GPS redundancy for SV-261?

[cbennet12]

The SV installation manual references that if you have a Dynon GPS 2020 that you do not NEED to have a direct GPS feed to pin 3 on the transponder. (My current config) It does not address the question (I believe) of redundancy.

So in the unlikely case that the SkyView HDX1100 went dark but there was still power, will the transponder operate and could it have a GTN (planned upgrade) on pin 3 providing position information?

If the above is “yes” would you need to have the serial out on the GTN off until needed or would the transponder default to one or the other source if it was receiving both?

Thanks!
Craig

 

[jakej]

I know of an installation just like that - SV 2020 for ADSB out & a wire from the Gps to the Txpdr 261 ready to connect if wanted/needed.
IF the HDX screen went black but you still have power then the Txpdr will work & be controllable from #2 HDX or if only a single SV fitted then the Txpdr will continue to work in the last configuration before the screen went out, IMO highly unlikely.

 

[cbennet12]

Hey Jake

So am I reading this correctly? The installation you’re referencing has “other” GPS always wired to pin 3 or is it switchable in the event of loss of Dynon provided positioning?

DYNON: any input from the experts?

 

[Raymo]

Having configured both types of GPS sources, if your Garmin source were enabled via switch, you would also need to change the source within Skyview.

My system has the old GPS-250 as backup, which is wired in parallel for redundancy. This configuration does not require switching (I don't think) or reconfiguration.

 

[Dynon]

So you wouldn't need to externally switch (I don't think - this is a corner case and not the envisioned usage), but you would need to reconfigure the transponder settings to switch over to the direct transponder GPS connection. Remember that this only affects ADS-B Out compliance and not any other aspect of system performance (IE, is it worth the additional complexity in the wiring, configuration, and procedures)

 

[swatson999]

So you wouldn't need to externally switch (I don't think - this is a corner case and not the envisioned usage), but you would need to reconfigure the transponder settings to switch over to the direct transponder GPS connection. Remember that this only affects ADS-B Out compliance and not any other aspect of system performance (IE, is it worth the additional complexity in the wiring, configuration, and procedures)

And how would you do that if the SV were OTS? Does the XPDR have an automatic switch-over mode available? If not, seems there isn't anything you can do if the EFIS goes dark, since that's your interface to the XPDR...

 

[cbennet12]

So you wouldn't need to externally switch (I don't think - this is a corner case and not the envisioned usage), but you would need to reconfigure the transponder settings to switch over to the direct transponder GPS connection. Remember that this only affects ADS-B Out compliance and not any other aspect of system performance (IE, is it worth the additional complexity in the wiring, configuration, and procedures)

And how would you do that if the SV were OTS?  Does the XPDR have an automatic switch-over mode available?  If not, seems there isn't anything you can do if the EFIS goes dark, since that's your interface to the XPDR...

That was my take as well Steve - you lose your only SV display, you lose GPS position updates to the transponder.

It’s not a safety of flight type failure but I have a lot of serial ports on the GTN and I would like to use some of them wherever it adds value.

Craig

 

[Raymo]

Why not configure the GTN as your primary source and have the GPS-2020 as backup. If the GTN fails, you can configure the 2020 in the EFIS. If the EFIS fails, you still have your position source.

 

[swatson999]

So you wouldn't need to externally switch (I don't think - this is a corner case and not the envisioned usage), but you would need to reconfigure the transponder settings to switch over to the direct transponder GPS connection. Remember that this only affects ADS-B Out compliance and not any other aspect of system performance (IE, is it worth the additional complexity in the wiring, configuration, and procedures)

And how would you do that if the SV were OTS?  Does the XPDR have an automatic switch-over mode available?  If not, seems there isn't anything you can do if the EFIS goes dark, since that's your interface to the XPDR...

That was my take as well Steve - you lose your only SV display, you lose GPS position updates to the transponder.

It’s not a safety of flight type failure but I have a lot of serial ports on the GTN and I would like to use some of them wherever it adds value. 

Craig

Well, you can't have two devices sending serial data at the same time on the same line into the XPDR, so you have to select one or the other, and the XPDR has to be configured correctly to receive the data (format, baud rate, etc.).

So how would you do that under your proposal?

 

[Raymo]

The installation manual shows that your GTN would connect to pin 3 (RX) of the transponder, while pins 5 (RX) and 7 (TX) would connect to your EFIS(s).

If, when Skyview is configured to use an external GPS source, it does not send data to the transponder, it would work as proposed.

Dynon would need to answer the IF part.

 

[Dynon]

So the transponder's listening behavior entirely depends on the software setting. So you could do this. You would need to reconfigure that setting, though, which is something you should really do in between flights.