VAF Forums

VAF Forums (https://vansairforce.net/community/index.php)
-   ADS-B (https://vansairforce.net/community/forumdisplay.php?f=113)
-   -   ADSB traffic Issues Freeflight Explorer (https://vansairforce.net/community/showthread.php?t=108069)

sailvi767 12-28-2013 03:09 PM

ADSB traffic Issues Freeflight Explorer
 
I thought I would post something interesting concerning a issue with ADSB traffic. We have been flying with a new panel. The basics are a AFS4500 with a Freeflight explorer ADSB box and a Trig22 transponder.
We have been getting traffic however it has always seemed very limited and only on a very rare occasion did we ever see a ADSB target. Most targets were TisB and even then we did not seem to be getting the complete picture. The Freeflight explorer is a 978UAT box and is far as I know not a dual band so no 1090 comm.
I decided to review all the setting in a attempt to improve performance. In checking to make sure that the Trig22 was properly configured and sending the 978 request signal I noted it was enabled properly. I also however noted that the 1090 mode was also enabled. I disabled the 1090 mode in the Trig setup simply because it was not needed. I did not expect it to have any bearing on the traffic issue. With no other changes made in any setup items I went up on a short flight to try and improve my wheel landings. I was very surprised to find that shortly after liftoff I had 11 ADSB targets! The entire flight I was seeing traffic like never before. Kind of scary actually. Lots of people out flying today.
I do not understand why disabling the 1090 mode in the transponder seems to have fixed the traffic issues and I would like to get a few more flights to confirm things but I saw more traffic on one flight today then I have seen on the last 20 flights before. Never have I had more then 1 ADSB target and normally none on a flight and today I always had at least one and up to 11. The only thought I have is that somehow having the 1090 mode enabled caused the TRIG to limit or not send the 978 requests. Perhaps because 1090 is considered a better mode.
If anyone is running a similar setup and feels they are not seeing as much traffic as the should check and make sure you have only the modes enabled in the transponder that your box is capable of. It seems to have made a huge difference in our aircraft.

George

Radomir 12-28-2013 03:30 PM

That setup (incorrect for your equipment) was telling the ground station that you have capability of receiving direct from other ADS-B equipped traffic, so ground station did not bother to re-broadcast (ADS-R). This was a small oversight, but the importance of proper setup of your IN capabilities (done in the Trig's setup menu) is often misunderstood. Ground station will not re-broadcast if you have capability to receive direct air-to-air.

sailvi767 12-28-2013 03:44 PM

Quote:

Originally Posted by Radomir (Post 838275)
That setup (incorrect for your equipment) was telling the ground station that you have capability of receiving direct from other ADS-B equipped traffic, so ground station did not bother to re-broadcast (ADS-R). This was a small oversight, but the importance of proper setup of your IN capabilities (done in the Trig's setup menu) is often misunderstood. Ground station will not re-broadcast if you have capability to receive direct air-to-air.

That makes sense and seems to explain things. Perhaps you can comment on one other thing that has me puzzled. Since we do not have 1090 cabability I did not expect to see airline targets with a callsign label attached. I was seeing labeled airline traffic on approach today. I assume the ADS-R you mention rebroadcasts the entire info tag with the traffic. Is that correct?

George

Brantel 12-28-2013 04:08 PM

Yes the ground station will rebroadcast 1090 aircraft on 978 as long as you tell it that you can only receive 978.

sailvi767 12-28-2013 04:34 PM

Ok, One last stupid question. 1090 has the Air to Air component so is somewhat independent of ground stations or radar when dealing with 1090 equipped aircraft. Does 978 have a air to air mode with other 978 targets or does it always rely on a rebroadcast? As we approach 2020 I expect most traffic below 18k will have 978 out capability.

George

Radomir 12-28-2013 05:44 PM

Yes, they all have air-to-air capability.. that's ultimately the goal.. and ground stations will only need to re-broadcast to ensure that you're "seeing" traffic that's broadcasting on the other frequency (and thus you're not receiving directly air-to-air)

PS.. Seeing the callsign/flight ID is normal.. it's part of the message.


All times are GMT -6. The time now is 09:08 AM.