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Thread: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

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    Member gderamel's Avatar
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    Default ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    Anyone know how to review this ADSB Performance report? It says my “SIL” and “SDA” failed. If others who have the same setup (Garmin GLD 39 & GPS 20A and Comant CI-2580-200 Antenna), please post your Configuration Page screenshots that’d be most helpful. Thanks!PAPR_20191220_AC4513_416776151.pdf

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    Senior Member Pete D's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    The GDL 39 is a ADSB reciever (https://buy.garmin.com/en-US/US/p/93601)

    The GPS 20A is your WAAS position source for the transponder (https://buy.garmin.com/en-US/US/p/525504)

    And the Comant is a VHF/GPS WAAS antenna.

    What transponder does your setup have?
    Pete Dougherty
    R & D Shop Manager
    Cub Crafters Inc

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    Member gderamel's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    Quote Originally Posted by Pete D View Post
    The GDL 39 is a ADSB reciever (https://buy.garmin.com/en-US/US/p/93601)

    The GPS 20A is your WAAS position source for the transponder (https://buy.garmin.com/en-US/US/p/525504)

    And the Comant is a VHF/GPS WAAS antenna.

    What transponder does your setup have?
    I have the Garmin GTX 23EX remote xponder. I already have those components you listed (with websites) installed. The GPS 20A has a steady green light for both the power and antenna, however my FAA Performance Report is showing two error codes ( “SIL” and “SDA”). Any idea what those error codes mean?

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    Junior Member Andrew Y's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    According to AC 20-165, SIL stands for Source Integrity Level, and SDA stands for System Design Assurance. These appear to pertain to ADS-B (GPS) position source. That looks like it points to the GPS 20A interface to the GTX 23ES transponder.

    Not knowing the details of the installation, I would look for two possibilities.

    First, does the GTX 23ES have software version 8.00 or higher? Looks like Dec 2015 is when that version was released, so if the unit is newer than 2015, it should work for ADS-B "out".

    Second, does the GPS 20A connect via direct serial connection to the GTX 23ES? Assuming a G3X touch avionics suite, the GPS 20A should have two data connections, CAN Bus to the G3X and RS-232 serial directly to the transponder. According to the Garmin documentation, there is no configuration required for the GTX 23ES and GPS 20A if connected per their (G3X) installation manual. The key GPS connection is between pins 5 and 6 of the GPS 20A going to (respective) pins 24 and 50 on GTX 23.

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    Member gderamel's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    Quote Originally Posted by Andrew Y View Post
    According to AC 20-165, SIL stands for Source Integrity Level, and SDA stands for System Design Assurance. These appear to pertain to ADS-B (GPS) position source. That looks like it points to the GPS 20A interface to the GTX 23ES transponder.

    Not knowing the details of the installation, I would look for two possibilities.

    First, does the GTX 23ES have software version 8.00 or higher? Looks like Dec 2015 is when that version was released, so if the unit is newer than 2015, it should work for ADS-B "out".

    Second, does the GPS 20A connect via direct serial connection to the GTX 23ES? Assuming a G3X touch avionics suite, the GPS 20A should have two data connections, CAN Bus to the G3X and RS-232 serial directly to the transponder. According to the Garmin documentation, there is no configuration required for the GTX 23ES and GPS 20A if connected per their (G3X) installation manual. The key GPS connection is between pins 5 and 6 of the GPS 20A going to (respective) pins 24 and 50 on GTX 23.
    Thanks Andrew! Very helpful.

    I’ll check the software version on the GTX 23ES (good thinking!). Pls remind me, it’s in the Config Page (hold the MENU button) in System Info? I purchased the ‘Executive Touch panel’ (G3X, etc) directly from Cubcrafters in 2015, so there’s a possibility that it’s below v8.0, but I’ve kept the CAN Bus components software up-to-date. I’ll check.

    I didn’t wire the GPS 20A into the CAN Bus. I followed Cubcrafters’ wiring diagram (schematic attached). Yes, I wired Pins #5 & 6 into the GTX 23EX pins #24 and 50. I didn’t include the optional CAN Bus terminator block because I didn't connect it into the CAN Bus. Hopefully that’s not the problem.
    Attached Images Attached Images

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    Junior Member Andrew Y's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    Yes, hold the Menu button while powering on the system. Then there is a System Info button that should show the software version of the transponder. The transponder does not update via the G3X system. It can only be updated from Garmin proprietary computer software.

    The CAN Bus connection is not required for ADS-B, the direct serial connection is the important one. And if the CAN bus is not used, then the CAN Bus terminator is also not used.
    Andrew Y
    Systems Engineering and Design
    Cub Crafters, Inc.

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    Member gderamel's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    I checked my the Systems page and my GTX 23ES is only running v7.04. Lucky me, I’m traveling without my laptop or the SD mini adapter to upload the software!


    Sent from my iPhone using Tapatalk

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    Junior Member Andrew Y's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    I may have misunderstood your comment about a laptop and SD card, but want to highlight the transponder does not update through the G3X system. It's a separate process as the transponder is a certified unit. The transponder needs to be removed and sent to Garmin, or an authorized dealer / installer / service center (like CubCrafters) for that update. If you would like to go through Cub Crafters, I would direct you towards Mitch or Jon.
    Andrew Y
    Systems Engineering and Design
    Cub Crafters, Inc.

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    Member gderamel's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    Thanks for the clarification! I’ve got an avionics guy looking at it next week. I’ll have him send it in for the software update. You’ve been most helpful! Thank you so much.


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    Junior Member Andrew Y's Avatar
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    Default Re: ADS-B Performance FAILURE Garmin GPS 20A +Comant Antenna

    You're welcome
    Andrew Y
    Systems Engineering and Design
    Cub Crafters, Inc.

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