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Thread: Garmin Synthetic Vision in the Carbon Cub?

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  1. #12
    Senior Member ceslaw's Avatar
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    Default Re: Garmin Synthetic Vision in the Carbon Cub?

    I am most interested in this topic. If one is going to spend big bucks for a panel it would be nice to know it can be upgraded to be ADS compatible when that requirement creeps up on us in six years.

    The Trigg TT21 comes with the World VFR panel, but some info suggests the TT22 will be needed to be ADSB out compliant. That issue will have to be resolved.

    The Trigg TT21 or TT22 will require a WAAS compliant source of GPS input to function as ADSB Out. A couple of units, including the Freeflight, were approved in 2010 according to Trigg's manual. Hopefully others will work now.

    Presumably a separate compliant GPS WAAS source could be simply added at a later date and simply plugged into the Trigg to make it ADSB Out legal. But having two separate GPS receivers seems redundant. One that could feed both the Trigg and the 796 would seem a more elegant solution.

    What about the Garmin GDL-39, which is a WAAS GPS source and ADSB in source for the Garmin 796 (among others)? I suspect it would produce a 'degraded' ADSB out signal on the Trigg 21 / 22 (meaning slight loss of altitude accuracy).

    So here is what I am wondering. If one starts with the World VFR panel, adds a Garmin GDL-39, connects it to the Trigg 21 and the 796, would you have not only ADSB in on the 796 but also legally sufficient ADSB Out on the Trigg 21 / 22? My guess is not. I question whether the Garmin GDL-39 has RAIM capability, yet another question I can't answer.

    Info from another site:
    www.sea-avionics.com

    Q: Do the Trig transponders offer Extended Squitter ADS-B out?
    A: As of 2010, the TT22 & TT31 transponders include support for Extended Squitter (ES) ADS-B Out. The software in the Trig transponders for the ES ADS-B Out provides all of the required parameters listed in EASA AMC20-24. AMC20-24 is ADS-B airworthiness approval for EASA. This "Acceptable Means of Compliance" spells out the performance requirements of such equipment.
    In order to utilize the ADS functions of the Trig transponders, a GPS receiver meeting specific criteria must be interfaced with the transponder. As of 2010, the Freeflight 1201 & NexNav 3101 are the only GPS receivers that can be used with the Trig transponders for this function.



    Q: Can the Trig transponders receive NMEA GPS data from any GPS receiver?
    A: Yes, you can connect any NMEA GPS position source to a Trig transponder, and with the correct configuration the transponder will broadcast ADS-B position squitters. However there are limitations with the NMEA data. The NMEA messages do not include Receiver Autonomous Integrity Monitoring (RAIM) information, which means that the position transmitted by the Trig transponder will be indentified as "low quality" on most traffic information systems. Please note that this type of NMEA GPS/transponder configuration will not meet forthcoming FAA ADS-B requirements, but in the end it will be rather beneficial for use in flight tracking and traffic avoidance.
    Last edited by ceslaw; 02-28-2014 at 07:35 PM.

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