WAAS upgrade woes

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mhoran
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Re: WAAS upgrade woes

Post by mhoran »

Charles K wrote: Wed Mar 09, 2022 4:11 am I might be wrong here - but these drawings are general for the new plane build and not specific to the upgrade. I'll have to dig up the paperwork I have but I believe new antenna cables and ethernet wiring are a part of the install kit.

Cannot find anything specific on paperwork but it is possible that the coax required for the WAAS is different than for non WAAS. All I know is that I have new antenna cables and a new ethernet wiring assembly that included an all new lightning protection resistor board as well. Have had no RFI issues.
My understanding is the drawings are specific to the WAAS upgrade. They mention removing existing GIA 63 LRUs, which wouldn't be the situation in a new build. Regardless, the coax in my plane is the required double shielded coax. I do have new antennas, but nothing was done to my ethernet wiring assembly. That's not mentioned in the drawings, so I'm not sure why it would be required.

Which version of the GIA 63W do you have? I have the -20 model. Perhaps this is a wild goose chase, but the STC mentions relocating the GTX 33 transponder "outboard" of the equipment rack when the -20 GIA 63W is installed. Nobody seems to know why this is. Of course, I don't have the GTX 33, I now have the GTX 345 like you, but am wondering where your transponder is located. Is it in the former position of your GTX 33, or has it been moved "outboard", whatever that means?
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Re: WAAS upgrade woes

Post by mhoran »

Boatguy wrote: Wed Mar 09, 2022 4:21 am
mhoran wrote: Wed Mar 09, 2022 2:03 am I went out again tonight to fly in the pattern where I can generally reproduce the issue. As I was turning base on my second lap of the pattern, I got a momentary ADS-B fail and traffic fail alert. They immediately cleared themselves, but they alerted nonetheless.
The ability to reproduce the error at a specific location seems interesting. Is there something at the airport that could be causing the interference? VOR, ILS, DME or ??
Yeah I've been thinking this as well. I fly out of Linden, NJ which is basically an extension runway to Newark. There's tons of traffic and multiple ILS approaches at Newark. Last night (and in the nights when I experience the traffic fail issue regularly,) Newark is landing nearly overhead Linden. But reproduction isn't *super* reliable, and I still haven't gotten *just* a traffic fail that persists like before, only an ADS-B fail (which is honestly a bit more concerning since I fly regularly in rule airspace.)
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Re: WAAS upgrade woes

Post by Rich »

From way back in '02, the DA40s were delivered with RG400 to the GPS antennas, such that when converting to WAAS, the antennas are replaced but the coax need not be. No problems for me in 15 years since.

Matt, I'm a little confused by your installation. Apparently your ADS-B has been working fine using the 345 GPS function with its own antenna. But in this topic there was a mention of not getting "heading" (from the GIAxxx ???). Are you getting multiple GPS feeds to the 345? Methinks this would not be good.
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Re: WAAS upgrade woes

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Rich wrote: Wed Mar 09, 2022 4:36 pm Matt, I'm a little confused by your installation. Apparently your ADS-B has been working fine using the 345 GPS function with its own antenna. But in this topic there was a mention of not getting "heading" (from the GIAxxx ???). Are you getting multiple GPS feeds to the 345? Methinks this would not be good.
There was a suspicion that the traffic fail alert (separate from ADS-B fail, which I now get sometimes) was due to GTX-345 losing its heading input, or some delay therein. However, that was ruled out. The GTX-345 gets its heading nearly immediately on startup.

Also, only one GPS source is configured -- internal. No other GPS source can be used with my G1000 software version anyway.

It's unfortunate that the only way to get the status of the transponder is with a laptop with proprietary, Garmin dealer only software. If I could run it myself perhaps I could catch the issue in action. But I only ever have access to that software at Lancaster on the ground, and everything always works fine there.

