GPS source from Garmin Transponder

[jaredyates]

I'm planning on a Skyview retrofit on a panel that already has a Garmin gtx335. The transponder has its own waas GPS source, and has serial outputs of that position data. Can I tie that serial GPS output from the transponder to a serial input on the Skyview system, and skip needing to use a Dynon GPS?

 

[Rhino]

Basic ADS-B question re: Skyview

Regarding the discussion of the dual-band 472, I might be working with incorrect information. My understanding is that with ADS-B Out and the 1090ES transponders, traffic information is relayed directly between like equipped aircraft. I'm equipped with the SV-XPNDR-261 (and the ADSB-470 box for...

forum.flydynon.com

Not sure if that answers your question, but the formats are compatible.

 

[Carl_Froehlich]

Perhaps, but a cleaner way to do this is to sell the GTX355 and use the very nice SkyView remote mounted XPDR along with the SkyView ADS-b receiver and Dynon 2020 GPS antenna/receiver. Now you have full integrated ADS-b in and out, TIS and XPDR. Perhaps you can do all this and even make a buck or two after you sell the GTX355.

Carl

 

[jaredyates]

Perhaps, but a cleaner way to do this is to sell the GTX355 and use the very nice SkyView remote mounted XPDR along with the SkyView ADS-b receiver and Dynon 2020 GPS antenna/receiver. Now you have full integrated ADS-b in and out, TIS and XPDR. Perhaps you can do all this and even make a buck or two after you sell the GTX355.

Carl

I appreciate the thinking outside of the box, but the Dynon transponder is $2230, and the Dynon 2020 gps is $650, so that's $2880 just to approach the level of the function that the Garmin already has. I paid $3000 for the Garmin with all of its accessories, and it is already installed, working, and checked. I doubt I could sell it for enough to pay for the Dynon parts, plus it would add a week or a month or so to the installation, and also require an additional visit with the avionics tech for $200-400.

 

[jaredyates]

Basic ADS-B question re: Skyview

Regarding the discussion of the dual-band 472, I might be working with incorrect information. My understanding is that with ADS-B Out and the 1090ES transponders, traffic information is relayed directly between like equipped aircraft. I'm equipped with the SV-XPNDR-261 (and the ADSB-470 box for...

forum.flydynon.com

Not sure if that answers your question, but the formats are compatible.

Thank you for the lead, I'll read that one and see if I can find any other experiences.

 

[Carl_Froehlich]

SNIP…..I doubt I could sell it for enough to pay for the Dynon parts, plus it would add a week or a month or so to the installation, and also require an additional visit with the avionics tech for $200-400.

You will break even and have a better install. On top of that, visits from any “avionics tech” are not required or desired. The SkyView install is about as plug and play as it gets.

Once you cut such ties to avionic shops you get control over your airplane - and in the process gain in depth system knowledge that will pay dividends over the years.

Carl

 

[jaredyates]

How do you comply with 91.413 without an avionics shop?

 

[Rhino]

You posted this in the experimental/light sport forums. Is this not an experimental aircraft? You don't need a Part 91 shop to install your own systems in an experimental aircraft. 91.413 only applies to transponder tests and biennial inspections anyway, not installs.

 

[jaredyates]

You posted this in the experimental/light sport forums. Is this not an experimental aircraft? You don't need a Part 91 shop to install your own systems in an experimental aircraft. 91.413 only applies to transponder tests and biennial inspections anyway, not installs.

I do all of my own installs but is it your understanding that a homebuilt doesn't need a transponder check?

 

[Albee]

91.413 applies and you have to get that done before flying any new transponder installation. To get back to your original post, it sounds like you're really asking if you can use your GTX355 serial GPS data instead of an SV-GPS-2020 or SV-GPS-250, so the Dynon knows where it is. I believe the answer is no.

Since you already have an installed ADSB-out setup you seem to be happy with, all you must have to make Skyview happy is an SV-GPS-250. You won't need to pay anyone to certify that, and the installation is simple. The -472 ADSB-in will work. One can hope the GPS-2020 provides better data for the additional $400, but other than supporting ADSB-out, it's not required. If there was an advantage other than compliance, seems like Dynon would say so on their product description and they don't.

I'm still using my pre-Dynon GTX-327 and GDL-82 for ADSB-out compliance. I couldn't see any reason to rip out perfectly functional equipment when I didn't need the panel space. If one of those fails, then I'll consider Dynon's solution as an alternative to repair.

 

[Rhino]

I do all of my own installs but is it your understanding that a homebuilt doesn't need a transponder check?

