Speedbird128 From Germany, joined Oct 2003, 1134 posts, RR: 2 Posted (3 years 5 months 1 day 16 hours ago) and read 2499 times:
Hi
I am an ATC, and i know all about the CPDLC side of things.
However, I would like to find out about the ADS-B side of things.
I know that a lot of info is available through ADS-B and Mode S.
Where is the data like Flight number etc inputed? The registration of the aircraft etc?
SA, for instance, have a A343 that they leased to 9W, and it still reports its VT-JWA registration. Is this registration stored onboard against the Mode-S address?
Speedbird128 From Germany, joined Oct 2003, 1134 posts, RR: 2 Reply 2, posted (3 years 5 months 1 day 2 hours ago) and read 2370 times:
Thanks for the information...
I am familiar with the FMC / MCDU, and I suspected this is where the flight number was entered.
I imagined that the Mode S address would have to be hard-programmed. I wasn't sure about the registration. Looking at the last couple of days ADS logs, I see there are some interesting errors.
Is the ADS-B output something that can be turned on and off?
On the same aeroplane, ADS-B data isn't always transmitted...
BeakerLTN From United Kingdom, joined Jul 2009, 282 posts, RR: 0 Reply 3, posted (3 years 5 months 1 day 1 hour ago) and read 2364 times:
All aircraft have a unique 20-bit address. This address in then decoded on the ground (or by anything containing the look up table) to give the Registration, so it's not smomething that's entered in. - The flight number however is entered in the flight management computer.
As far as I am aware, the registration is not transmitted. The extended mode s transponder 24 bit address is transmitted on the long and short squitters.
The first 4 to 14 bits define the state of registry, this should change if the aircraft changes from the South African to Indian registry, but the aircraft maybe operating under its original registration while under lease. Your ATC system then should lookup the 24 bit address to get the registration.
In the long squitter, the aircraft identification is broadcast every 5 to 10 seconds, but my understanding of that does not include the registration, just the ICAO wake category and the ICAO callsign (useful for the air to air ADS-B).
Quoting Speedbird128 (Thread starter):
SA, for instance, have a A343 that they leased to 9W, and it still reports its VT-JWA registration. Is this registration stored onboard against the Mode-S address?
Not that I am aware of, have you checked to see if that is the address still on the flight plan ?
Quoting Speedbird128 (Reply 2): Is the ADS-B output something that can be turned on and off?
Yes, it can be turned off, just like a transponder.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
Zeke From Hong Kong, joined Dec 2006, 7725 posts, RR: 73 Reply 6, posted (3 years 5 months 23 hours ago) and read 2340 times:
Quoting BeakerLTN (Reply 5): But on a commercial transponder, can you turn off just the ADSB transmission, but keep mode S on? - I think this was probably what the OP was asking?
Yes, on the Airbus that is FANS equipped, under the ATC menu/Connection Status, the pilot can toggle ADS ON or ADS OFF.
Quoting BeakerLTN (Reply 5): (and sorry, I stand corrected, it is a 24bit add, not 20 bit)
Some people think 20 bit as that is what is the unique part, e.g. in the USA, the first 4 bits are common (FAA registered), the remaining 20 bits is the unique part of the address. Other countries have different number of bits (up to the fist 14) to make up the state of registry, e.g. Austria, the first 9 bits are common, the remaining 15 bits are unique on the Austrian registry.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
Speedbird128 From Germany, joined Oct 2003, 1134 posts, RR: 2 Reply 7, posted (3 years 5 months 18 hours ago) and read 2310 times:
Thanks all, especially Zeke!
Having researched the Mode S and ADS-B bit a little more, I am getting a better understanding.
Currently our Radar System only uses Mode C, and ADS/CPDLC - although I am certain it's Mode S capable, but due to the lack of Mode S equipped planes, it's currently turned off.
It's more for my personal ADS receiver which i'm using to research for my upcoming new job which will be in Mode S/ADS territory.
Regarding the SAA A343 question, it actually applies to two of their A343's they leased out to Jet.
ZS-SXE for instance is transmitting 80018B as it's Mode S code. This is the Indian one that should have been re-set to the original 00B1F3.
I have gathered that it's my software that looks up the Mode S code, and then gets the reg and type of the aircraft.
Zeke From Hong Kong, joined Dec 2006, 7725 posts, RR: 73 Reply 8, posted (3 years 5 months 14 hours ago) and read 2275 times:
Quoting Speedbird128 (Reply 7):
Currently our Radar System only uses Mode C, and ADS/CPDLC - although I am certain it's Mode S capable, but due to the lack of Mode S equipped planes, it's currently turned off.
I take it you mean ADS-C/CPDLC over SAT/VHF/HF datalinks ?
Quoting Speedbird128 (Reply 7):
ZS-SXE for instance is transmitting 80018B as it's Mode S code. This is the Indian one that should have been re-set to the original 00B1F3.
Both of those seem possible to me.
India should start with 1000 00 --- --- -- ----------, they have 262,144 possible unique registrations. 80018B (1000 00 000 000 00 0110001011) is within their range.
South Africa should start with 0000 00 001 --- -- ---------- giving them 32768 possible unique registrations. 00B1F3 (0000 00 001 011 00 0111110011) is within their range.
My guess is someone just did not covert the transponder over during the South African certification of airworthiness process.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
Speedbird128 From Germany, joined Oct 2003, 1134 posts, RR: 2 Reply 9, posted (3 years 5 months 12 hours ago) and read 2258 times:
Quoting Zeke (Reply 8): I take it you mean ADS-C/CPDLC over SAT/VHF/HF datalinks ?
Purely SAT based as far as i know from the system architecture of the Eurocat X system.
The Mode-C I referred to was the SSR mode, we don't use Mode S.
Quoting Zeke (Reply 8): My guess is someone just did not covert the transponder over during the South African certification of airworthiness process.
It was originally correct upon delivery, but was changed to the Indian Mode-S code when it went to Jet, and when returned from lease, was not reprogrammed to the South African code...
I'm confused, at least in the states, every part 121 (airline) or part 135 (charter) aircraft MUST have mode S transponders, as it is a requirement for TCAS II.
Are you saying your facilities only pick up Tx signals as if they were only Mode C?
Speedbird128 From Germany, joined Oct 2003, 1134 posts, RR: 2 Reply 11, posted (3 years 5 months 12 hours ago) and read 2251 times:
Sorry i confused the issue i think.
There is no requirement in South Africa for Mode S transponders *as far as I am aware*. We have a lot of ex-1st world planes here now (a-la MD82 etc), and back in their hayday they had only mode C. And as there is no requirement for Mode S, they haven't been retrofitted.
The radar heads we have pick up both Mode S and Mode C. However, *our radar displays*, only give us Mode C data on our screens. ie the 4 digit squawk code, and the flight level.
The radar heads we have pick up both Mode S and Mode C. However, *our radar displays*, only give us Mode C data on our screens. ie the 4 digit squawk code, and the flight level.
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