Why Am I Not Waking Up Ground Stations?

[RV7ator]

See post #4 for updated information.

JS


At least I presume I'm not. The TIS-B uplink box is usually X-d out on the 795 or G370. When not, I think I'm piggybacking but no way to confirm. Equipment is 370+73/GTN650/795/GDL39/GTX23ES. 650 & 23 firmware are up-to-date. I still get wrapped around the axle with this NextGen complication, so a few questions and details that might help clarify the situation.

Depending on locale, I've been within range of multiple ground stations, but the box is X-d. In the middle of Wyoming I can believe there's no traffic in the service volume to report (or not filtered out on board), but the X comes and goes in all sorts of high density traffic areas occasionally containing airliners, and on different days/time in my home area (Boise). Is this because there's no TIS-B traffic to report?

But...FIS-B seems to be working fine. I see wx, notams, etc, and UAT traffic.

The GTX23 manual requires only 232 Out (I'm using port 4 configured ADS-B) from the 650, but I have wired the 232 In line, configured "Off". Does this really neuter the In line, or should I physically cut it mayhaps it's screwing the Out port?

I've requested an FAA ADS-B performance report, but it's Sunday, and nothing back yet.

So, am I waking up grounds stations or not, and if not, why?

John Siebold

[g3xpert]

Originally Posted by RV7ator

At least I presume I'm not. The TIS-B uplink box is usually X-d out on the 795 or G370. When not, I think I'm piggybacking but no way to confirm. Equipment is 370+73/GTN650/795/GDL39/GTX23ES. 650 & 23 firmware are up-to-date. I still get wrapped around the axle with this NextGen complication, so a few questions and details that might help clarify the situation.

Depending on locale, I've been within range of multiple ground stations, but the box is X-d. In the middle of Wyoming I can believe there's no traffic in the service volume to report (or not filtered out on board), but the X comes and goes in all sorts of high density traffic areas occasionally containing airliners, and on different days/time in my home area (Boise). Is this because there's no TIS-B traffic to report?

But...FIS-B seems to be working fine. I see wx, notams, etc, and UAT traffic.

The GTX23 manual requires only 232 Out (I'm using port 4 configured ADS-B) from the 650, but I have wired the 232 In line, configured "Off". Does this really neuter the In line, or should I physically cut it mayhaps it's screwing the Out port?

I've requested an FAA ADS-B performance report, but it's Sunday, and nothing back yet.

So, am I waking up grounds stations or not, and if not, why?

John Siebold

Hello John,

Page 20-10 (GSU25/GTX23ES) and 21-6 (GSU73/GTX23ES) of the Rev. M G3X Installation Manual provide installation and configuration guidance.

You are correct that the RS-232 port on your GTN650 provides ADS-B Out using 2 wires (Transmit and Ground). The GTN RS-232 port should be configured for ADS-B Out+.

RS-232 In 2 on your GTX23ES is automatically configured for ADS-B In by your G3X system.

This posting provides the minimum software required for what is referred to as Version 2 compliance (ready for 2020) and also provides the other settings like position integrity (1E-7) that must be used.

We are happy to review your installation wiring and configuration settings and help review your ADS-B report when you receive it. We have yet to find someone who couldn't get a clean report with the equipment you have.

With regard to receiving TIS-B uplink services, there are two ways that a GDL39 determines whether or not you are being provided these services by a ground station:

1. The ground stations uplink a list of ADS-B Out participating aircraft (identified by ICAO address) receiving TIS-B services each 10 seconds. Each time one of these lists is received by the GDL39 it searches the list for your aircraft address, and if found tells the display device that your aircraft is receiving TIS-B services so the TIS-B uplink icon can be enabled and shown to the pilot. If your address is not found in any TIS-B service list from any station for a given amount of time, the icon is turned off.
   
2. If the GDL39 detects your aircraft is operating within the TIS-B service volume of another aircraft reported to be receiving TIS-B services, you are shown to also be receiving those services due to your proximity to the participating aircraft.

As you probably know, you must both be identified as a participating aircraft transmitting ADS-B Out and be in radar contact to be provided TIS-B services by the ground stations.

We have also seen occasions when we were reportedly not receiving TIS-B services when perhaps we should have been, and are collecting and evaluating data to identify potential software improvements.

Thanks,
Steve

[RV7ator]

G'day, Steve,

Several points regarding your response (for which I thank you).

