What are they?

[kma371]

That would be done on 978 MHz (UAT) band, also known as ADS-R. I know of no ADS-B software for a home user that can receive and decode that data packets on that band. I would love to have a link to one if available! There are some 'ADS-B IN' receivers available for airborne use, that would have TIS-B, but they are pricey and the software does not work with SDR type radios that home users and Hobby listeners use.

1090 Mode S has 24 bit identifiers but does not send position information. Only 1090 Mode ES and 978 (UAT) ADS-B systems send position information.

yes they are done on 978, but retransmitted on 1090. trust me I receive them all the time.

TIS-B is broadcast to aircraft using both the 1090 MHz extended squitter (1090 ES) and the universal access transceiver (UAT) band of automatic dependent surveillance-broadcast (ADS-B).

 

[ki5gf]

That would be done on 978 MHz (UAT) band, also known as ADS-R. I know of no ADS-B software for a home user that can receive and decode that data packets on that band. I would love to have a link to one if available! There are some 'ADS-B IN' receivers available for airborne use, that would have TIS-B, but they are pricey and the software does not work with SDR type radios that home users and Hobby listeners use.

1090 Mode S has 24 bit identifiers but does not send position information. Only 1090 Mode ES and 978 (UAT) ADS-B systems send position information.

Steve,
I don't know who or what is doing it but someone or something just dumped 13 one line ADS-B type spots
in 2 minutes (1859Z to 1902Z). My receiver copied them and RTL1090 decoded them. The spots all had
positional data and all used 288xxx ICAO numbers. All 13 were dumped in one continuous string. That's been going on since 1149Z this morning and had some last night and some the day before too. Quite a few in total. So I'm lost AGAIN (so what else is new).

 

[kma371]

nothing to be lost about. it's the ground station transmitting them all at once. nothing unusual.

 

[freqhopping]

I used to receive mode-S ground transmissions from KIAD. But all were in the ADFXXX range. Altitudes and squawks would constantly change but they never broadcasted location.

 

[mmcgee]

What you are seeing are indeed TIS-B retransmissions. Attached is a spreadsheet I found showing the hex codes allocated to various areas (in the case of 288xxx Houston Center).

 

[ki5gf]

What you are seeing are indeed TIS-B retransmissions. Attached is a spreadsheet I found showing the hex codes allocated to various areas (in the case of 288xxx Houston Center).

Thanks, McGee
Useful data. That answers the big question for sure. I guess you'd need to be fairly close to a broadcasting ground station in order to receive that 1090mhz signal at another ground location.

 

[BM82557]

Thanks for the info on TIS-B, I found this - http://www.faa.gov/nextgen/programs...ce_change_summary_final_508_5-13-15-webv2.pdf while researching it this afternoon.

 

[kma371]

I guess you'd need to be fairly close to a broadcasting ground station in order to receive that 1090mhz signal at another ground location.

yes

 

[ColoradoRedlands]

Oops, I was going to respond, but now that I read all the posts I see you have already found my TIS-B spreadsheet.

 

[SteveEJ]

Thanks, McGee
Useful data. That answers the big question for sure. I guess you'd need to be fairly close to a broadcasting ground station in order to receive that 1090mhz signal at another ground location.

You live close to the south side of Calaveras Lake? To the northwest near Boerne? Or maybe to the northeast near San Marcos?

 

[ki5gf]

You live close to the south side of Calaveras Lake? To the northwest near Boerne? Or maybe to the northeast near San Marcos?

Far west side near Sea World but I get ADS-B ground hits from SAT all the time. Especially those LOUD
FEDX birds (A320s I think). Can even tell when they make turns after landing by watching their ADS-B
"headings" change. Something to do late at night when nothing much else is flying. SAT is 15 miles from
me.

 

[SteveEJ]

Far west side near Sea World but I get ADS-B ground hits from SAT all the time. Especially those LOUD
FEDX birds (A320s I think). Can even tell when they make turns after landing by watching their ADS-B
"headings" change. Something to do late at night when nothing much else is flying. SAT is 15 miles from
me.

