They do.

Josef Sent from a phone with a tiny screen

On Jan 31, 2019, at 2:13 PM, cyoung notifications@github.com wrote:

I don't know exactly, but I think ForeFlight does try to detect ownship based on altitude. I've experienced the same as you, when GPS and pressure altitude are quite different then the ghost target shows up more often.

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