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Thread: Trig TT22 transponder fed by other GPS

  1. #1

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    Trig TT22 transponder fed by other GPS

    Has anyone interfaced an iLevil WAAS source with a Trig? The serial interface works fine, lat/lon displays on the Trig, but there is some issue with side lobe suppression. Confidence level set to uncertified. The iLevil has been a good traffic and weather rcv, but I wonder if their $400 approved WAAS option has ever been used successfully. The source has a NORSEE letter approving it for experimental ac.
    What's a go-around?

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    wireweinie's Avatar
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    'Approved' as in ok'd for certified aircraft or just for experimental used? Seems like some codes are different from one to another (remember Navworx?) Have you contacted Trig?

    Web
    Life's tough . . . wear a cup.

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    I think it is approved for uncertified aircraft. The Trig can be set for 4 levels of confidence in the position, and there is a 5th setting for "uncertified". (not in Trig doc, but if you explore the menus its in there.) This is how iLevil told me to set the Trig. No config on the iLevil source other than getting the serial interface to work. As I understand it, side lobe suppression is part of the word being sent to the ground station, which has multiple elements and can change its radiation pattern. I don't see how I can change the ac antenna pattern by sending something different down the coax. The pattern is determined by antenna design and placement, right? I sent screenshots of the fail to Trig, in the Netherlands. They said, oh, "you are voluntarily equipped, not 2020 compliant." Huh?
    What's a go-around?

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    wireweinie's Avatar
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    Quote Originally Posted by Skywalker View Post
    "you are voluntarily equipped, not 2020 compliant."
    Just means you are experimental not trying to meet requirements for 01Jan20. \

    Trig will have the final word on programming. If you know some one at the local avionics shop, they might have the equipment to look at your signal and let you know if it will pass muster for experimental with the feds.

    Web
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    I understand the advantage of being visible, but does voluntary get me into towered airports?
    What's a go-around?

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    wireweinie's Avatar
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    It's my understanding that experimental equipment (non TSO'd) is good in an experimental aircraft but the equipment must still conform to Part 91.227 requirements.

    Anyone else heard different?

    Web
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    From everything I've read, Web is 100% correct (as usual). For experimental aircraft, the GPS vendor must state that their product meets the performance required by Part 91.227 (thus meeting the performance required by the TSO). That vendor statement must be supported by testing they've done, but it does NOT need to rise to the level of having received an FAA TSO. As the experimental owner/operator, it falls on you to confirm that the vendor has made such a statement.

    Prior to the 2020 mandata taking effect, experimental (and perhaps standard-cert – I'm a little unclear on that one) aircraft could voluntarily be equipped with ADS-B OUT where the GPS did NOT meet the TSO requirements. They would be classified by the FAA as "voluntarily equipped, but non-compliant" with the rule. Until the 2020 mandate goes into effect, their data will be used in the system and re-broadcast to other aircraft. But once the deadline passes, that "non-compliant GPS" data will be suppressed by the FAA, and such aircraft will NOT meet the equipment mandates to fly in "ADS-B-required" airspace.

    At one point, it was understood that such "non-compliant ADS-B" equipped aircraft would receive notices requiring them to disable / remove that equipment, or upgrade it to "compliant" status to keep using it. I'm not really sure how that decision played out in the end... Anyone else know?
    Jim Parker
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    Thanks Skywalker thanked for this post

  8. #8
    wireweinie's Avatar
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    Thanks Jim. Are there any AC's or letters, from the feds, that spell out their policy on experimental ADS-B equipment after 01Jan20? I'm having a hard time finding 'official' info?

    Web
    Last edited by wireweinie; 10-10-2019 at 10:52 AM. Reason: sppeling arrers
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    Sorry, Web. It took me a while to find the document I used for that info, but here it is: https://www.faa.gov/nextgen/equipadsb/installation/

    Here's the paragraph that discusses the "manufacturer's statement" for experimentals: (Bold/Italics added by me for emphasis)
    The FAA recommends a WAAS GPS that is compliant with TSO-C145 or TSO-C146. These units are readily available for general aviation and provide sufficient performance to meet the 14 CFR 91.227 requirements. Avionics vendors offer stand-alone GPS receivers and package them with ADS-B transmitters or with GPS Navigators. GPS and ADS-B transmitter pairings installed on Type Certificated aircraft require FAA approval. ADS-B Out systems marketed for installation on Experimental and Light Sport aircraft must have a 14 CFR 91.227 compliance statement from the applicable airframe and/or equipment manufacturer. Be sure to contact your manufacturer before installation if you are unsure of ADS-B Out system component compatibility.

    You should be able to follow the trail from there, if necessary. But any "legitimate" manufacturer of compliant ADS-B Out equipment for experimentals is well aware of this requirement, and should have the "14 CFR 91.227 compliance statement" readily available for you. Some include it on their website for easy download, and others have it in their installation manuals.
    Jim Parker
    '65 Champion 7ECA - Flying
    ?? Bearhawk Patrol - Building
    Thanks wireweinie, Skywalker thanked for this post

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