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ADS-B  
User currently offlineSpeedbird128 From Pitcairn Islands, joined Oct 2003, 1648 posts, RR: 2
Posted (4 years 7 months 5 days 10 hours ago) and read 3122 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?

Thanks for any help!!

BAW128


A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7
15 replies: All unread, jump to last
 
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 1, posted (4 years 7 months 5 days 4 hours ago) and read 3056 times:



Quoting Speedbird128 (Thread starter):
Is this registration stored onboard against the Mode-S address?

I believe they do it through the flight management computer. Even in some planes without ADS-B the FMS will ask for the flight number.

Quoting Speedbird128 (Thread starter):
. Is this registration stored onboard against the Mode-S address?

IIRC yes as well but only MX people can change the ICAO Mode S address.


I have plenty of experience with ADS-B but mostly limited to GA operations.


User currently offlineSpeedbird128 From Pitcairn Islands, joined Oct 2003, 1648 posts, RR: 2
Reply 2, posted (4 years 7 months 4 days 21 hours ago) and read 2993 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...

Thanks!



A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7
User currently offlineBeakerLTN From United Kingdom, joined Jul 2009, 291 posts, RR: 0
Reply 3, posted (4 years 7 months 4 days 20 hours ago) and read 2987 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.

Beaker.



300/319/320/321/330/732/733/734/73G/738/744/772/77W/146/EMB135/EMB145
User currently offlineZeke From Hong Kong, joined Dec 2006, 8861 posts, RR: 75
Reply 4, posted (4 years 7 months 4 days 19 hours ago) and read 2974 times:



Quoting Speedbird128 (Thread starter):

Where is the data like Flight number etc inputed?

On the Airbus, it is on the INIT page on the FMGEC.

Quoting Speedbird128 (Thread starter):
The registration of the aircraft etc?

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
User currently offlineBeakerLTN From United Kingdom, joined Jul 2009, 291 posts, RR: 0
Reply 5, posted (4 years 7 months 4 days 18 hours ago) and read 2967 times:



Quoting Zeke (Reply 4):
Yes, it can be turned off, just like a transponder.

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?

(and sorry, I stand corrected, it is a 24bit add, not 20 bit)



300/319/320/321/330/732/733/734/73G/738/744/772/77W/146/EMB135/EMB145
User currently offlineZeke From Hong Kong, joined Dec 2006, 8861 posts, RR: 75
Reply 6, posted (4 years 7 months 4 days 18 hours ago) and read 2963 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
User currently offlineSpeedbird128 From Pitcairn Islands, joined Oct 2003, 1648 posts, RR: 2
Reply 7, posted (4 years 7 months 4 days 13 hours ago) and read 2933 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.

Thanks guys!



A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7
User currently offlineZeke From Hong Kong, joined Dec 2006, 8861 posts, RR: 75
Reply 8, posted (4 years 7 months 4 days 9 hours ago) and read 2898 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
User currently offlineSpeedbird128 From Pitcairn Islands, joined Oct 2003, 1648 posts, RR: 2
Reply 9, posted (4 years 7 months 4 days 7 hours ago) and read 2881 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...



A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 10, posted (4 years 7 months 4 days 7 hours ago) and read 2875 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



Quoting Speedbird128 (Reply 9):
we don't use Mode S.

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?


User currently offlineSpeedbird128 From Pitcairn Islands, joined Oct 2003, 1648 posts, RR: 2
Reply 11, posted (4 years 7 months 4 days 6 hours ago) and read 2874 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.



A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 12, posted (4 years 7 months 4 days 6 hours ago) and read 2866 times:



Quoting Speedbird128 (Reply 11):


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.

Ah gotcha. Makes sense now.


User currently offlineScooter01 From Norway, joined Nov 2006, 1199 posts, RR: 8
Reply 13, posted (4 years 7 months 3 days 4 hours ago) and read 2793 times:
Support Airliners.net - become a First Class Member!

Ha-ha!

Check who is out for a test-spin right now -heading due north over the Baltic Sea

http://www.flightradar24.com/


Scooter01



"We all have a girl and her name is nostalgia" - Hemingway
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 14, posted (4 years 7 months 3 days 3 hours ago) and read 2783 times:



Quoting Scooter01 (Reply 13):
Check who is out for a test-spin right now -heading due north over the Baltic Sea

Uhm, who?  Confused


User currently offlineScooter01 From Norway, joined Nov 2006, 1199 posts, RR: 8
Reply 15, posted (4 years 7 months 2 days 14 hours ago) and read 2733 times:
Support Airliners.net - become a First Class Member!

Quoting FLY2HMO (Reply 14):
Uhm, who?

Callsign was Merry X , altitude was 50000ft, speed 10000knots, so no wonder you guys missed it.

Here's a screenshot made of the track a few minutes after my first post:
http://i50.tinypic.com/15qoyzn.jpg

Merry Christmas everyone!

Scooter01   

[Edited 2009-12-24 06:35:42]


"We all have a girl and her name is nostalgia" - Hemingway
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