VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #11  
Old 12-12-2016, 06:53 PM
dynonsupport's Avatar
dynonsupport dynonsupport is offline
 
Join Date: Jun 2005
Location: Woodinville, WA
Posts: 1,493
Default

Quote:
Originally Posted by g3xpert View Post
So, lots of words here to say that you "should" have been receiving TIS-B services as long as you were flying high enough on this 36 min. flight to be in radar contact. Was this the case? This is one of the protections in place to make sure there is little chance of someone spoofing the system. No radar contact, no TIS-B client services provided. You say that Madison was vectoring you for traffic, so it sure seems like you should have been in good radar contact, but since this might have been terminal radar approach control, I don't know if this satisfies the radar contact requirements for ADS-B TIS-B services.
Steve,
Lots of good information here! ADS-B seems like it should be 1/4 of ground school today.

It's my understanding that the reason TIS-B and ADS-R services are not provided to aircraft without radar contact is to prevent the pilot from thinking they have a complete traffic picture when they do not. If the ADS-B system can't see you on radar, then there's no reason to believe it can see the aircraft that is a threat to you either. So while they don't send out TIS-B and ADS-R, they also importantly don't send you the client status bits so your cockpit display can warn you of the incomplete picture so you don't rely on the traffic display too much.

Another bump we've run into at Dynon before- data links being down to ADS-B ground stations. There was one in Tucson that was down for 9 months because the link to the ground station was severed, but the tower was still "online," transmitting that it was fine. It just wasn't transmitting any FIS-B data or TIS-B, which of course meant that you were never a TIS-B client because it had no radar link to see you on. This caused all sorts of weird behavior.

All this to agree that there are external issues which can cause TIS-B service issues, which have nothing to do with your plane. Which is why it's important that your cockpit traffic display shows if you are a TIS-B/ADS-R client. On Dynon this is "ADS-B OK" and on the Garmins this is the radar icon being present.

--Ian
Dynon Avionics
__________________
_______________________
Dynon Avionics
support@dynonavionics.com
425-402-0433
www.DynonAvionics.com
Reply With Quote
  #12  
Old 12-13-2016, 09:32 AM
tsneidin tsneidin is offline
 
Join Date: Jul 2005
Posts: 107
Default Fixing SDA did not fix the issue

I did have GPS certification level set to Level D for all my previous flights. Last night I changed it to Level C (the proper value) and went flying.

Here is the ADS-B performance report for the flight.

https://drive.google.com/open?id=0B8...pFZ05OUFVUcHl3

It now shows the correct SDA=2 value and no errors but again I received no traffic and 696 and Garmin pilot did not display the correct symbols.
__________________
Todd Neidinger
RV-9 Flying
Reply With Quote
  #13  
Old 12-13-2016, 01:32 PM
g3xpert's Avatar
g3xpert g3xpert is offline
 
Join Date: Sep 2010
Location: Olathe, KS
Posts: 2,052
Post

Quote:
Originally Posted by tsneidin View Post
I did have GPS certification level set to Level D for all my previous flights. Last night I changed it to Level C (the proper value) and went flying.

Here is the ADS-B performance report for the flight.

https://drive.google.com/open?id=0B8...pFZ05OUFVUcHl3

It now shows the correct SDA=2 value and no errors but again I received no traffic and 696 and Garmin pilot did not display the correct symbols.
Hello Todd,

We didn't expect that changing the SDA to 2 would change anything since the current minimum required for TIS-B services is SDA=1, but good to know, so thanks for trying that.

You say that "696 and Garmin Pilot did not display the correct symbols". Not sure what that means, but since your report indicates you were a TIS-B client 0% of the flight, it would have been correct for the 696 to show that you were not receiving TIS-B uplink data on this flight.

You might contact our friend at the FAA, Jim M. and see if he can provide any additional information for this flight which might explain why the ground system was not providing you with TIS-B services. He may have access to this information.

Thanks,
Steve
__________________
Garmin G3X Support
g3xpert@garmin.com
1-866-854-8433 - 7 to 7 Central Time M to F
Please email us for support instead of using Private Messaging due to the limitations of the latter.
Reply With Quote
  #14  
Old 12-13-2016, 02:46 PM
Kentsrv7a's Avatar
Kentsrv7a Kentsrv7a is offline
 
Join Date: Dec 2005
Location: Yorktown, VA
Posts: 127
Default G3X Config Issue?

g3xpert Steve,
I have a newly installed G3X Touch, GTX-23ES and GDL-39R with a GTN 650. I recently flew a flight for the FAA ADS-B Rebate program and I failed the SDA and SIL 100% with values of 0.0. My report says I also was TIS-B Client 0%. I believe this is because I did not configure the G3X to enable the external GPS at power up. I assume then the failure was because it used the internal GPS to the GDU 460. I have not been receiving any ADS-B weather or traffic. If I understand this correctly I need to select the external GPS (GTN-650) in the configuration for startup and I should see weather and traffic services when in radar contact.
Thanks!
Kent
__________________
Kent Stitt
RV-7A
TMX-IO-360w/ P-Mags, Hartzell CS Prop, Slider,
Dual Garmin G3X Touch w/ GTN-650
Currently flying!

