Stratus/1090ES question

ahkahn

ahkahn

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So, just got the plane out of my small-intended avionics upgrade. Today was my first test ride. Had an interesting observation that I would love to learn more about, and can't find much in the forums as far as answers go.

- Upgraded my GTX-330 to ES for 1090 out.
- Use Stratus 1 with ForeFlight.
- Reconfigured the GTX-330ES for 978-in only capability as per John Collins' recommendations which seemed to help... but not positive at this point if that made a big difference from the VFR ride back from the shop. Today was a hard IFR day here so there was very little traffic displayed.

So I noticed for most of the ride that it would not detect my ADS-B ownship. But, there were a couple of points where it did. At one point it was pulling my ownship and displayed all of the data, etc for around 15 minutes.

I believe I've seen where the Stratus 1 and 330ES will not detect ownship in ForeFlight. How did this happen? What can I do to make it happen more?

Thanks!
Andrew
 
Be sure your SIL ("signal integrity" on the 330ES is set to 10E-7). Did you get test results back from the FAA email address?
 
So I requested the FAA test last night at 11:41pm. I received the report this morning at 6:10am. Fastest gov't work I've ever seen. They said all looked good!

So if my research is correct, to get a complete traffic picture you need the following:

ADS-R (ground based tower up) shows Mode C/Non-ADS-B traffic only. This is being broadcast through 978UAT band and picked up by Stratus 1.
ADS-B (978 UAT out from other equipped planes) is being picked up by Stratus 1.
ADS-B (1090ES out from other equipped planes) is NOT being picked up from Stratus 1, so I am missing out on that traffic.

Mode S traffic on my 430W and Aspen did not usually match up with the ADS-B in in ForeFlight.

If all of that is the case, why did I see my ownship detected? Was it being rebroadcasted by another plane on the UAT band?

John Collins, you're the resident guru on this stuff. Am I understanding all of this correctly?
 
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I can't wait to have these kinds of problems...I'm still flying in the Stone Ages though :/
 
Your avionics shop should have set the 330ES to indicate you have 978 in. When the ground stations see that, assuming you are in range of a tower, they will re-broadcast 1090 traffic on 978 for you so you can see the traffic. They should also broadcast all mode C/S traffic on 978 so you can see that as well.

As long as you are in range of a tower, you should be seeing all traffic that ATC sees.
 
BGF_Yankee said:
I can't wait to have these kinds of problems...I'm still flying in the Stone Ages though :/
Click to expand...

Maybe so, but your plane is still a very nice plane! The 3 digit tail number is pretty cool, if you ask me.
 
dans2992 said:
Your avionics shop should have set the 330ES to indicate you have 978 in. When the ground stations see that, assuming you are in range of a tower, they will re-broadcast 1090 traffic on 978 for you so you can see the traffic. They should also broadcast all mode C/S traffic on 978 so you can see that as well.

As long as you are in range of a tower, you should be seeing all traffic that ATC sees.
Click to expand...

So you're saying that I'll see everything ATC sees, but it won't detect my own ship? It's a bummer that ForeFlight won't do traffic callouts without own ship detected.
 
ahkahn said:
So you're saying that I'll see everything ATC sees, but it won't detect my own ship? It's a bummer that ForeFlight won't do traffic callouts without own ship detected.
Click to expand...


Since you only have a single frequency stratus, you need to be within range of an ADSB tower that will rebroadcast your 1090 onto 978 so the stratus will see it. Once your stratus sees "ownship" you should be seeing everything ATC sees. (Well, not primary targets, but everything else).

Dan
 
dans2992 said:
Since you only have a single frequency stratus, you need to be within range of an ADSB tower that will rebroadcast your 1090 onto 978 so the stratus will see it. Once your stratus sees "ownship" you should be seeing everything ATC sees. (Well, not primary targets, but everything else).

Dan
Click to expand...

Well that was my original question. It is only seeing the own ship some of the time. 20% maybe? The 330ES is configured for UAT in only. I got the test results from the FAA and all is set up properly. I will say though, after reconfiguring for UAT in only, I have yet to see Mode S (TIS) traffic that I don't pick up on the ADS-B also.

So with UAT only and a Stratus, will it pick everything up EXCEPT for my own ship?
 
