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Thread: ADS-B Retransmissions decoding

  1. #1
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    ADS-B Retransmissions decoding

    I live in Orlando Florida and use an RTL dongle with Raspberry Pi to feed 1090 ADS-B to FR24. A lot of the local flight schools and GA traffic use the 978MHz UAT (US only) to transmit ADS-B Out. The FAA retransmits these position reports on 1090 so that other aircraft may see them. Has anyone successfully hacked their system to pick up and decode these retransmissions to see this extra traffic? Thanks.

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    no one yet

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    OK, I found the information on Dump978. I will load this up and feedback my findings to the forum.

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    I'm using the following command on my linux box with an rtl sdr dongle

    Code:
    sudo rtl_sdr -f 978000000 -s 2083334 -g 48 - | ./dump978 | ./uat2esnt | nc -q1 127.0.0.1 30001
    This is fed to an instance of dump1090 which is acting as my rebroadcast server that fr24feed connects to. The issue I am running into is I think fr24feed is filtering out DF=18 messages which is how uat2esnt re-encodes the data. I have not been able to get fr24feed to connect to the basestation datafeed from dump1090
    Last edited by kjablonski; 2015-10-08 at 17:57.

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    Quote Originally Posted by kjablonski View Post
    I'm using the following command on my linux box with an rtl sdr dongle

    Code:
    sudo rtl_sdr -f 978000000 -s 2083334 -g 48 - | ./dump978 | ./uat2esnt | nc -q1 127.0.0.1 30001
    This is fed to an instance of dump1090 which is acting as my rebroadcast server that fr24feed connects to. The issue I am running into is I think fr24feed is filtering out DF=18 messages which is how uat2esnt re-encodes the data. I have not been able to get fr24feed to connect to the basestation datafeed from dump1090
    I would think there would be a great difference between you picking up 978Mhz data and FR24 doing the same. Just like ABC cannot pick up and retransmit CNN broadcasts, FR24 can not just utillize FAA data without permission. So that would be why they filter out DF=18 I guess.

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    Any idea where i can find specs on df18 vs df17? im not receiving any tis-b uplinks. All my data is from the a/c themselves so, I would like to try and reencode them to df17 but cant find specs

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    From a post over at Flight Aware (is it cool to link to the competition?):
    http://discussions.flightaware.com/a...us-t18256.html

    obj (the creator of dump978) says df17 and 18 use the same encoding format. I modified the uat2esnt program to change the df type to 17.
    quick runs with test data pumping it to VRS show the ADSB payloads are all valid as DF17. I'll try to get live data captured over the weekend and report back
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    Quote Originally Posted by CGT View Post
    I live in Orlando Florida and use an RTL dongle with Raspberry Pi to feed 1090 ADS-B to FR24. A lot of the local flight schools and GA traffic use the 978MHz UAT (US only) to transmit ADS-B Out. The FAA retransmits these position reports on 1090 so that other aircraft may see them. Has anyone successfully hacked their system to pick up and decode these retransmissions to see this extra traffic? Thanks.
    The USA always tried to be different - and cause problems to users.

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    Success! I have successfully converted converted the messages from DF18 to DF17 and fr24 is accepting and displaying them.

    Sent from my HTC One M9 using Tapatalk
    Feed Provider:
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    T-KDWH8 (Experimental UAT)

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    Congratlations

    Quote Originally Posted by kjablonski View Post
    Success! I have successfully converted converted the messages from DF18 to DF17 and fr24 is accepting and displaying them.

    Sent from my HTC One M9 using Tapatalk
    Did you have to do anything else to get this to work? I will try it when I get a chance as I have a lot of UAT traffic in my area.

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