No. I was addressing the install, not the inspection. What Carl suggested does not require an avionics shop for the install, and I think that was where he was suggesting a cost savings, not a savings on the inspection after the install is done. You didn't originally specify you were doing the install, so I made that comment based on the assumption a shop was doing the install instead, and apparently Carl thought the same. 94.411 and 94.413 require an inspection every two years or after any install or maintenance "where data correspondence error could be introduced". That includes changes to the pitot/static system (for IFR anyway). Any actual new TSO'd box by itself (the transponder) does not require a new inspection because it's considered inspected upon manufacture. It's the overall system that needs inspection. Since your system has an internal WAAS source, no such data correspondence error should be introduced by what you propose, so I suppose you could consider that a grey area. I'm not advising you to skip an inspection though. I'd personally get one anyway, whether I felt a data error could have been introduced or not.

 

[jaredyates]

Carl is saying that I can save money or break even by removing an existing transponder to install a dynon transponder, which is true by magical math that only he knows. The new installation would require an inspection that I can't do, with an explicit cost alone of $200-400 not counting the other related costs. Contrary to his assurances, I don't see how it is possible to sell a used transponder for a 7% discount from what someone can buy a brand new one for. His math also seems to be based on the non-trivial removal and installation, which has a considerable cost even if I am the one doing the work. I think he was trying to help which I appreciate, but he is not correct, though oddly we continue to talk about that, which is what forums are all about I guess?

Getting back to the question at hand or to phrase it another way, does the Skyview accept position data input through any external source other than a 429 module or a Dynon GPS? Is there any information about what formats are acceptable to the Skyview?

 

[Rhino]

You should be able to.

SV 1000 operation with no XPNDR-261 installed

I all ready have a garmin GTX 335 with it's own GPS source .... it's independent and works great, 2020 compliant...I don't want to remove it Adding New SV1000 / ahrs-200, with GPS-2020 or GPS 250 and ADSB-470, Maps will I see traffic and weather on the SV1000? do I loose anything without...

forum.flydynon.com

Garmin GTX 335 compatibility

Woundering if the Garmin GTX 335 ads-b out transponder is compatable with skyview. Currently running Skyview, Dynon ADS-B in and a Garmin 327. Thoughts? Thanks

forum.flydynon.com

 

[jakej]

Hope this helps -
Position source for ADSB purposes can be
1 . Via SV Port 5 using the SV2020 antenna & SV-261 Txpdr.
2. External GPS using an RS232 output of ADSB + (different to ‘std’ GPS signal) or similar, direct to pin 3 of a SV-261 (aka Trig) Transponder.
3. Or use a totally separate external - but why do that as the Dynon system is simpler, much more cost effective & easier to set up, weighs a
lot less & you get 3 years warranty - what I’d cal a ‘no brainer’.
btw - the ADSB needed position source never goes through the 429 module.
Ps -“does the Skyview accept position data input through any external source other than a 429 module or a Dynon GPS?”
yes - you can connect it to another available SV port & use it as a selectable HSI ‘source’ input’ - if I’m interpretations your question correctly.

 

[Carl_Froehlich]

Carl is saying that I can save money or break even by removing an existing transponder to install a dynon transponder, which is true by magical math that only he knows. The new installation would require an inspection that I can't do, with an explicit cost alone of $200-400 not counting the other related costs. Contrary to his assurances, I don't see how it is possible to sell a used transponder for a 7% discount from what someone can buy a brand new one for. His math also seems to be based on the non-trivial removal and installation, which has a considerable cost even if I am the one doing the work. I think he was trying to help which I appreciate, but he is not correct, though oddly we continue to talk about that, which is what forums are all about I guess?

Getting back to the question at hand or to phrase it another way, does the Skyview accept position data input through any external source other than a 429 module or a Dynon GPS? Is there any information about what formats are acceptable to the Skyview?

So shoot fire - I may have been off on my cost assumptions - a little.

I suggest however you do not discount the ease of use of the final install. If you really must keep unnecessary Garmin stuff on your panel than proceed as desired. SkyView will take take this GPS input just fine.

Regardless of keeping your Garmin XPDR or shifting to the Dynon XPDR, the cost for the biannual XPDR check is the same. Side note - I still get irritated that this is the one thing I have to have an external shop do on my planes. I verify the pitot/static system has no leaks (I’m cheaper than some kid at the shop fixing leaks), fly the plane over to the shop then 45 minutes and $225 later I’m done for another two years.

BTW, have you figured out how to display the XPDR TIS data and your ADS-b in on the very nice SkyView display?

Carl

 

[HR2PLT]

I'm planning on a Skyview retrofit on a panel that already has a Garmin gtx335. The transponder has its own waas GPS source, and has serial outputs of that position data. Can I tie that serial GPS output from the transponder to a serial input on the Skyview system, and skip needing to use a Dynon GPS?