Were you receiving ADSB towers for your entire flight? Did it correctly identify your tail # as ownship, or was it picking up others?
 
dans2992 said:
Were you receiving ADSB towers for your entire flight? Did it correctly identify your tail # as ownship, or was it picking up others?
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Yes, consistently 5-8 towers. No, it would only identify my tail # as ownship about 10-20% of the time. Mostly, not detected. Will a GBT rebroadcast my 1090ES location over ADS-R on the UAT band? Or, is it just other planes it rebroadcasts? Is it possible that another plane was rebroadcasting my 1090ES location on the UAT band and that is how ForeFlight was picking up the ownship when it was actually picking it up?
 
ahkahn said:
So I requested the FAA test last night at 11:41pm. I received the report this morning at 6:10am. Fastest gov't work I've ever seen. They said all looked good!

So if my research is correct, to get a complete traffic picture you need the following:

ADS-R (ground based tower up) shows Mode C/Non-ADS-B traffic only. This is being broadcast through 978UAT band and picked up by Stratus 1.
Click to expand...

This is not accurate. ADS-R does not show non compliant Mode A/C traffic. You are describing TISB which does this. Change the ADS-R to TISB and your understanding is correct. Since you are a valid client, a TISB is not generated for your own ship.

ADS-B (978 UAT out from other equipped planes) is being picked up by Stratus 1.
Click to expand...

Correct.

ADS-B (1090ES out from other equipped planes) is NOT being picked up from Stratus 1, so I am missing out on that traffic.
Click to expand...

This is where ADS-R kicks in. The R is for Rebroadcast. You setup your 1090ES Out to indicate that you only receive on UAT. The ground station uses that information to send a re-broadcast ADS-R of all 1090ES targets in your vicinity (radius 15 NM and +/- 5000 feet) on the UAT frequency so you can see these guys as well. The ground station does not generate an ADS-R for your own ship as you are a client and don't need your own position. The ADS-R services only applies to other aircraft who you can't see on 1090ES.

Mode S traffic on my 430W and Aspen did not usually match up with the ADS-B in in ForeFlight.
Click to expand...

This is possible for a variety of reasons. TISB does not broadcast targets that only are squawking mode A. They will show up on your mode S TIS as targets without a relative altitude.

If all of that is the case, why did I see my ownship detected? Was it being rebroadcasted by another plane on the UAT band?
Click to expand...

Not exactly, but if you were in the vicinity of another aircraft that was similarly equipped, your 1090ES ADS-B position reports would be re-broadcast on UAT for the other aircraft. Both aircraft will receive the ADS-R. There is no need for the ground station to re-broadcast a client's position for its own ADS-R nor will a client generate a TISB. So for a period of time while the ground station was generating an ADS-R for your aircraft, own ship data would have been available to be detected and displayed. Normally, I would recommend a Stratus 2 for someone who has 1090ES because with a Stratus 1, you can't receive your own broadcasts.

Sell your Stratus 1 and buy a Stratus 2. The Stratus 1 will work with your installation, but since you won't normally be able to detect own ship, you won't get the audio alerts for traffic and you won't be able to see what your system is broadcasting.
 
Ah ha! Mystery solved. That makes sense! So someone else around me was similarly equipped and I was picking myself up through ADS-R meant for someone else.

Thank you, John, for your explanations. You really make avionics understandable. PoA (and Beechtalk) are very lucky groups to have you as a resource. Thank you for all you do!
 
If you have something dual-band, that will fix your issue...
 
ahkahn said:
Yep, I plan to. Right now I am waiting until Osh Kosh to see if a Stratus 3 is announced.
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Apart from bringing down the price of the Stratus 2, what could a Stratus 3 really offer?
 
rocketflyer84 said:
Apart from bringing down the price of the Stratus 2, what could a Stratus 3 really offer?
Click to expand...

I have no idea, but if you look closely, the Stratus 1 has been quietly removed from both Appareo and Sporty's website.

The only things I can think of would be extended battery life, better AHRS, and more sensors. Oxygen sensor? Pressure Altimeter? CO sensor?

-Andrew
 
I almost pulled the trigger for a Stratus 2 but noticed the 1 wasn't around. I thought they may have a newer model coming out and as soon as I bought one it would drop in price.
 
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