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RV8iator
03-14-2013, 12:59 PM
I have a question about ADSB indications that I thought I would toss out and see if anybody can give me the answer.

I just flew out to Abilene and back and went just south of the DFW Class B. On the way out I noticed I was getting all kinds of ADSB traffic indicated around the Class B but almost none inside the Class B. I was receiving anywhere from 4 to 11 ADSB towers with several actually showing up on the DFW airport.

http://farm9.staticflickr.com/8507/8558158298_3515080abb_b.jpg

Everyonce in a while I would then get all kinds of traffic inside the Class B. I have ADSB in and out and always received numerous targets around me so I know my equipment was working. Here's what DFW looked like for a while and then it would all just disappear. It has me baffled.

http://farm9.staticflickr.com/8525/8557049179_7b615f98f3_b.jpg

Does anybody have any ideas as to why it's there for a while and then it's not. It was not displaying for the majority of the time.

BobTurner
03-14-2013, 01:07 PM
This is a guess, I'm no expert. The system only sends you traffic that is near you. But you may be picking up traffic uploads intended for other aircraft. Once those other aircraft (only aircraft with ADS-B out count) move away then those distant traffic uploads stop, and you go back to only those near you.
What do the experts say?

Clarkie
03-14-2013, 01:22 PM
Thread creep.... Wouldn't it be cool if Wing XPro would turn the lettering around on the sectional when in track up mode?

RV8iator
03-14-2013, 01:34 PM
Thread creep.... Wouldn't it be cool if Wing XPro would turn the lettering around on the sectional when in track up mode?

UN-Thread Creep..

Any body have and ideas. Bob your answer kind of works, except I get traffic many miles from me routinely. Airliners or other high altitude stuff as well as low altitude, maybe a hundred miles away.

rocketbob
03-14-2013, 01:54 PM
I believe that they deliberately reduce the range in class-B to reduce the congestion on 1090Mhz.

RV8iator
03-14-2013, 02:31 PM
I believe that they deliberately reduce the range in class-B to reduce the congestion on 1090Mhz.

That may be but I was just on the south side of the B, not more than 35 miles south and still had virtually no traffic inside the rings.

Keep answering..

Thermos
03-14-2013, 02:46 PM
The ADS-B ground system is set up to only broadcast TIS-B and/or ADS-R tracks within a certain altitude and distance of aircraft that are transmitting ADS-B Out positions *and* are also capable of receiving ADS-B In.

So, you may be seeing traffic within that alt/distance of somebody else who's participating in the ADS-B system?

Dave

Radomir
03-14-2013, 03:57 PM
Receiver and/or display issues...

Dan B
03-14-2013, 04:52 PM
The DFW area and the central part of the country will be the last areas of ADS-B to be turned on. The flight inspection commissioning for this area is not scheduled until late 2013 or early 2014. The Houston area is commissioned and is providing service in southern Texas.

However, we will be seeing some functions, sometimes intermittently, of the ADS-B in this area as the system is being installed and tested prior to the actual commissioning.