APRS from an aircraft?

Discussion in 'General Technical Questions and Answers' started by WA7ARK, Sep 1, 2019.

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  1. WA7ARK

    WA7ARK Ham Member QRZ Page

    What path should be used from an aircraft flying ~10kft msl in the western US?

    At what altitude is it ok to use WIDE2-1?

    Do any trackers switch PATH automatically based on GPS-derived altitude?
    If not, has anybody written Arduino code to parse altitude out of GPS sentences?
  2. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    On Your path from AZ to Canada in the western Rockies you'll be okay on wide.

    I've never had any complaints in fact a lot of people like to see airplanes logo pop up anyway, I get a lot of positive response.

    It is not much different than if you were driving the mountain tops at 14000 feet, which I do in my Jeep in Colorado with APRS.

    And I don't know about the trackers I haven't really thought about that or checked it. It'll be interesting to hear from others

    Have a fun trip
    73 K0UO Steve
  3. WA7ARK

    WA7ARK Ham Member QRZ Page

    The best on-line guidance I found since my post is here:


    That page ends with: If it flies: WIDE2-1, once every minute or two minutes. ...which is what I have been doing.
    KG4RRH and K4LCA like this.
  4. WJ4U

    WJ4U Subscriber QRZ Page

    I'd be careful flying ~10kft msl around mountain tops at 14000 feet. :eek:

    Will be on the lookout for you on APRS.fi

  5. WA7ARK

    WA7ARK Ham Member QRZ Page

    Those packets were sent with the TT3 tracker sitting on my work bench, and with the GPS up in a skylight...

    At the present time, I can transmit two different APRS sequences based on the position of a toggle switch:

    "High": switch setting: WIDE2-1, every two minutes with smart pegging of turns.

    "Low" : WIDE1-1,WIDE2-1.

    I am thinking of automating the switch by adding an Arduino which gets the same GPS ASCII stream as the TT3, decodes the GPS altitude, and then toggles the TT3 input port pin based on GPS derived altitude.

    Last edited: Sep 2, 2019
    K4LCA likes this.
  6. VE7BPB

    VE7BPB Ham Member QRZ Page

    Since an Arduino Nano is about 5 cents out of the gumball machine how could you not implement that idea, hi.

    regards, Roy
    WA7ARK likes this.
  7. WA7ARK

    WA7ARK Ham Member QRZ Page

    I was hoping someone already has.... (so I could "reuse" their code, ;))
  8. N3HGB

    N3HGB Ham Member QRZ Page

    I have had good luck with a TinyTrak 3 that could change path with altitude. I don't have it in front of me, but I think I was WIDE2-2 below 1500 feet and WIDE1-1 or maybe no path at all above that.
    KK4NSF and K0UO like this.
  9. WA7ARK

    WA7ARK Ham Member QRZ Page


    I have an older TT3 (without the plus). The TT3 just has two messages which can be selected based on the state of a port pin (high/low). You would have to flip the switch manually to select which of the two messages gets sent.

    I could replace the switch with an Arduino port pin where the Arduino watches the GPS sentences to determine altitude and then signals the TT3 to switch messages.
  10. N3HGB

    N3HGB Ham Member QRZ Page

    Way easier to just get a new one ;)

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