Jared,

The simple answer is “YES” you should, but I never tried it.

Since the GTX should have the GPS source for ADS-B out, you will need to get a GPS position for the SkyView. The easiest is just find a used GPS-250 for around $75 and install it on port 5 per SkyView’s install manual, and be done with it. You don’t need the GPS-2020 as you already have that in the GTX335. If you don’t want to go that route, below should get you in the right direction.

Connect one of the GTX335 RS232 TX outputs to SkyView serial port 5 RX, and set the GTX335 RS232 TX output to ADS-B+ FMT 2, and the SkyView serial port 5 to GPS-250. The GPS-250 baud rate is 38,400, and the GPS-2020 is like 115,200, so that won’t work as the max baud rate for the GTX335 is 38,400. So you need to set the GTX335 to ADS-B+ FMT 2 which will give you the output baud rate of 38,400.

That should work, in theory anyway.

Good luck, and if it doesn’t, then I have a few GPS-250 laying around, and would let one go for $75 plus shipping. You can email me at hr2plt@yahoo.com if needed.

Brian

 

[jaredyates]

Jared,

The simple answer is “YES” you should, but I never tried it.

Since the GTX should have the GPS source for ADS-B out, you will need to get a GPS position for the SkyView. The easiest is just find a used GPS-250 for around $75 and install it on port 5 per SkyView’s install manual, and be done with it. You don’t need the GPS-2020 as you already have that in the GTX335. If you don’t want to go that route, below should get you in the right direction.

Connect one of the GTX335 RS232 TX outputs to SkyView serial port 5 RX, and set the GTX335 RS232 TX output to ADS-B+ FMT 2, and the SkyView serial port 5 to GPS-250. The GPS-250 baud rate is 38,400, and the GPS-2020 is like 115,200, so that won’t work as the max baud rate for the GTX335 is 38,400. So you need to set the GTX335 to ADS-B+ FMT 2 which will give you the output baud rate of 38,400.

That should work, in theory anyway.

Good luck, and if it doesn’t, then I have a few GPS-250 laying around, and would let one go for $75 plus shipping. You can email me at hr2plt@yahoo.com if needed.

Brian

Thank you, this is very helpful. I'll proceed with this possibility and the backup plan is to install a gps-250 but it seems so silly to add more holes and hardware to the plane, just to feed a less-good GPS signal to the Dynon, when there is already a better signal sitting a few inches away in the Garmin.

 

[HR2PLT]

Thank you, this is very helpful. I'll proceed with this possibility and the backup plan is to install a gps-250 but it seems so silly to add more holes and hardware to the plane, just to feed a less-good GPS signal to the Dynon, when there is already a better signal sitting a few inches away in the Garmin.

Jared,

Let me know if that works.

Brian

 

[Carl_Froehlich]

Thank you, this is very helpful. I'll proceed with this possibility and the backup plan is to install a gps-250 but it seems so silly to add more holes and hardware to the plane, just to feed a less-good GPS signal to the Dynon, when there is already a better signal sitting a few inches away in the Garmin.

For non IFR or ADS-b out I think you will find the GPS-250 to lockup faster than any WAAS GPS system. It might only be accurate to a 3’ radius or so but for navigation it is just fine. I run a 250 in my RV-8 as the primary HDX GPS source. The horrible GTN-650 provides ADS-b GPS out data to the SkyView XPDR and to the Dynon ARINC for IFR work.

I also suggest that having this second GPS capability for so little cost is a very good value.

Carl

 

[HR2PLT]

Connect one of the GTX335 RS232 TX outputs to SkyView serial port 5 RX, and set the GTX335 RS232 TX output to ADS-B+ FMT 2, and the SkyView serial port 5 to GPS-250. The GPS-250 baud rate is 38,400, and the GPS-2020 is like 115,200, so that won’t work as the max baud rate for the GTX335 is 38,400. So you need to set the GTX335 to ADS-B+ FMT 2 which will give you the output baud rate of 38,400.

Jared,

If that didn’t work, you can try this SkyView setting. Set the SkyView settings for serial port 5, to POS 1, and the input device to NMEA basic, and the baud rate to 38,400.

See if that works. The ADS-B GPS string might not be correct, and then nothing from the 355 will work. If it had a aviation format, that should work, but the manual doesn’t show that format output.

If you just don’t want to drill more holes in you skin, the GPS250 is pretty sensitive, you can mount it on the dash, and some mount it under the engine cowling, with good results, but Dynon doesn’t recommend it due to the heat. You could mount it in the wingtip so it won’t show. A lot of places available, to avoid more holes.

Brian