2018 Dues Paid!
Reply With Quote
  #15  
Old 12-13-2016, 03:17 PM
Brantel's Avatar
Brantel Brantel is offline
 
Join Date: Mar 2006
Location: Newport, TN
Posts: 7,005
Default

Quote:
Originally Posted by Kentsrv7a View Post
g3xpert Steve,
I have a newly installed G3X Touch, GTX-23ES and GDL-39R with a GTN 650. I recently flew a flight for the FAA ADS-B Rebate program and I failed the SDA and SIL 100% with values of 0.0. My report says I also was TIS-B Client 0%. I believe this is because I did not configure the G3X to enable the external GPS at power up. I assume then the failure was because it used the internal GPS to the GDU 460. I have not been receiving any ADS-B weather or traffic. If I understand this correctly I need to select the external GPS (GTN-650) in the configuration for startup and I should see weather and traffic services when in radar contact.
Thanks!
Kent
Steve should be along shortly but the bottom line is you will need to work with TeamX to get this ironed out. What you are describing is not normal and I am almost certain it does not relate to the navigation source selection option on power up. I recommend you email them ASAP to get the ball rolling on troubleshooting. g3xpert@garmin.com
__________________
Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Working on Emp/Tail Cone
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook
Reply With Quote
  #16  
Old 12-13-2016, 03:45 PM
g3xpert's Avatar
g3xpert g3xpert is offline
 
Join Date: Sep 2010
Location: Olathe, KS
Posts: 2,052
Post

Quote:
Originally Posted by Kentsrv7a View Post
g3xpert Steve,
I have a newly installed G3X Touch, GTX-23ES and GDL-39R with a GTN 650. I recently flew a flight for the FAA ADS-B Rebate program and I failed the SDA and SIL 100% with values of 0.0. My report says I also was TIS-B Client 0%. I believe this is because I did not configure the G3X to enable the external GPS at power up. I assume then the failure was because it used the internal GPS to the GDU 460. I have not been receiving any ADS-B weather or traffic. If I understand this correctly I need to select the external GPS (GTN-650) in the configuration for startup and I should see weather and traffic services when in radar contact.
Thanks!
Kent
Hi Kent,

No, you don't need to configure the G3X to select or enable the external GPS at power-up. As long as the GTN 650 is turned on and operating with a good GPS fix and the ADS-B+ RS-232 output is properly connected to pins 24,50 of the GTX 23ES (page 24-19 or Rev. AA G3X Installation Manual), the GTN will be providing GPS position to the transponder.

Additionally, please make sure that the Position Integrity field on the transponder configuration page is set to "1E-7" instead of "VFR" as shown on page 32-129 of the Rev. AA G3X Installation Manual. This would indeed cause what you describe to happen. While you are in there, make sure that ALL transponder configuration fields (such as airplane width) are filled in.

Let us know if you have additional questions.

Thanks,
Steve
__________________
Garmin G3X Support
g3xpert@garmin.com
1-866-854-8433 - 7 to 7 Central Time M to F
Please email us for support instead of using Private Messaging due to the limitations of the latter.
Reply With Quote
  #17  
Old 12-13-2016, 04:39 PM
jwyatt jwyatt is offline
 
Join Date: Feb 2006
Location: Goodhue, MN
Posts: 149
Default

Quote:
Originally Posted by g3xpert View Post
to quote the FAA service change document "In the FAA system, ADS-R client status is identical to TIS-B client status", so the posting above could have referred to "TIS-B/ADS-R client status" in every place it refers to TIS-B client status.

Good or bad, the U.S. is a dual frequency country with some ADS-B Out aircraft transmitting on 978 Mhz and some on 1090 Mhz, which makes it important to have a dual frequency ADS-B receiver.
Quote:
Originally Posted by dynonsupport View Post
ADS-B seems like it should be 1/4 of ground school today.