At some point apparently the internal GPS was dropping out from my GTX-345, but after installing two notch filters, fixing the ground planes, and replacing my ELT, the transponder GPS seems fine. Then this ADS-B fail alert started showing up, in addition to the traffic fail which is where this all started.
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Re: WAAS upgrade woes

Post by dant »

Regarding the ethernet wiring replacement, ethernet cables in the IT world are somewhat notorious for failing randomly after a while and causing _very weird_ errors. I don't know how hard it is to do that replacement in a plane, but if it's low barrier I would do it.
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Re: WAAS upgrade woes

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dant wrote: Wed Mar 09, 2022 4:56 pm Regarding the ethernet wiring replacement, ethernet cables in the IT world are somewhat notorious for failing randomly after a while and causing _very weird_ errors. I don't know how hard it is to do that replacement in a plane, but if it's low barrier I would do it.
I'm definitely starting to suspect something in the wiring harness. We've re-seated all the LRUs a few times now, but not checked the wiring, so far as I know. That *shouldn't* have been touched as part of my upgrade or any other work, but who knows. They did have to touch it to run the GPS feed for my ELT, and the ADS-B fail started subsequent to that (though I had traffic fail prior) so that could be a good lead.

The only ethernet on the legacy G1000 is between the GDUs and the GDUs and the GIAs. Seeing as I'm generally not having any issues with that data path, I don't suspect the ethernet here. But there are also RS323, RS455 and ARINC 429 data paths as well that could be to blame.
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Re: WAAS upgrade woes

Post by Rich »

I've long been curious about the physical media used for the Ethernet in the G1000 stuff. Is it the common CAT5 w/RJ45 terminals? I'm old enough to remember Ethernet distributed via coax/BNC.
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Re: WAAS upgrade woes

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Rich wrote: Wed Mar 09, 2022 5:31 pm I've long been curious about the physical media used for the Ethernet in the G1000 stuff. Is it the common CAT5 w/RJ45 terminals? I'm old enough to remember Ethernet distributed via coax/BNC.
The G1000 maintenance manual suggests it's not standard category wire nor terminated with RJ45 connectors. I certainly haven't seen any CAT5 wiring running under my glare shield. I think it's just bare wires bundled with the rest, but maybe I'm wrong. The GIA shows ethernet pins on P603 pins 2, 3, 76 and 77. The GDUs, having to cross connect and also link with their corresponding GIAs, have more ethernet pins on P10001 (pins 2-13.)

Really getting into the weeds, Garmin says that the protocol is in fact not Ethernet, but a proprietary protocol called HSDB. However, the underlying signalling is 802.3, the same used for Ethernet.
The G1000 utilizes a proprietary communication protocol called HSDB (High‐Speed Data Bus) to provide
upper level communication capabilities, with point‐to‐point, full duplex channels capable of 10 Mbits/s
data rates. This protocol was designed to give the required integrity and functionality with minimal
additional overhead found in other more standard higher level Ethernet communication protocols and
provides guaranteed delivery of asynchronous packets through an acknowledge protocol. Additionally,
the HSDB communication protocol monitors the age of the communication data and contains routing
information that the receiving sub‐system utilizes to determine if the data needs to be passed along to
another sub‐system. The communication packets use an IEEE Standard 802.3 data link layer that utilizes
broadcast messages. In the G1000 system this protocol is utilized as follows:
* Exclusive communication path between GDUs, GIAs, GSDs, GWX, GTS, and GDL.
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Re: WAAS upgrade woes

Post by Charles K »

N5WU - 2 Lower Res b.jpg
Mine are the 020s and are quite recent having been pulled from a DA62 by my shop shortly before my upgrade as they were going to NXi and 64s.

Here is a photo of data label and of the rack (you can see 345R to left of GIA63W I - that is best photo I could find). You can see it is a -20 which is a newer version which has slightly better radio specs. 345R is still in same place and not on the outside (outboard) of the rack as far as I can tell.
mhoran wrote: Wed Mar 09, 2022 3:28 pm Which version of the GIA 63W do you have? I have the -20 model. Perhaps this is a wild goose chase, but the STC mentions relocating the GTX 33 transponder "outboard" of the equipment rack when the -20 GIA 63W is installed. Nobody seems to know why this is. Of course, I don't have the GTX 33, I now have the GTX 345 like you, but am wondering where your transponder is located. Is it in the former position of your GTX 33, or has it been moved "outboard", whatever that means?
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Re: WAAS upgrade woes

Post by Charles K »

Did they replace the lightning protection resistor array - they are at least supposed to do that was my understanding. The only way to do that is to splice the new one into the old wiring or replace the wiring. Since we were given a new wiring bundle with lightning protection resistor array - we decided why not replace the 17 year old wiring.
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