Here is a good link for the CSA: NextGen – ADS-B Coverage Map

You can click on the Radio Station button on the bottom left for a PDF. Look for 162-10, 162-11 and 135-01. Those make up the SAT Service Volume. Remember they are line of sight as well and in the 'General Locations'. They don't put out Lat's and Long's on their public pages and probably a good thing.

Fedex does not have Version 2 equipment yet so you are seeing output from Version 1 (260A/282A) which does not have the accuracy/reliability of the Version 2 (260B/282B) equipment. The FAA requires Version 2 for input into their trackers that the controllers use. Anything earlier is filtered at the RDP if not by the service provider prior to that.

Like I said earlier, I wish there was software for SDR's that worked on UAT. Much more information to be received of you are near a RS. NexRad Weather, TIS-B/FIS-B as well as tracking. Pretty cool stuff.

SAT Approach has had it for several years. All aircraft, that fly in certain airspace, are required to have it by 2020.

 

[ki5gf]

Thanks for all that info, Steve. Something else for me to read and dig into. Really appreciate all your input -- keep it up.

 

[kma371]

Thanks for all that info, Steve. Something else for me to read and dig into. Really appreciate all your input -- keep it up.

Yeah, the guy that originally said we were all wrong about TIS-B jk

 

[SteveEJ]

Nice..

 

[kma371]

Nice..

It's a joke

 

[SteveEJ]

Ok.. Let's look at something reference your statement:
"correct answer is they are ads-b positions of aircraft without ads-b capability. they are transmitted by ground stations to the aircraft."

1 - If they don't have ADS-B then they are only 1090mhz Mode 3A/C or Mode S (Not ES)
2 - If they are UAT with a transponder then 1090 is ATCRBS or Mode S and UAT (978) is ADS-B. UAT (978) will be re-broadcast to 1090. It could also be a Mode S broadcast if in certain airspace that supports it. (in this case it was not Mode S broadcast because of the 288xxx SV/CTV identifier).
3 - Raw ATC RADAR position is used re-broadcast 1090 aircraft + RADAR position to UAT(978). There is a installed interface for this. The information is transmitted from the ADS-B radio stations.

Based on the 288xxx, which I assumed (never should do that), it is a re-broadcast but whether it has ADS-B is not a factor in certain areas. Without looking at the data packet, which has a identifier in it, you will not know if it is 1090 or 978. The 288xxx is a identifier, as pointed out, of engineered airspace in the form of a 'Service Volume (SV)' or 'Composite Traffic Volume (CTV)' that radio stations and their coverage areas are assigned to.

Since 1090 NON-ES (non-ADS-B) transponders do not have position information the position is derived from another source, i.e.: a RADAR that is tracking them. The TIS-B information for those is from ADS-R. ADS-B from 1090ES and UAT position information is used for position sharing when available as it is updated much faster and more accurate.

So, thru all of this, they could be positions of aircraft without ADS-B or positions of aircraft with ADS-B on the 'other' ADS-B frequency. They are not ADS-B positions of aircraft without ADS-B. That would not be possible.

More general info:
ADS-B IN is being installed on a lot of aircraft, by itself, because of the aircraft position sharing on UAT (978). It will process ADS-R and ADS-B out from other UAT OUT equipped aircraft. The larger aircraft, i.e.: Air Carriers and Cargo Haulers have TCAS with Mode S (ATCRBS being phased out) and their own WX RADAR on board. UAT (978) has TIS-B and FIS-B as it pseudo TCAS and WX RADAR. Traffic info on ADS-B In does not provide collision avoidance information and the WX RADAR information is not live real time updated information.

 

[kma371]

Someone took it way too serious. I was just trying to explain something in general terms so all would understand but ok

 

[SteveEJ]

And I was trying to do the same and add the value of having a UAT decoder like the 1090 decoders out there. Not knowing you or the way you convey jokes left me with the feeling that I was the subject of a hidden joke, not really, type of situation. Rather than getting into a contest I decided to clarify for others so they could learn and point out the inaccuracy in your statement and the inaccuracy in mine as well.

Hopefully folks have a better picture of how ADS-B works.

Time to rest now.

 

[MtnBiker2005]

Some software shows the TIS-B hex in lower case letters/numbers and ModeS/ADS-B hex in upper case.