It's my understanding that the reason TIS-B and ADS-R services are not provided to aircraft without radar contact is to prevent the pilot from thinking they have a complete traffic picture when they do not. If the ADS-B system can't see you on radar, then there's no reason to believe it can see the aircraft that is a threat to you either.
I thought I had a pretty good handle on ADS-B and a couple different plans for equipment, but this was new info to me -- I'm certainly learning, thanks to you guys for sharing.

So for those of us who are regularly out of radar coverage due to terrain, altitude, or other factors, the dual-band receive is going to be an important thing if we want to have the most traffic assistance as possible. Ian, are there plans afoot to produce a dual-band Dynon/AFS receiver module to fill this gap? Unfortunately the new GTX boxes all omitted the legacy protocols that would allow traffic to feed older EFIS's; I even looked at adding a GDU370 just for mapping & traffic/weather, but the GTX won't feed those either (without the 39R).

Freeflight is rumored to have a dual-band unit in the works, but they did not respond to my request for additional information.
__________________
Joshua Wyatt | Goodhue, Minn.
RV-9A N627DW @ KRGK - Flying since 2012
rv9a.pacificrimsound.com
Reply With Quote
  #18  
Old 12-13-2016, 04:46 PM
BobTurner BobTurner is online now
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,354
Default

Quote:
Originally Posted by jwyatt View Post
So for those of us who are regularly out of radar coverage due to terrain, altitude, or other factors, the dual-band receive is going to be an important thing if we want to have the most traffic assistance as possible. Ian, are there plans afoot to produce a dual-band Dynon/AFS receiver module to fill this gap? Unfortunately the new GTX boxes all omitted the legacy protocols that would allow traffic to feed older EFIS's; I even looked at adding a GDU370 just for mapping & traffic/weather, but the GTX won't feed those either (without the 39R).

Freeflight is rumored to have a dual-band unit in the works, but they did not respond to my request for additional information.
I bought a factory overhauled SkyRadar D2 for $500. Dual band. Feeds GRT HX via USB, iPad (WingX) via WiFi. Works great using internal antennas on the fiberglass doorposts of the -10.
Reply With Quote
  #19  
Old 05-14-2018, 06:59 AM
snopercod's Avatar
snopercod snopercod is offline
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 1,388
Default

May I revive this old thread? I just installed a Garmin GDL-82 and it seems to be working as advertised, but my "TIS-B Client Percentage" has been in the 20% to 50% range. On my latest flight, I was out of radar contact for a few minutes, so that probably explains it. (I thought the whole idea of ADS-B was that you no longer needed ground-based radar, but that doesn't seem to be the case.) In my area, there is only a single low-powered ground station, surrounded by mountains, so that is probably another factor. Steve's explanation (above) was very helpful in understanding how the system works, but I still have some questions: Is my GDL-82 transmitting to the radar facility, a ground station, other UAT-equipped aircraft, or all of the above? Steve wrote earlier that "the ground stations send out a list of ICAO addresses that are receiving TIS-B client services every 20 seconds". How does an aircraft get on that list? When I'm taxiing for takeoff at KAVL, I seem to be receiving traffic from somewhere, although I'm out of range of the nearest ground station. Does ATC radar at KAVL put me on "the list", or do I have to wait until I'm airborne and in range of the ground station? If my transponder antenna was weak or poorly placed, could that cause a low Client percentage? Speaking of transponder antennas, mine was cut for the original 1090 MHz output of my Garmin GTX-327. Should I have replaced it with a 978 MHz antenna which is around 10% longer?
__________________
(2018 dues paid)

Last edited by snopercod : 05-14-2018 at 10:41 AM. Reason: shorter=longer doh!
Reply With Quote
  #20  
Old 05-14-2018, 01:15 PM
snopercod's Avatar
snopercod snopercod is offline
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 1,388
Default more information

I'll have to try this next time I'm up. From the Foreflight website:
Quote:

When you tap on a traffic target while using a Stratus ADS-B receiver, you will get an information pop-up. In the description, you may see the frequency band used (978 or 1090ES) followed by "ADS-B", "ADS-R", or "TIS-B".

When "ADS-B" is shown in the description it indicates that the information was obtained via Air-to-Air broadcast, which is a direct broadcast from an ADS-B Out-equipped aircraft.

When “ADS-R” is shown in the description, it indicates that the ground station re-broadcast the ADS-B message it received on the other ADS-B frequency. This is a service provided to client aircraft that indicate they do not have a dual frequency receiver.

When "TIS-B" is shown in the description it indicates that the information was obtained via broadcast from a ground station. Ground stations provide the TISB service for ADS-B Out-equipped client aircraft. The TISB target is not ADS-B Out-equipped and is detected by a secondary radar system. All TISB targets must have an operating mode C transponder.
__________________
(2018 dues paid)
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 01:33 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.