"ADS-B Out+" is not a 232 option on my 650. Best it gets is "ADS-B", which is exactly what the 23 manual (Rev A, 2011, which is current) directs. 650 system software is V4.02 IIRC. GTX has SB1240 incorporated.

I'm using Rev G of the G3X manual, appropriate for my vintage. I'm rather sure I selected "GTX23ES" on the xpdr configuration page, but I'll check later tomorrow.

TIS-B points: I have know way of knowing if the 39 finds my aircraft on a TIS-B list, Point 1; Point 2 is what I think is happening. I'm definitely in range of ground stations and radar.

Left unanswered is whether or not I should physically cut the 232 In line from the GTX to the GTN. I have configured "OFF", but maybe that's not good enough.

John

[RV7ator]

The GTN650 manual appropriate for the hardware vintage at the time of installation specified using "ADS-B" for the 232 connection to the GTX. Since then, "ADS-B+" is now used. Changing to this setting seems to get the ground station's attention. Yet the latest FAA performance report still shows data missing 3.46% of the time. And a flight today while I was switching off and on avionics in search of other gremlins, the box was X'd more than connected. Here's the flight path for the reported performance.

http://i61.tinypic.com/nwlo3q.gif[/IMG]

Pilots and ATC are in for mighty fun times if this is typical ADS-B performance.

John Siebold

[MarkW]

John,
Did you also double check the integrity setting in the G3x.
Here was my comment from my test.

I found that I had not set the GTN650 RS-232 to the proper setting. I had it off and it needed to be ADS-B +. I also had not noticed that the transponder set-up required changing so it was still on "GPS Position" " VFR" and I have now changed it to IE-7. I flew this morning and will check with big brother again Monday to see if it fixed it.

[Brantel]

Originally Posted by RV7ator

The GTN650 manual appropriate for the hardware vintage at the time of installation specified using "ADS-B" for the 232 connection to the GTX. Since then, "ADS-B+" is now used. Changing to this setting seems to get the ground station's attention. Yet the latest FAA performance report still shows data missing 3.46% of the time. And a flight today while I was switching off and on avionics in search of other gremlins, the box was X'd more than connected. Here's the flight path for the reported performance.

http://i61.tinypic.com/nwlo3q.gif[/IMG]

Pilots and ATC are in for mighty fun times if this is typical ADS-B performance.

John Siebold

John,

It is not typical of a properly installed and configured system. Keep working with TeamX and they will help you get it sorted. The manuals changes and firmware revisions have changed rapidly the past couple years but that is slowing down now.

I highly recommend you ensure everything is at the latest revision and to use the latest manuals.

Flew all the way to Osh and back from East Tn and got an updated performance report from the FAA after getting my xponder updated at Osh to the latest rev. The system worked very well and my performance report was flawless (as was my last report prior to the update). I have a G3X touch, GTX23ES and GTN650 with a GDL39 3D.

This should give you confidence that the package will work properly....

[Brantel]

Originally Posted by RV7ator

Left unanswered is whether or not I should physically cut the 232 In line from the GTX to the GTN. I have configured "OFF", but maybe that's not good enough.

John

Should not hurt anything to have it connected and have it set to OFF.

[g3xpert]

We have been working with John and he has done a great job getting his setup squared away.

He now has his position integrity set to 1E-7 on the GTX23ES configuration and the GTN serial port providing position data to the transponder is now set to ADS-B+, so his system is properly reporting SIL=3, and SDA=2 just like it should and as required by FAR 91.227.

John was maneuvering on this flight and the report indicates that there was missed output 3.5% of the time. John confirms that he had a wing low with the antenna pointed away from the ground station where the data was reported missing, so this doesn't seem like a concern to us that these data drop outs were recorded by the FAA during maneuvers like this.

What is perhaps a bit misleading is that the FAA report shows that a SIL of 3 is transmitted 96.5% of the time and a SIL of 0 transmitted 3.5% of the time. We believe this is a reporting anomaly and not actual data transmitted by this system. The report showed the same thing for SDA. A value of 2 reported 96.5% and a value of 0 reported 3.5%. Again, we don't believe it is correct that the system was ever sending out an SDA of 0, so the report is more than likely incorrectly showing red in some areas where the data is fine when transmitted, but missing during maneuvers.

Perhaps our friend Jim will help clarify. Again, we want to thank Jim for providing such a great service and making it easier to get these systems tuned up as needed.

Thanks,
Steve